Fuels such as coal and petroleum are non renewable sources of energy, and they take more that one thousand years to form. So if they are used up once, they will take a lot of time to form, and the generations in that time span will not recieve these sources. Thus, we should conserve them for future generations. (Next para) We can conserve fuel by using public transport, which use petrol, obtained from petroleum. Each car uses an amount of petrol, so if we all use one one car each, a lot is used. So, we should use buses or trains, so many people can use one car and thus save fuel. Also, we should use biofuels, solar energy or biogases which are renewable and can be used in abundance.