By switching from fuels with high carbon content (such as coal) to others with lower carbon content (such as natural gas and biomass), energy can be produced with fewer emissions. Many coal-fire generation plants can use biomass to burn along with coal (known as "co-firing"). The amount of carbon released into the atmosphere from the burning of biomass came be captured with the growing of a new crop of biomass fuel-plants. This differs from coal as the carbon contained in coal is much older (i.e. fossil), and hence cannot be easily or affordably captured and stored with current technology.