Keeping the Energy Debate Clean: How Do We Supply the World's Energy Needs?

We take a fresh look at the major nonrenewable and renewable energy sources and examine their long-term viability, scalability, and the sustainability of the resources that they use. We achieve this by asking what would happen if each energy source was a single supply of power for the world, as a gedanken experiment. From this perspective, a solar hydrogen economy emerges as a dominant solution to the world's energy needs. If we globally tap sunlight over only 1% of the incident area at only an energy conversion efficiency of 1%, it is simple to show that this meets our current world energy consumption. As 9% of the planet surface area is taken up by desert and efficiencies well over 1% are possible, in practice, this opens up many exciting future opportunities. Specifically, we find solar thermal collection via parabolic reflectors - where focussed sunlight heats steam to about 600?C to drive a turbine - is the best available technology for generating electricity. For static power storage, to provide electricity at night, there are a number of viable options that are discussed. For mobile power storage, such as for fueling vehicles, we argue the case for both liquid and gaseous hydrogen for use in internal combustion engines. We outline a number of reasons why semiconductor solar cells and hydrogen fuel cells do not appear to scale up for a global solution. We adopt an approach that envisions exploiting massive economy of scale by establishing large arrays of solar collectors in hot desert regions of the world. For nonrenewable sources we argue that we cannot wait for them to be exhausted - we need to start conserving them imminently. What is often forgotten in the energy debate is that oil, natural gas, and coal are not only used as energy sources, but we also rely on them for embodying many crucial physical products. It is this fact that requires us to develop a solar hydrogen platform with urgency. It is argued that a solar future is unavoidable, as ultimately humankind has no other choice.