Lakes continuously absorb CO2from the atmosphere through the growth of phytoplankton. Microbes convert the carbon, fixed by photosynthesis, into methane when they process biomass. That way, carbon bound in the methane remains within the natural cycle during combustion. Fossil fuels could be partially replaced by “natural” renewable methane. Methane gas is already burned in gas-fired power plants for electricity production and used as a fuel in the form of liquid methanol.