There’s a lot of excitement about electric cars these days, but I don’t think a lot of people realize that making one’s own biodiesel can be even cheaper than running an electric car. Let’s do the math. According to research I’ve done (do your own!), Nissan Leaf drivers are getting 2.8 to 3 miles per KwH. The EPA says the average price of electricity in the US (in 2011) was 10 c / KwH, although I realize it can be half of that in places like Seattle and is often less at night. But let’s start with that figure. This would mean that it’s costing folks around 3 c / mile to run their Leafs (see for example this post), so 100 miles would cost them around 3 bucks.
I have calculated that it costs me less than 50 c / gal to make my own biodiesel (email me if you want to see how I arrive at that figure), and my VW Jetta TDI (diesel) Wagon gets around 40 mpg. That comes out to 1.25 c / mile, or $1.25 for that same 100 miles that cost the electric car $3. And I don’t have to worry about finding a recharging station every 73 miles! (typical Leaf range). Granted, your electricity might be significantly cheaper than 10 c/ KwH and it may cost you up to twice as much to make your own biodiesel (depending on the price of the chemicals), but the homebrew biodiesel equation (especially for high mpg diesels like the Jetta) still comes out looking similar or below that for the electric car.
In terms of sustainability, of course we also need to think about how that electricity is generated. According to the Dept of Energy, 42% of electricity in the US is still generated by burning coal. 25% is from natural gas, 19% from nuclear, and 13% from “renewable” sources which includes hydropower, wind, biomass, geothermal, and solar. So eg in Seattle where we get most of our power from hydro (and 8% from coal), running an electric car would be better environmentally than running one in N. Dakota which gets 93.5% of its electricity from coal (see this great site to compare the states). And if you’ve got solar panels on your roof (like I do) the electric car is looking even better. Also making biodiesel requires the use of some methanol which is commercially derived from natural gas (ok, nobody’s perfect..) but can also be derived from more sustainable sources such as wood chips (see this exciting research) which is why it’s often called wood alcohol. That said, homebrewed biodiesel can be an excellent option for many.