The main gas produced by burning fossil fuels is carbon dioxide (CO2). When fossil fuels such as coal, oil, and natural gas are burned for energy, they undergo combustion, which releases CO2 as a byproduct. This greenhouse gas is a significant contributor to global warming and climate change. Efforts to reduce CO2 emissions have led to increased interest in renewable energy sources and technologies aimed at improving fuel efficiency and reducing reliance on fossil fuels for energy production.