Modernizing Movie Theaters

It's no secret that I have a few issues with people who use their phones or talk during movies.  These people are not necessarily as awful as the images I conjur while building up the energy to tell them to be quiet*, they simply have a different way of enjoying their movie experience.  What is challenging for these individuals and myself is that our clashing perspectives cannot really co-exist in a 200+ person theater.  Unfortunately most movie theaters will only an announcement at the beginning of the film and they will leave it up to movie patrons to actually do something.  I don't know about anyone else, but if I'm paying north of $15 per person before we even get to the hyperinflated snacks I really don't want to be the one who has to shush people, alas the poor/poorly paid theater staff is also not really paid enough to enforce things.  Beyond that concern, there is a non-trivial percentage of the population who does want to talk/text/tweet/tinder/(t word for using the internet)/(some other t word for going against movie theater etiquette) and honestly there should be an opportunity for them to go to movies and truly enjoy themselves.  For the current model of large movie screens and large audiences, there really isn't much that can be done to consistently ensure that guests get an experience that they would really enjoy.  Movie theaters could embrace the slightly smaller screen experience to make people happier.

When I suggest that movie theaters could embrace smaller screen experiences, I'm not referring to a theater where everyone just brings their phone and watches a movie on their phone. (but that could be a business idea, I would just need to tell investors that it uses AI and blockchain) What I would like to propose is a movie theater franchise that would have smaller screening rooms for a small number of guests, think 1-25 person screening rooms.  Reducing the number of seats would allow for the seats to be comfortably placed closer next to the screen, allowing the perceived screen size to remain roughly the same, but drastically reduing the actual size.
Smaller screens change how you can structure the movie theater design rational, instead of the theater owner needing to invest in massive infrastructure, their screening spaces can be more distributed.  One could envision a movie chain where their screening spaces are more evenly distributed throughout a city, instead of having massive multiplex, screening spaces could take over more flexible shorter term leases allowing the theater owner to be more flexible in where they expand their market space.  This sounds nice for a theater owner but why might consumers embrace this model?  Because they get more choice, right now your choices of movie theater are basically screen size and seat type, a mini-theater means you have more choice.

Potential features/upsells to interest the business side of things
-watch movies past their theatrical release
-watch movies with people who are willing to share a space with your desired experience, aka, your baby, your friend who needs the plot explained, color commentary  (obviously you use an app and AI to achieve the matching, because investors love buzz words)
-reduced transit time to the theater (there is the possibility that the small screens could take over old retail leases, in theory getting you that much closer)
-being able to pause the movie, this would most likely be an upsell, but I could see a group put up cash to allow for intermissions to make the viewing more pleasant
-stream non-traditional content, want to watch a twitch stream on the big screen, the operator doesn't care, if anything they would prefer it as they don't have to split the proceeds


downsides
more theaters at disperate locations creates the possibility that maintenance schedules would get more complicated and could impact both cost structures and prices as a result
how would concessions work for locations that literally have just one screen with like 10 seats (I say fancy vending machine, but it is a complication.


Anyways, I hope you liked the concept, feedback and comments are welcome



*note I acknowledge that I will be on the more agressive end of the spectrum in telling people to be quiet and that's probably not as nice as Mr Rogers would like me to be

Looking at the future of Low Earth Orbit

One hundred kilometers above the Earth's surface space is starting to fill up with debris, with hundreds of now defunct satellites and tens of thousands of smaller bits of waste.  As the cost for launching into space continues to go down the volume of satellites will continue to rise.  While we are unlikely to see a dramatic loss of orbiting equipment as portrayed in the movie Gravity, there is a risk that the volume of debris could reduce the overall life expectancy of spacecraft in more crowded orbits.  Researchers from around the world have suggested various ways to clear orbits, ranging from designing satellites that will intentionally fall back to Earth at the end of their useful life, to using high tech harpoons, and using lasers to slow down materials sufficiently for them to burn up in the atmosphere.

As of May 2019, there have only been handful of small-scale experiments intended to test some of the proposed methods of eliminating space debris.  While the results for these removal methodologies appear to show positive results, humans have yet to establish a standard for cleaning our space-based messes.  While all reasonable solutions to space debris should be given consideration, this article will make an argument for the use of satellite-based laser platforms as a way to control space debris.

