That makes them attractive as backup power sources for hospitals and manufacturing plants, as well as for producing distributed power systems not connected to the grid. (sciencemag.org)
Obviously, beast mills were not a viable backup power source for sailing ships either. (lowtechmagazine.com)
The availability of large shale gas reserves in the US has led some to propose natural gas - fired power plants as lower - carbon emission replacements for coal plants, and as backup power sources for wind energy. (en.wikipedia.org)