Suddenly, hydrogen fuel-cell cars are back in the news. Headlines have proclaimed a coming battle between plug-in electric cars and the new shining hope, hydrogen-powered vehicles.

If you tried to list the biggest contributors to greenhouse gas emissions, you might say cars, or cows, or airplanes. Those are all major problem sources, but they're not the only ones, or even necessarily the biggest ones.

Japanese officials report they've produced natural gas from underwater methane hydrate, a frozen mix of water and methane known as "burning ice." Previous experiments have successfully extracted gas from on-shore deposits, but this is the first time we've been able to do it with deep sea reserves.

Back in July 2011, we spoke to Jeremy Bentham, Shell's VP of Global Business Environment. He told us how his research team helps the company be smart about the future. Read on to discover how sometimes the common-sense approach is actually the result of a lot of deep thinking.

Most communities in the US treat their wastewater just enough to legally dump it, but not reuse it. Pasteurisation Technology Group has developed an inexpensive treatment system that yields water clean enough to be returned to aquifers. Instead of using chlorine, the system pasteurises wastewater by heating it to 80ºC. The warmth comes from the waste heat of a nearby electricity generator running on either natural gas or biogas produced by an associated sewage digester. A PTG water plant opening next year in California expects to make a $160,000 annual profit by selling its extra biogas-generated electricity. Even if the turbine is fuelled with natural gas, the pasteurisation is energy-efficient enough to be about half the cost of chlorine treatment.