Lasers can be used in two primary ways to eliminate space debris ablation and vaporization.  For most readers when they think of using a laser to clear space debris, they are likely thinking about vaporization.  Vaporization is achieved by aiming a strong laser at a piece of material as long as it takes to heat the material enough for it to be broken down into microscopic components.  This requires a very strong laser, several megawatts, and as a result a large amount of power.  The approach preferred by researchers at NASA deals with ablation.  Laser ablation happens when a strong laser is focused on a target for several hundred nano-seconds, this very short pulse is sufficient to cause microscopic pieces of material to be ejected from the target material, while leaving the remainder of the target seemingly unscathed.  As microscopic pieces are ejected from the target material, they create a small amount of thrust that causes the space junk's orbit to change.  Eventually the changes in orbit caused by the ablation of the space debris are sufficient to send the material back into the Earth's atmosphere, where the remainder of the debris will burn up.  Because ablation is only burning enough material to change the orbit of the debris, the overall energy requirements are drastically lower than vaporization, the tradeoff that it will take more time to clear out materials.

Currently there are proposals for both ground and space based laser platforms that could be used for clearing orbit.  According to this NASA paper, a single space based laser would be massive, where the solar panels alone would need to be over 500 meters in diameter to supply the roughly 108 Megawatts of power the laser would require.  At first glance a massive solar array in orbit would seem prohibitively expensive, such a massive undertaking needs a longer-term perspective.  Early in the life of the Anti-Debris Laser System (ADLS), almost all power generated by the solar arrays would be used to clear debris and maintain orbit.  Over the years the volume of debris would begin to drop off and soon our ADLS would have a power surplus and the ability to transmit that energy over a long distance.  The primary debris clearing laser could be augmented by a collection of smaller energy transmitters.  Much as the International Space Station now serves as energy source and orbital platform for a range of experiments, the ADLS could serve both as platform and power source for countless future scientific projects.

One extreme example of the ADLS being used as a remote power source would be for low Earth orbit satellites proposed by the European Space Agency.  These air breathing ion engines are intended to capture the rarified gases that orbit the Earth and use these materials to supply fuel for their ion engines.  A challenge facing current design proposals is the added drag that their solar panels would supply.  If the satellites were designed with the ability to receive additional energy from a directed energy source they would be able to get by with fewer solar panels, which would both reduce the weight of the space craft and reduce drag, a nice little win win.

Future Scenario

April 12th 2051

A new satellite communications start-up has submitted a power purchasing agreement from the United Nations Space Agency's ADLS division.  According to their filing, they are looking to buy sufficient power to supply a constellation of at least 2500 Ultra Low Orbit communication satellites.  These satellites will have some of the lowest orbits ever authorized to a non-governmental body.  In a press release yesterday their spokesbot said "Fastest Trade is looking forward to working with the United Nations Space Agency to help provide 7G Micro Latency communications to the global market of ideas.  Our technology will allow consumers around the world to shave critical nano-seconds off of their communications."  The press release was positively received by several High Frequency firms.  A researcher from the European Space Agency noted that without the external power provided by the ADLS, the orbits of the Fastest Trade satellites would need to be several kilometers* higher than what they have filed for.**

(Scenario 2)

12 hours ago disaster struck Bigelow Research Station El Dorado, due to a series of software errors the station's on board solar panels stopped orienting towards the Sun.  Seven minutes after the error was confirmed support teams from available ADLS platforms were able to add the El Dorado to the orbital power grid user base.  While investigators try to determine how and why the solar panels ceased to function, researchers were able to continue their various projects.  Currently the software team is pointing fingers at an unauthorized 3rd party addition to the solar control platform.

* yeah the scenario is fictional, but I do want to say its on the hard science side of things and the several kilometers value is basically random.  That being said lower drag with a better engine should mean a lower orbit I just don't know by how much.

** honestly high frequency trading is the only reason I can think of  as a long term use for satellites at a really low orbit, that being said I hope there are more generally beneficial uses of this concept.

I hope this idea was interesting, it was inspired by a friend asking me about the potential for using existing satellites and space debris as a source material for future missions.  If you are interested in ideas around re-using old satellites, feel free to check out this post I did a few years ago

Questions and comments are welcome

Electric Airplanes Continued

Some follow up thoughts on the post "Automatic Refueling..." where we looked into a possible path for extending the range of electric aircraft. 

