Making fuel out of air

[Alram]

Fascinating achievement. If it ever becomes affordable...

"Air Fuel Synthesis converts carbon dioxide and water into synthetic hydrocarbon liquids from which sustainable fuels or other oil based products can be made.

AFS fuels provide a proven solution for sustainable transport fuels of all types, ultimately up to and including renewable aviation fuel - a fuel that is particularly difficult to obtain from other non-fossil sources."

http://www.telegraph.co.uk/earth/energy/...ology.html

http://www.airfuelsynthesis.com/home.html

[kandrathe]

Our recent Sandy storm reconfirms my view that some chemical based fuels will always be needed, and not just for planes and plastics. Depending on it's economics and ecological impact, it may be a good dense chemical fuel replacement for fossil based liquid fuels.

It would be interesting to know the cost of this process as it obviously takes energy+H2O+CO2 to make this storable dense energy. I was wondering how comparable is is to the ethanol process (fermentation C6H12O6 → 2 C2H5OH + 2 CO2) and then the energy used to distill?

Here is from the company FAQ --

How much CO2, power and water does AFS need to make a litre of fuel?

We need 3.9kg of CO2 to make one kilogram, or about 3.1kg to make one litre of gasoline. A typical ammonia plant would make well over 1000 tons of CO2 per day. So a large gasoline reactor would probably use all the CO2 from a very large ammonia plant. We need about 30 kilowatts of power to make one kilogram of gasoline. The main energy cost is the cost of making the hydrogen through electrolysis of water. Most hydrogen is manufactured by steam reforming fossil fuels but our objective is to use sustainable energy, such as wind, hydro, and perhaps solar.

To make a ton of gasoline we would need about four and a half tons of water. However, all the water used to make the hydrogen is regenerated during methanol and gasoline synthesis, and some could be recycled.

I'll assume they meant 30 KwH of power, which makes sense as the EPA estimate a gallon of gasoline produces 33.7 kWh. And, then there are about 320 gallons in a ton of gasoline.

In looking at Ammonia production; Haber-Bosch process is depends on H2 and a catalyst (Iron FE) to transform N2 into Ammonia (N2+3H2 -> 2NH3). So, for now it seems to depend on Methane or Natural Gas for Steam reforming for the needed CO2 ( CH4 + H2O ⇌ CO + 3 H2 --> CO + H2O → CO2 + H2 , so overall CH4 + 2H20 --> CO2 + 4H2) I guess eventually, they would plan on pulling the gases more directly from air and water, which would be more cool.

Assuming they produce just Octane, their process would use 8C02 + 9H2 --> C8H18 + 9O2 -- and from above, and excess of H2 which could be actually used to make Ammonia as well. Anyway, it would be interesting to understand which hydrocarbons they can produce.

In the US, at least, we have quite a bit of Natural Gas now, which doesn't work as jet fuel -- so this seems to be a good conversion option. For general use, it may be simpler just to use LNG directly.

[Taem]

Believe it or not, this isn't new. DARPA has had this technology for awhile now to reach supersonic speed. I'll find a link when I get home.

[Taem]

Here we go: LINK

The aircraft uses "scramjet" technology, an engine with virtually no moving parts. It uses oxygen from the atmosphere for its engines, as opposed to carrying large fuel tanks that rockets require, making it a more efficient vehicle for military or commercial purposes.

Additionally, because of the high speeds the vehicle is also able to ride on the shockwave it creates at six times the speed of sound, increasing efficiency, according to an Air Force factsheet on the X-51A. It says that is also the genesis of the vehicle's nickname, the Waverider.

I believe THIS is the unmanned plane DARPA tested, but it went too fast and could not control itself. I heard about it on the news back in August and found out it uses oxygen for fuel. Sounds great, until you think of all the oxygen in the air getting burned up.