- Renewable diesel is not biodiesel
- Aims to be cost competitive with conventional diesel
- Made by fermentation with microbes out of organic matter, just like beer
It may be made out of organic material like conventional biodiesel, but whatever you do don't call the diesel-like fuel being tested in VW's year-long partnership with two next generation biofuel companies, Amyris and Solazyme, "biodiesel"; the fact that it's made out of organic material is pretty much where the similarities end.
In the world of Amyris and Solazyme, biodiesel is a messy substance that gels at temperatures just above freezing, leaves clogging residues in engines and associated emissions equipment, and doesn't burn efficiently. For these reasons the two companies spend much of their time explaining how their "renewable diesel" is completely different than biodiesel - and in some respects even better than conventional petroleum-based diesel.
Although a bit different in process, both companies' renewable diesel is made through fermentation of organic materials such as sugar cane using specially engineered organisms, similar to the way alcohol is produced. Instead of producing alcohol, the organisms have been altered to produce diesel. We're not talking about something that kind of resembles diesel; the product of this process is a real, honest-to-goodness diesel substitute that can be dropped-in to the existing diesel infrastructure and nobody would even notice a difference.
Renewable diesel isn't made from food crops and the fermentation process is incredibly efficient, meaning that its environmental and economic benefits tend to be a bit easier to follow than a traditional biodiesel made by squeezing oil out of food seeds like canola. Both companies have been around for several years now and are in the advanced startup phase with commercial scale pilot plants in operation in the U.S. and around the world.
As the largest volume seller of diesel vehicles in the U.S., Volkswagen saw an opportunity to take advantage of both renewable diesel companies' advanced technology. Although diesel vehicles are about 30% more efficient than gas-powered vehicles, they are still dependent on a fuel that has a ton of economic, environmental, health and social pitfalls tied into it. Traditional biodiesel can't be used in high quantities in modern diesels because it gums up the engine and emissions equipment, but renewable diesel is virtually indistinguishable from petroleum diesel to both humans and cars - except for the fact that it's not mined out of the ground.
The partnership between the three companies will last for the next 12 months, with VW providing two test cars to each company to ensure that renewable diesel fuels don't have any hidden negative effects on a diesel drivetrain. Fuel economy, engine residue, emissions and performance will be evaluated as part of the project. If all goes well, renewable diesel may just start showing up at your local gas station sometime in the next few years.
What it means to you: With rising fuel costs and concerns about emissions, diesels are gaining in popularity but still depend on petroleum for power. VW's new partnership with Amyris and Solazyme aims to promote renewable diesel as a way to make modern diesels even more enticing.