What if there could be a new source for renewable diesel that could both reduce dependence on fossil fuels and also be a cover crop? Field pennycress (Thlapsi arvense) is a common plant in the Midwest, which is now being studied both for its potential as a source of renewable diesel jet fuel and a cover crop. This will be the first of two articles on field pennycress. This one will focus on the characteristics of pennycress and the second one will look at how it is used for renewable diesel.
Field pennycress is both a winter and spring annual. It can be grown over the winter months and harvested in late May or early June and then followed with corn or soybeans. The seeds are approximately 36% oil, thus its potential as renewable diesel source. It is in the mustard family, native to the Mediterranean region, and produces a flat heart shaped seed pod, which contains approximately 14 small oil seeds. Winthrop Phippen, professor of plant breeding and genetics at Western Illinois University, said that the winter variety of pennycress was better due to both its higher seed yield and its earlier flowering, which then allows the same land to be used for another crop. He did, however, say there were other uses for the spring variety. He also said it was a viable alternative to petroleum and it was “estimated” that 2 billion gallons of fuel could be produced from pennycress. Phippen noted that the U. S. demand for aviation fuel was about 10 billion gallons a year, but there were other plants that could also be used for renewable diesel and he mentioned the Camelina sativa and the Brassica carinata or Ethiopian mustard.
As was previously mentioned, field pennycress is native to the Mediterranean region and was introduced into the U.S. There are often concerns with introduced species, due to a lack to predators to keep their numbers in check. However, Phippen said that field pennycress is not aggressive, easy to control, and doesn’t grow in the summer months. He also said it was in the process of being domesticated through gene editing. In this process, genes can be turned on and off, such as the ones that control color or contain poisonous chemicals. Phippen gave the example of rape seed, which is wild canola. Rape seed contains the poisonous chemical sinigrin, but this has been bred out of domestic stock. In the case of field pennycress, gene editing is being used to change the color so it can be fed to livestock. Phippen wanted to clarify the difference between genetic editing and genetic modification (GMO). Genetic editing only involves altering the genes that are already there, whereas GMO is mixing the genes of two or more species. Field pennycress is one of several pennycress species. There are native varieties of pennycress, which can also be a source for oil, but Phippen said native varieties can’t be fed to animals and have fewer uses.
Fossil fuels, which have been main economic driver, are not renewable and have created air pollution, serious health problems, and rising temperatures. While it is important to be mindful of our fuel usage, it is equally true that we travel, heat our homes, and turn lights on. The importance of innovation and imagination in finding sustainable solutions will be a necessity going forward. The next article will focus on how pennycress can be used as a fuel as well as its potential to be a significant renewable energy.
The Nature Journal 