Published on January 17, 2008
Power Sources: Power Sources With thanks to nbsp.sonoma.edu Transferring Energy : Electric current is generated in a power plant, and then sent out over a power grid to your homes, and ultimately to your power outlets. Transferring Energy Power Plant: Power Plant Anything that generates energy: 1 – Wind Mills 2 – Hydroelectric 3 – Solar (Photovoltaic) 4 – Nuclear 5 – Coal, Oil, or Natural Gas 6 – Tidal Converters 7 – Biomass Converters 8 – Geothermal 9 – Ocean Thermal 10 – Solar (Heat Dish) Slide4: When an electric current flows through a wire it generates a magnetic field. A magnet can attract and move metal. Moving metal can be useful. How DO We Generate Energy? Example: Example The magnetic pull causes the armature to spin. If a Fan blade is attached to that armature then you get a cool breeze! Power In Slide6: In this case, wind power applies a force to the blades that turns them. The spinning blades, spin an armature that turns the wire relative to the magnetic field. As long as the blades spin, electricity will be generated! How DO We Generate Energy? Power Out Generator & Turbine: Generator & Turbine Typically something spins the turbine, which spins the magnet in the coil, which creates a current. Two Terms: Two Terms Watt – The amount of energy something can supply. Efficiency – How much actual energy a material supplies vs. its ideal potential. Common Non-renewable Power Sources: Common Non-renewable Power Sources Hydrocarbon Burning (Coal, Oil, and Natural Gas), And Nuclear Slide10: Fossil Fuels comes from the long held, although perhaps inaccurate, belief that natural gas, oil, and coal are the products of dead dinosaurs and plants (hence fossil) Hydrocarbons (Fossil Fuels) Slide11: Hydrocarbon is the term for anything made up of hydrogens and carbons (i.e. oil, natural gas, etc). Hydrocarbons (Fossil Fuels) Hydrocarbons (Fossil Fuels): Standard Large Power Plants Provide 500 MW – 1000 MW of energy and twice that in thermal waste. Hydrocarbons (Fossil Fuels) Coal or Oil powered plants are 30 – 40% efficient Slide13: To power one standard light bulb for a year would require you to burn 714 pounds of coal. Hydrocarbons (Fossil Fuels) A typical 500MW coal power plant produces 3.5 billion kWh per year. That is enough energy for 4 million of our light bulbs to operate year round. To produce this amount of electrical energy, the plant burns 1.43 million tons of coal. How it Works: How it Works Oil, or Coal, or Natural Gas is burned. The heat boils water, or the hot gas itself turns a turbine. Where Does a Hydrocarbon Come From?: Where Does a Hydrocarbon Come From? Oil Fields and Coal Mines Slide16: Where Does a Hydrocarbon Come From? Oil Fields and Coal Mines Problems with Hydrocarbons: Problems with Hydrocarbons Very low efficiency Very high pollution (CO2, Sulfurs, Acid Rain, Heat, etc.) Ecological disruption Resource Wars! Limited Resource? The Nukes!: The Nukes! The use of radioactive material to produce energy! The Nukes!: Plant electrical output 1220 MW Plant efficiency 34% Approximately 100 reactors in the United States Produce 22% of our electricity The Nukes! How Nuclear Power Works: How Nuclear Power Works Radioactive material heats up water. The steam from the water turns a turbine. Problems with Nuclear Power: In normal operations a nuclear reactor produces some environmental emissions (i.e. the escape of radioactive material through cracks in the system). The possibility of a Core Meltdown, like in Chernobyl Problems with Nuclear Power Slide22: Continuous Cooling: Even after shutdown there is enough power for a meltdown if cooling water is not supplied Problems with Nuclear Power Terrorism & Nuclear Proliferation: This 5.3kg ring of plutonium is enough for a modern nuclear weapon. Problems with Nuclear Power: Problems with Nuclear Power Nuclear power is a limited resource just like Fossil Fuels. Natural/Passive/Renewable Power Sources: Natural/Passive/Renewable Power Sources Wind, Hydroelectric, Solar (Heat), Solar (Photovoltaic), Because they are made from either easily renewable resources or can run completely off of the Earth’s natural cycles. Biomass Converters, Geothermal, Ocean Thermal, and Tidal Wind Power: Wind Power Attains ~ 50% efficiency Windmill’s average energy output depends on the amount of wind present and the size of the windmill. Wind farms tend to generate between ½ and 1 MW Annual Average Wind Power Density at 50m: Annual Average Wind Power Density at 50m Problems With Wind Power: Wind variability Basic energy Storage Dangerous to Birds Can be noisy Can be Ugly! Problems With Wind Power Hydroelectric Power: Conversion from potential energy of water to electric energy is at ~70% or higher! Hydroelectric projects in the United States have rated capacities from 950 – 6,480 MW Hydroelectric Power Slide29: Hydroelectric Power The Hydrologic Cycle: The Hydrologic Cycle Water evaporates, rains down onto the land, then runs down rivers where it can push a water wheel and power a generator! Problems With Hydroelectric Power: Problems With Hydroelectric Power About 50% of the United States potential for hydroelectric energy has been tapped. Thus, further advances are unlikely. The Wild and Scenic River Act and the Endangered Species Act have inhibited development of some sites