The term COAL ALTERNATIVE can be solved by the 3 letter word OIL. OIL is a fossil fuel that has been used for centuries as an energy source. It is a non-renewable resource, meaning it cannot be replenished once it is used up. As a result, many countries are looking for alternatives to OIL in order to reduce their dependence on this finite resource. Coal is another fossil fuel that is also non-renewable, and so it too is being replaced with more sustainable sources of energy.