Renewable Energy Sources: Solar, Biomass, and Geothermal Power

Storing Wind and Solar Power

Water reservoirs at different altitudes can be used to store energy generated from wind and solar power.

Solar Power Generation

Solar power involves several methods:

• Using solar cells (photovoltaics) to convert sunlight directly into electricity.
• Using sunlight hitting solar thermal panels to heat water or air.
• Using sunlight hitting a parabolic mirror to heat water, producing steam.
• Using sunlight entering windows for passive solar heating of a building.

It would be advantageous to place solar panels in regions with the highest solar radiation. Many solar photovoltaic power stations have been built, mainly in Europe.

Agricultural Biomass Energy

Biomass production involves using garbage or other renewable resources, such as corn or other vegetation, to generate electricity.

• When garbage decomposes, the methane produced can be captured in pipes and later burned to produce electricity.
• Vegetation and wood can be burned directly to generate energy, similar to fossil fuels, or processed to form alcohols (biofuels).

Brazil has one of the largest renewable energy programs in the world, involving the production of ethanol fuel from sugar cane. Ethanol now provides 18% of the country's automotive fuel. Ethanol fuel is also widely available in the USA.

Geothermal Energy Utilization

Geothermal energy harnesses the heat energy present underneath the Earth and is capable of supplying significant energy needs. The process typically involves drilling two wells:

1. One well injects water into the ground.
2. Hot rocks heat the water to produce steam.
3. The steam that shoots back up the other well(s) is purified and used to drive turbines, which power electric generators.

When the water temperature is below the boiling point, a binary cycle system is used. In this system, a liquid with a low boiling point drives a turbine and generator in a closed loop, similar to a refrigeration unit running in reverse.

There are also natural sources of geothermal energy, including:

• Volcanoes
• Geysers
• Hot springs
• Steam vents

The world's largest geothermal power installation is The Geysers in California, with a rated capacity of 750 MW. A key advantage of geothermal power is its consistency, unlike the variability of many other renewable sources.

Factors for 100% Renewable Energy

Achieving 100% of a country's energy from renewable sources requires considering four key factors:

• Transmission: Managing energy transfer when local resources exceed or fall short of local needs.
• Storage: Storing excess energy generated for times when production is low or demand is high.
• Excess Capacity: Building more generation capacity than typically needed to ensure sufficient supply during peak demand or low production periods.
• Baseload Power: Utilizing consistent sources like biomass or geothermal energy to fill gaps when variable sources like wind and solar are insufficient.