Shorter Range Cars Saving the World

March 31, 2022
In what has been an accelerating trend of global decarbonization a spokeswoman for the VW group has made a surprise announcement on their rumored Project Maultier.  Speculations on Maultier have ranged from a new type of fuel cell to vehicle capable of assembling like Voltron into an even larger and more spacious vessel.  Instead of a giant mech, VW has unveiled a suite of solutions under the Maultier brand.

Maultier is being promoted as the solution ecosystem that will allow the world to make all cars electric.  The aspect of Maultier that will be most visible to consumers is the Burro a small trailer that could be described as a souped-up hoverboard.  The Burro is a semi-autonomous battery pack designed to dock with cars and provide extra range without needing to stop and recharge.  Using a sophisticated suite of sensors Burros has the ability to automatically dock and undock with vehicles moving along approved highways.  For regions where road laws prevent autonomous driving on highways, the Burros will need to be picked up and dropped off at certified servicing centers. 

In addition to the Burro hardware, there will be a suite of patents and software opened up to the global automotive industries.  The appropriate patients and schematics associated with charge ports that the Burro will require to safely connect with vehicles are being made open to any businesses that want them.  It is believed that the EU council will soon provide legal incentives for automotive manufacturers to...

(I'm having a hard time making this feel super sexy so here's some background)


One of the big challenges associated with making the world's cars electric is the cost of batteries.  Economists estimate that when electric car batteries get below $100/kWhr gas cars will be unable to compete on price in any meaningful fashion and the transition to an all-electric future would soon follow.  To put things in perspective for the "entry" Tesla Model 3 Costs $35,000, and it has a 50 kWhr battery.  At current battery prices, roughly $200/kWhr*, the battery pack alone costs about $10,000 for each vehicle.  This means about 28% of the car's cost is the battery pack.  The benefit of this large battery is a range of over 200 miles on a single charge, keeping customers pretty happy.  While this makes sense for a luxury car most consumers are unlikely to be able to afford the high sticker prices. 

The cost of batteries is more than their direct dollar amount, there is also a question on weight.  Lithium-ion batteries have an energy density of 100-265 watt-hours per kilogram.  For every kilowatt-hour of battery life, you want to add to an electric car you'll need to add 4-10 kilograms of battery cells, plus any additional packaging, and after that potentially make your frame that much stronger.  If we could get everyone to be ok with an electric car that could drive 100 miles on a full charge but have almost unlimited range while in the network of charging robots, we could do some really cool stuff.

Some considerations for implementing external electric batteries for electric cars

Pricing out the Burro.  While I do think this is a cool idea, there is always the question about money, the Burro is only making money when it is reselling electricity back to a customer, either through providing mobile power for vehicles going down the highway, or reselling electricity to the grid when demand for electricity is high, but driving demand is low.  Honestly, I don't currently have the info to even hope to estimate what costs would look like.  On the plus side, as the Burro makes the most sense as a service and not as a consumer purchase you don't have to think about sticker shock so long as the overall financing makes sense.

Societal Buy-in  As mentioned in the news from the future section, if only one brand of cars has a Burro compatible plug then its going to be hard for the financing to make sense, very much a chick and egg problem.  Plug compatibility goes beyond just the shape, but also positioning, the more variable the plug-in point for connecting car to Burro, the more complicated the Burros would need to be.  Ideally, you'd get something like the EU's guidelines on phone charger standardization.  In my current opinion, the ideal would be a charge port at the centerof either the front or rear bumper (or both, but at least one of the two).  There would also need to be a narrow-ish range of heights that the plug could be at.

(Semi-related, why don't more electric cars have charge points at the front or back of a car, it's not like you have the same fluid considerations of gas?  Or why isn't someone selling folks on multiple plug in locations on a vehicle so that people don't need to factor in how they park when they want to charge)

Battery Costs As battery prices continue to go down this idea could make less overall sense.  Once cell costs get low enough it's likely that consumer habits would lend themselves to buying a car with an oversized battery, vs buying a vehicle dependent on an additional ecosystem.  (this is similar to people buying SUVs over minivans even though the minivan is way more practical)


While sanity checking for this post I did find a design company that outlined a similar concept but instead had the extra batter using a single spherical wheel, which looks cool but makes zero engineering sense.

*there are a lot of different numbers associated with battery costs ranging from a low of $141/kWhr to $205 for an EIA study  (I'm using 200 because, well it makes the math clean)

I hope this was interesting, any questions, feedback are welcome.

Lunar Land Rights (news from the future)

(Exert from Space Resources Quarterly)
January 27, 2027

To celebrate the 60th anniversary of the United Nations' Outer Space Treaty, leaders around the world have ratified the most comprehensive, and possibly complicated, legal document for treating the common resources of humanity.  With today's vote, there is now a line in the sand to the legality of the dozens of proposed space-based ventures to the moon and beyond.  For our readers, the most significant near term change is how land and resource rights on the lunar surface will be handled.  I sat down with Eryn Lambert to get her perspective on how the new Outer Space Treaty will be implemented.

"What would your summary of the new Outer Space Treaty be?"

"The really short answer would be that the new treaty lets businesses and governments know who they need to talk to do something on a celestial body.  Anything from landing a probe, to setting up a research station, mine will now require some interaction with the UNOOSA (United Nations Office of Outer Space Affairs)."

"When you say that someone needs to interact with the UNOOSA, would that be like an American pilot registering their flight plan with the FAA?"

"It's certainly a bit more complicated than that, and it really depends on what you're hoping to do, for example, if I'm a small research organization and I want to send a rover to Mars' moon Phobos not much has really changed from the old treaty, I still need to register my mission with my government who would share that information with the UN.  What is different is that organizations can now register their mission directly with the UNOOSA.  When you start talking about bases and resource extraction, that's where things have really changed."

"What are the changes to resource extraction rules?"

"Before the new treaty was signed there really weren't any real international laws or treaties on how resource rights were defined.  I mean several nations did pass the Moon Treaty in the '80s, the fact that no one on the security council ratified the thing makes it pretty toothless.  The new treaty creates very clear guidelines for the Moon and mapped near-Earth asteroids. For the Moon, the surface has been divided into billions of individual plots of land.  Each plot of land will be associated with one or more countries if you want to extract resources from that plot you will need to make an agreement with representatives from those nations."

"Wow that does sound complicated"

"We've barely started.  Lunar land plots are not actually considered a nation's territory, this would violate the original Outer Space Treaty, each plot will instead be a legal entity, referred to as a Tile with its own unique charter for how long the Tile will exist and who its shareholders are.  At the end of the Tiles designated period, any funds paid into the Tile will be distributed to the shareholders.  When a tile reaches its expiration date the Tile will be broken apart a new set of Tiles will be generated to cover the Lunar surface.  Currently, there are 4 major classes of Tile, 1 year, 10 years, 100 years, and 1000 years.  One thousand year Tiles will cover the near side of the Lunar Surface and a 1 km radius around any historic landing site predating the new Treaty.  Tiles are intended to help ensure that every nation can directly earn revenue from extraction, to that end there are contract minimums for any and all Tiles.  This was intended to avoid a race to the bottom..."

Welcome to the present

I hope you enjoyed this rather different post, while the article was on the headier end of the spectrum I think it is a helpful part of the equation for thinking about the future in terms beyond just what kind of hardware will people use, but what legal framework we will use.

