Environmental Engineering Reference
In-Depth Information
Second generation
Second-generation biofuels process fuel from non-food biomass and are
not yet commercially available. They derive from cellulosic substances
such as wood and grassy products and by-products, rather than food or
feed crops needed for people or livestock.
But extracting sugars from them is not easy. All plants contain cellulose
and lignin - two complex carbohydrates which are tough to break down.
Cattle manage to digest cellulose and turn it into glucose, but they have a
very complex digestive system with which to do it. Which, incidentally,
means it is hardly surprising that cows belch so much: most of the methane
emissions of cows derives from their belching (and not, as is commonly
believed, from farting).
Third generation
Third-generation biofuels are derived from algae. The idea here is to
make biofuel with algae - or “oilgae”, as they is dubbed. Algae, essentially
slimy underwater plants, are grown in water infused with CO
2
. The algae
In 2007, a team of University of Georgia researchers announced that they had
developed a new biofuel derived from wood chips. Unlike previous fuels derived
from wood, the fuel can be blended with bio-diesel and petroleum diesel to
power conventional engines.
