Steve Heckeroth had a number of potential buyers for his crawler tractor when the price of gas and diesel was high. Alternative-energy enthusiast Steve Heckeroth says the increasing use of electric tractors will depend largely on the economics, even though there are other good reasons to switch from ­fossil fuels. Heckeroth, who is based in Albion, California, has been making electric vehicles for almost 20 years, motivated by a concern about the depletion of non­renewable energy sources and the pollution caused by their use. As an architect, Heckeroth focused initially on designing homes that could function entirely on solar energy. […]