Ethanol vs. Biodiesel: Just the Facts
by Jeff McIntire-Strasburg, St. Louis, MO on 07. 4.06
Reader Jacob Varghese asked yesterday "what's the difference between ethanol and biodiesel? which one is better, cheaper..." While some of us responded "Well, that's the fundamental philosophical question of our day (or, at the very least, the $64,000 question)," we decided not to go there. Instead, here are some of the facts about ethanol and biodiesel, with a few thoughts on which on might be better, depending on your transportation needs.
What are they?
Ethanol is "an alcohol product produced from corn, sorghum, potatoes, wheat, sugar cane, even biomass such as cornstalks and vegetable waste. When combined with gasoline, it increases octane levels while also promoting more complete fuel burning that reduces harmful tailpipe emissions such as carbon monoxide and hydrocarbons." (Abengoa Bioenergy)
Biodiesel is "a domestic, renewable fuel for diesel engines derived from natural oils like soybean oil, and which meets the specifications of ASTM D 6751." Or, for those of you who want a more technical definition, it is "a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats..." (National Biodiesel Board)
How are the produced?
According to the Renewable Fuels Association (the US ethanol trade organization), there are two processes for making ethanol: wet milling and dry milling. Each process is explained in detail on the RFA's site.
Biodiesel is made through a chemical process called transesterification "whereby the glycerin is separated from the fat or vegetable oil. The process leaves behind two products -- methyl esters (the chemical name for biodiesel) and glycerin (a valuable byproduct usually sold to be used in soaps and other products). (NBB)
Which one is better for the environment?
Both forms of biofuel have definite environmental advantages over petroleum-based gasoline and diesel fuel.
According to the RFA, "Ethanol contains 35% oxygen. Adding oxygen to fuel results in more complete fuel combustion, thus reducing harmful tailpipe emissions. Ethanol also displaces the use of toxic gasoline components such as benzene, a carcinogen. Ethanol is non-toxic, water soluble and quickly biodegradable."
Biodiesel, on the other hand, "is the only alternative fuel to have fully completed the health effects testing requirements of the Clean Air Act. The use of biodiesel in a conventional diesel engine results in substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter compared to emissions from diesel fuel. In addition, the exhaust emissions of sulfur oxides and sulfates (major components of acid rain) from biodiesel are essentially eliminated compared to diesel." (NBB)
Which biofuel should I use?
Unless you already own or plan to buy a vehicle with a diesel engine (which is no small feat these days), ethanol-blended gasoline is likely your best option for biofuel use. Biodiesel, however, could provide a great environmental benefit to trucking fleets, which consist almost entirely of vehicles with diesel engines.
If you're a do-it-yourselfer, though, biodiesel can be made at home -- a real DIYer can even make his/her own biodiesel reactor with open-source plans available on the Internet. Ryan Thibodaux, a political blogger, recorded his own efforts to build a reactor, buy diesel cars and actually start producing the stuff at his blog The Higher Pie
Still have questions?
A quick Google search can provide you with plenty of information on biofuels. Both the Renewable Fuels Association and the Biodiesel Board have tons of educational materials on their respective sites. And, as reader Mat pointed out, Wikipedia has extensive entries on ethanol and biodiesel.
UPDATE: In response to Mike's question below, Gristmill has a handy chart showing estimated fuel yields of certain crops. Those numbers look like they tend to favor ethanol.
All I really want to know is which one is easier to make? I keep hearing about how biofuels are not sustainable and that it would take more land area then we have to produce enough fuel. Which one has more yield per acre?
if we stopped growing food we still wouldn't be able to produce enough of either to replace oil . . .
there are no quick fixes . . .
however, improved efficiency of our vehicles, as well as more efficient use of our vehicles, and you have a winner.
However there are possible improvements in the works to the yield per acre issue. Studies have shown massively higher yields of biodiesel from certain algaes. And there are emerging technologies to turn farm waste products, like plant stalks, into ethanol. Such improvements could make biofuels a viable part of the mix longer term.
Thanks for the answers!
Considering the better fuel economy of diesel engines, I'm wondering why you aren't recommending that readers choose diesel for their next car purchase.
After reading about the Greasy Rabbit project, where a Rabbit was converted to use free waste vegetable oil, I wondering when we'll some a company offering up refined waste vegetable oil to consumers.
Biodiesel can also be used in trucks and in many ships.
Algae can produce something like 30 times as much fuel as corn.
Corn ethanol is a scam anyway, in Sweden ford are researching ethanol from waste. If all diesel vehicles ran on bio and say 10-20% ethanol produced from waste was added to petrolium we would see massive reductions in the amount of oil we used. Shutting down all oild fired powerstations would also be a good plan, natural gas/biogas burns way cleaner.
Ooh, and recylce plastics properly as well, rather than just ship them to poor countries.
PJ Nery;
Ethanol from bio-waste has been around for a number of years - google "Iogen" for more information.
