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

Improving the stability fo shipping

this idea is heavily inspired by a proposal to make oil tankers more energy efficient by reducing the sloshing of shippoed oil by using air bags to keep the liquid in place.


For large volume mailers like amazon and USPS there is a risk that packages will tumble if not stored correctly, this is part of the reason why amazon sends you a large box with not much inside sometimes,  instead of mailing empty boxes through the full lifecycle, instead have an air sac that would fill into hold packages in place.  For the airbag solution for fuel tankers, a single large bladder is used to fill the entire volume of the tank, which works as the liquid would be all at one level (assuming the tanker was on flat ground).  The packages would be a more complicated affair, the collection of boxes would invariably be uneven, and would therefore require a more complicated airbag system.  At this time it would be difficult to say what the final design would be, but the technologies of softrobotics could be a cool place to start (or maybe I just really like the tech). 

One approach that might be used would be a grid of air bags that would expand themselves to create an inverse of the topology of ther boxes being shipped.  The grid pattern is unlikely to perfectly secure the items being shipped, but it would be better than just a hope and a prayer. 

Integrating Pykrete and Daytime Blackbody Emitters

During World War 2 a shortage of steel led inventor Geoffrey Pyke to suggest to the British government the development of an ice based carrier to aid in the war effort.  The  carrier was made from simple water ice and deemed too weak to serve as a proper launching platform.  The need for a stronger cheap material to make into a carrier led to the development of what is now called pykrete, ice that has been mixed with sawdust, cheap to manufacturer and much stronger than simple water.  By 1943 government interest waned on the development of the ice carrier as the tide of the war shifted in the favor of the Allies and pykrete became a historic curiosity.  

A big weakness of pykrete as a material for fabrication stems from its need to be kept cold to maintain its strength, while steel and concrete are more expensive they benefit from working in temperatures above freezing.  With research and development into daytime blackbody cooling technologies, pykrete might have its day in the sun at last.  New research into blackbody cooling surface coatings have already acheived materials that according to papers, are affordable to manufacture and provide the ability to cool surfaces by 8.2 degrees C (about 15 degrees F) from ambient air temperature.  By combining these passive coolilng films on the outside of a pykrete structure, it would be conceiveable to create a floating iceberg capable of surviving year round (in the right latituteds).

These permanent ice masses could have tremendous applications at extreme latitudes, providing a working platform for weather stations and communications relays.  The design of the ice platform would be complicated to say the least, it would be unlikely that you could make a year round ice block just by making a cube of pykrete and wrapping it the cooling film.  The corrosive nature of sea water and limited surface area would minimize the benefit of having a cooling surface coating in the first place.  The most likely design (broad strokes) would be a large mass of pykrete, internally permiated with tunnels for refrigerants to be circulated through the system to keep it from melting.  The side of the platform that would be exposed to open air would be covered in a complex topology of cooling fins, designed to maximize the surface area of the system capable of disipating as much heat as possible. 

Realistic use cases:

Long term research station for you know northern scientsits

Radio relay:  create a network of these platforms above the Arctic circle and use them to connect the various parts of Europe, North America, and Asia

Platforms for telescopes  As the North Pole only needs to compete with Santa Clause's workshop with respect to light/radio polution, these pykrete platforms could be used to make a really massive array of radio dishes to get a unique perspective on the galaxy.

(the really real option)
Russian missile launch platforms, why waste a fully fledged submarine when you could make a passive block of ice with a radio receiver awaiting launch codes.

Pros
The artificial land masses could be used, in a small way, to shore up icemasses in the Arctic and Antarctic, their material properties and cooling characteristics could help other ice masses stabalize year round



Cons
Limited range of use.  By requiring such relatively low temperatures to remain structurally sound there would be a relatively small number of regions on the planet where you could make these platforms 

Who actually likes their upstairs neighbor?

I have yet to meet anyone who lives in an apartment/multi-family home who actually likes their upstairs neighbor.  More often than not this is not the fault of the upstairs neighbor, but the building designer/builder, without sufficient accoustic insulation it becomes that much more likely that we will hear our neighbor's music and footsteps.  While the "simple" solution would be to simply increase the amount of insulation between floors modern alternatives should also be considered.

A)  Build true mixed use buildings where you alternate floors between office space and residential capacity.  By alternating the use case of floors you add additional accoustic insulation that is valuable to developers.  During the day time the majority of the residential units are likely to be minimally occupied and act as a sound barrier between office floors.  At night the reverse would be true, the office floors would be mostly empty and the residents of the alternative floors would benefit from there being a full layer of unused volume above and below.

B)  Vertical farming, while less immediately profitable (heck you'd probably need a big tax incentive), way cooler sounding.  Similar in approach to idea A) above you could insulate apartments by having small 'half floor' grow rooms filled with plants.  These small spaces would again deaden sound while providing volume for crops to be grown.  These vertical growth volumes would not necessarily need to be only half a floor in height (I just think it would be cute, it also might help to limit the cost of building the structure as you don't need to build as many floors)

To make the grow floors work with the limited height and to minimize the complexity of the overall system engineers could take advantage of the shelf moving robots that are used in industrial warehouses (similar to what you would see in an Amazon fulfillment center)

The long term goal would be a smart system where the vertical farm not only was used to produce residential food calories but was used to filter the water and air of a building.  For cleaning up air most people would be pretty happy to know that their air is being "naturally filtered" (well if not most people at least yuppies).  Now waste water filtering would be another story, people aren't as comfortable with the idea of food being grown in their waste.  Worst case scenario the plants used to filter waste water could be used as a feedstock for some other organism, or maybe some other clever use like making mycelium into packaging and insulative materials

Here are some articles that I read while looking into writing this

https://www.newyorker.com/magazine/2017/01/09/the-vertical-farm  

gives some great background on vertical farmland development, one big detail is that the Island of Manhatten under ideal circumstances could produce about 2% of its food calories if every roof was turned into farm land.  If alternatively you had specialized buildings used for crop growth (about 200) you would be able to produce enough calories for all of the island, assuming a vegetarian diet.  Personally I like the idea of this mixed approach to building design as it give residents that sweet sweet sound protection (that being said I acknowledge that there might be some design requirements that make mixing vertical farming and other building needs undesirable)

The mycelium article 

https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=126288  

Basically you grow mushrooms from waste materials and use that to package items, instead of using foam.