Hi,
Thermophotovoltaic's are being actively developed to directly convert heat into electrical current:
If this is developed successfully it will revolutionize energy more than anything else as it can be used for solar photovoltaics to convert more of the sun's energy into electricity, as well as to replace steam turbines, and also allow geothermal power to be used without deep drilling.
Geothermal energy is a vast largely untapped resource, largely untapped only due to the temperature difference required to make it practical for steam turbines requiring deep accurate drilling in most places on earth, and the deep drilling is high risk and expensive.
If thermophotovoltaics are developed that can work efficiently at low temperature then geothermal energy can be extracted right from the surface of the earth, ie maybe a large buried sheet of thermophotovoltaic material buried below the frost line, producing energy like a solar panel, except year round 24/7.
cheers, Jamie