Battery energy density.  While there is no disputing that electric airplanes will need incredibly high energy densities to allow for sufficient range to be super appealing to consumers (even with range extending support craft).  One thing to keep in mind is that the calculations for energy density are based on the assumption that the batteries are only storing power and doing nothing for the structure of the vehcicle.  If researchers are able to develop a storage mechanism that can improve structural integrity, that would be just fantastic.  While structural batteries would be really cool I don't want to be so naive as to assume that a structural battery would have the same energy density as those that purely store energy.  As they could not readily be removed from the body of the airplane structural batteries would need to have incredibly long life expectancies, most lithium ion batteries will lose something along the lines of 20+% of their energy density after a few thousand full charge discharge cycles.  The Physics World article "Structural supercapacitors take a load on" shows that developments are already underway.

Assistive Take Off and Landing.  While midflight recharging is cool, to ensure maximum range for your electric plane it may be a good idea to have assisted take off and landing, similar to what was described in "Giving Planes an Electric Boost".

Modes of recharging mid flight:  In "Automatic Refueling..." we talked about the need for relatively rapid rates of energy transfer between the primary electric airplane and the support vehicle.  If only one support vehicle at a time is able to transfer power there is a concern as to how quickly it can move that power from one unit to another.  As of now it is hard to say how support vehicles and the primary electric plane will dock with eachother and how frequently, in principal there should be no difference with having one support vehicle or many docking at various times to move energy.  In practice it would most likely be more complicated, if a physical connection is used to transfer power, each docking vehicle will require some degree of additional complexity and wiring.  On the other hand if energy is transferred wirelessly there are concerns about interference in navigation tools and the weight of the reciever, as well as transmission range (basically this is a really hard engineering problem)

Mid-Flight Passenger Transfer  In the future scenario, it was suggested that support aircraft might be designed to carry a small number of passengers.  One big concern for this idea to work is ensuring the safe transfer of passengers mid flight.  For passengers to be able to get into a small transfer vehicle and safely reach their destination there would need to be a way of ensuring that consumers could avoid the disruption of turbulence without them being excessivley jostled by the air all without flying to far from their destination.  One option might be to simply have a clause on every ticket saying that for destinations that are not being visited by the primary electric vehicle, they will only guarntee that they will get you to the closest support vehicl landing pad that they can safely move you to.


Those are my thoughts as of now, if you have any questions or insights of your own please feel free to add them

I will add on that I have been trying to get details about the ranges and capabilities of hydrogen fuel cell airplanes, at this time I can't get solid enough info to say much.  From my perspective I will say I'm more ok with electric aircraft using fuelcell tech than cars, my reasoning is that for electric cars our biggest concern is per person affordability and for ground based vehicles current battery tech is on a good enough trajectory.  The economics of the airline industry are a closer match to the particular characteristics of hydrogen fuelcell tech (as I understand things).

Automatic Refueling of Drones and Developing Electric Airplanes of the Future

Electric Airplanes have a basic physics problem, batteries currently don't hold enough energy to power the vehicle for a long enough flight to be commercially useful on  a large scale.   (the youtube channel Real Engineering does a great overview of the balancing of range of a plane relative to the size of the batteries)  Commercial airplanes like the 737-900 has a range of 5900 kilometers ( a bit more than 3600 miles) current examples of passenger electric airplanes have a range of about 160 kilometers (100 miles).  Flying 100 miles can be helpful, but not many people are going to want to take 25 legs to fly from Seattle to Boston.  For electric aircraft to be able to actually begin to replace more conventional planes on a larger scale range will need to be drastically expanded.  The range of electric airplanes are limited by how much energy can be stored in each gram of battery, this is referred to as the energy density.  Battery energy density will often be listed in watt hours per kilogram, the idea being, under ideal circumstances if you have a battery technology that provides 100 watt hours/kilogram, you should be able to power ten 10 Watt LED bulbs for an hour using a 1 kilogram battery pack.  Modern Lithium Ion batteries currently fall in around 150-190 Whr/kg  impressive, but nowhere close to the 1000 Whrs/kg that you would need to make a commercially competative electric airplane under current paradigms.

