No matter how well homes and businesses recycle, some stuff like food, feedstock and farm waste is inevitably going to end up in a landfill. Though they are thought to harmlessly decompose, this waste organic material still emits methane, which traps a lot more heat in the atmosphere than CO2.

Already some landfills trap methane, but scientists in the UK think they can use two forms of bacteria in a complementary way to produce "biohydrogen" or a biologically-derived form of the energy-dense element. Science Daily brings us an intriguing report from the Microbiology Today.

When there is no oxygen, fermentative bacteria use carbohydrates like sugar to produce hydrogen and acids. Others, like purple bacteria, use light to produce energy (photosynthesis) and make hydrogen to help them break down molecules such as acids. These two reactions fit together as the purple bacteria can use the acids produced by the fermentation bacteria. Professor Lynne Macaskie's Unit of Functional Bionanomaterials at the University of Birmingham has created two bioreactors that provide the ideal conditions for these two types of bacteria to produce hydrogen.

"By working together the two types of bacteria can produce much more hydrogen than either could alone," said Dr Mark Redwood. "A significant challenge for the development of this process to a productive scale is to design a kind of photobioreactor that is cheap to construct and able to harvest light from a large area. A second issue is connecting the process with a reliable supply of sugary feedstock."

Already, work is being done to commercialize the technology. A side benefit is that enzymes created by the process can be used to "scavenge precious metals from spent automotive catalysts." If they can produce hydrogen in quantity cost-effectively, then it looks like good news all around.