The Outer Space Treaty and Moon treaty are both real and right now we don't have a global agreement on how the benefits of space exploration will actually help everyone.  I mean, yes the UN OOSA does have a website on how using space will help to benefit humanity, but right now it's along the lines of using satellites to help us use terrestrial resources better (a great thing to do, just that's not the only thing we can do in space)

What this article advocates, and for the moment (Sept 2019) matches what I think should be done. 
Basically, I think we should create a collection of trusts that are responsible for the Moon, asteroids, etc.. these trusts would charge companies that want to extract resources from these objects.  The last two lines about a minimum cost for mining rights is based on a personal belief that if such rules are not codified some nations with corrupt leadership will simply accept a bribe and officially charge nothing for resource extraction, defeating the purpose of having a global charter on resource extraction. 


The fees raised from the resource rights would then be used to fund programs in various nations here on Earth.  Now there are several ways we can distribute the money and at that point, I'm not even remotely qualified to give a firm answer on how the money gets distributed.

Here are some possibilities that I could see being used to distribute money raised from Tile leases

1)  Giving the money equally to all citizens of the nations that have shares in a leased Tile

2)  Mandating that all funds from Tile leases be invested into sovereign wealth funds, where the money is only distributed after several years of growth

3)  Designating Tile funds for development projects

4)  Replacing taxes

Etc...

There is also the question of how many Tiles a country gets.  Personally, I think the number of tiles given to a country would ideally be some calculation based on what percentage of the global population your country has, how economically developed your economy is, possibly environmental considerations and other things.

Ex.  The US is pretty wealthy as such our 4ish% of the world's population, would grant us less than 4% of the lunar tile rights.  The current environmental policies of the US Federal government would further decrease the number of tiles that we would be eligible for.

For a country like India where per capita income is far lower, the number of tiles would likely be greater relative to their population. 


I acknowledge that this idea is complicated and what the world agrees to is unlikely to match what is outlined here.  I do hope that whatever legislation for space-based resource extraction does develop does strive to ensure that all of humanity benefits from our solar system's resources. 


possible thoughts on asteroid rights


For near-Earth asteroids, there are dozens of classifications and sub-categories, but broad strokes, every mapped asteroid is now under the jurisdiction of at least 2 countries.  If you want to mine that asteroid you need to meet with representatives of the nations that own that asteroid.  Right now there are two options, you can negotiate with the nations who claim the asteroid or you can choose to pay the minimum extraction rate, where you pay into a shared account held by
 so long as the asteroid is smaller than a cubic kilometer

Growing the Growing Season

Nov 3, 2024

Sarah Bishop looks anxiously out at her old cornfields.  For the first time in almost 100 years, the view has had a dramatic change.  Instead of bare ground and debris from the corn harvest, there is row after row of silver mirrored tubes and a faint hint of green.  Sarah is one of the first large scale beta-testers of Smart Farms' brand new Winter Green Bioreactors.  If everything works out as Smart Farms has advertised Sarah will be able to produce enough bio-diesel to power all of her farm and maybe even sell some fuel to neighbors.  If something goes wrong Sarah will have missed her chance to lock in fuel prices for next year and could take a huge hit on the incredibly volatile oil market.

"I still can't believe Sachin (Gupta, Smart Farms' CEO) talked me into this.  Lots of my neighbors think I'm crazy to try, but my kids are getting older and I want them to know that their mom took the chance to keep the farm in the family."

For so many American farmers facing the challenges of climate change, Sarah knows that business, as usual, ended 4 years ago and now she is ready to be bold.  Sachin Gupta is the mastermind of this bold innovation in the algae biofuel market.  "For people like Sarah winter on the farm is a lost opportunity, cold dark days mean you have 4 months where you are just anxiously hoping that the next growing season will work out.  Our team wanted to create something that would help farmers become more self-sufficient while lowering emissions."  

To meet the goal of promoting farmer's self-reliance Sachin's team has developed a new type of bio-reactor.  Using a deceptively simple-looking collection of nested inflatable tubes the Winter Green Bioreactor helps to create a self-regulating algae growth chamber that helps convert sunlight and carbon dioxide into useful biofuel.  The outer tube helps to concentrate weaker winter sunlight onto a collection of tubes nested inside where the algae can grow.  By using adaptive materials and clever use of insulation the Winter Green Bioreactor will help keep the algae at just the right temperature to grow.  

Cutaway view of the Winter Green Bioreactor

Dotted among the silver tubes of Winter Green are non-descript boxes covered in solar panels.  These boxes are another part of the secret sauce of the system.  They help to move the water and air that the algae need to grow.  In addition to the pumps and circulation system, the boxes will automatically filter out surplus algae.

"That was one of our biggest challenges was training the filter mechanisms.  If you take out too much algae you're wasting sunlight, too little and you start running out of nutrients slowing growth"

If things go according to plan, fuel from farms like Sarah's will be producing low carbon fuel for less than $2/gallon.  

Follow up 

Jan 12, 2025

Sarah looks much happier now, algae growth has gone better than expected.  Two weeks after the original article was published a neighboring dairy farm reached out to Sarah and the other Beta Testers.  It has been a win-win for both communities, for the dairy farm they no longer need to worry about too much manure leaching into the groundwater, for Sarah, the algae on her farm have plenty of nutrients to grow as fast as the sun will let them.  

"I'm pretty happy, we already have enough fuel to power all of our equipment for the next growing season and we have six more weeks to hopefully make enough for the Johnsons next door"

*welcome back to the present

This idea originally came about from my article on Agrivoltaics in farming, trying to imagine other uses for the agrivoltaic structure during the winter months when you aren't growing.  Originally I was thinking that you would hang special algae growth bags, after a collection of random thoughts I cane to the concept above.

Some technical stuff

Growing algae is a balancing act of sufficient nutrients, sunlight, and temperature.  The idea of having nested inflatable bags I believe could solve several of those.  The outer tube would help to regulate the interior temperature as well as provide the structure necessary for the reflector elements to focus sunlight.  For most algae the preferred temperature of growth is between 16 C and 30 C, there are species who can happily grow at higher or lower temperatures.  

I intentionally didn't include an actual scaling value in the image because, well I'm just not qualified at the moment to have a firm value, that being said, almost every article I've read indicates that anything deeper than 3-4 inches for a thick algae growth is a waste as there isn't sufficient sunlight,  so I would pretend that the center tube has only about 3 inches between the surface and the nutrient dispersal tube in the middle.

The $2/gallon value was inspired by a biofuel company's claim that their system could produce fuel at $1.27 gallon (assuming you are producing 8,000 gallons per year per hectare (1 hectare (10,000sq meters)  = 2.47 acres))).  I have no idea how the economics would work for a system trying to grow algae during the darkest parts of the year, but I wanted a plausible adjacent number.  

The best-case scenario for these seasonal inflatable bioreactors is for people like Sarah.  People who want to produce their fuel for super local consumption.  If the plan is to export the biofuel hundreds of miles the environment would probably be better off having the fuel made in places where year-round production was possible.  That being said I do think a part of our future will include things like algae being grown incredibly locally, it wouldn't be too crazy to imagine homes having bio-walls producing small quantities of biofuel year-round, so on those days where there hasn't been enough sun or wind to charge the batteries there is a back up energy source.