Slide32: Problems With Hydroelectric Power Silt (sand) collection in hydroelectric Dam storage volumes over time causes maintenance issues, as well as environmental concerns The loss of free flowing streams and land due to flooding behind the Dam disturbs the life of species (e.g. Salmon) Possibility of Dam failure Solar (Heat) Dish Power: Solar (Heat) Dish Power This relies on the same principles of evaporation and condensation. The Sun heats up some water, which rises as steam and turns a turbine. This in turn generates electricity via a standard magnet coil generator. Finally, the water condenses and falls back down to repeat the cycle. Slide34: Solar (Heat) Power Problems The output depends on the amount of sunshine that an area gets. Therefore, areas with little sunlight will not be able to utilize this. More often, this technology is used to heat water for a home rather than power it. Slide35: Solar (Heat) Dish Power Slide36: Solar Photovoltaic Cells Efficiency Between 6% and 40.7% depending on the type and usage of the cell. The ~ avg. is 15%. Actual total power output depends on the size of the cell. The larger the cell, the more light it collects, the more power it generates and the more it costs to make. Solar (Photovoltaic) Cells: Solar (Photovoltaic) Cells On a bright, sunny day, the sun shines approximately 1,000 watts of energy per square meter of the planet's surface. The process of using semiconductors to convert solar light into electrical energy. Slide38: How Solar Cells Work When light hits certain materials it energizes it, usually in the form of heat. However, when the object is a semiconductor, particularly Silicon doped with Phosphorous. The light “knocks” electrons loose that can then flow through the material. Slide39: Solar Cells Problems Only good where there is lots of sunlight. Requires the mining of silicon which can require lots of energy and increases the costs of computers. The panels are ugly Biomass Converters: Biomass Converters The burning of recently living materials or the byproducts of them. Palm or Olive Oils Wood Corn, Husks, Flaxseed, Grasses, Leaves Manures Slide41: Biomass Converters These work just as every other burned fuel: They turn a turbine! Ethanol is very inefficient, 3/4 of a gallon of fuel is required to produce one gallon of ethanol. Whereas gasoline is about 1/20 for 1. Some biomass material is used to create bio-fuel: Ethanol from corn. Problems with Biomass: Problems with Biomass Inefficient (worse than hydrocarbons). Require a widespread cultural change to be effective (not everyone has access to cow poop!) Ethanol cannot be transported long distances like gasoline. Produce similar pollution to oil and coal. Geothermal Energy: Geothermal Energy This is the process of taking heat energy from the earth to power turbines and generate energy. GEO THERMAL GEO = EARTH THERMAL = HEAT Slide44: Geothermal Energy The Earth’s core produces huge amounts of heat, partially due to radioactive activity underground. This heat often rises to the surface in the form of lava or hot water springs (geysers). Geothermal: Geothermal The heat from the Earth can be used to drive a turbine and thus spin a generator. Steam is let out of fractures in the ground as it rises it pushes the fan blades of the turbine and spins it Slide46: Geothermal Geothermal power plant in the Philippines Slide47: Right now the plants are running at about 15MW to 65MW. Although 100MW plants are planned. Geothermal Problems The only real problem with Geothermal energy is that it can only be used where there is sufficient thermal/volcanic activity. Slide48: Geothermal Ocean Thermal: Ocean Thermal The differences in temperature of various layers or locations of water in the ocean is harnessed to create electricity via a turbine. Slide50: Ocean Thermal Warmer water is used to boil a working fluid like ammonia. The ammonia boils and the vapors turn a turbine. Slide51: Ocean Thermal Colder water cools off the ammonia vapor which condenses back to the bottom. Slide52: Problems with Ocean Thermal Right now the plants only pump out about 1MW at their best. The plants can only be built near the tropics. The system is not cost-competitive (too expensive) with other power systems). Tidal: Tidal The ever changing Tides are used to push a turbine that is placed into a box. Slide54: Tidal Method 1 It works a lot like a hydroelectric plant mixed with a windmill – tide goes in as the currents flow and spins a turbine that generates a current. Tidal Method 2: Tidal Method 2 Another method is to use a box that fills with water at high tide. The box has a hole at the top above a turbine. When the water rises it pushes air out that turns a turbine. When it falls it pulls air in through and turns a turbine! They can get from ½ MW to 240 MW depending on the size of the project and ~80% efficiency. Problems with Tidal Generators: Problems with Tidal Generators Tidal power schemes do not produce energy all day but rather for 6 to 12 hours. As the tidal cycle is based on the rotation of the Earth with respect to the Moon, and the demand for electricity is based on the Earth’s day (24 hours), the two don’t always jive. It can kill fish too. Now That You Know: Now That You Know What power option do you think is the BEST for us here in Michigan? Why?