The reason I mention current paradigms for electric airplanes is that the 1000 watt hour/kilogram calculation was done under the premise that you are designing an airplane that would have the same parts and components at both take off and landing.  This is a valid assumption. for the last 100 years of the aerospace industry almost all planes have been designed under the impression that a plane will start its trip with everything it needs to complete a journey.  For long haul electric aircraft to be considered a viable alternative, without allowing for revolutionary battery technologies, it may be necessary to look at our design parameters from a different perspective, what happens when you open your design considerations to include recharging in flight?

The United States' Department of Defense has been concerned with the range of its aircraft since they started to use them as part of our strategy for projecting American might around the world.  This desire for extending the range of planes has lead to a littany of strategies and innovations including midflight refueling.  In 2015 the US Navy released news that they had refueled an autonomous aircraft in mid flight.  If an autonomous vehicle can refuel in midflight, would it be possible to do the reverse, have an autonomous aircraft dock with designated vehicle and resupply it.  (At this time I can't find any materials that contradict this general premise so I'm gonna go with it)

Imagine a large electric plane that was designed from the ground up with the understanding that it was only required to carry enough energy for traveling 100-250+ miles while powered, this would provide a reasonable starting point for designers and engineers to work from.  For longer journeys to be appealing to consumers it would be necessary to recharge the plane in mid-flight, one way would be to have small scall aircraft designed to meet planes along their flight path dock and top off onboard energy stores.  These smaller aircraft would need to be able to be quickly charged and discharged so that they could rapidly cycle from their base of operations to charging a cruising plane to returning to their base to recharge and meet the next plane on their list.

There are several major challenges with respect to using support aircraft to keep bigger electric plane up in the air.  The first is challenge is that of the efficiency of the recharging aircraft, if the drone supplying power cannot provide enough power quickly enough to appreciably extend the range of the electric plane the project would be a non-starter.  Ex.  If my parent electric plane has a range of 100 miles and a cruising speed of 300 mph and recharging provides enough power to extend my range by 10 miles and it takes more than 2 minutes to rechage the parent aircraft, the drone isn't helping that much*.  Right after the concern of providing enough power quickly enough, the next big concern for our electric plane system is how much drag the recharging system is adding to the design of the plane.  If the recharge system impedes flight range significantly the design will not be commercially viable.  Infrastructure is another concern, each of the recharge drones will need a base of operations to get its power and be maintained.  Realistically it would make the most sense to have the recharge drone stations near regions with existing grid infrastructure (or at least a low maintenance sustainable energy source) these requirements make water based platforms unlikely in any obvious narrative for a technology approach like this, as a result our electric aircraft would be limited to operating in regions with relatively short water crossings.  Most importantly (and like super outside of the scope of an afternoon's writing and research) is the overall ecological impact of making the infrastructure necessary to make our rechargeable electric airplane viable, if the life cycle emissions of the plane, rechargeable drones, drone base stations, and increased grid supply exceeds that of carbon neutral fuels** then it is unlikely to be a good decision from just a green house gas emissions perspective.


(A possible vision of the future)
The year is 2045 and the eEU (expanded European Union) and the European parliment is celebrating beating their zero emissions goals by 5 years.  Many attribute their success to the Airbus Electric Aircraft Network.  Citizens and visitors are able to travel across the economic zone with mobility once thought impossible.  Electric Heavy Lifters follow set routes connecting the continent's capital cities.  Travelers wishing to quickly go from Budapest to Berlin simply request transit to the nearest Airbus Sky terminal, here they match with a Passenger Certified Recharge Drone, that will dock them with the Electric Heavy Lifter going towards their destination.  Once they dock with their Electric Heavy Lifter they will have space to sit relax, or meet in a cafe for coffee.  Ten minutes before they are set arrive at their target destination they are reminded by the EHL's systems that a smaller plane will be docking to take them to on of Berlin's many Sky Terminals.  As new battery chemistries enter the market there are questions as to whether Airbus will continue to build out the Sky Terminal platform.  Investors across the African Union and Brazil have answered with their wallets investing millions into bringing Sky Terminals into their countries, noting the advantage of standardized components and decade of safe operations.

I hope you enjoyed this post if you have any questions, feedback, would like more details please feel free to comment. 