Further Reading 

https://www.energy.gov/eere/bioenergy/algal-biofuels

https://en.wikipedia.org/wiki/Algae_fuel

https://www.energy.gov/eere/bioenergy/algal-production

if you want an art project someone has a cool algae wall they made using recycled water bottles https://www.instructables.com/id/An-Algae-Bioreactor-from-Recycled-Water-Bottles/
https://www.sciencedirect.com/science/article/pii/B9780444595669000028

NASA's work with a company to develop floating algae farms https://www.nasa.gov/ames-partnerships/technology/technology-opportunity-algae-photobioreactor-using-floating-enclosures-with-semi-permeable

As always questions and feedback are welcome

America's Hunting Eyes in the Sky (A Version of the Future)

Thursday, April 7, 2044

Watch out world, because the sky above you just got a lot more watchful.  On April 5th, a US Air Force spokesperson officially confirmed that the MIL-Cast satellite network is more than a communications and observation platform, but is also a space-based weapons platform, as suggested in our 2039 Article "Secrets of MIL-Cast"

"Good morning everyone, I am here to announce that as of 0200 this morning the robotic geoengineering platform Jotunn has ceased operation after illegally entering the waters of South Georgia Island.  At the request of the UN Climate council and with permission from the British government US forces deployed 3 Falcon Earth Observation Drones to perform a kinetic observation of the Jotunn...."

When asked why the Air Force was finally acknowledging the offensive capabilities of the MIL-Cast General O'Neill was rather blunt.  "We're running out of the darn things, every other week we need to 'kinetically observe' some bad guys and hiding the launches was too much of a hassle"......

From our research, we believe there are between 20 and 30 thousand Falcon satellites in the MIL-Cast network.  With a mass of about 50 kgs, they share many characteristics with other atmosphere skimming communication/observation satellites used by civilian firms.  Most experts who were willing to go on the record believe the biggest differentiator for the spacecraft comes in the way they are designed to re-enter the atmosphere.  Civilian satellites are designed to safely break apart when they enter the atmosphere. The Falcon appears to be able to precisely control entry depending on the mission when the craft reaches its end of life it will disintegrate like a shooting star, as many Americans saw in the 2040 Seatle Summer Olympics opening ceremony.  The secondary re-entry method allows 10-20 kg of the vehicle to strike a target with over 100 megajoules of kinetic energy.  

Would you like to know more?

This article is a continuation of my post "Looking at the Future of Low Earth Orbit".  Basically, the idea is that a future government might use really low orbiting satellites as more than just communications/observation platforms.  As satellites get cheaper and cheaper to launch it isn't crazy to imagine that a large nation-state like the US would look for additional ways to weaponize space.  The idea of dropping heavy objects from space as a weapon has been around since the 1950s.  The proposed Falcon above would be a much smaller vehicle than what the Air Force has investigated previously.  

The 100 Megajoules was based on the Wikipedia entry on how much kinetic energy orbiting objects have.  To put things in perspective 100 MJ of energy is the equivalent of about 23kg (52.5 ish lbs) of TNT.  Depending on where the Falcon hits the explosive energy would be enough to either really mess up your day or to just really really surprise you.

For those of us concerned about peace one thing to find comfort in this suggested weapon is that at this time I have no good idea on how you would actually make a satellite that goes magically from safely breaking up to something that will stay together at speeds high enough to do real damage.

I hope this was interesting, questions, comments, and general feedback are welcome

Fricken Rockets Getting Boosted by Fricken Lasers (oh its a bit longer now)

In part 1 of Fricken Rockets Getting Boosted by Fricken Lasers we got some background on the concept of laser enhanced rockets.  (If you haven't read it yet, I would suggest clicking here first) 

Powering our Saturn 5's electric turbopumps is incredibly energy-intensive, requiring almost as much energy as the propellers on a nuclear carrier.*  The variable that most directly impacts our turbopump's energy demand is the flow rate of the engines, the flow rate for the engines is dependent on the mass of the spacecraft.  The bigger our spaceship, the more flow rate we need to keep the engines fed.  The Saturn 5 was capable of transporting 140,000 kg to Low Earth Orbit for sake of comparison a SpaceX Falcon 9 Full Thrust is capable of transporting 22,800 kg to the same orbit**.  The Falcon 9 Full Thrust uses its 9 Merlin Engines to achieve about 16.3% of the payload capacity of the Saturn 5.  Each Merlin Engine has a massive turbopump supplying 7.5 MW of pumping capacity, meaning that the Falcon 9 FT needs about 67.5 MW of total pumping capacity.  Observant readers, with probably insane levels of recall, might note that the Saturn 5's first stage pump requirements totaled 205 MW when we compare this to the Falcon 9 FT's 67.5 MW turbopump power we see that the Falcon has about 32.9% the total pump capacity of the Saturn 5.  What the Falcon 9 has over the Saturn 5 in our energy concerns is that there is relatively more surface area for our lasers.

For our Saturn 5 calculations, we assumed that about half of the area of the first stage would be devoted to our power receivers, giving the lasers about 200 square meters of effective area to target.  A Falcon 9 first stage is 42.6 meters tall and 3.6 meters in diameter, that means that if we covered the body of the first stage with collectors our lasers could reasonably expect an effective target area of about 75 square meters.  This surface area is fantastic news laser boosted rockets while 75 meters is only about 38% of the area of the Saturn 5, the energy demand for the Falcon's pumps is only 32.9% of what the Saturn 5 needed.  Using our 40% conversion efficiency, we can estimate that the rocket will need to receive 168.75 MW  of energy from the lasers (67.5MW/0.4).  The average peak flux of energy on the rocket would be 2.25 MW/m^2, or about 12% less than what the Saturn 5's receivers would need to handle. 

Scaling down to the Electron rocket the math gets even more interesting.  At 17 meters in total height and 1.2 meters in diameter, we can conservatively estimate the ability to have 6 square meters of receivers.  These 6 square meters will need to supply up to 1 MW of power to the pumps, giving us 2.5 MW of laser energy needing to get to the rocket (1MW/0/4).  For the Electron rocket the panels would only need to handle 416 kW/m^2 of flux (2.5MW/6m^2).  While this isn't a small amount of energy, it is way more manageable than what would be needed for larger rocket launches.

By modeling three different sizes of rockets we can see that the smaller the rocket the smaller the energy overall needed to power the turbopumps.  A combination of needing less energy for the turbopumps in tandem with increases with relative surface area gives an exciting opening for developing laser enhanced rockets, start small and build bigger as technology improves.*(3)

Developing laser Enhanced Rockets might follow a timeline something like this

Step 1
Wireless power transfer testing.  Create a competition where teams are challenged on their ability to have a combination system capable of transferring Energy densities of over 400 kW/m^2 without exceeding design envelope for first stage rocket body simulant

Step 2
Wireless power transfer testing with moving targets
Winners of Step 1 and additional applicants will compete to wireless beam energy at sample liquid fuel rockets.  These rockets will still use traditional turbo-pumps, teams are judged on their ability to continuously supply a set energy intensity to the rocket.

Step 3
Small Scale Pump testing
Competing institutions will be challenged to build liquid fuel powered sounding rockets with electric turbopumps.  Scoring parameters might include factoring what percentage of power for the turbopump came from wireless energy sources.

Step 4
Moving into commercial development of electric turbopumps

Step 5 Launch a spacecraft where some of the power needed for launch comes from wireless energy


Step N
Next-generation laser enhanced competition, as energy densities of long range wireless power transfer increase to certain pre-determined values, organizations like NASA and DARPA have competitions where teams compete on their ability to propel rockets where some amount of direct thrust comes from heat provided by lasers.

 (at this point I ramble a bit, feel free to keep reading, but I won't judge if your eyes just glaze over and you just decide to read something else)

Developing a laser enhanced rocket system will not be an easy undertaking, while the abstract principle is straightforward there are many risks to commercialization.

Cost of developing the laser platform will be the biggest challenge, our world is rife with innovations that came too late after market forces chose a solution.*(4)  Theoretically, a laser enhanced rocket should be cheaper than a more conventional design in the real world this is not a guarantee.  Getting laser enhanced rockets to the point where they can compete on cost will not be easy.

