Fuel From Plants! The Basics of Biofuels

Learn more about the different types of biofuels, from the ethanol you’re already using to biodiesel from algae and other fuels of the future.

| GUIDE TO GREEN CARS, Summer 2012

Ethanol from Corn

Most ethanol comes from a few crops, including corn and sugar cane, but there are other promising sources that aren’t food crops.


Petroleum has been the transportation fuel of choice for more than a century now, but it’s not the only fuel that can run our cars and trucks. Some of the most promising replacements for oil come from organic biomass, including crops such as corn and soybeans. Those are the main sources for the most common types of biofuels in use today, ethanol and biodiesel fuel.

Biofuels are attractive because they can be used in gasoline and diesel engines, but unlike oil, they’re renewable. Biofuels also help lower tailpipe emissions because they burn cleaner than petroleum fuels, with lower greenhouse gas emissions. In addition, biofuels are generally grown and produced domestically rather than shipped from halfway around the world. However, there are trade-offs. Within the limits of current technology, biofuels can be costly and energy-intensive to produce. Another major knock against biofuels is that using potential food crops for fuel can reduce availability and raise prices of those crops. How successful biofuels will be in the future will depend on how well researchers are able to overcome these obstacles, and how wise we are in choosing government policies that give us the best results.

Though biofuels can be used in their pure form, they are generally used as a blend to stretch other fuels. Ethanol is blended with gasoline, and biodiesel is blended with petroleum diesel. Whether you’re aware of it or not, you probably have some biofuel in your gas tank right now. Most gasoline we pump today is E10 — 10 percent ethanol and 90 percent gasoline.

The federal government is also working to increase the use of biofuels: Under the Energy Independence and Security Act of 2007, the volume of required biofuel was increased from 9 billion gallons in 2008 to 36 billion gallons by 2022. Recently, there has been a push for the standard use of a higher, 15-percent ethanol blend, or E15, but there are questions about compatibility with all vehicles.

What Is Ethanol Fuel?

Ethanol is simply alcohol fermented and distilled from the sugars in plants. Most ethanol comes from a few crops, including corn and sugar cane, but there are other promising sources that aren’t food crops. Cellulosic ethanol production uses the non-edible parts of plants such as corn stover, lawn and tree waste, wood chips, and quick-growing plants such as switchgrass and miscanthus. The cellulosic ethanol industry is struggling to get off the ground, but it could be more cost competitive in the future with new technical breakthroughs and if gasoline prices keep rising.

Ethanol has less energy density than gasoline. You won’t notice much difference in performance with the common E10 blend, but you will with higher blends such as E85, which can be used in flex-fuel vehicles. At this mixture, E85 will deliver lower fuel economy than gasoline. The reduction varies by vehicle, but it’s been my experience that, when filling up with E85, you can expect fuel economy to drop by 15 to 25 percent. Range between fuel stops is reduced, but E85 is priced significantly lower than regular gasoline, so the cost at the pump is about the same (see E85 Gas Prices). On the plus side, the higher octane will increase power output and performance.

1/28/2015 1:18:15 PM

We might as well just stop looking for renewable shit and face reality. We are running out of resources and we might need to do some Avatar shit. Invade a planet and steal its resources. SURVIVAL OF THE FITTEST!!111!!!!!

1/20/2014 9:50:52 AM

What a lot of people dont realize in the food vs. fuel debate is that only 1.8% of the corn grown is used for human consumption. That means that 98.2% of corn grown is not food! Much of this corn is used to feed animals and some of it used to make fuel. In reality, it is a "food for food vs fuel" debate for ethanol but why are we feeding corn to cows anyway? Their bodies are not made to digest it properly, they are made to digest grasses. Algae fuel has been researched for years and is still a long way off. Biodiesel manufacturers have been using other non-food sources for years. They have been using a food THEN fuel approach. These sources often include dried distiller grain oils which are a waste product from ethanol production, used cooking oils (think restaurant greases) and leftover fat from rendering processes. These all used to be waste greases that are being made into fuel TODAY, right now! Not 10-20 years in the future like algae. Because biodiesel uses many waste products and bi-products that restaurant companies or meat producers used to have to pay to dispose of and now get paid for, biodiesel actually reduces the cost of food.

