"Second-generation biofuels” can be derived from plants like Jatropha, Pongamia, and Camelina. Also in this category is seaweed (“algae”) and straw or switchgrass.

As stated above, biodiesel can be made from vegetable oils, animal fats, or recycled greases. Biodiesel can be used as a fuel for vehicles or cruise ships, or backup power in its purest form, but it is usually used as a diesel additive to reduce levels of particulate matter, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe. Figure 2.2 shows average yield rates per hectare under optimal conditions. However, bear in mind that these extraction rates can vary greatly, due to global warming, droughts, floods, fertilizer use, pesticide use, and so on. As can be seen in Figure 2.2, it is remarkable that palm oil has by far the biggest yield: 7133 liters per hectare. A lot of money and research is going into Jatropha, and I am convinced that the yield of Jatropha will be doubled in the coming 5 years. It is also remarkable how small the oil yield from soybeans or corn is, compared to Jatropha!

2.5