Why is it important to investigate sources of energy other than fossil fuels?

Fossil fuels are limited in quantity, and we are already running out of them, so we need to replace them with something else.

Also, burning fossil fuels in the large quantities we do changes the balance of nature. We are experiencing global warming, but also there have long been pollution problems with fossil fuels.

Fortunately, there are already alternatives. There are many of these, but one example might suffice to provide an example.

Fire wood can be gasified. The tars that are created, which often go into the atmosphere when wood is burned, can be trapped quite easily, and have commercial value or can be burned to fuel continued wood gasification. The wood gas produced can be catalyzed into alkanes, a class of chemicals that includes propane, butane, and octane. You can get just about any alkane you want, so you can decided to produce diesel oil, if that is what you want, and what you get is superior in nearly all respects to what is pumped from the ground. Five kilos of wood produces one liter of diesel oil - that is about 120 gallons from a cord of wood. If this is done using sustainable forestry techniques, the effect on the forest is probably beneficial, and the carbon footprint is quite possibly about a third of that of nuclear power.

A problem that we have with energy is that we are limited to very few sources for economic reasons. The model of centralized power generation and fuel production is easy to fund because it makes sense for big businesses to invest in. The tendency is for the few centralized sources to crowd out a larger number of smaller, distributed sources. But the distributed alternative can derive power from a larger variety of sources, producing a smaller environmental impact with each, and using less in the way of non-renewable resources.