The document discusses different heating and cooling systems. It describes how hot-water and warm-air heating systems work, and how insulation reduces heat transfer. It also explains that solar heating systems use energy from the sun. Heat engines are described as machines that transform heat into work, with examples of external combustion engines like steam engines and internal combustion engines like car engines. Cooling systems are also outlined, noting they require electricity to power compressors that move refrigerant to condense and cool an area. Thermal pollution from excess heat released into bodies of water by power plants is briefly mentioned.

4. Heat engines burn fuel through a process called combustion.

10. Thermal pollution can happen near large power plants, which are often located near a body of water.