Biofuels debate

By 2050 the world will need twice as much energy while emitting half of today's greenhouse gases. As the global population heads for 9 billion, supplies of conventional oil and gas will not keep up. Solar and wind will struggle to fill the gap and nuclear will be needed, but poses its own environmental challenges. Shell say biofuels cannot be left out of the mix and have the potential to be an affordable, genuinely low CO2 fuel in the near term.
Rob Rout, in charge of Shell's expansion of biofuels, answers your questions on the most controversial issue being debated by the energy giants.
Send your questions to biofuelsdebate@thetimes.co.uk