Biofuels are energy sources made from recently grown biomass (plant or animal matter). Biofuels are a renewable resource because they are continually replenished.
The generations of biofuels are discussed below:
• First Generation biofuels are produced directly from food crops by abstracting the oils for use in biodiesel or producing bioethanol through fermentation. Crops such as wheat and sugar are the most widely used feedstock for bioethanol while oil seed rape has proved a very effective crop for use in biodiesel.
Pros: Stable, known technology that, depending on feedstock cost, can be cost competitive with fossil fuels.
Cons: Open to food vs fuel criticisms, and generally have feedstock commodity price volatility, as well as geographic limitations that do not always match up well with fuel demand.
• Second Generation biofuels: They are produced from non-food crops such as wood, organic waste, food crop waste and specific biomass crops. Cellulosic ethanol technology fits in here, as do non-food crop technologies such as jatropha-based biofuels.
Pros: A wider selection of geographies; more available biomass; less controversial.
Cons: Early days for the technology; high capital costs; domestication issues with some feedstocks such as jatropha.
• Third Generation of biofuels is based on improvements in the production of biomass. It takes advantage of specially engineered energy crops such as algae as its energy source. The algae are cultured to act as a low-cost, high-energy and entirely renewable feedstock. It is predicted that algae will have the potential to produce more energy per acre than conventional crops.
Pros: Can be made anywhere where CO2 and water is found in sufficient concentration; less controversial.
Cons: Early days for the technology; domestication issues with the feedstock platforms such as algae, cyanobacteria; high capital costs.
• Fourth Generation Biofuels are aimed at not only producing sustainable energy but also a way of capturing and storing co2.
Pros: Can be made anywhere where CO2 and water is found in sufficient concentration; less controversial for biodiversity, environment advocates. Generally, the processes produce drop-in fuels.
Cons: Early days for the technology; can de dependent on a source for low-cost sugars, or CO2; high capital costs; generally speaking, use microbial organisms to do the fuel conversion and processing times generally need to be improved to make fuels cost-competitive.