Achieving Energy Sustainably
Chapter 13
Renewable Energy
•Nonrenewable Refresher
a. petroleum, natural gas, coal, and uranium
•Renewable Energy
a. biomass – potentially renewable
b. solar, wind, geothermal,
hydroelectric, and tidal
- nondepletable
http://bcs.whfreeman.com/friedlandapes/#668210__690868__
•Facts about Renewable Energy
a. 13% of energy used worldwide
b. biomass – most widely used today
c. 7% of energy use in US (biomass and hydroelectricity)
d. more sustainable than nonrenewable, but still has
environmental impacts
Using Energy Less
Energy Conservation and Efficiency
a. conservation – ways to use the source less
1. locally
- turning down thermostat when out of house
- turning off lights when not in the room
2. government
- taxing electricity, oil, and natural gas
- offer rebates or tax credits
3. can increase efficiency by conserving
- get the same amount of work from using less
energy
b. sustainable design
1. passive solar heating
- solar radiation maintaining building
temperatures
- carefully placed windows (heating and lighting)
- dark-colored roofs v. light-colored roofs
2. “green roofs”
3. recycled denim insulation in walls and ceilings
http://science.howstuffworks.com/environmental/green-science/green-rooftop.htm
Biomass
•Fuel Types
a. wood, charcoal, animal wastes, plant remains,
and municipal solid waste (MSW)
b. ethanol and biodiesel (biofuels)
•United States
a. 2/3 – wood
b. 1/3 – MSW and biofuels
Solid Biomass
a. wood
1. heating, pulp and paper industries, power plants
2. sustainable if forest growth is able to keep up
b. charcoal
1. contains more energy than wood
2. produces less smoke
c. manure
1. indoor heating and cooking
2. reduces risk of disease transmission, but does give
off pollutants causing respiratory illnesses
Biofuels
a. ethanol
1. derived from mostly corn products
2. sugarcane, wood chips, crop waste, or switchgrass
3. US world leader in production of ethanol, Brazil
second
4. Gasohol
- ethanol mixed with gasoline
- produces less air pollutants
- reduces gas mileage
b. biodiesel
1. derived from soybean oil or processed
vegetable oil
2. typically diluted to B-20
3. lower emissions of CO compared to
petroleum diesel
http://bionews-tx.com/news/2013/05/27/benefuel-flint-hill-resources-to-develop-usbiodiesel-projects/
Hydroelectricity
• Hydroelectricity – electricity generated by the kinetic energy
of moving water
• 2nd most common form of renewable energy in U.S. and world
• Most widely used for electricity generation
• China world’s leading producer, followed by Brazil and U.S.
• Water-impoundment, run-of-the-river, and tidal energy
• Amount of electricity depends on 2 factors
a. flow rate
1. amount of water that flows paste a certain point
per unit time
2. higher the flow rate = more KE, more electricity
b. vertical distance water falls
1. greater the distance = more PE water has, more
electricity
• Approaches of Hydroelectricity
a. run-of-the-river
1. water retained behind low dam, runs through channel
2. advantages
- little flooding upstream
- seasonal changes in river flow not interrupted
3. disadvantages
- small
- intermittent electricity generation
- no electricity generated when hot and dry
b. water impoundment systems
1. water stored in reservoir behind dam
2. most common method
3. largest in U.S. – Grand Coulee Dam in Washington
State
4. largest in world – Three Gorges Dam in China
c. tidal systems
- movement of water driven by the gravitational pull
of the moon
- use gates and turbines to capture KE of moving
water flowing through estuaries, rivers, etc
- can be disruptive to coastlines
• Sustainable Practice?
a. expensive to build, but minimal fossil fuel once built
b. no air pollution, waste, or CO2
c. reservoir provide recreational opportunities
d. environmental impacts
1. force people to relocate
2. disrupt a free-flowing river
3. reservoirs contain less oxygen than free-flowing
Solar Energy
• Passive Solar Heating
a. “solar ovens”
b. carefully placed windows, dark v. lightcolored
• Active Solar Energy
a. captures sunlight with use of technology
b. solar heating systems
1. provides hot water, heating swimming pools
2. backup is available for cloudy or cold days
c. photovoltaic systems
1. capture energy from Sun as light, not heat and convert
directly into energy
2. “solar panels”
d. concentrating solar thermal systems (CST)
1. use lenses and tracking systems to focus the
sunlight on a large area into a small beam
2. heat of beam evaporates water, produces steam
that turns turbine to generate electricity
3. uses lots of land
4. can’t generate electricity at night
• Advantages of active solar energy
a. no air pollution, water pollution or CO2
b. produces electricity when needed the most
c. economically feasible
• Drawbacks
a. solar panels are expensive to manufacture and install,
requires lots of energy and water, and involves toxic
metals and chemicals
Geothermal Energy
• Geothermal Energy
a. heat that comes from natural radioactive decay
of elements deep within the Earth
b. geyser and springs
c. direct source of heat, generate electricity
d. United States, China, and Iceland – largest
producers
e. nondepletable as long as we don’t deplete
the groundwater source
f. drawback
1. hazardous gases emitted from power plant
http://commerce.mt.gov/energy/geothermal.mcpx
Wind Energy
• Wind Energy
a. largest amounts of electricity generated by
wind – California and Texas
b. wind turbine
1. converts KE of moving air into electricity
2. wind parks
http://www.pterra.com/index.php/transient-temporary-and-ground-fault-overvoltages-at-windfarm-installations/
c. advantages
1. produces no air pollution, no greenhouse
gases
2. wind farms can share land with other uses
d. disadvantages
1. rely on batteries
2. noise
3. appearance
4. kill birds and bats
http://sayanythingblog.com/entry/federal-wildlife-officials-give-their-blessing-to-killingendangered-birds/
Hydrogen Fuel Cells
• Fuel cell
a. operates like a battery
b. produces electricity as long as it is supplied
with fuel
c. free hydrogen gas
1. rare
2. explosive
3. obtain through electrolysis
http://butane.chem.uiuc.edu/pshapley/Enlist/Labs/FuelCellLab/FuelCell.html
d. alternative energy source?
1. 80% efficient creating electricity and
byproduct is water
2. need a safe delivery of hydrogen (could
explode)
3. hydrogen-fueled car can use an electric
motor
Improving Electrical Grid
• Smart Grid
a. efficient, self-regulating network that
accepts any source of electricity and
distributes it
b. coordinates energy use with energy
availability