Because geothermal produces consistent, base-load power--it doesn't depend on the wind blowing or the sun shining--utilities will pay up to three times more for geothermal electricity than for electricity from an intermittent source, like wind.
It is also an "enabler" for renewable energy, providing a source of electricity that can step in to fill the gap when the wind is not blowing or the sun is not shining.
To use that excess electricity (obviously, only excess when the wind is blowing just right, or the Sun shining) to electrolyse water by passing it through a fuel cell and then store the resultant hydrogen.