Biofuels are seen as one of the most feasible options for reducing carbon emissions and improving fuel efficiency for the typical lightweight car and truck. For heavy-duty vehicles, marine vessels and airplanes in particular, biofuels will play an increasing role to reduce carbon dioxide emissions since electric vehicles and fuel cells are not feasible for these transport modes.
In response to the need of alternative fuels, global biofuel production has been increasing over the last several years but important concerns have been raised about its sustainability; in particular, the sustainability of many first-generation biofuels, which are produced primarily from food crops such as grains, sugar cane, and vegetable oils. The specific concerns include the displacement of food crops, effects on the environment, increasing monoculture agriculture, transportation costs, and concern over climate change.
The concerns over first-generation biofuels have raised attention to the potential of second-generation biofuels. Depending on the feedstock choice and the cultivation technique, second-generation biofuel production has the potential to provide benefits such as consuming food and nonfood waste residues.
The goal of second-generation biofuels is to extend the amount of biofuel that can be produced by using biomass consisting of the residual non-food parts of current crops, such as stems, leaves and husks that are left behind once the food crop has been extracted, as well as other crops that are not used for food purposes. Once manufactured, second-generation biofuel can either be blended with petroleum-based fuels combusted in existing internal combustion engines or it can be dedicated for the use in slightly adapted vehicles with internal combustion engines.
However, while second-generation biofuel crops and production technologies are more efficient than many first-generation biofuels, they still compete with food crops and the risk of displacement could undermine food security in developing regions. Developing countries also face the challenge to balance large-scale industrial development of biofuels with small-scale local value chains, which would be required to ensure environmental, economical and social sustainability.
As of 2010, second-generation biofuels are not yet produced commercially and are considered to still be in the demonstration stage with a considerable number of pilot and demonstration plants have been announced or set up in recent years. Ambitious biofuel support policies have recently been adopted in the United States (with 60 billion gallons of second-generation biofuel by 2022) and in the European Union.
These mandates as well as corporate and emerging economies (Brazil, China, Indian) investment into research and development of second-generation biofuels will be an important driver for the global development of second-generation biofuels.