In a 2006 blog post, Musk wrote, «The overarching purpose of Tesla Motors (and the reason I am funding the company) is to help expedite the move from a mine - and - burn hydrocarbon economy towards a solar electric economy.» (canadianbusiness.com)
The event that precipitated the project was the United Nations - sponsored meeting in Kyoto, Japan, which produced the Kyoto Protocol, demanding global rationing of energy, ostensibly to save the world from the non-crisis of warming supposedly caused by burning hydrocarbon fuels. (thenewamerican.com)
CO2 from burning hydrocarbons hit the atmosphere with about 150 deg C. Much higher than that reduces the efficiency and it's usually avoided. (judithcurry.com)