While listening to the new Air America network the other night, I heard a commercial for Biodiesel . According to the commercial, it’s a form of diesel fuel manufactured from vegetable oil and grease recycled from restaurants. The ad described the product as clean-burning, renewable, and more efficient than ordinary gasoline.
Is Biodiesel really an effective alternative to gasoline and petrodiesel?
Yes, it is effective. No, it’s not the solution- there isn’t enough of it. Still a few fleets of light trucks or small buses converted to it will help a bit.
Doesn’t help with Greenhouse gasses, however.
Carbon Dioxide is the main greenhouse gas, yes? BioDiesel is made from vegetable oils. These are renewable resources and do not release the CO2 locked up in mineral oil deposits, but simply recycle atmospheric CO2 via the plants that must grow to create the oil.
Sunlight provides the energy to do this.
However it may not reduce other localised pollutants depending upon how clean the biodiesel is and how weel its burnt.
Basing it in recycled waste oil is most likely makes it an efficient energy source. Some folks are doubtful that the energy needed to harvest vegetable oil is less than the energy it produces (as per alcohol additives from corn).
I don’t think there’s any sort of fundamental law that means harvesting the stuff must require more energy than is actually produced, it just happens to work out that way at the moment.
The main problem is that it requires a lot of space to do this, even if we had very efficient harvesting methods, there simply isn’t enough available land to grow sufficient raw materials to satisfy demand.
I think it would be better to work on converting the solar energy more directly into something usable by vehicles and save the oil for manufacturing plastics etc.
It’s “fossil fuels” that contribute to the greenhouse effect, because they add carbon to the environment which would otherwise be locked away in a mineral deposit deep underground. Biodiesel should help ameliorate this problem, but it won’t be the solution.
I am shocked, shocked that no one has yet mentioned the single most important fact about biodiesel fuels: The exhaust that results smells like French fries. Greenhouse gasses or not, biodiesel will clearly destroy humanity by making us all crave McDonalds all the time. 
They still burn the oil, which produces CO2.
The Inland Revenue here scooped up a whole load of motorists - evading fuel duties - by the smell of the exhaust. Some were using recycled oil from kebab joints, others just using straight Mazola. The local Asda (Wal-Mart) wondered why they were selling so much corn oil all of a sudden.
Fuel tax is VERY high here.
You know, people talk a lot about the energy balance of biodiesel here back and forth, but I don’t think I’ve seen too many cites on detailed studies. Maybe there were and the Board was locked up that week; I don’t know.
Anyone interested might want to look at this report from the U.S. Department of Agriculture and U.S. Department of Energy. “Life Cycle Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus”
http://www.ott.doe.gov/biofuels/lifecycle_pdf.html
This quote on Page v is interesting:
But I have to admit, I’ve only “heavily skimmed” the report at this time and I can’t say if I agree with them or not. It is 311 pages long, and will take a while to read.
Ethanol fans might also want to go to this page, and download and read the report “Estimating the Net Energy Balance of Corn Ethanol” by the USDA.
http://www.mda.state.mn.us/ethanol/balance.html
In it, it also has this quote:
However, only having skimmed it as well, my impression is that there is a lot of uncertainty involved in their estimates of crop yields, conversion process efficiencym and co-product energy “credits”. See Table 1 in there for a summary of what I mean.
More if I can find good links later. Most of my best reports have NDAs and I can’t link to them…not without being sued.
Considering that it got the carbon from the air in the first place (mostly), it counts as recycling the carbon.
So did the Oil in the ground- true - a VERY long time ago, but still…
Ah, a thread in which I have some experience…
I generally stick with waste vegetable oil (WVO). Why spend so much on chemicals to convert endless batches of crease to utilize an end product, when you can invest in hardware to convert the engine ONCE and use the raw grease directly.
Imagine a fuel tank full of used deep-fryer grease heated with an antifreeze line; this lowers the viscocity of the grease to where it flows easily through the injectors.
I’m currently converting a junkyard special…an old postal jeep with a transplanted Olds 5.7L diesel…to run WVO.
Other members of this board do similar conversions on VW and Mercedes diesels.