*to avoid making this more visually messy than it already is I'm moving the math down here, basically the electric plane is moving at 5 miles per minute so if the drone can only provide enough power to add 10 miles of cruising range it needs to dock, top off the batteries and get out of the way before the electric plane has exceeded that range boost, so it would need to be under 2 minutes (pretty darn fast)  (please feel free to ask for clarification)

** so far I'm honestly pretty skeptical of claims of developments in "carbon neutral fuels" and how sustainable they would actually be.  That being said if someone produces a peer reviewed article in nature (that I skim the synopsis of on slashdot) saying that they have developed a carbon neutral fuel that is legitimately sustainable I will be supportive of using that technology in airplanes while we develop better battery technology



random text I didn't use, but I might use if I do a different version of this post


Without a more indepth analysis it would be premature to provide exact specifications on things like flight behavior, size of vehicle


  Your average passenger doesn't care about how their plane gets from point A to point B, so long as they can travel safely and affordibly, if this means that their airplane is recharged midflight. 



There are several ways that an electric airplane can extend its range, wireless charging in flight, recharging in flight, and ejecting useless mass through out fligh.  Ejecting useless mass through out flight is technically feasible, you design a plane with battery packs that can easily be released as their voltage falls below a certain value.  Conceptually straight forward, but not too many people under a flight path would appreciate having massive battery backs rain down from the sky.  The fact that these batteries are expensive would be another mark against tossing discharged batteries overboard through out flight.  Wireless charging has more potential, as outlined in the web comic Saturday Morning Breakfast Cereal, you could build a network of towers (or airships) with lasers on them, as airplanes fly past the laser would aim at the airplane's recharge surface and top off the battery. 
As of today there are no obvious innovations in battery technologies that seem likely to give an aircraft the necessary range at take off to take passenger distances in excess of 1000 miles.

Black holes are Weird

On April 10th scientists from around the world came together to show the first ever picture of a blackhole.  This was really cool.  A strange thing to learn from all of the science tweets that came about as a result of the black hole news was a twitter thread where the author went into how the density of a black hole can be surprisingly low, like lower than the density of air at sea level.   This is because the radius of a black hole is proportional to the mass of a black hole (the thread I linked will do a better job of explaining why this is the case), accepting this fact means that when you double the mass of the blackhole, you've doubled the radius, but the volume of will have gone up 8X.  This then asks the question, is there a mass of a black hole that would be so massive that its density would be less than that of the interstellar void?

The goodnews is that there is already a solid starting point with the Wikipedia entry on the Schwarzschild radius, in this article there is a hand table that highlights the various densities of blackholes made from various amounts of stuff.

Observable universe[7]	8.8×1052 kg	1.3×1026 m (13.7 billion ly)	9.5×10−27 kg/m3
Milky Way	1.6×1042 kg	2.4×1015 m (~0.25 ly)	0.000029 kg/m3
SMBH in NGC 4889	4.2×1040 kg	6.2×1013 m	0.042 kg/m3
SMBH in Messier 87[9]	1.3×1040 kg	1.9×1013 m	0.44 kg/m3
SMBH in Andromeda Galaxy[10]	3.4×1038 kg	5.0×1011 m	640 kg/m3
Sagittarius A* (SMBH)	8.2×1036 kg	1.2×1010 m	1.1×106 kg/m3
Sun	1.99×1030 kg	2.95×103 m	1.84×1019 kg/m3
Jupiter	1.90×1027 kg	2.82 meters	2.02×1025 kg/m3
Earth	5.97×1024 kg	8.87×10−3 m	2.04×1030 kg/m3
Moon	7.35×1022 kg	1.09×10−4 m	1.35×1034 kg/m3
Human	70 kilograms	1.04×10−25 m	1.49×1076 kg/m3
Big Mac	0.215 kilograms	3.19×10−28 m	1.58×1081 kg/m3
Planck mass	2.18×10−8 kg	3.23×10−35 m	1.54×1095 kg/m3

With this starting point we now need to know what the density of the interstellar space is, this number  slightly varies from source to source, but seems to ballpark between 0.1 and 1 particle per cm^3, for sake of consistency (and the fact that its the most common element) we will assume that these particles are hydrogen atoms.  Therefore the average cubic meter of the interstellar void has between one hundred thousand and one million hydrogen atoms.  A single hydrogen atom has a mass of about 1.66 *10^-27 kg.  This gives a density of the interstallar medium of between 1.66*10^-22 kg/m^3 and 1.66*10^-21kg/m^3.
Now we need to determine how much mass our black hole needs to have to achieve this rather rarified density.  Right off the bat we know we can bound the mass somewhere between the Milky Way and the Observable universe.  As the Milky Way mass blackhole is too dense, and the Observable universe is roughly the density of 6 hydrogen atoms/cubic meter.
Plugging the Equation [3*C^3]/[32*π*G^3*M2] into Excel  (where C is the speed of light in meters/second, G is the gravitational constant, and M is the mass of the object)

We are able to determine that the blackhole would need to have a mass of 6.63*10^50 kilograms of mass to achieve our lower density of 1.66*10^-22 kilograms/m^3, and 2.10*10^50 kukigrams to get to 1.66*10-21 kilograms/m^3.

