Renewable Energy Lecture

*Sources replenished quickly to maintain constant supply*

Major Sources of Renewable Energy

  • A. Solar: energy derived from sun’s heat. Can be direct or indirect (wind, water, biomass)

    • Advantages: does not directly produce air pollutants, greenhouse gas, emissions, or water pollutants

    • Disadvantages: Manufacturing of photovoltaic cells requires water, fossil fuel use, and toxic materials. Location and installation costs. Transmission and storage.

  • Types

    • 1. Active Solar

      • technological devices are used to focus, move, and store solar energy

      • ex: flute plate solar collectors, PV solar cells, concentrated solar power (CSP), and solar cookers

    • 2. Passive Solar

      • buildings are designed and building materials are chosen to maximize their direct absorption of sunlight in winter and cool buildings in summer

  • B. Hydroelectric Power: causes kinetic energy of moving water to turn turbines and generate electricity

    • must impound water from rivers and streams behind dams or “run-off-water” approach (no reservoir, lower dam)

    • Advantages: renewable as long as precipitation recharges rivers and streams. High EROI (80:1), no carbon emissions during use

    • Disadvantages: fossil fuels used in constructing and mandating dams. Large reservoirs release methane. Environmental impacts: destruction of habitat, disruption of flood cycles, thermal pollution

  • C. Wind Energy

    • derived from movement of air. Indirect solar.

      • power of wind harvested by using wind turbines, convert kinetic energy to electrical energy

    • Advantages: nondepleatable no emissions once equipment is mandatory. Can be scaled up or down. Land can be shared for —, creates green jobs

    • Disadvantages: unpredictable supply of energy. Storage batteries are expensive and hard to dispose of, NIMBY, pose threat to birds and bats

  • Geothermal

    • thermal energy beneath Earth’s surface, due to radioactive decay of elements under high pressure

      • related to volcanically active areas, geyser and hot spring systems.

        • harnesses energy from heated groundwater and steam to turn turbines to generate electricity

          • enhanced geothermal systems: cord water injected into then heated

    • Advantages: reduced emissions relative to fossil fuels

    • Disadvantages: may not be truly renewable. Heated water may be used quicker than groundwater is recharged. Some emissions from dissolved gasses