Thought the WotD was a one-time thing, huh?
Before anyone gets up in arms about my reduction of such a cool technology to a simple vocabulary word, realize that there are not a lot of people out there who really know what biodiesel is. And, who better to explain it to the people than me, right? My readership, at this point, must be in the low millions, my delivery style is smart but accessible, and I almost have a degree so... yeah.
First thing is first - let's consult Wikipedia on the matter:
This article is about transesterified plant and animal oils.For thermally processed biodiesel, see Biomass to liquid. For hydrogenated alkane renewable diesel, see NExBTL. For organic waste to light crude production, see Thermal Depolymerization. For unmodified vegetable oil used as motor fuel, see Vegetable oil used as fuel.
What the...? Already we have a problem: there are a bunch of different kinds of biodiesel. Maybe that is where some of the common confusion comes from. We'll get into a technical description of all of that in a bit.
For a more general description, I went to biodiesel.org. They tell me that there are three different kinds of "biodiesel" happening in the world today (I assume these are the pirmary types with many other variations)...
-> The fuel with the true Biodiesel moniker is one made of "mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats." Long chain fatty acids are components of fat (yes, that fat) and it is what gives them their greasy feeling and ability to cling to your dishes. This also means they are "hydrophobic" or do not mix with water (for all of you that thought 'non-polar,' that's right too). Calling something a 'mono-alkyl ester' means that, instead of an acid group (making it a 'fatty acid'), there is an ester group (the acidic hydrogen of the acid is replaced by one carbon and three non-acidic hydrogens). This process basically makes the compound more energetic and easier to burn.
-> The next fuel that is more or less biodiesel but doesn't get the name is Renewable Diesel. This is described as "fuel produced from biological material using a process called 'thermal depolymerization.'" Polymerization is a process (natural and otherwise) where small molecules are turned into larger molecules. As an example, plastics are polymers - 'poly' indicating many repetitions and 'mer' indicating a unit. So, reverse it and think about what happens when you depolymerize something thermally - you change the temperature enough so that large (in this case biological) molecule break into smaller ones to be used. As molecules polymerize, they typically become more stable and less likely to combust. Break them down and you might get something that can burn.
-> Last but not least (and possibly more likely to be popular for the time being) is co-produced renewable diesel which is generated "when an oil company adds small amounts vegetable oils or animal fats to the traditional petroleum refining process when producing diesel fuel (coprocessing)." Think E85 but, like, B15. A portion of the diesel fuel being produced is replaced with something renewable, likely similar to the biodiesel defined above. This, IMHO, is a nice gesture but too little too late.
Here are the FAQs (that I've heard at least)
Can any diesel car run on biodiesel?
This is a great question and the answer, through the reading that I have done, is yes. I've read that it may have a better solvent effect (meaning that material is more easily transported by biodiesel compared to regular diesel) which actually would lead to a cleaner engine and fuel system. This, however, may also "degrade natural rubber gaskets and hoses in vehicles [mostly found in vehicles manufactured before 1992]" (Wiki). All-in-all, you shouldn't have to worry about it too much but, to be safe, I would probably recommend taking your car to a good diesel mechanic and consulting him/her about it (JIC).
Does biodiesel have a greater or lesser impact on the environment?
A very important question, especially when you start talking about a fuel that is known for being, in the past at least, quite dirty. Here's what biodiesel.org has to saw about the matter (in their FAQ section):
A 1998 biodiesel lifecycle study, jointly sponsored by the US Department of Energy and the US Department of Agriculture, concluded biodiesel reduces net CO² emissions by 78 percent compared to petroleum diesel. This is due to biodiesel’s closed carbon cycle. The CO² released into the atmosphere when biodiesel is burned is recycled by growing plants, which are later processed into fuel..Is biodiesel safer than petroleum diesel? Scientific research confirms that biodiesel exhaust has a less harmful impact on human health than petroleum diesel fuel. Biodiesel emissions have decreased levels of polycyclic aromatic hydrocarbons (PAH) and nitrited PAH compounds that have been identified as potential cancer causing compounds.
Brilliant! I, honestly, never realized how green that fuel really is. A diesel hybrid running off of biodiesel fuel is a great way to drastically reduce your carbon footprint and save a bit of cash!
FYI, EPA says a 67% reduction... a bit less
Is it hard to find? Does it cost more?
There are over Does biodiesel have a greater or lesser impact on the environment?">1,200 places pumping biodiesel fuel in the United States so, no, not too hard to find if you're near a major metro area. Cost-wise, it's hard to say... I want to swing by Pearson Fuel nearby my place to see what it goes for. There is not a lot of current, accurate information on how much biodiesel costs; I've seen $1 to 2 or $3 to more in my random Google search.
There is certainly much more to know and learn... this is a technology I'm going to keep my eye on.