A highly efficient way to use gas to generate electricity is to combine a gas combustion turbine with a steam turbine in a power plant called a combined-cycle unit. This technology first uses a combustion turbine to generate electricity and then captures the heat of the exhaust gas to create steam, which is then run through a steam turbine. By using the energy of the initial fuel twice, once in the gas turbine and then again in the steam turbine, the efficiency of the process is greatly improved.