A best-case development scenario for laser enhanced rockets would come from a partnership of multiple space launch companies agreeing to implement the technologies mentioned above.  Each partner organization would share the cost of the laser power base stations maintenance and upkeep. 

Realistically for laser enhanced rockets to become a mainstream innovation the number of launches will need to increase drastically.  Frustratingly for futurists, we need a large volume of launches from the same general geographic vicinity and for those launches to have a fairly similar first stage flight path.  The more variation in launches the less useful our laser platforms would be (or more expensive as the lasers would need to cover more area).  These realizations should not be treated as an absolute negative.  For much of the commercial sector flexibility in space-craft orbits is incredibly useful, but for projects like sending missions beyond the Earth-Moon system, a standardized orbit isn't necessarily a bad thing.  A standardized orbit and rendezvous location would allow for the development of an orbital dry dock facility.  At this drydock fuel and materials could be stockpiled for future missions.  Refueling and assembling in orbit could allow for much more flexible deep space missions, instead of requiring the first missions to Mars to produce all of their return fuel on Mars mission planners could take advantage of fuel stockpiles that built up as secondary payloads for other launches.

Another approach to improve the utility of laser enhanced rockets in the early stages is by creating an open standard booster stage and docking mechanism.  These open standard boosters could supply additional early-stage power with a more narrowly defined flight path than a full first stage. 

I hope you found this idea interesting, I know its a complicated topic, feedback and questions are welcomed.

*according to the Wikipedia article linked above, a Nimitz carrier's nuclear powerplant supplies about 260 MW of power to the propellers, vs our 205 MW of pumping power (some might say 78.8% isn't almost but I'm gonna, because finding analogous power requirements was wasting way too much time)

**okay so not like perfectly exact, this is because the Saturn 5 article lists its lift capacity for getting to an orbit of 170 km with an inclination of 30 degrees, on the flip side the Falcon 9 Full Thrust just lists low earth orbit and an inclination of 28.5 degrees (where low earth orbit isn't well-bounded) for those who want to crunch the numbers in greater detail to minimize the confusion on the comparison please feel free to let me know.  That being said these numbers probably get us in the ballpark.

*(3)  we shouldn't ignore the fact that turbopumps do in fact get more power-efficient as they get bigger.  The Electron can only get about 200 kg into orbit less than 1% of what a Falcon 9 FT can get into orbit, at the same time, the Electron's pumps need about 1.48% of the power than the Falcon 9 does.  Basically, Falcon 9's can move 48% more cargo per unit of pumping power (not a useful actual rubric but interesting)

*(4)  this is along the lines of BetaMax vs VHS or BluRay vs HDDVD, not some kind of conspiracy

*(5)  we are going to assume these panels are designed to be readily added to a rocket and have the appropriate mass properties

The best-case scenario for a country like the United States would be something like this. 

The US Airforce in a continuing desire to increase launch cadence declares that launches must meet certain cost performance goals, to that end they offer affordable access to an Air Force owned power transfer station and a partnering business would supply the necessary panels*(5) to capture the energy required for launching.  The added weight of these panels and the associated electrical sub-systems is offset by the improved fuel efficiency as more rocket fuel can be used to actually propel the spacecraft.

Without a government backing laser enhanced rockets, we are unlikely to see this technology hitting mainstream uses.  The aerospace industry has sunk billions of dollars developing the rocket technology they use

Fricken Rockets Getting Boosted by Fricken Lasers

(now for part 2 of "The Polls Are In")

At its most basic, rocket science sounds really easy, just get something going fast enough that it will leave a planet's atmosphere.  Once you start accounting for things like cost efficiency it starts getting harder.  Over the past 20 years, the barriers to launching into orbit have dropped dramatically, with companies like Blue Origin, Rocket Labs, and SpaceX competing against traditional launch firms, prices have started to come down.  Space tourism is still out of reach for much of the world's population, but for businesses that need satellites affordably transported into orbit, times have never been better.  A key driver in lowering the barrier of entry to launching a rocket comes from a combination of being able to launch smaller/lighter satellites with more affordable rockets themselves.  

There are several ways to make a rocket more affordable, better manufacturing techniques, reusing components, large volumes of production, and making a rocket's engines more efficient.  For each of these cost-saving techniques, there are countless proposed approaches to make improvements.  Making rocket engines more efficient is an incredibly complicated challenge, where engineers must account for the chemical reaction creating thrust, the heat produced by the engine, moving fuel fast enough to keep everything moving, and countless other subtle variables.  One possible way to enhance engine efficiency is to make the rocket's exhaust hotter, hotter exhaust equals more thrust for a given amount of fuel*.  Scientists Arthur Kantrowitz and Wolfgang Moekel realized that the boost of higher exhaust temperatures didn't necessarily have to come from the reaction of rocket fuel and its oxidizer.  In the 1970's they proposed using lasers to enhance the exhaust temperature of a rocket.  Instead of having to carry rocket fuel and liquid oxygen, these laser enhanced rockets would only need to carry a propellent, like water.  

Laser thermal rockets would benefit from having a relatively safe first stage if engineers noticed any problems with the rocket, they could simply turn off the lasers supplying the heat power and drastically reduce the risks faced by those near the launch site.  This boost to safety comes with a cost, having enough powerful lasers to heat water to high enough temperatures to propel a decent sized rocket would be incredibly capital expensive, consequently, laser thermal rockets have been relegated to small scale academic research.  What laser enhanced rockets need is a path from academia to industrial use.  Enter the electric turbopump.

Turbopumps are what you think they are super powerful pumps inside of rockets that help to make sure that there is always the right amount and mix of fuel and oxidizer.  For the Saturn 5, these turbopumps were truly massive, producing 41 MW of power (55,000 brake horsepower) to move 58,560 liters (15,471 gallons) of rocket fuel and 93,920 liters (24,811 gallons) of liquid oxygen.  To generate all this power it was necessary for engineers to make a complicated design that diverted some of the energy of the rocket motor to powering the turbopump.  The aerospace company Rocket Labs has recently broken with industry traditions and developed the Rutherford Engine a rocket engine that uses a battery-powered turbopump.  This innovation of a battery-powered turbopump is possible due in part to improvements in battery energy density.  While development is very exciting for the small satellite launch community, the energy requirements of fluid pumping for larger rockets make this innovation unlikely to scale if batteries are used as the energy source for the turbopump.  

Larger rockets would need a lot of power to run their turbopumps.  For the Saturn 5's first stage you have 5 engines needing 41 MW of pumping power each.  Each of these engines will need to run for 168 seconds, and assuming a safety margin of 12 extra seconds of burn time, let's say the pumps need to be able to run for 180 seconds (3 minutes).  We also need to assume that powering the turbopumps is only 90% efficient, meaning the electrical systems for each turbopump would need to supply 45.6 MW of power.  Putting all our variables together we see that our 5 engines, consuming 45.6 MW each, for 180 seconds would require 41.04 GJ** of energy.  That's a lot of energy, to put things in comparison a Tesla Model 3 with the largest battery option has a 75 kWhr battery which holds about 270 MJ (0.27 GJ).  Our new Saturn 5 would need 152 Tesla Model 3 battery packs to run its turbopumps for all of 3 minutes.  It gets more complicated, traditional batteries have a maximum discharge rate; it would be unlikely that we could design a battery pack that would be able to go from 100% charge to nothing in only 3 minutes***.

Instead of batteries what if our turbopumps got most of the electricity from power wirelessly sent from base stations?  

