Even the most incurious observer will have noticed the growing calls for a move away from fossil fuel dependence for our energy needs. A host of interrelated issues make this one of the most pressing technological challenges of our time. Whether it be the impact of fuel use (climate change, pollution) or the geopolitical consequences of where that fuel comes from, alternatives that didn't involve fossil fuels would plainly be beneficial.
In practice however, there is unlikely to be a single silver bullet that cures what ails us. Oil has a high energy density and is readily transported. Most of the hard work has already been done by the conversion of sunlight to chemical energy and then the slow geological conversion of those sugars and other complex molecules into crude oil. Fossil fuels will likely require application-specific replacements. For transportation needs, biofuels are currently enjoying widespread support, although they have many critics. The need to develop cleaner transportation fuels is highlighted by an article in PNAS this week1, which shows that transport accounts for around 15 percent of anthropogenic CO2 emissions worldwide.
Brazil has a thriving biofuel industry, using its climate to grow sugar cane, which can then be refined to ethanol. However, this strategy is unsuited to most other regions due to shorter growing seasons. In the US, the current political vogue is for ethanol to be made from corn, despite corn-based ethanol's many problems, Already, increased demand for corn for energy uses has seen a huge increase in the crop's pricing, with serious knock-on consequences for poorer countries and their food supplies.
