There was a time when mankind used only renewable energy sources. This was hunderds of years ago, before the industrial revolution of the 1800s.
Back then, to heat your dwellings or cook your food, you used wood. And to travel you used horses, or wind-powered ships. This was a sustainable lifestyle, but who would want to live like that today? Life was hard for most people, travel was very difficult, and life-expectancy was low.
What was it that made the difference, which transformed the world?
Well, it was the industrial revolution. We invented machines to do things for us. We also used these machines to build more machines — and so on.
There was, and still is, one major problem with that: those machines are usually powered (directly or indirectly) by fossil fuels — coal and oil, ie. “ancient sunlight“.
This is especially so for moving machines; cars, ships and airplanes — but our houses are also often powered by fossil energy. For instance, the electricity we use is often (at least in the U.S.) generated in a coal-fired power plant.
Coal and oil have been cheap and abundant, while we have lacked the technology to use renewable energy sources efficiently — with the exception of hydroelectric power.
Although abundant sources of renewable energy are there right under our noses, we just haven’t known how to harness them.
However, as the sources of fossil energy, especially oil, are becoming scarce, plus there is an increasing awareness of the dangerous long-term consequences of using fossil energy, there is nowadays a growing interest in renewable energy.
For example: solar cells were once so expensive they were only used to power things like satellites — but intense research efforts have now resulted in the invention of fairly cheap photovoltaic cells.
Solar panels made with such cells are becoming so cheap they will soon be able to compete directly with electricity from the grid.
These cheap solar panels can for instance be installed on the roof of your house, and once there they require no maintainance for many years.
Indeed, home solar panels are likely to revolutionize the way ordinary homes use electric power. Recently I heard of a modern house which used ZERO electicity from the grid! It had solar panels on the roof, and these supplied, on average, 100% of the electricity for that household.
When the solar panels delivered an excess it was sold to the utility company, and if there was some shortage the balance was delivered from the grid. The net effect over a year was about zero, ie. the utility bill was zero dollars.
