A recent special section of Science is devoted to the discussion of alternative energy and its technical and economic challenges (content requires subscription or payment).
Robert Service  reports how investment in ‘cellulosic’ biofuel production in the US, in face of global recession, is dependent upon out-competing current maize ethanol production. A 10% ethanol requirement for petroleum blending is already embedded in the US market, including the car manufacturing industry, and this 10% can already be overproduced from existing maize ethanol factories. This leaves little incentive for US investment in lignocellulosic biofuel research.
Maize crops may not be the best use of finite resources for producing ethanol and with this in mind, Chris Somerville et. al.  prospect alternative plant species and new hybrids for fuel production. Factors such as land, light, water and nitrogen efficiency are compared. Whilst grasses and sugar cane are most suitable in temperate climates, agave production is considered viable for arid zones. The feasibilty of C4 plants, including softwoods, is restricted to rainy areas. These higher yields depend upon improved technologies for lignocellulose conversion to ethanol – a breakthrough that is also needed before we can utilise agricultural waste feedstocks. A recent publication in Biotechnology for Biofuels shows that research into new biofuel crops such as switchgrass  is alive and kicking. Innovation in genetic and protein engineering for lignocellulose conversion by yeast  and other fungi such as Hypocrea jecorina  is also gaining momentum.
Nevertheless, the IEA 2050 target (150 EJ/year) for lignocellulosic bioenergy awaits a significant policy and investment framework, as discussed by Tom Richard . His report examines how production and shipping of high volume biomass might be approached and mentions how technological advances in pre-treatment could reduce transport volumes or potentially be carried out in transit (e.g.[7,8]).
Wifjels and Barbosa  discuss the potential for algal biofuels and propose that widespread use is only 10 to 15 years away. They explain that, at present, an area the size of Portugal would be needed to supply enough microalgal lipid biodiesel to Europe. Whilst algal biotechnology remains in its’ infancy, a rapid catch-up is achievable in the footsteps of groundbreaking genetic and metabolic engineering research. Whether associated investment in production technology and infrastructure should be predicted within two decades seems less certain.
What is made clear across this overview is that rapid progress requires an integrated approach from government to land use policy and laboratory, farm to refinery and from pump to engine.
1.Service RF (2010) Is There a Road Ahead for Cellulosic Ethanol? Science 329 (5993) 784 – 785. | Publisher Full Text |
2.Somerville C, Youngs H, Taylor C, Davis SC, Long, SP (2010) Feedstocks for Lignocellulosic Biofuels. Science 329 (5993), 790 | Publisher Full Text |
3.Chen X, Equi R, Baxter H, Berk K, Han J, Agarwal S, Zale J (2010) A high-throughput transient gene expression system for switchgrass (Panicum virgatum L.) seedlings. Biotechnol Biofuels 3:9 | Publisher Full Text |
4.Garcia Sanchez R, Hahn-Hägerdal B, Gorwa-Grauslund MF (2010) Cross-reactions between engineered xylose and galactose pathways in recombinant Saccharomyces cerevisiae. Biotechnol Biofuels 3:19 | Publisher Full Text |
5.Lantz SE, Goedegebuur F, Hommes R, Kaper T, Kelemen BR, Mitchinson C, Wallace L, Ståhlberg J, Larenas EA (2010) Hypocrea jecorina CEL6A protein engineering. Biotechnol Biofuels 3:20 | Publisher Full Text |
6.Richard TL (2010) Challenges in scaling up biofuels infrastructure. Science 329 (5993):793-6. | Publisher Full Text |
7.Brown RF, Agbogbo FK, Holtzapple MT (2010) Comparison of mechanistic models in the initial rate enzymatic hydrolysis of AFEX-treated wheat straw. Biotechnol Biofuels 3:6 | Publisher Full Text |
8.Arantes V, Saddler JN (2010) Access to cellulose limits the efficiency of enzymatic hydrolysis: the role of amorphogenesis. Biotechnol Biofuels 3:4 | Publisher Full Text |
9.Wijffels RH, Barbosa MJ (2010) An outlook on microalgal biofuels. Science 329 (5993):796-9 | Publisher Full Text |