It is estimated that 1/3 of the straw produced in 3 of Canada's western provinces would be able to replace 10% of the gasoline usage in Canada.
Imagine the possible replacement capacity if North Americans were also utilizing other crop residues and plant wastes to produce ethanol.
both biodiesel and ethanol are inefficent ways of producing fuel on the farm. 60 gal per acre net is about the top one can get from either forms of farming fuels. so lets use some real #'s when talking about this.
there are roughly 2.3bil acres in the usa.
450mil = ag use
580mil = pasture use
66mil = urban use
the usa uses about 20 quad's of fuel. a quad = 7.5bil gal of diesel.
so we would need 150bil gal of diesel to complete switch from oil to bio. by my calc's, we could only produce 27bil gal of biofuel @ 60g/acre.
ummm, does anyone see a problem here? where is our food gonna come from? what about marginal farm land that is now in CRP land?
not only that, but that 60g/acre is only a reasonable # if u add in cheap dino oil. if u subtract that out, the whole system will break down. the fact is, this is NOT a viable solution to our problems.
so what is the answer? we need to either more efficently farm fuels (switchgrass = 200g/acre net, algae = 10000+g/acre, palm oil = 600g/acre, etc. there are already better ways than corn and soy)
or we need to come up with a completely different way of producing energy.
Great post.. but how about actually "taking it up a notch?"
Treehugger has always provided poignant commentary on the latest "green" or "enviromental" thing coming down the pipeline. It manages to get a few nice soundbites and move on to the next glam shot of the Eco-day.
How about going a bit deeper? How about actually looking at energy per gallon? How about looking at thermal efficiencies? How about even just explaining things like energy density and thermodynamics?
"Green is good" and "Ethanol reduces pollution".
Great, but if you don't also list the caveats and fully explain what the trade-offs are then your still just paying it all lip service.
We all know math is hard, and lord knows Journalists can't hardly count beyond 10 with their shoes on, but come on!!! Some one over there should be able to at aleast come up with a "Primer on Thermodynamics for dummies"
Go a bit deeper, explain the concepts, break down alternative fuels into how much energy is used in producing, etc.. Do it for ethanol, bio-D, wood, coal, hydrogen, solar, etc..
A small post on current engine technologies and how different fuel systems are more efficient, etc.. Go beyond saying Hybrids are good, and explain why some of them are scams.. Saturn Vue for instance... do a bit more homework. Make some people think beyond bamboo flooring for crying out loud.
The answer is right here in Tree Hugger, riding a bike is the most efficiant way to get around. I am a typical suburban mom and small business owner and I thought I could not change my life so bikes were part of my transportation plan, but over a year or two, I have come to the point where I run at least 4-5 errands that I would have used a car for, on my bike. I have three kids, so it helps that they are big enough to ride their bikes now. Some days I do not start my car at all, and some days I put 6-10 miles on my bike. I can't affort a hybrid or electric yet, so this helps my offset my aging volvo. Hop on a bike, now, and enjoy the debate over alt fuels forever.
While walking and biking will always beat driving for sustainability, if you have to own a non-electric vehicle then there's no doubt that a diesel vehicle fueled with biodiesel is the least damaging choice. I base this opinion on the data within articles like this one: (http://www.mda.state.mn.us/ethanol/balance.html) which states Summary - Energy Balance/Energy Life Cycle Inventory
Fuel * Energy yield Net Energy (loss) or gain
Gasoline 0.805 (19.5 percent)
Diesel 0.843 (15.7 percent)
Ethanol 1.34 34 percent
Biodiesel 3.20 220 percent
and
(http://www1.umn.edu/umnnews/Feature_Stories/Ethanol_fuel_presents_a_cornundrum.html)
Emissions from the production and use of corn grain ethanol were 12 percent lower than the net emissions from gasoline; the reduction was 41 percent for biodiesel from soybeans.
At this point, however, depending on where you live, you will probably have to make your own biodiesel as I do from the open source instructions on (http://biodieselcommunity.org). I make 30 gallons at a time from used vegetable oil from a restaurant.
On a commercial level, a great deal of work is going into developing algae as a crop, as there are certain varieties that are 50% oil. The trick to algae production is exposing lower layers of algae to light, as the top layer on a typical pond limits production to the first couple of inches of the algae surface. Field trials to date on algae production include a system of spiraling tubes that rotate the algae crop to expose the lower layers to the sun, grain silos repurposed with tubes and fiber optic light sources to grow a vertical crop, and algae crops utilized to feed on CO2 from smokestack scrubbers on coal-fired power plants.
Biodiesel is not favored by the same interest or level of subsidies that currently support work in hydrogen fuel cells (an absolute boondoggle) and ethanol (a distant second to biodiesel IMHO.) I'd like to see effort brought to bear to gain more attention and funding to this renewable fuel.