1/17/2014 12:41:31 PM

I appreciate this balanced and informative article. I have my concerns about biofuels, but am definitely not a proponent of the petroleum industry! My concerns are mainly those mentioned in the article, about biofuels competing with humans for food. I would point out that these conflicts can come not only directly (corn goes into gas tanks instead of bellies) but also in the competition for water resources and arable land. I was very encouraged to read about the potential for algae production, since this would presumably require less water overall than growing, say, a corn plant out in an open field, and production could take place in non-arable locations (maybe otherwise unusable city space?), and perhaps close to the markets, reducing fuel transportation costs. Could algae production and refinement be economically viable on a small scale, allowing relocalization of some of the fuel supply? I also would like to gild the lily of this fine article with a reminder that all fuel combustion, greener or all-petroleum, contributes to our environmental problems, and so the very greenest thing we can all do is get used to sticking closer to home as much as possible. But of course Mother's readers are surely aware of that already.

1/17/2014 9:23:09 AM

There are some methods you can use to separate the alcohol from the gasoline available today. This may be suitable for small quantities for your small engines, but in my opinion it is not practical for automotive use. Adding 20 to 25% water to a container of E-10 gasoline, than shaking or agitating to mix the water as well as possible. Then using a section of clear tubing attached to the can spout with a valve at the bottom, invert the container and wait for the water to settle to the bottom. The alcohol mixes with the water and when you drain off the water at the bottom of the mix, you are left with gasoline containing a much smaller quantity of alcohol. (You can see the difference in color of the gas when you get the water out) Be careful to do this away from sources of ignition. If you were to store the water/alcohol mix it could later be re-distilled to make fuel for stoves etc.

1/17/2014 9:00:09 AM

At the end of the first page, you said that increased octane gives you more power output and performance, but that really isn't accurate. Generally fuels like CNG or E85 have less energy per gallon, but also a significantly higher octane. And I know that when running on CNG you will notice a decrease in both mpg and horsepower because the engines aren't designed for it. Octane is just basically a measure of how much you can compress a a fuel before it auto ignites like a diesel engine. The way I understand it, compressing a fuel more can help you get more of the energy out of that fuel (i.e. higher efficiency) and technically more performance. But if your engine is still designed with lower compression for gasoline, then the higher octane of these alternative fuels will add nothing to your performance because you aren't compressing them to the fullest. Octane is not a magic performance booster, compression is what we're after. Higher octane is just a means to get to that compression. However the manufacturers do "simulate" higher compression ratios by adjusting the spark timing early so that the gasoline ignites while the piston is still on the way up, but it really isn't as effective as having an engine mechanically designed with higher compression.

John LeDoux
8/5/2012 1:56:13 PM

Thank you for saying it so well.

8/5/2012 2:07:28 AM

The article is informative in it's very narrow scope (passenger vehicles). What is not common knowledge is the fact that "small" engines are not designed to use bio-fuel or blended fuel mixes. Lawn Mowers, tillers, weed eaters, chain saws etc. etc. suffer a multitude of problems useing blended gasoline. The fuel lines, fuel tanks, fuel filters get disolved by either Methanol or Ethanol blended fuels as these plastic/rubber parts are not formulated for use with blended gasoline. I learned this the hard way by constantly having carb problems as well as disolved/brittle fuel lines and pinholes and cracks develope in the primer bulbs of small engines, both two-stroke and four-stroke including my outboard motor on my bass boat and it's fuel system. I would suggest that an article covering such a topic be researched and published in this fine magazine so that the folks out there are made aware of the pitfalls of blended fuels. I might also add that an article on the use of synthetic lubricants would be timely and benificial.

8/4/2012 9:57:01 PM

Please advise as to where I can obtain an E85 conversion kit for my gas designed vehicle. This basic information should be front and center in this article.

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