1. Achieving Energy Sustainably
Chapter 13

2. 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
Potentially renewable – as long as we do not consume them more quickly than they can be replenished
Nondepletable – no matter how much is used, it will not run out and what is used one day will not affect what is available the next day
Renewable energy resources *

3. 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
Environmental impacts
Biomass – only renewable if used sustainably
Wood – can lead to deforestation of overharvested
Wind turbines – kill birds and bats
Hydroelectric turbines – kill fish
Photovoltaic solar cells – requires heavy metals and lots of water

4. 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
Rebates or tax credits are given to those who will retrofit their home to operate on less energy
Higher taxes on energy will force people to use it less
You can conserve energy by not using an electrical appliance or using a more energy efficient appliance (LED bulbs)

5. 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
Can improve the efficiency of the buildings and communities we live and work in
Build houses close to where people work can reduce fossil fuel through transportation
Green roofs and recycled denim – provide insulation and reduce heating and cooling costs
Green roofs also help in improving air quality due to their photosynthetic nature

6. 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
Wood and manure are used directly as fuel. Inexpensive materials and abundant in supply
Ethanol and biodiesel are limited in quantity due to the demands associated with their use

7. 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
* Burning biomass fuels produces pollutants such as carbon monoxide (CO) and nitrogen oxides (NOx) which are components of photocenh
Wood
Removing trees increases the amount of CO2 into the atmosphere as well as burning wood
If tree growth is not equally balanced with the wood that is being burned, it ultimately increases the amount of CO2 and is no longer a sustainable approach
Manure
Removes harmful microorganisms from the environment
Problem of illness is accelerated when it is burned indoors that are poorly ventilated

8. Biofuels a. ethanol 1. derived from mostly corn products 2
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
Made by converting sugars and starches from plant material into alcohol and carbon dioxide
Switchgrass is actually a source that researchers are looking into because it is a perennial crop that can be harvested without replanting which minimizes soil erosion. Only negative thing is that it is composed primarily of cellulose which has to be broken down into sugars whereas corn is easier due to the high sugar content already there
Gasohol
- gasoline has a higher energy content within the carbon bonds so when paired with ethanol it in turn reduces the mileage that can be covered compared to when using 100% gasoline

9. b. biodiesel 1. derived from soybean oil or processed vegetable oil 2
b. biodiesel 1. derived from soybean oil or processed vegetable oil 2. typically diluted to B lower emissions of CO compared to petroleum diesel

10. 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

11. 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
Hydroelectricity generation
Moving water contains kinetic energy
Power plant captures the kinetic energy and uses it to turn a turbine, which turns the water into electricity

12. 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
No reservoir of water
Intermittent electricity because it depends on the natural flow of the river
Cannot generate electricity during the hot and dry periods because of the low flow rate of the water

13. b. water impoundment systems 1. water stored in reservoir behind dam 2
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
Most common because it allows for electricity on demand
Since the gates can be controlled when opened and closed, the operators of the dam can control the flow rate and how much electricity is generated

14. 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

15. 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

16. Solar Energy Passive Solar Heating a. “solar ovens”
b. carefully placed windows, dark v. light-
colored
Solar ovens can reduce deforestation

17. a. captures sunlight with use of technology b. solar heating systems
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”
Heating swimming is the most common in the united states
Circulating liquid moves from a water storage tank to a solar collector on the roof where it is heated and back to the tank

18. d. concentrating solar thermal systems (CST) 1
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

19. 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

20. 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
When magma comes close enough to grounwater, that groundwater is heated and sometimes theres enough pressure from the groundwater to the surface that it makes an appearance as a geyser or hotspring
The steam that runs the turbine now comes from the water that is evaporated by the Earth’s internal heat

21. e. nondepletable as long as we don’t deplete the groundwater source f
e. nondepletable as long as we don’t deplete the groundwater source f. drawback 1. hazardous gases emitted from power plant

22. 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
Wind is a result of the unequal heating of the earth’s surface
Warm air rises and cold air sinks
Sun is the source of all winds – it’s solar radiation and ground surface heating drives air ciruclation
Offshore wind conditions are more desirable for electricity because there is lots of land and the turbines can be even larger

23. c. advantages 1. produces no air pollution, no greenhouse gases 2
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

24. 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
Basic process of hydrogen fuel cells forces protons from hydrogen gas through a membrane while the electrons take a different path and these paths in opposite
Electrolysis – electric current applied to water to split the hydrogen and oxygen atoms

25. d. alternative energy source. 1
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

26. 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