Earth's Heat and Biological Fuel
Geothermal Energy
Geothermal energy is thermal energy generated and stored in the Earth. The heat is a combination of leftover heat from the planet's formation and heat from the radioactive decay of minerals.
Principle for Power Generation:
1.In areas with high geothermal activity, wells are drilled deep into underground reservoirs of hot water and steam.
2.The high-pressure steam is brought to the surface and used to spin a turbine.
3.The turbine powers a generator, producing electricity.
4.The steam is then cooled, condensed back into water, and injected back into the reservoir to be reheated.
Direct Use/Heating: In some areas, geothermal hot water can be piped directly into buildings for heating.
Advantages: Highly reliable and consistent (not intermittent), very low greenhouse gas emissions, small physical footprint on the surface.
Disadvantages: Geographically limited to tectonically active regions, high initial drilling costs, can release small amounts of dissolved gases like hydrogen sulfide.
Bioenergy
Bioenergy is renewable energy derived from biomass.
Biomass: Organic matter from recently living organisms, such as plants, wood, and agricultural waste.
Forms of Bioenergy:
Direct Combustion: The most common method. Burning solid biomass like wood, agricultural residue, or municipal solid waste to produce heat, which can then be used to generate steam for electricity.
Biofuels: Converting biomass into liquid fuels.
Ethanol: An alcohol produced by fermenting the sugars and starches in plants (like corn or sugarcane). It is often blended with gasoline.
Biodiesel: Produced from vegetable oils, animal fats, or recycled cooking grease.
Biogas: Produced by the anaerobic (oxygen-free) decomposition of organic waste (e.g., in landfills or manure lagoons). It is primarily composed of methane (CH₄) and can be burned for heat or electricity.
Advantages: Can be carbon-neutral (the CO₂ released was recently captured from the atmosphere by the plants), uses waste materials, can be converted into liquid fuels for transportation.
Disadvantages: Can compete with food production for land and water, can lead to deforestation if not sustainably managed, combustion still produces local air pollutants.