Joule adds CO2 to sunlight to make fuel

July 27, 2009 12:37 AM PDT Let's assume that everything works out as planned. Then, we can produce 20,000 gallons of ethanol for every acre each year, which is a HUGE output, considering that an acre of corn, for example, can normally yield fewer than 400 gallons per year. How many cars would that fuel? Assuming a car drives 20,000 miles per year (high, I know, but I want to be conservative), and assuming that each car got 20 MPG using ethanol (which contains less energy than gasoline, so a car like a Toyota Camry, which gets 30MPG using gas, would only get 20 MPG on ethanol), one acre could fuel 20 cars for one year.

Now, suppose you used that same acre for Concentrated Solar Power (not photovoltaic), such as Nevada Solar One. This solar farm occupies 400 acres and produces a nominal 64MW. Assume it can generate rated power only an average of 4 hours per day. That means 64MW * 4hr = 256MWH per day, or 256000 kwH per day. Divide by 400 to get the approximate yield of a single acre: 640 kWh per acre per day. A decently-engineered EV can get 4 miles to the kWh, so this means that each acre can, on average, give an EV 2560 miles worth of energy per day. Multiply by 365 and you get 934,400 miles of EV travel generated each year by each acre devoted to CSP. Divide by the average 20,000 miles traveled per year, and you get 46.72, so assume 46 cars would get a year's worth of juice from one acre of CSP than from one acre of Joule-produced ethanol. Even if you assume 50% transmission and charging losses for the electricity, you could still, on average, power 3 more cars per year with CSP than with the Joule-produced ethanol.

I think the Joule advancements, if they pan out as claimed, are amazing; there is no question that a 61-fold increase in per-acre productivity of ethanol would rank as one of the marvels of our age. But is even that enough to make the use of ethanol as fuel economically desirable -- at least as economically and ecologically desirable as phasing over to EVs and using CSP to generate the necessary electricity?

If the idea is to fuel big-rig or long-haul vehicles that cannot be EVs, then I think using ethanol produced by processes such as Joule's may make sense for many different reasons -- being carbon neutral, reducing or eliminating reliance on oil imports, etc. Also, over the decades that will be necessary to gently convert the auto fleet to EVs, Joule-produced ethanol could help us enjoy "energy independence" without having to pay through the nose for the privilege. But I hope that this development won't dampen the efforts to convert the private transportation fleet to EVs. An internal combustion vehicle that runs on alcohol still has most of the problems and expenses of a vehicle that runs on gasoline. An EV not only runs more cheaply, on electricity, but also dispenses with a great deal of complexity, unreliability, and expense that is associated with the internal combustion power-train and fuel subsystems. It's fair to keep the internal combustion cars around until they break down. But it is definitely wise (and will, in the future, definitely be POSSIBLE and ATTRACTIVE) to replace them with pure electric vehicles. Reply to this comment by wobbles-grogan July 27, 2009 1:30 AM PDT What about the genetically engineered organism? It only needs CO2 and Sunlight to produce energy, to grow. What if there was a leak and some of the organism got out of its containment. It could take over the world and we wouldnt be able to do anything cos we cant starve it of its fuel source!!!! AHHHHHH THE END IS NIGH!! Reply to this comment

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