Keeping our requirements from the previous section of 5 engines each needing 41 MW of pumping output running for a period of up to 180 seconds, but now we have a different consideration make sure we can safely transmit sufficient power to run the pumps while keeping the system's weight to less than that of using batteries****.  The two most popular long-distance/low loss means of transmitting energy wirelessly are lasers and microwaves.  Converting laser light into electricity is currently estimated to have an efficiency from 40-50+% that means that if your system needs 1 watt of power, your laser will need to have an output of about 2 watts.  Documentation on using microwaves to transmit DC power has been harder to come by, but values as high as 95% are listed on Wikipedia.  Conversion efficiency is important from a heat management standpoint, the less efficient the conversion process, the more heat the vehicle's design will need to account for.  

Beyond conversion efficiency, engineers would need to account for the maximum flux the receivers can handle.  Flux is a measure in Watts per Square meter of how much energy an object can handle, for example, certain plants are adapted to grow in shade, they are happiest when they get soft indirect light if the plant gets too sunlight, they could end up damaged.  For something like a Saturn 5 to get its 205 MW of power to the turbopumps, our 40% efficient panels would need to be absorbing over 512.5 MW of laser energy*(5).  The Saturn 5's first stage was 41 meters tall and 10 meters in diameter, we are going to assume at any given moment about 200 square meters of the first stage will be able to absorb our laser's energy.  To achieve our model's requirements our panels would need to be able to handle 2.5625 MW/m^2, for sake of comparison sunlight in space produces about 1360 watts/m^2.  The power receivers would need to handle 2000x more energy than sunlight.  

We should keep in mind that the estimated power hitting the receiver assumes that the lasers are targeting a flat surface.  A more detailed analysis would factor in the curvature of the rocket, where only a small percentage would experience the 2.56+MW/m^2 of peak laser radiant flux.

At this point this post is already way longer than I originally planned, it turns out rocket science is hard and I hadn't done any actual deep analysis until I started writing and I would like to give this concept the analysis I feel it deserves.  What to expect in the next post.

A rant about the square cubed law, the Saturn 5 has less area per unit mass than say a Falcon 9 or an Electron rocket, this means the lasers need to power the Saturn 5 pumps would need to have a much higher energy density when hitting the side of the rocket.  The 9 Merlin Engines on a Falcon 9 have 7.5 MW turbopumps.  The Electron Rocket from Rocket Labs has 9 Rutherford Engines, with each engine requiring roughly 75 kW to power their turbopumps (37 kW for oxygen, 37 kW for fuel)

A proposed timeline for how commercialization might go (start small and build)

Thoughts on cost efficacy of this proposal (it would depend on many market forces and how long investors are willing to amortize costs)

I hope this was an interesting start

*there are probably some exceptions to high exhaust temperature vs produced thrust, but from this rocketry 101 article from NASA it appears this is generally the case https://www.grc.nasa.gov/WWW/K-12/rocket/rktthsum.html

**GJ is shorthand for gigajoule or 1 billion joules, lots of energy MJ is a megajoule 1 million joules

***This is to acknowledge that supercapacitors are a thing, while they have a lower energy density, they can discharge that energy much faster than a traditional battery can.  So yes, they are a thing, and yes, they might be part of the solution, but giving supercapacitors their proper depth would make this article way way too long

**** I mean technically the most important comparison is competitiveness with traditional turbopump launches, but c'mon, do you guys want a book?  (seriously if you do let me know)

*(5) this is just the laser hitting the spacecraft, depending on energy lost to the atmosphere we could be seeing some really big lasers being needed to get power to the spaceship

*(6)

The Polls Are In

A couple of weeks ago, I asked folks what they wanted from an upcoming post: solar power on farmland, laws about Lunar mining rights, or laser enhanced rockets. The winner is...

A TIE

Solar Power on Farmland and Laser Enhanced Rockets received equal interest. Consequently, I will be doing posts on both. Today we will be looking into making solar power production more symbiotic with farming.

Agrophotovoltaics is a relatively new field of development in the world of renewable energy production. For those of you who are language geeks, you might infer from the name agrivoltaics that it deals with agriculture (farming) and photovoltaics (one of the types of solar electricity energy production). For the rest of you, I hope that this cleared things up. The motivation behind agrivoltaics is relatively straightforward. Traditional commercial-scale solar farms are optimized to do one thing—converting sunlight into electricity. The efficiency of large scale solar farms comes with the trade-off that the land devoted to electricity production can't really be used for anything else*.

As our planet heats up, farmers are faced with the question. What will they do with fields that have climates that no longer match the crops they've grown historically? For many farmers in California, they are making the choice to replace some of their plant-based crops with solar farms. While adding tradition solar capacity to farmland is a great way for these farmers to gain a new source of revenue while reducing water consumption, there are some trade-offs.  

Many traditional solar leases require that farmers sign a 20-year contract—the average life span of a solar farm. For the life of the lease that farmland cannot be used for any other purpose. The 20-year contract is generally considered a good deal for both parties. The farmer has guaranteed lease revenue and the solar company knows that the land will be useful for the operational life of the solar panels. During dry years, where farmers are unable to irrigate all of their lands anyway, the acreage devoted to a solar farm is a boon. Revenue will continue to be earned even if plants don't grow. In wetter years, with good crop prices, farmers may lament the unavailable acreage that could have increased their revenue that season.

Famers who implement agrivoltaic systems on their fields can exchange higher upfront costs for a guarantee that every acre of useable land that they had before installing solar panels is still available for the life of their installation. The risk associated with using agrivoltaics over utility photovoltaics should not be taken lightly. Current published materials indicate that the cost of installing an agrivoltaic to be roughly the same as installing rooftop solar on a home, about $3/watt installed. Depending on how you model the upfront/operational costs of an agrivoltaic system, the cost efficiency for farmers will vary drastically.  

Assuming an installation cost of $2.58/Wac installed (the current low end for electricity installation costs) and using Dr. Ramon Sanchez's solar calculating tool,** we can estimate that farmers and customers would need to buy the electricity wholesale at $0.113/kWhr. The upper bound installation cost of $3.38/Wac would leave us with an estimated wholesale value of $0.148/kWhr. When you consider that the average consumer only spends $0.1332/kWhr on electricity, it becomes more difficult to make a simple recommendation to use agrivoltaics, unless you get clever***. Traditional farming requires a lot of energy in the form of fossil fuels used to move tractors and other equipment, a farmer who embraces local energy production and storage could look at their costs in a very different way. Instead of looking at their solar installation as a way to make money from the sale of electricity on the wholesale market, they could see as a way to reduce the impact on the variability of fuel oil prices.  

Manufacturers are already starting to sell electric tractors. As time goes on, farmers who embrace solar will be able to have a more consistent energy budget for their farm in the form of the mortgage for their solar installation.  

Other potential benefits of an agrivoltaic installation include providing a scaffolding structure for robotic farming technologies. Companies like FarmBot are working hard to make robotically enhanced garden beds that will automatically handle the majority of a garden's lifecycle. The scaffolding structure of the agrivoltaic system could very readily be designed to act as a structural trackway for robotic arms to move across a field, optimizing plant growth while minimizing the number of labor hours needed from humans.  

There is one more idea I wanted to share, but as this article is already rather long, I felt it would be better to give the idea its own post. That being said, the core concept is right below.

• Inflatable algae greenhouse for producing biofuels during the winter months

(I hope you're intrigued, any questions and feedback are welcome)

*There are some options for doing a few other things on commercial solar fields. As an example, you can graze animals off of the grasses that grow around the panels.  

