Which is better- nuclear energy, solar power, or coal?
There is no true answer, but there are benefits of each- with their disadvantages (some more obvious than others).
Coal first off is a fuel we have been using for thousands of years. The way we produce energy from it has also changed little, that being through combustion in which it converts chemical energy into thermal and light energy, although we often prefer the former.
Chemical Energy (+ thermal energy, smaller than output) -> Thermal Energy (+ Light Energy)
Its advantages include the fact it is easy to start up quickly being able to meet demands quickly, it is also relatively easy to store and build coal power stations.
It is however disadvantaged in the fact it is non-renewable, releases toxic gases into the environment, such as Sulfur Dioxide- which causes acid rain which is harmful to the environment, and Carbon Dioxide, which adds to the greenhouse effect.
Solar Energy can be utilized in a many different ways, the common two is in heating water and producing electrical energy via photocells.
Light Energy -> Electrical Energy
Thermal Energy -> Thermal Energy
Advantages include the fact they are renewable, can be easily installed in homes and fields.
Disadvantages include the fact you need a lot to produce a lot of electrical energy (see the solar power stations in California), due to this they can take up a lot of land. They also rely on the Sun, so if it is cold, you'll get cold water, and usually a lot less electrical energy from the panels. They also require materials which are becoming scarcer.
Nuclear power produces a lot of energy from nuclear reactions to produce electrical energy by heating water to move a turbine like coal. It is also a more recent development, like solar power.
Nuclear Energy -> Thermal Energy
Advantages include the huge amount of energy they produce, the little byproducts of nuclear energy.
However, it is disadvantaged in the fact to build a nuclear station it requires an AWFUL lot of land, you also have to build a place to store used Nuclear fuel and any byproducts which are radioactive and cannot be released safely into the environment.
It is dangerous also if not done safely, it is also slightly non-renewable, however the amount of nuclear fuel we have is huge as well as a small bit produces a tonne of energy so this is tiny.
They all have their advantages and disadvantages, but we do need to phase out and reduce our use of fossil fuels like coal, gas and oil.
Hope this helps!