Chapter 18 Renewable Energy Sources

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Chapter 18 Renewable Energy Sources
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Sources of renewable energy

• Solar
• Direct solar energy
• Biomass/biofuels
• Wind
• Hydro-electric
• Geothermal
• Tidal

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Electrical Generation Costs
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Direct Solar Energy

• Energy directly from the sun
• Tremendous amount
• Always available
• Must be collected

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Active Solar Heating

• Collectors absorb solar energy
• Pumps or fans distribute heat
• Primarily for heating water

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Passive Solar Heating

• No mechanical devices to distribute heat
• New home design
• Room temperature
  is steady
• Convection
• Save on heating!

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Photovoltaic (PV) Solar Cells

• Convert sunlight into electricity
• Thin wafers or films
• No pollution
• Minimal maintenance

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Photovoltaic (PV) Solar Cells

• Can be used in remote areas
• Good choice for developing countries why?
• School, home use
• Can look like conventional roofing
• Prices are coming down but future progress is
  critical

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Solar Thermal Electric Generation

• Suns energy concentrated by mirrors, lenses
• Heat a working fluid
• Fluid is circulated to boil water
• Steam generates electricity

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Hydrogen As A Fuel Source

• Could be the fuel of the future
• Where does the hydrogen come from?
• Electrolysis
• Must use renewable fuel source to obtain the
  hydrogen!
• Few pollutants produced when burned
• Can be used for transportation

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Solar-Generated Hydrogen

• Use PV cells for electrolysis of water
• Currently not very efficient
• Still expensive
• Would need new distribution system for
  transportation
• Future development is critical

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Solar-Generated Hydrogen

• Fuel cells
• Electrochemical cell
• Like a battery
• Major carmakers working on it

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Indirect Solar Energy

• Indirect use of suns energy
• Biomass, wind power, hydroelectricity

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Biomass Energy

• Wood, plants, animal wastes
• Potentially renewable why?
• Burned to release energy
• Half of human population
  relies on
• Cooking, heating

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Biogas

• Mixture of gases
• Similar to natural gas
• Animal wastes
• Biogas digesters
• Decompose wastes
• Use gas for cooking, lighting
• Solid remains are fertilizer
• Can also be used to power fuel cells

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Biomass As A Liquid Fuel

• Methanol, ethanol
• Gasohol mix gasoline and ethanol
• Biodiesel
• Plant, animal oils (sometimes waste products)
• Becoming more popular
• Burns cleaner than regular diesel

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Ethanol

• Sugarcane, corn, wood, agricultural and municipal
  wastes
• Government subsidizes
• Good outlet for some wastes
• Problems
• Land and water use
• Soil erosion
• Decreased food production

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Wind Energy

• Fastest growing energy source
• No waste, emissions
• Electricity
• Costs are declining
• Denmark is a world leader
• Need steady winds
• Great Plains of U.S.

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Wind Energy Problems

• Birds and bats killed by turbines
• Avoid migration routes
• Operate only at certain times
• Monitor the project
• Visual pollution
• Often on ridge tops or out in open fields, water
  where they are highly visible
• Some people feel they obstruct pretty views

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Hydropower

• Flowing or falling water spins turbines
• Most efficient way to produce
  electricity
• 19 worlds electricity
• 2200 U.S. plants

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Hydropower Problems

• Damages ecosystem, species
• Reduces downstream flow
• Reservoirs eventually fill in
• Danger of collapse
• Degrades river
• Increase in waterborne disease schistosomiasis

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Geothermal Energy

• Use energy from Earths interior
• Big potential source
• Electricity
• Hydrothermal reservoir hot fluid
• Bring fluid to surface to generate electricity
• Emits very few pollutants
• Is it truly renewable?
• Land may subside

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Geothermal Heat Pumps

• Used for heating and cooling
• Ground temperature relatively constant
• Underground pipes carry water
• Fluids circulate or pump and dump ground water
• Can be expensive to install
• Very efficient!

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Tidal Energy

• Use power of the tides to generate electricity
• France, Russia, China, Canada
• Very few ideal locations
• May be damaging to ecosystems

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Conservation Efficiency

• Energy conservation
• Using less energy
• Reduce use, waste
• Carpooling
• Energy efficiency
• Using less energy for a task
• More fuel-efficient cars
• Both very important!

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Energy Consumption Trends

• Use is on the increase
• Greatest increase in developing countries why?

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Energy-Efficient Technologies

• Appliances, automobiles, light bulbs, furnaces,
  etc
• Superinsulated buildings
• May cost more, but will save money!

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Cogeneration

• Combined heat and power (CHP)
• Recycling waste heat
• Generate electricity, use steam before cooling it
  back down

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Energy Conservation At Home

• Average household 1500/year on utilities
• Use energy-efficient technologies
• Better insulation, windows
• Seal cracks
• Replace inefficient appliances

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Energy Conservation At Home
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Case Study Green Architecture

• Adam Joseph Lewis Center for Environmental
  Studies, Oberlin College
• Geothermal heat pump
• PV cells for electricity
• Triple-paned windows
• Motion sensors for light switches
• Recycle wastewater
• Sustainable wood
• Recycled carpet

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Course overview

• Environmental challenges and sustainability
• Climate change
• Ecosystems and their services
• Natural resources
• Freshwater and oceans
• Land resources (forests, rangelands, etc.)
• Agriculture
• Biodiversity
• Energy
• Nonrenewable
• Renewable

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Course overview major focus of Final

• Environmental challenges and sustainability
• Climate change
• Ecosystems and their services
• Natural resources
• Freshwater and oceans
• Land resources (forests, rangelands, etc.)
• Agriculture
• Biodiversity
• Energy
• Nonrenewable
• Renewable
• Plus major concepts from throughout semester