**These calculations were done for San Juan, Puerto Rico (I had some old models from a class project I did last week). For a region with less sunlight, the cost of production would be even higher. We are also assuming a DC to AC conversion efficiency of 82.5%

***If you assume that the agrivoltaic systems are being built to sell electricity wholesale because you need to pay a grid operator to transmit your power to other consumers a lower wholesale cost is important. On the flip side, it is worth noting that the current cost for installing agrivoltaics is heavily impacted by the generally custom nature of the frames used to mount the panels. In theory bulk manufacture of agrivoltaic scaffolds designed to make installation more affordable could lower the effective cost of electricity production.

Urbanizing Deserts Part 3 Powering It All

Providing enough power for 1.5 billion humans to live and work at a high standard of living is a massive challenge.  A large reason for the challenges associated with transitioning the world's energy grids to using lower-carbon energy sources stems from the fact that humans can consume a large amount of power in their daily lives and generally speaking people in developed economies have gotten used to the idea that they can microwave their burrito whenever they want.  While the human desire for electricity seems insatiable renewable energy technologies are already starting to compete against more "conventional" (*cough* carbon-intensive *cough*) energy sources.  According to several sources, including this Forbes post, the world's energy needs could theoretically be met by covering about 1% of the Sahara in solar panels, assuming we could conveniently store all of that energy for times when the sun wasn't shining.

Cool, we've solved our desert urbanization goal, and we didn't even have to go into much detail.  Lots and lots of solar panels combined with some magic way to efficiently store the surplus for the night time.  Boom, blog post complete, Obie can shut up.  If you want the high-level explanation then yes, you can consider yourself done with class, for those interested in some more nuanced solutions, please follow along.

Solar power is fast becoming one of the best options for more and more of the world's energy needs, solar is not quite the silver bullet that will solve all of our energy problems.  Even in places like the Sahara, the Arabian Penninsula's Empty Quarter, or the Australian Outback, where the sun shines for more than 3000 hours per year aka really sunny there will still be night time and a random storm system that blocks your panels.  For your non-sunny periods, you are going to need some ability to store that energy, there are several technologies that can be used to store solar energy and they all have one thing in common, no matter how good your storage technology is, you are only going to get a part of the input energy back.  Engineers describe the energy losses of energy storage as round trip efficiency, the worse your round trip efficiency the less energy you can use later. 

The most common way for power grids to store surplus electricity is to pump water uphill this technology is called "Pumped Hydro".  Pumped hydro is amazing in its simplicity when power is cheap pump it uphill when there isn't enough power to meet the grid demand you let the water go downhill to move a turbine.  The round trip efficiency for pumped hydro is generally estimated to be about 70-80+% which means that if you had a megawatt-hour of surplus power you would get about 700-kilowatt hours of power out on the other side.  As of 2019 pumped hydro represents roughly 95% of the world's large scale energy storage capacity.  In regions where you have the necessary geology and climate pumped hydro makes a lot of sense, unfortunately, our desert cities are unlikely to be built near a river that isn't already being used for something else.  Fortunately for our future city developers, we clever humans have come up with many ways to store electricity.

Stealing from the Environmental and Energy Study Institute's table here are some of the alternative energy storage methods (I am also adding a few additional technologies and will provide appropriate links otherwise info came from here).

Technology                                Efficiency

Pumped Hydro                          70-85%

Compressed Air                         40-70%

Molten Salt                                80-90%

Li-ion Battery                            85-95%

Flow Battery                              60-85%

Liquid Air Energy Storage        60-100%*

While this information is cool and hopefully starts you thinking about ways to store the energy our cities will need, it doesn't tell a complete story.  The round trip efficiencies listed above assume you are using the power stored by the respective technologies under optimal conditions.  For example molten salt sounds really awesome, engineers can get up to 90% of their energy back into the grid, what's the problem?  In the case of molten salt, our challenge is heat loss, the longer something is stored the more energy you lose, and at some point, you can't cost-effectively produce electricity from the remaining heat.  If our cities are only trying to produce enough electricity for their day to day needs the efficiencies of the above storage technologies might be sufficient.  For our cities to be future economic powerhouses they will need to be able to produce enough energy to export to the nations of the world and for that grid-storage might not be sufficient.  Instead of just electricity from photovoltaics and batteries, our city planners might want to consider some additional technologies.

Come back Friday for Powering It All part Dos, where we will look at other ways to power our city to make sure it is as robust as possible.  I hope this article was interesting if you have any questions or feedback feel free to ping me or leave a comment.

*Liquid Air Energy Storage is a bit wonky as its round trip efficiency depends on whether or not it is working independently as energy storage or if it is working in concert with other systems.  If they have surplus heat coming from some other facility that increases the efficiency by causing the liquid air to expand more.  If there is a surplus of cold coming from another facility then the liquid air energy system uses less energy to cool the air to a liquid state.   The article linked below provides some detail 

https://www.rechargenews.com/transition/1821297/liquid-air-storage-offers-cheapest-route-to-24-hour-wind-and-sola

Urbanizing Deserts Part 2.5 Making it sustainably more on water

At the end of the last part of Urbanizing Deserts I went on a bit of a confused number crunching expedition as I was confused as to how the UN was estimating that people consumed 2000 cubic meters of water per year (528,000 gallons).  It turned out that they were using a method that included the amount of water used both directly and indirectly by humans, producing clothing and food is rather water intensive.  This was good news as it put our desert cities back into the realm of at least passably viable.  Anyways, this section is going to continue on some of the broad strokes technologies and tools that could be used to make it so our cities' citizens get to live comfortable low carbon intensity lives.

Some of the ways our Desert cities can stretch their water supply
Direct Air Capture (Two ways)

Using materials with a high affinity for water, researchers have been able to create a special type of Metal Organic Framework that for each kilogram of capture material they are able to capture 2.8 liters of water, even from air as dry as the Sahara (the Sahara has an average humidity of 25% and the material is known to work at 20% humidity).  To supply the 70 liters of water per person that Cape Town currently limits citizens to you would need 25 kilograms of material per person.  25 kilograms for something that captures water from the air sounds like a pretty good deal, unfortunately the material costs $150 dollars per kilogram (and that's before we have to account for the fact that we would need some extra material as a just in case, in tandem with no idea how long the lifespan of the material is)

More mechanically involved solutions from companies like Zero Mass Water use solar power to dehumidify air and capture the water generated.  According to their faq page their system produces about 6 liters of water a day at a price of around $6,000 US, that means that for each resident of our Desert city, if all of the water came from air capture, the system would cost $72,000 per person, not exactly the most cost effective solution for mega cities**.  These numbers would make it seem like harvesting water using dehumidifier technologies would be prohibatively expensive, what the math I showed previously ignores is the fact that Zero Mass Water is selling their product as a self contained stand alone product.  Their design integrates solar panels, compressors, and other equipment into, more or less, a single box, by doing this they have increased their individual unit cost, but decreased their infastructure costs (well eliminated them actually).  Developing industrial scale dehumidifiers that only do that task, and the power is generated somewhere else would cost less, but we now have an upper bound on costs.

From our basic math, it becomes obvious that air capture on its own is unlikely to provide sufficient cost effective water for our 1.5 billion future residents.  So let us look into water filteration technology (oh yeah we're getting super exciting here, less sarcastically, water filtration makes the world work and will likely be critical)

While there are more than a few ways to produce drinkable water (about 10 according to this wikipedia article) we are going to focus on desalination, the process of removing salt and other materials from sea water for human usage.  Now you might be asking, "hey Obie, I thought we were building in the middle of the desert, aren't we going to be a bit of a ways from the coast?"  Dear reader, you are not wrong, I shall explain my rationale (I hope).

