There’s a large and growing list of renewable energy projects pumping out cleaner electricity these days. Photovoltaic panels produce direct current and solar concentrators drive steam turbines using sunlight. Wind turbines churning out megawatts of power dot the landscape of many countries. Other projects are looking to light communities through tides, running rivers and even the heat of the Earth.
Creating current is all well and good for energizing homes, businesses and even motor vehicles, but when it comes to flying airplanes or turning the screws on big ships, batteries storing alternative-energy-produced electricity just can’t yet deliver the power needed. That’s why these large machines still need combustible liquids like diesel, aviation fuel and bunker oil that pack a bunch of energy into small volumes to drive their engines.
For these and other high-power applications, renewable energy needs to up its oomph. The best way to do that would be to concentrate sunlight’s energy, for instance, into a machine that converts it directly into fuel. For well over a century, we’ve been using a version of this that comes out of the ground in the form of petroleum products, which are the hydrocarbon-rich remnants of organic matter that lived eons ago. The ancient organisms that form our fossil fuels are the concentrated distillates of sunlight.