Cleaner fuels refer to alternative sources of energy that produce fewer emissions and pollutants compared to traditional fossil fuels. These cleaner fuels are generally more environmentally friendly, producing less greenhouse gas emissions, particulate matter, sulfur dioxide, nitrogen oxides, and other air pollutants. Examples of cleaner fuels include biofuels such as ethanol or biodiesel, hydroelectric power, wind energy, solar energy, geothermal energy, and nuclear energy. The use of these cleaner fuels can help reduce the negative impacts of climate change and improve air quality, making them an important part of sustainable energy solutions for the future.