In Helmand province, Afghanistan, marines use solar panels to cut down on fuel use in generators. The more gas the marines save, the less that has to be brought in on dangerous convoys. The military is turning to alternative energy to both improve security and cut costs. Many hope a customer of its size will provide a kick-start to a fledgling industry. But in an era of tightening budgets, investing in more expensive technologies could prove difficult. As part of our Environmental Outlook series we look at the emerging partnership between the military and the renewable energy industry.