Renewable energy comes from natural sources. Sun, wind and the earth are the commonest sources.
With specially made and installed solar thermal panels on a principally south facing surface, probably a roof or a purpose-made ground level A-frame, you can generate your own hot water. It can be introduced into your central heating system so that the boiler does not have work so hard to bring it up to the right temperature.
Or, if you want to be really sophisticated, photovoltaic (PV) panels can generate enough energy to power your entire home’s electrical system.
They are, of course, expensive to install and have a fairly long payback period. But, by using a special meter, any surplus energy from your home can be sold back into the grid on the ‘feed-in tariff’ basis.
What’s more these panels usually work on the dullest of days and, as technology progresses, they are becoming less costly to manufacture.
Wind power is growing in popularity and, depending on its capacity, a domestic turbine can also produce enough electricity for your home and may leave enough sell back to the grid.
Ground or air source heat pumps can produce hot water, too, to help raise the temperature in your existing heating system and so reduce costs. Ground source heat pumps use the natural warmth from the heat in our earth, which is collected in water pipes buried low down.
Air source heat pumps cleverly capture heat from the air, which, surprisingly enough contains a lot of warmth.
Then there are modern biomass and biofuel systems using wood or other sustainable fuels.