The radius of our blackhole would be between 3.11*10^23 and 9.84*10^23 meters in radius.  In light years that would be between 32.9 and 104 million light years.  Otherwise really effing big

Any questions/feedback are welcome. 

Preliminary Investigation on Greenhouse gas sequestration via Liquid Air Energy Storage

Global innovations in renewable energy give hope that humans will be able to curtail greenhouse gas emissions and slowly mitigate the impact of human caused climate change.  While innovations in renewable energy are significant the majority of innovations do nothing to offset warming that results from surplus greenhouse gases that are already in the atmosphere.  So called "negative emissions" technologies may serve as a way to reduce the volume of greenhouse gases dispersed in the atmosphere.  There are 6 major technologies that can be used to help remove surplus carbon dioxide they are reforrestation, bioenergy with carbon capture and storage, soil carbon, biochar, enhanced weathering, and direct air capture.  Each of these technologies should be considered as part of a long term solution to mitigating climate change, this paper will focus on means of enhancing Direct Air Capture technologies. 

Direct Air Capture is a very clean description of the technology, broadly speaking researchers are developing various means of blowing air across a capture medium, as the air flows past the capture medium grabs carbon-dioxide molecules.  Once the capture medium becomes saturated a second process will be used to extract that carbon dioxide where it can be used to help plants grow in a greenhouse, or to carbonate a beverage, or with an altruistic enough buyer that carbon dioxide can be buried underground.  As of the writing of this article estimates for Direct Air Capture put the cost of removing a metric ton of carbon dioxide from the atmosphere at somewhere between $250-$800 not a small cost.  To put this in perspective the United States produces something like 6.5 billion metric ton of carbon dioxide equivalent green house gases*, this means that to capture American greenhouse emissions you would need to spend between 1.625 and 5.2  trillion** dollars per year, to remove those emissions (for perspective the American economy in 2017 was about $19.5 trillion).  Part of the reason it costs so much to capture the carbon dioxide is a tremendous amount of energy is being used to do one thing, capture the carbon dioxide, of the publicly available information on direct air capture technologies, no firm indicates that they are doing anything but capture carbon from ambient air.  What these technologies need is a way to concentrate the air that they are extracting carbon dioxide from.

Liquid Air Energy Storage(LAES) is a relatively new entrant to the world of grid energy storage.  Using advanced refrigeration, companies like Highview Power are developing tools to use surplus grid energy to turn air into a liquid.  When electricity prices are low a refrigeration cycle is run on the air around the power storage facility.  This refrigeration process turns the air into a liquid that can be stored in massive cryo-tanks.  As the electric grid goes from a surplus to needing more power, that liquid air is cycled to expand back into its gaseous state, this expansion is used to run a turbine that provides electricity for the grid  (a more in depth explanation can be found here).  What is exciting about liquid air energy storage is that you are already moving the air for useful work, providing an opportunity to create symbiosis between the liquid air and direct air capture.  

There are at least two potential ways where Liquid Air Energy Storage can be used to augment Direct Air Capture.

1.  Add carbon scrubbers at either the beginning or end of the energy cycle.  During either the capture or release phase of the LAES lifecycle the air is run past a carbon capture materials.  This approach allows you to augment an already existing LAES system.  The tradeoff is that the capture medium is going to directly impact your intake/release systems ability to work efficiently.  On intake your intake fans will need to work that much harder to bring in the source air.  On the other end of the cycle where the "exhaust" of regasified air is being released the filter mediums will also be able to take advantage of exiting outflow, but the outflow will be slowed down by the obstruction (this is the same reason why you should clean filters on your computer and AC system)

