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Making Ethanol Worth the Effort

Engineer Poet has pointed out on several occasions that ethanol is not really a useful fuel. It's produced at a net energy loss - more energy goes into making the stuff than we get out of it.

One MIT scientist has an idea that might make the fuel worthwhile anyway.

About three years ago, while working on an experiment for growing algae on the International Space Station, [Dr. Berzin] came up with the idea for using it to clean up power-plant exhaust.

If he could find the right strain of algae, he figured he could turn the nation's greenhouse-gas-belching power plants into clean-green generators with an attached algae farm next door.

After considerable trial and error, Berzin has demonstrated that the idea works.

Fed a generous helping of CO2-laden emissions, courtesy of the power plant's exhaust stack, the algae grow quickly even in the wan rays of a New England sun. The cleansed exhaust bubbles skyward, but with 40% less CO2 (a larger cut than the Kyoto treaty mandates) and another bonus: 86% less nitrous oxide.

The algae is harvested daily for biodiesel. The pulpy substance that remains can be refined further into ethanol. Ethanol harvested in this fashion might be just as inefficient as that from corn, but since it's part of a process that makes the air cleaner, reduces greenhouse gases, and produces biodiesel, maybe it's worth a second look.


I guess I'm unclear why everyone says ethanol is a 'useless' fuel. While yes, technically it takes more energy to refine a gallon of ethanol than it produces, remember that what you are buying with fuel is as much about form factor as about actual energy.

Ethanol, like gasoline, is a convenient way to transfer solar radiation into the fuel tank of a vehicle for use in internal combustion engines. Unlike gasoline, it does not come prepackaged for refining with a lot of other petroleum products, some of which are useful only to burn to heat the refining processes.

Nothing, however, stops you from distilling your ethanol with solar energy, or with corn stalk energy, or with burned corn kernel energy, or any number of other forms of energy which will work for simple combustion but are inconvenient for liquid fueled vehicle use. Useless? I think not.


With regard to the form factor, alcohol is less effective than gasoline. It has a lower energy density. I've been reading about alcohol as automobile fuel since the 1960s. Drag racers liked it because it allowed them to build more powerful engines - more compression, more boost, more spark advance. Fuel mileage doesn't matter when you run a quarter mile at a time. Just drill out the carburator jets and swap in a bigger fuel pump. Nowadays the ECU makes the adjustments, but anecdotal evidence supports the engineering theory. Cars get poorer fuel mileage when running ethanol blend.

I'll still support ethanol motor fuel, come such time as they advertise that they are using stills running off nuclear-generated electricity

All true, certainly, but ethanol as a fuel has two important advantages. First, the production of the underlying biomass (corn, let's say, for simplicity) consumes carbon dioxide out of the atmosphere, meaning that instead of liberating ancient carbon dioxide we're in a zero sum carbon dioxide situation. Second, it is renewable, so long as we can grow corn.


Ethanol raises octane when used with gasoline. This allows a higher compression ratio. But much of that advantage is gone now that computers handle ignition.

As far aa the zero sum CO2 argument. Whether you grow for ethanol or food it cycles the CO2. So if you want higher food prices then promote biomass. Other nations will eagerly use fossil fuels as the price falls because we don't buy them.

To really save fossil fuel promote pure solar and nuclear for electricity. Heat and cool buildings with the electicity and huge amounts of natural gas, coal, and oil will be saved.

Nuclear and solar are the two power sources that can be used around the world. Biomass is only feasible in a few areas. And the unequal distribution of fossil fuels causes terrible political problems.

As for nuclear bombs. About 10 nations have them. Roughly 30 countries can easily produce them. And many more could get it done with some difficulty. So nuclear war or terrorism is not going to be decided by power reactors but by political factors.

I agree that nuclear/electric is a better long term solution, but there's a staggering investment in vehicles in this country. Bio-fuels (diesel and ethanol) would allow that investment to amortize normally, and allow battery technology to get that much better. My diesel VW, for example, will (I've read) happily burn biodiesel without any modifications short of replacing the fuel filter. (Apparently petroleum diesel is dirtier and biodiesel liberates deposits in the fuel system when you first switch over).

Biofuel would also keep air travel feasible, whereas battery charge densities and power output to weight ratios for electric motors don't seem like they'll be up to the task for decades yet.

As for other countries buying petroleum up at cheaper prices if we aren't, this might follow in the short term, but there are two things that will change this. First, if we begin exporting biofuels as cheap or cheaper than petroleum, people will buy them. Second, petroleum is a fixed resource. As supplies begin to dwindle it will become too expensive and valuable (for making polymers and other chemicals) to burn as fuel. This has happened to humanity before. Witness the transition from wood to fossil fuel.


re Jim. You missed the point about vehicles. I didn't say make them obsolete. I said stop using fossil for powerplants. Many people think oil is used only for vehicles and don't think about their utilities at all. Check the statistics.

A reduction in our use of fossil will lower cost somewhere and then others will use more. That is exactly my point - solar and nuclear are the technologies that can produce power in most areas of the world. Areas where there is no prospect of finding fossil fuels or growing enough biomass.

As for airplanes. They need high power/weight. Volume is also important. Alcohol isn't the fuel. And hydrogen, even if proved, would require massive changes at every airport in the world.

If we concentrate on biomass or cleaning up coal or oil shale extraction, etc. we may get some relief but then we are developing methods that will not help most other nations clean up CO2 or reduce fossil imports. Solar and nuclear do both.

I regard the political problems with fossil fuels as more important than the likely price. That is why I don't want more. And biomass crops, as I said, are not practical in huge areas of the world.

Batteries and pure electric vehicles will work when and if they work. I hope big improvements are near. And where does that power come from?

Fossil will remain the big vehicle fuel for a long time.

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