a. Hydrogen------uses a fuel cell
b. Solar power----harnesses the energy of the sun directly
c. Natural gas---not renewable
d. Hydroelectricity-----can only operate near rivers
Solar power harnesses energy from the sun via photo-voltaic cells. Natural gas is a non-renewable resource because it takes millions of years to create the resource and if it is used up will take millions of years before it is replenished. Hydroelectricity harnesses the power of water to turn turbines to generate electricity.