If we ran out of fossil fuels which could replace them.

Hydroelectric
Wind
Solar
GeoThermal

If we were to run out of fossil fuels, there are several renewable energy sources that could potentially replace them. Let's explore the ones you mentioned: hydroelectric, wind, solar, and geothermal energy.

1. Hydroelectric Energy: Hydroelectric power is generated by harnessing the energy of flowing or falling water. Dams are typically built to control the water flow, and as the water passes through turbines, it spins them to generate electricity. To find out more about hydroelectric energy sources in different regions or countries, you can search for relevant government websites, environmental organizations, or academic research.

2. Wind Energy: Wind power converts the kinetic energy of the wind into electricity. Large wind turbines are installed to harness the wind's power, and as the wind blows, it spins the turbine's blades, generating electricity. To understand the availability and potential of wind energy in various locations, you can refer to reports published by energy agencies, browse scientific articles, or consult industry experts.

3. Solar Energy: Solar power harnesses energy from the sun by using photovoltaic (PV) cells, which convert sunlight directly into electricity. Solar panels are typically installed on rooftops or in open spaces to capture the sunlight. To determine the feasibility of solar energy in different areas, you can access solar resource maps, examine solar panel efficiency data, or consult solar installation companies.

4. Geothermal Energy: Geothermal power utilizes heat from within the Earth's crust to generate electricity. This is typically done using geothermal power plants, which extract heat from the Earth's subsurface through wells and convert it into electricity. To explore the potential of geothermal energy in specific regions, you can examine geological surveys, research geothermal resource maps, or consult specialized geothermal energy organizations.

Whenever you seek detailed information about renewable energy sources, it is crucial to consult reputable sources such as government websites, academics, industry reports, and scientific publications. These sources can provide you with reliable and up-to-date information about the feasibility, costs, and environmental impacts of different renewable energy sources.