Alternatives to Nuclear Energy: Classifications
and Technology
Erica Raheja04/13/08
Power Conversion: Turbines
• Almost all electrical energy produced• Driven by a fluid
Most common: steam Other: wind or water
• Used to convert energy into electrical energy (attach to generator) Simplest: shaft with blades attached Early examples: windmills or waterwheels
Alternative Energy Sources
• Fossil fuels: coal, petroleum, natural gas• Solar power• Wind power• Water power
Hydro-electric Tidal Wave
• Geothermal power• Biofuel
Fossil Fuels
• Coal, petroleum, natural gas• Found in the earth’s crust• Non-renewable resource• Burned to create steam which turns
turbine
Fossil Fuels cont.
Pros of Fossil Fuels
• Large amounts of energy produced• Relatively cheap• Can build a plant almost anywhere• Transportation of fuel relatively easy
Cons of Fossil Fuels
• Pollution Burning fossil fuels produces carbon
dioxide, a “greenhouse” gas
• Obtaining the fuel can have negative effects on the environment
• Acid rain• Release of radioactive material• Non-renewable resource
Solar Power
• Three major categories Photovoltaic cells Solar power heating Solar furnaces
• Other research
Solar Power cont.
• Photovoltaic (PV) cells Convert solar energy directly into electrical Photons from the light knock the electrons into
an excited state, generating electricity Cells connected together in panels for more
electricity
Solar Power cont.
• Solar power heating Sun heats water in exposed glass panels Require less electrical power to heat Problem: water in panels can freeze
Solar Power cont.
• Solar furnaces or Concentrating Solar Power (CSP) system Concentrate sunlight into small beam by
use of mirrors or lenses Can then use as heat source
Solar Power cont.
• Trough system
Solar Power cont.
• Power tower system
Solar Power cont.
• Dish engine system
Solar Power cont.
• More pictures
Solar Power cont.
• Research/Experimental Technology Solar updraft tower
A large greenhouse funnels heated air into a central tower which can turn turbines
Solar pond A pool of salt water
collects and stores solar energy
Solar Power Pros
• It is free• Can be used in remote locations• Good for low-power usage• Renewable resource
Solar Power Cons
• Does not work at night• Extremely expensive to build solar
power stations• Unreliable except in sunny climates
Wind Power
• Wind blows in and turns propeller blades, turning a generator
• Pitch can be changed according to wind speed
• Made to turn and face wind
Wind Power cont.
• Often build many wind towers together to create “farm”
• Need places where wind is reliable and strong
Wind Power Pros
• Wind is free • No waste products• Land underneath potentially used for
farming purposes• Way of providing energy to remote
locations• Renewable resource
Wind Power Cons
• Wind unpredictable, unreliable source of power
• Coastal land expensive• Can kill birds• Noise pollution
Water Power
• Three major categories Hydro-electric power Tidal Wave
Water Power cont.
• Hydro-electric power• Running water has kinetic energy
(converted from potential energy height)• Generally dam built to trap water• Water flows through dam, turning turbines
as it passes by
Water Power cont.
• Dam must be thicker at bottom to withstand pressure
• Expensive to build but water is free and produces cheap energy
• Evaporation from sun keeps lake filled with water
Water Power cont.
• Hoover dam
Water Power cont.
• Hydro-electric advantages Energy cheap after dam is built No waste or pollution produced Reliable source of power Water can be stored for peak usage Can increase to full power relatively fast Electricity can be produced constantly Renewable
• Disadvantages Expensive to build dams Changes to the environment Suitable sites can be difficult to find
Water Power cont.
• Tidal power• Dam built across a
river estuary• Ebb and flow of
the tides either turns a turbine or pushes air through a pipe that turns a turbine
Water Power cont.
• Largest tidal power station in the world: Rance estuary in France
• Only can generate power when the tide is going in or out
Water Power cont.
• Other option: offshore turbines or tidal stream systems
• Similar to underwater wind farm• Need locations in fast currents
Water Power cont.
• “Swanturbines” design from University of Wales Swansea
Water Power cont.
• Advantages Tidal power is essentially free, renewable, and
clean once the original installation is made Produces electricity reliably - tides are
predictable Not expensive to maintain Offshore turbines relatively inexpensive and
low-impact on environment
• Disadvantages A barrage across an estuary is expensive Few sites (about 20 around the world) Only provides power for 10 hours
Water Power cont.
• Wave power
Water Power cont.
• Advantages Wave power is free, clean, and
renewable Inexpensive to build and maintain Can produce a lot of energy
• Disadvantages Waves unpredictable - need suitable site Can be noisy Must be able to withstand all weather
Geothermal Power
• Heat from the earth used for power• Dry steam
Steam from fractures used to drive turbine
• Flash Hot water rises and boils as it comes to the
surface. Steam used to drive turbine
• Binary Hot water run through heat exchangers, boiling
organic fluid used to drive turbine
Geothermal Power cont.
• If there is not already water below ground, can pump water down
• Called Enhanced Geothermal System (EGS)
Geothermal Power cont.
• Important resource in volcanically active areas: Iceland, New Zealand
• Efficiency depends on the temperature of the water
• Can deplete a site
Geothermal Power cont.
• The Nesjavellir Geothermal Power Plant in Iceland
Geothermal Power Pros
• No pollution• Power plants take up little room,
giving it a low impact on the environment
• No fuel is needed• Once built, energy almost free• Work continuously• Renewable resource
Geothermal Power Cons
• Few places viable to build power stations
• Depletion of a site can occur• Hazardous gas can rise to the
surface• Can lower land stability
Biofuel
• Generally, biofuel is burned and used to heat steam
• Made of or derived from dead biological matter
• Exist in solid, liquid, and gaseous forms
Biofuel cont.
• Solid biofuel: wood, biogenic municipal solid waste, unused portions of field crops, animal wastes
• Can be burned for heat to warm homes or be used in external combustion engines
• Can convert wood and byproducts into liquid or gas via gasification
Biofuel cont.
• Liquid biofuel: bioalcohol (ethanol) or bio-oil (biodiesel or vegetable oil)
• Generally used in diesel engines No modifications needed for
biodiesel
• Reduce emissions from fossil fuels
• Made from corn, sugarbeets, sugar cane, etc.
Biofuel Pros
• Makes sense to use waste products when possible
• Fuel tends to be cheap• Less demand on the earth’s
resources• Renewable resource
Biofuel Cons
• Collecting in sufficient quantities can be difficult
• Burning does still produce greenhouse gases
• Some materials are not available all year round
Biofuel cont.
• Biogas: methane gas• Produced from current waste streams like
paper and sugar production and sewage• Naturally ferment to create methane• Mechanical biological treatment: use
anaerobic digesters to process biodegradable material
• Renewable natural gas: upgraded to quality like natural gas
World Primary Energy Production
• (Data from 2005)• 36.8% petroleum• 26.6% coal• 22.9% dry natural gas• 6.3% hydro power• 6.0% nuclear power• 0.9% other (geothermal, solar, wind,
and biofuel)
Top Related