2.  Capture the carbon dioxide during the refrigeration process.  The nitrogen, oxygen, and carbon dioxide in our atmosphere all of their own temperature for when they turn into a liquid (or solid in the case of carbon dioxide at 1 atmosphere of pressure).  This range of temperatures gives us an opportunity to integrate a way to scrub out the carbon dioxide by capturing it as it changes state from a gas to a solid.  Nitrogen becomes a liquid at −195.79 °C, oxygen liquifies at −182.96 °C, and carbon dioxide sublimates at −78.5 °C.  The relatively high temperature of carbon dioxide's freezing appears to give an opportunity to add a stage to the LAES lifecycle where solid carbon dioxide is scrubbed from the liquid air energy storage before being returned to the atmosphere.  The potential risks of this approach, would include, increased complexity of the refrigeration cycle, as the chamber/stage where the carbon dioxide is removed might not work with standard approaches to making cryo-liquids, and maintenance cost increases.  

At this time there is no way to cleanly model*** how Liquid Air Energy Storage would impact the cost of Direct Air Capture, that being said we can at least estimate how much energy the US would need to store to impact carbon dioxide levels.

So it turns out liquid air systems already filter out the carbon dioxide, this is just an inherrent part of the design, so basically I like this technology.

REGARDLESS we can still look into how much power you would need to store to filter out CO2

According to the wikipedia entry on liquid nitrogen engines, a kilogram of nitrogen stores about 100 watt hours of power.  To make life easier we are going to assume that all liquid air has about the same energy density.

From the table above we see that for every 1625 kilograms of air you liquify, about 1 kilogram of carbon dioxide would be extracted from the atmosphere

that indicates that for every kilogram of carbon dioxide you remove from the atmosphere you would be able to supply the grid with about

1625 kilograms of air - 1 kilogram of carbon dioxide =1624 kilograms of air for power

1624 kilograms *100 Wh/kg= 162,400 watt hours or 162.4 kWhrs

to extract a metric ton of carbon dioxide you would store enough energy to produce 162.4 megawatt hours of power

to extract all American produced carbon dioxide through LAES how many kilowatt hours of power would we need to store?

the US produces 6.5 billion metric tons of carbon dioxide equivalent green house gases of those 6.5 billion metric tons 82% are actuall carbon dioxide  (to make life easier the author is assuming that it isn't possible to capture the remaining 18% of green house gases through air liquification)

This means that the US currently produces 5.33 billion metric tons of CO2

the total energy storage requirement would therefore be

[162,400 kilowatt hours/metric ton of CO2 ]*5.33 billion metric tons of CO2

which works out to 865.6 trillion kilowatt hours of energy stored.  To put things in perspective the US currently consumes 3.7 trillion kilowatt hours of energy.  What is even crazier, the 865.6 trillion kilowatt hours is how much power is being stored, LAES is about 60-75% efficient which would mean the grid would need to produce closer to 1200 trillion kilowatt hours of electric power.

Obviously the United States can't afford to capture its carbon emissions in the way described above, but what if the country decided that we were going to go to 100% renewable energy and we, for some bizarre reason, decided that all power would be first used for carbon capture via liquid air before the energy went to the grid.  How much carbon dioxide could we capture?

3.7 trillion kilowatt hours of energy*(1 metric ton CO2/162400 kilowatt hours)= 22.783 million metric tons of Carbon dioxide

Thoughts and feelings

Honestly when I started this post I was hopeful that the math would indicate that there was a relatively
 affordable technology that was waiting in the wings to make our world more efficient.  The above
calculations are a great way to highlight how complicated the climate change challenge really is.
I still feel that liquid air energy storage should be considered, even if it doesn't filter the atmosphere 
as aggressively as I had hoped.  As of 2017 something like 28% of American green house gas emissions
are from electricity production, smart grid technologies can offset a tremendous amount of emissions.
Large scale grid storage also makes it that much easier for electric cars to be run in a cost effective 
fashion.  As a society we should challenge ourselves to look for solutiosn to the major problems facing 
us.  Fingers crossed that technologies like direct air capture and liquid air energy storage help to make 
our future more sustainable

*an equivalent ton of carbon dioxide is a way for scientists to communicate that while not all greenhouse gases have the same greenhouse effect, they can use this equivalency to communicate what the warming impact is.