If individual automotive transportation is to remain an option in the U.S., at this point in alt-fuel technology the most sustainable option would be diesel-electric hybrids running on biodiesel. In the US, locomotives are already diesel-electric hybrids (although I believe they generally running on petro diesel.) However, in Europe diesel-electric hybrid test vehicles that can get hundreds of miles to the gallon have already been developed.
The technology is already available. We simply lack the will to implement it on a broad scale.
you-all may find Vinod Kholsa, well-knows KPCB VC, interesting on this topic:
http://www.khoslaventures.com/presentations/Biofuels.Apr2006.ppt
i am from calicut india . im chemical engiineering student .bio petrol will change history of world . ihave a new way /but only theoritical . but much better than etanol blended petrol . this research has got immence scope ,if iprove it practically . now only theoritically possible by me .contact raveendra .k abhilash azchavattom calicut kerala india
(I am a 3rd year ChE *with bioprocess minor student trying to get into the Alt Energy field)
The key to any solution is diversity and small scale operations.
When the operation is kept small (eg the farm that will use the ethanol or biodiesel) it helps tremendously. The transportation costs decline when the source of the fuel is near its intended market. Scaling up large enzymatic operations is one of the challenges of our time when it comes to cellulosic ethanol. The main source of energy for biofuels is the sun. It lacks in energy density. Only about 200W/m^2 actually makes it to the surface of the earth (http://en.wikipedia.org/wiki/Solar_power). Plants use this energy for a variety of purposes, protein synthesis, nucleic acid synthesis, transport (inter and intracellular), carbohydrate synthesis (this is the key for ethanol although we can’t utilize lignin the backbone of the plant, Plus fermentation looses some energy in the form of heat. The yeast use 2 ATP to make one 2 ethanol molecules), lipid synthesis (the key for biodiesel). In the end, the fields of energy are pretty dilute. The big problem is we are quite used to just punching a hole in the ground and separating the compressed energy ( carbon also) from millions of years of dilute sunlight falling on the earth. It will take a lot of work to make these processes profitable in terms of energy and finance. I propose small scale operations.
One of the main issues that many experts are debating is total energy returns for each fuel. They do an energy balance on the whole process. An example of some of the costs that get overlooked frequently are fuel spent tending to the raw materials, transport of raw materials, fertilizer, chemicals used in pretreatments as well as refining, transportation of the product to the market, and other losses that are unforeseen. Other problems must be dealt with: If we use cellulosic ethanol by recycling paper waste or by using plant matter from the fields, will we spend more making paper and using more fertilizers.
Diversity is the key. We have only so much farm-land. Besides, a drought or a famine would be devastating to an agricultural based fuel economy.
There are answers out there. We will have to find them. It won't come easily or cheaply.
I will try to find some of the information on efficiency, thermodynamics and conversion rates for the different processes.
so isn't water vapor a GHG as well and a product of ethanol?
also, since we are trying to change all of our cars right now to part ethanol, wouldn't we assume that we could do that with biodiesel as welll. all one needs is a part to add on to the diesel engine, and it is now a biodiesel vehicle.
aslo, isn't it much easier and more affordable to produce soy beans, which is the main component that the US would use for biodiesel production compared to corn?
and one last thing, aren't prices around the globe increasing on bushels of corn, and now impovershed nations are suffereing, and soy is a much less used item, still affordable, and we would not be hurting others in our late quest for sustainability? i think these items may need to be addressed in the above article for a more clear and broader understanding of the big picture. could the government be involved in pushing corn instead of soy because of the amount of corn farmers compared to the amount oif soy farmers, or the land that can produce these things? what is the policy and agenda setting look like for ethanol compared to soy? i think i will write a paper on this and try to submit it to this website for further clarification
i`m a treehugger . :]]
Great post and comments. I just bought an old diesel wagon and I fuel up with B99.99 that's pumped out of a station in West Los Angeles. The oil is from Walnuts grown here in California. I am still conflicted about my choice but I felt the movement away from petroleum is a necessary one.
i ahte biodiesel that is all i hear about in this science class! but what ever if you people want to obsees over this thing then okay i love evan pike
-brittney
percy
i am a tree hugger!!:))) and i love evan pike lol knowledge to the world!! love brittney percy!! peace out
Hey guys ( and girls ). At our university we have a project in which we have to design and build a micro bio-diesel plant. If any of you have any suggestions or plans whatsoever, please help me, because if we can reduce the damage to the enviroment, it will be a big advantage to our building team... E-mail me at ettienne89@gmail.com Thanx, your help will be appreciated...
what are the algae which can be used as bio-disel? Has any body yet extarcted biodisel from algae??
I know I may be just a kid but biofuel is a great way to save the Earth from Global Warming and it's a renewable source at hand. I think that biofuel is just another great way to help save our Earth from polluting and to make our air clean for everyone. I am researching a whole lot about bio energy at school and it tauhg tme a whole lot.
Save a horse ride a cowboy.