Which of the following is NOT a type of renewable energy system?

The combustion of treated wood is not considered a renewable energy system because it typically involves burning material that may not regenerate in a sustainable manner or can release harmful pollutants, depending on how the wood was treated.

In contrast, renewable energy systems like wind energy systems, hydroelectric power systems, and geothermal energy systems harness natural processes that are continually replenished. Wind energy captures kinetic energy from moving air, hydroelectric power utilizes the energy of flowing water, and geothermal energy taps into the Earth's internal heat. Each of these systems relies on natural phenomena that are abundant and will not deplete over time, distinguishing them from methods that involve the burning of materials which may not be sustainable or could have adverse environmental impacts.