Desalination generally encompasses two technologies distillation and reverse osmosis.  Distillation involves boiling water and then collecting the water vapor.  Reverse osmosis involves using massive amounts of pressure to push salt water through a series of filters to make it clean enough to drink.  Many environmentalists find the use of desalination technologies problematic due in part to the quantity of waste brine that is produced.  Desalination brine is the concentrated left overs from filtering the salt water, according to some estimates, for each gallon of fresh water you produce, 1 to 1.5 gallons of very salty water are generated.  Normally this salty water will be dumped back into the ocean, potentially doing massive amounts of harm to aquatic life near the desalination plant.  Now our desert cities are a bit too further from the ocean than most and they can use that to their advantage.  Instead of dumping brine back into the ocean, or into ecologically critical water tables, city developers could desalinate water, and store waste salt water in evaporation ponds.  These evaporation ponds would allow for less potable water to be evaporated off (it might be possible to capture this moisture, but there would be further economic considerations that are currently beyond my level of understanding).  The products within the evaporation include a range of materials, incluing simple salts and metals.  One major caveat with using desalination and brine mining as a part of our urban development requirements would be developing these resources in such a way that resources can be used sustainably.  If evaporation ponds aren't well built and closely monitored, it would be all to easy for hundreds of thousands of gallons of extremely salty water poisoning natural water sources used by desert creatures and indiginous communities.

For all of the concerns associated with desalination techniques, one concern that our desert residents won't have is the energy necessary to refine all of this water.  Current estimates estimate that drinking water derived from salt water would cost about $3.60-$5.80 for every 1000 gallons of fresh water made.  While these estimates don't account for the cost of transporting our water supplies inland, they also ignore any potential revenue made from brine (ok that's unlikely to really offset costs that much, but I wanted to be positive).  More pragmatically, while the evaporation ponds would be unlikely to produce a massive financial windfall, it would be reasonable, considering the value of water in the desert and how much sunlight there is, to have at least a particular stage of the evaporation pond process to occur in greenhouses that utilize some percentage of the waste brine.


The most important way to ensure that water is affordable is to use it efficiently.  Desalination, air capture, imported water, and recycled water are all well and good, but the water you don't use could be the cheapest.  For example when most Americans use their toilet, the water that is used to flush the water is just as drinkable as the water that comes from the tap (to be clear we are talking about the water that goes into the tank).  Many regions in the world are now embracing a more local life cycle for water that goes into homes.  Instead of using clean water for every domestic task flushing can now be done using "grey water".  Grey water is the water that is generated from tasks like washing your dishes, clothes, or your hands, basically the water that doesn't have poo in it.  This waste water is stored in local tanks which are then routed to toilets or to irrigation systems.  As the grey water doesn't have too many nasty bugs in it, it is generally safe for people to handle.  After the grey water is used in a toilet it becomes black water, otherwise known as sewage, and at that point you really shouldn't use it for traditional home use.  Current water management tools are limited to clean, grey, and black water, that doesn't mean that as tools get better we won't see further distinctions in water quality that will aid in efficiencies.  Our approach to bathroom design has been pretty good about increasing hygene, but only recently have we started seriously looking into making bathrooms water efficient, it is reaonsable that technologies could devlop that would allow for some amount of bodily maintenance be done with almost zero water useage, and the resultant products get reused as fertilizer creation (yeah this is gross but to make a civilization that makes people feel clean you gotta plan around a lot of wastemanagement)

Ok, I hope that was infomative, any questions and feedback are welcome, next post will look into energy production and storage and how those things might be treated in a modern city built from scratch.




*  (ok so I did some follow up on the number that popped up and it was some promo info for a humidifier supplier advertising in Oklohoma, shows me for using the google immediate response feature, that being said I did find a page that showed the humidity in the Mojave (similar desert different continent) ranged from 10-30% peaking at 50% at night so 25% on average felt reasonable) https://sciencing.com/humidity-mojave-desert-19526.html  my source, anyways, if anyone has a better source please feel free to leave a commenta nd we can fix it
** as we are using the Cape Town water alotment of 70 liters per person per day the work goes this way 70 liters/day divided by 6 liters/(day for $6,000 ) = 70/6= just shy of 12 and I decided to err on the side of caution

*** I didn't plan that paragraph off as well as I wanted 

Urbanizing the World's Deserts Part 2 Making it Sustainably

In Part 1 of Urbanizing the world's deserts we looked into how much land would need to be repurposed to allow for relatively high density cities.  To move about 20% of the world's current population into cities with a density of 6300 residents per square kilometer.  The total area of these new cities would be about 245,000 sq km or a bit smaller than the state of Oregon.  Building said cities in just the Sahara, would require that about 3% of the Sahara's 9.2 million sq kilometers.


No matter how you approach the problem converting 3-15*% of the Saharah Desert in relatively high density cities would be a massive undertaking.  Building these cities in such a way that the impact of building and maintaining them is done as sustainably as possible will be even more complicated.  This article will attempt to highlight some of the challenges and sollutions for developing sustainable cities in water poor regions of the world.

The two most abundant materials in building modern cities are also some of the largest sources of carbon dioxide emissions on the planet.  Concrete and steel production are responsible for between 15 and 17% of humanities carbon emmissions.    Making concrete produces roughly 8% of the world's CO2 emissions, due in large part to the heat and chemistry involved in the concrete fabrication process.  Steel similarly produces 7-9% of global green house gas emissions, where the average tonne of steel requires 1.83 tonnes of carbon dioxide to be emitted.  Efforts to find lower carbon alternatives to concrete and steel will be critical in helping to offset the impact of creating a new city.  A relative new comer to the construction industry is cross laminated timber, similar to plywood sheets but way thicker.  Cross laminated timber has already been used to build structures over 10 floors in height, more than tall enough to achieve a target population density of 6300 people per square kilometer.

Reducing the carbon impact of concrete on urban development is more complicated, concrete is one of the most commonly used materials by human civilization, only water is consumed in greater volumes.  Each year humans consume over 4 billion tonnes of concrete, emitting 1.5 billion tonnes of carbon dioxide.  Research is ongoing into ways to make types of concrete that produce fewer carbon emissions but the easiest way to reduce these emissions is to simply not use the concrete in the first place.  Some of the lowest hanging fruit for city planners to eliminate concrete from their cities is to drastically reduce private car ownership.  Estimates for the volume of parking spaces around the world vary, for the United States it is estimated that for our 327 million residents there are 27 thousand square kilometers of parking spaces.  To put that in perspective the US has roughly 1/5th the population of our future mega cities, and consumes over 10% of the land that our 1.5 billion city dwellers would need, just for parking.  Reducing private car ownership and promoting various forms of mass transit could drastically reduce concrete useage.**

Low carbon construction and design are important, but making buildings truly efficient will be critical to the long term sustainability of our desert cities.  As we are building in arid and semi-arid regions of the planet, one primary concern will be water conservation.  In 2018 Cape Town, South Africa was fast approaching "Day Zero" a cut off point where the city's water reserves would effectively run out.  At the height of the crysis Cape Town residents were limited to 13 gallons of water per person in each household, the average American directly consumes between 80-100 gallons per day.  According to the United Nations humans require around 2000 cubic meters of water (520,000 gallons) per year.  The Sahara, on average recieves between 1 and 4 inches of rain fall.  If we assume that our cities are built in the drier regions of the Sahara, so 2 inches of rain fall on an average year, it becomes obvious that the Sahara cannot support 1.5 billion humans from natural percipitation***.  Our future cities will most likely agressively capture and recycle as much water as they possibly can, but realistically some percentage of water used will need to be imported, thankfully enough our cities have a commodity to trade for their water, heat and electricity produced from the 3000+ hours of sulight they recieve each year.