** 250 dollars/metric ton *6.5 billion metric tons = $1.625 trillion

     800 dollars/metric ton *6.5 billion metric tons = $5.2 trillion 

(this math assumes all greenhouse gas emissions are carbon dioxide as I am lazy and it gets me within 25% of the actual answer and I wanted this to look clean)
*** for me, I mean I don't doubt if I could get some Direct Air Capture and Liquid Air experts in a room we could figur it out, but that's just not in the cards right now, sorry 'bout that

America's Mountain of imaginary ice

Every day across the Unites States, an army of compressors work tirelessly to keep our food cold and our living spaces comfortable.  On their best days, cooling technologies fade into the background, unobtrusively making life better, it is high time we thought a bit more about the energy used to keep our nation cooled.
Before the invention of modern refrigeration technologies humans would sometimes use giant blocks of ice that had been harvested in the winter to make life more bearable.  What would it look like if we had to keep our civilization cold with one giant block of ice, and how big would that block of ice end up being?
Every year the United States consumes about 3.7 trillion kilowatt hours of electricity.  Of those 3.7 trillion kilowatt hours 697 billion kilowatt hours are used for some kind of cooling or refrigeration (about 19% of the national total (1)).  Right now we have a nicely estimated number based on some federal data from the Energy Information Administration what we need now is a way to turn kilowatt hours into a block of ice.
Making ice is a cool process (bad pun intended) where you remove enough heat from water to cause the water to go from a liquid to a solid, this is called the heat of solidification.  Water has a relatively high heat of solidification, which is helpful as our iceberg would be really massive otherwise.  The size of the iceberg will depend on several assumptions, for this post we are going to do the a rather basic calculation where all of the cooling will come from melting ice into water*.
And now the math....  (feel free to skip to the BIG NUMBER section to see the size of the iceberg)
First we need to make our units as easy as possible to handle, converting kilowatt hours into joules
kWh*J/kWh =

0.697 trillion kilowatt hours * (3.6*10^18 J/trillion kilowatt hours) = 2.51*10^18 J

now to calculate the mass of the ice that would need to be melted to meet our needs

Cooling requirement/Heat of fusion of ice

2.51*10^18 Joules/(333.55 J/1 gram of water) =7.52*10^15 grams

Finally the total volume of the ice

Ice has a density of 0.92 grams/ cm^3
Mass of ice/density = Volume
7.52*10^15 grams/density of ice at 0 degrees C
7.52*10^15 grams/0.92 grams/cm^3  =  8.17*10^15 cubic centimeters
8.17*10^9 cubic meters

Volume of the empire state building =37 million cubic feet
35.3147 cubic feet/cubic meter
Empire State building =1.048 million cubic meters
8.17*10^9 cubic meters* 1 Empire State Building/1.048*10^6 cubic meters = 7800 Empire State Buildings



BIG NUMBER
8.17 billion cubic meters  or the equivalent of about 7800 Empire State buildings of Ice

Hope this was interesting, if you have any questions please feel free to ask, I am attaching a screen grab of the excel file I used to do my calculations, if you would like a copy please let me know.


Sources for information are provided below.


Sources
Wikipedia "Ice storage air conditioning"  big stat: 1 cubic meter of water can store 334 MJ  the equivalent of 93 kWh  Fun fact:  the origianl definition of 1 ton of cooling, meant the total heat energy you would need to cool a 3000 square foot home in Boston (this is fun as I am Boston based)
Wikipedia "Enthalpy of fusion"  1 gram of water requires 333.55 joules to go from liquid to solid or vice versa
EIA (US Energy Information Administration) The United States uses a mix of energy sources
EIA  Use of Electricity 

Main stats (from 2017) Residantial energy consumption was 1.38 trillion kWh (about 37.4 % of all energy demand) for domestic consumption cooling/airconditioining composed 15.4% of energy use  Refrigeration is 7.2% and freezing was 1.6%
Commercial was 1.35 trillion kWh (36.6% of all electricity demand)  Refrigeration was 14%  Space cooling was 10.6%
Industrial was 0.95 trillion kWh (25.7% of all American electricity demand)  Facility heating, ventilation, air conditioning, and cooling is 9.5%  (this is where math would get rather fuzzy)  Process cooling and refrigeration 7.3%

(1)  see attached excel screen grab (core data taken from EIA page Use of Electricity)

* Assumptions include but are not limited to, assuming that the energy needed to melt the ice is only coming from cooling things, and that there is no solar gain