Energy efficiency
Until we can revoke Carnot's theorem we are stuck with engines that operate based upon a disequilibrium between two thermal environments. That remains as true for electrical systems as it does for systems running on combustion sources. So, replacing hydrocarbons as energy sources comes down to how great a gradient can be developed between ho the energy is stored, how it is extracted as work, and how it is dissipated as heat after the work is completed. If you can develop a high energy (battery, fuel cell, photoelectric unit) that can release energy in a flow equivalent to hydrocarbon combustion, and costs no more to fabricate than gasoline costs to extract from petroleum, you might have something.
However, there's very clear evidence from nature that this probably won't happen. Life - as we know it - is carbon based. Primary producers (plants) use hydrocarbons for energy storage as oils, sugars and starches and all the rest of us carbon based life forms consume those very same stored energy sources at one or more removes. Life is not only the movement of energy through the ecosystem, it is the movement of fixed carbon. Less available carbon means - inevitably - less life. There are no ifs, and or buts here. Less carbon means less living mass, regardless of how much light falls on the planet.
Biting the hand that feeds IT
