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 LessEnergy 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-us-biodiesel-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. light- colored

• 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-wind-farm-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-killing-endangered-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