In the never-ending search for improved ways to store energy, two groups are looking to biology, enlisting microbes to produce methane and viruses to build batteries.
Penn State environmental engineer Bruce Logan and his colleagues identified microorganisms called methanogens that efficiently reduce carbon dioxide to methane. When the microbes receive an electric jolt, Logan reported in March, they use the electrons to combine CO2 and protons, creating methane gas. Methane can be stored and later used to fuel a vehicle or run a generator. Exploiting the microbes’ chemistry might be a way to make inconsistent energy sources like wind and solar more practical.
Along the same lines, MIT materials scientist Angela Belcher has engineered viruses to help store electricity. Her genetically modified bacteriophages (viruses that infect bacteria) cloak themselves in iron phosphate, a metal salt, then attach to carbon nanotubes to produce a framework of microscopic conductive wires that can hold a charge just like a car battery. Genetic tweaks enabled the virus to bind tightly to the carbon nanotube, creating a high-powered battery, as she described in a May issue of Science. Unlike traditional battery manufacturing, the process requires no toxic chemicals and can be set up very cheaply. Belcher is working to improve the batteries’ storage capacity further by experimenting with different virus-coat materials.