Because Non-renewable energy is energy that could become depleted, we have to be thrifty with it. If we persist with our present behaviour, oil will be depleted within 32 years, gas will be depleted in 72 years and we will have coal till the year 2259.

Another minus of non-renewable energy is that it is more pollutant than renewable energy. Polar ice is melting, ocean- and seawater levels are rising, and air pollution is every days reality. Because of these facts we are developing techniques to mass-produce renewable energy.