Making Liquid Fuels From Sun and Air

GregLaden writes: There is promising research on converting atmospheric CO2 and water, using sunlight as a source of energy, into burnable liquid fuels. This is not a carbon capture technique because the CO2 ultimately returns to the atmosphere after burning the fuel, but it could allow the production of enough liquid fuel to allow the rest of the motorized economy to switch to mainly electric. There are key uses for liquid fuels, even if most 'engines' become electric motors. The science of how this works is fairly interesting, and a recent writeup in Science gives some of the details.

Comments

Re:This is what I look forward most in hydrogen ec

[Rei]

The hydrogen economy is, and always has been, a stupid idea. The cycle throws away two thirds of the energy for no good reason. And the fuel to store is detonation prone (not just deflagration), very low density, metal-embrittling, ignites with trivially weak static sparks (which common household devices are not rated to prevent), destroys ozone when it leaks, leaks trivially easily, and has a bunch of other nasty properties like pooling under overhangs, entering pipes from the outside, flowing to their destination, and then pooling there. People should read NASA's guidelines for safe handling of hydrogen - it includes things like for any building that handles more than a dozen or so kilograms at a time, the roof should be designed to be blown off in an explosion, among other gems. But all that pales in comparison to the main issue: the hydrogen cycle is just way, way inefficient.

Just stick with electricity. It's what you start with, it's what you want to end with... it's stupid to convert forms. (Okay, technically, storing in a battery is conversion to chemical energy, but it's extremely efficient in doing so - at least with modern forms like li-ion).

And no, hydrogen fuel cells are NOT "cheaper than batteries", they're absurdly expensive systems (and with, I should add, shorter lifespans than batteries to boot). A FCV with the performance of Honda Civic will run you several hundred thousand USD. And one should note that they still have to have a battery pack (hybrid-sized) to average out the demand fluctuations. And yes, batteries are coming down significantly in price (way more than fuel cells), and are predicted to drop even faster in the coming years due to developments like the gigafactory coming online.

Re:so many things wrong with EV tech pushing

[Alioth]

* Power transmission is not anywhere near as inefficient as you suggest. The UK National Grid for instance suffers losses of only 7% power station to consumer.
* Electric motors are not anywhere near as inefficient as you suggest. A decent brushless motor will do better than 90%
* Batteries are not anywhere near as inefficient as you suggest. A good Li-Ion type battery has an efficiency of over 90%

So, a petrol engine is not demonstrably more efficient. Overall, electric vehicles significantly beat petrol (gasoline) engines for thermodynamic efficiency even including power generation losses (a large generator tends to be more thermodynamically efficient than millions of tiny ones). Then add to that an electric car can effectively be nuclear powered or wind powered or solar powered or combinations of those if they are the local generating plants.