Importing enough water for 1.5 billion people would be an incredible undertaking, so much so that it is likely to be unrealistic.  To provide 2000 cubic meters of water for 1.5 billion people, you would need 3,000 cubic kilometers of water.  For perspective so called super-tankers in the world can transport 320,000 cubic meters of water, which is only enough to provide enough water for 160 people for a year.****  For sake of continuing this series I'm going to act as if the complexities of water use are reasonably solved.

Thanks for reading, if you have any questions please ask, Part 3 will provide a narrative of what life in our cities might look like.

*15% was for the estimation that you were moving all of humanity into the Sahara.


** this article isn't saying that private car ownership within these future cities is an absolute no, I'm just suggesting that reducing private car ownership and promoting mass transit could free up a lot of land for other uses, and ideally be done without requiring as much concrete.

According to UN statistics the Earth is covered in 25.5 million square kilometers of Arid and Semi Arid terrain

https://www.un.org/en/events/desertification_decade/whynow.shtml

*** for those who want to see the math, 2 inches of water is about 5 cm (I'm rounding down but it gets us close enough considering the scope)

that means that to collect 1 cubic meter of water of rainfall, we need to collect all of the water that falls over a year for an area of 20 square meters

0.05cm water/year/sq meter/year *X = 1 cubic meter of water and X = 20 square meters  (ok I'm not showing the right units but I'm like 90% sure the math is good, corrections welcome)

to meet one person's water needs according to the UN we are going to need 2,000 cubic meters, that works out to 40,000 square meters per person

that means that 1 sq kilometer (1,000,000 sq meters) can, at best, with no recycling  but perfect water capture, 1 sq kilometer can support 250 people, less than 1/25th of the population density we require.

**** so it wasn't until I started to write this section that I began to appreciate how difficult it would be to transport enough water into our hypothetical collection of cities, that being said this assumes you're making your megacities all at once and they need all of their water all at once, the more realistic/gradual approach, is that you build smart sustainable cities gradually, building up sufficient water reserves before building new cities would make a huge difference.  Also I'm going to spend some time looking into the 2000 cubic meters per person stat, because when I compared the stat vs American personal water consumption there was quite a gap, ex. Americans consume 80-100 gallons of water per year, ok so that means that every 2.5 days we consume about a cubic meter of water that means in a given year Americans directly consume about 146 cubic meters of water, for things like drinking, bathing etc....

OK so I spent a few minutes looking into this and it looks like the water volume value comes from things like agricultural water requirements, for example, when you eat a donut, it took some amount of water to grow the crops that were used to make the ingredients for our donut, that is where the 2000 cubic meters comes from  https://www.theworldcounts.com/stories/average-daily-water-usage

alright, I will probably talk about updated numbers in part 3

Urbanizing the World's Deserts Part 1

There are a lot of people in the world, over 7.5 billion these days, and that number will continue to climb over the coming decades.  According to UN statistics, in 2018 53% of the world's population live in urban centers, this number will rise to 60% by 2030.  Urbanization, overall has been fantastic in helping to improve the quality of life of the world's population.  Greater density means that resources can be utilized to greater effect, meaning that per capita environmental impacts are generally lower for urbanites than their sub-urban and rural counter parts.  While many modern cities are working hard to further reduce their per capita environmental impact there is one inescapable fact, when a city is built or expands it is often displacing arable land that could either remain more wild or at least used as farmland.  As humans continue to urbanize we should consider the possibility of creating cities in places that cannot be used as farmland.

According to the United Nations over 17% of the world's land mass is either desert or semi desert (hyper arad and arad), land that historically has made very little sense for large human populations to gather.  What would it look like if humans were to begin moving their population into these desert regions by building sustainable cities of the future?

Before we look at the technologies and potential urban planning solutions that could be used to make these proposed desert cities sustainable, let us first look into the math of estimating how big these new urban centers would need to be.  Our first assumption is that these cities are unlikely to get their food from traditional farmlands located within the bounds of the city (this would still allow for either food imports, vertical farming, a mix of the previous two, or something entirely unimagined by this author).  The next assumption has to do with how many people will relocate to these new urban centers, the lower bound is obviously zero, for any number of reasons people just don't want to move to a manufactured urban center, the upper bound is almost 100% of humans, where authoritarian regimes have forced all people to live in these new cities, and only a few hold outs remain outside city limits.  The last variable (for the basic calculation) is the population density of our new cities.

Population densities can have a tremendous impact on how efficiently resources can be shared by residents of a city, but it also can impact your quality of life.  While it might be super efficient to have 50 people share a single dorm style bathroom many would consider that a less than desireable compremise on quality of life. Kowloon Walled City is considered one of the most densely populated urban environments in human history, at its height Kowloon WalledCity had an effective population density of 1.2 million people per square kilometer (I say effective population density as the city only covered 0.026 square kilometers)    To put things into perspective, if all humans lived at the density of the Walled City, you could fit every human being into an urban environment just about the size of Delaware  (this sounds like it could have a decent chance of being rather unpleasant).   On the other end of the spectrum we have the city of Anchorage Alaska, with a population density of about 60 people per square kilometer, at the population density of Anchorage, we would need to create a city that covered 128.3 million square kilometers (the entire Earth only has 510 million square kilometers of land)  A sweet spot might be something like the population density of a place like Boston Massachusetts, with a density of 5100 people per square kilometer, you would only need 1.5 million square kilometers of city to house all of humanity.  At this time you might be questioning the statistic used for the population density of Boston, as you have likely seen photos of Boston, with its collection of sky-scrapers and ability to play act at being a big city.  The reason for your confusion stems from the fact that much of Boston is devoted to things like office space for people who come into the city from other communities to work.  North of Boston in Cambridge the population density is much higher at 6300 per square kilometer, with Somerville taking the cake with an average density of 7100 residents per square kilometer, all without resorting to large tracts of skyscrapers (this may change over time).

For sake of argument we will assume our desert cities will strive for a population density like Cambridge, Massachusetts.  We will now assume that roughly 20% of the world’s population could be convinced to move into these new urban centers that means we are going to be making cities for 1.5 billion people, that is more than the population of either India or China.  These new cities will require roughly 245 thousand square kilometers (95 thousand sq miles or just shy of the area of the state of Oregon) of land to be converted into cities.  Now this amount of desert being converted into cities seems like a lot and in human terms it is, for comparison, the Sahara Desert is 9.2 million square kilometers (3.5 million square miles).  That means that our new cities would cover less than 3 percent of the entire Sahara, let alone the other large deserts of the planet.  It also means that if we decided to move all humans into the Sahara, we could do so with land left over*.

Thanks for reading part 1 of the desert development outline,  Part 2 will focus on some of the technologies and policies that might be useful to ensuring that people actually want to live in these new Desert Cities

*7.7 billion humans / 6300 humans/sq km = 1.2222 million sq kilometers

1.2 million sq kilometers/9.2 million sq kilometers of sahara *100%= 13.3 % of the Sahara Desert

Reduced per capita environmental impacts are beneficial, but we can do better.

In most instances when a city needs to expand, the city willwill do so by acquiring neighboring land and converting it into a part of the city, by building more dense structures.  This is natural and not unreasonable, unfortunately there are times where that expansion is done at the cost more ecologically sensitive regions

As humans continue to urbanize many urban planners and architects are working hard to make their cities as sustainable as possible for future generations

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