All energy resources are pollution free. It is extracting some of the energy from those resources that causes pollution. Extracting energy, by any means, from any resource, will cause pollutions of some kind somewhere in that cycle.
There is no way to extract energy from anything without doing so in some way.
Solar power plant
yes it is pollution free
Resource pollution means contaminating a given resource. Contamination of water can be considered as a good example of resource pollution.
In hydro power or solar power the energy source is pollution free but the process of manufacturing and building the plant is not of course.
Hydroelectric.
yes, because it is a renewable resource it is free
all of these
Renewable energy can't run out. Non-renewable energy WILL run out. Renewable energy is produced at a constant rate, non-renewable is not. Renewable energy is free when the generator is built, non-renewable is not. Renewable energy does not cause pollution (with the exception of biofuels), non-renewable energy does.
As energy is the main source of air pollution, pollution free sources of energy can help. Thus, solar, wind, and hydroelectric technologies can help.
After the initial set costs, solar energy on paper is "free" energy, it is very low maintenance and pollution free
Actually solar energy systems do generate pollution, but the vast majority of that pollution is generated during manufacture not use. This makes containing and limiting the pollution much easier. After approximately 3 months of use, the renewable energy produced by the panels has compensated for the initial pollution. Then the panels produce free, clean, renewable energy with no carbon dioxide pollution.
Although geoothermal energy is considered to be pollution free as it uses hot water or steam from deep in the Earth. As a consequence it does not require fuels which produce emissions. However there are hot water (condensate) releases which may cause thermal pollution.