1. Renewable Energy
Chapter 16

2. Core Case Study: Iceland’s Vision of a Renewable-Energy Economy
Supplies 75% of its primary energy and almost all of its electrical energy using
Geothermal energy
Hydroelectric power
No fossil fuel deposits
imports oil

3. Wasted Energy
Energy Conservation -
Energy Efficiency -

4. The Second Law of Thermodynamics in Living Systems

5. Wasted Energy Four widely used devices that waste energy
Incandescent light bulb
Motor vehicle with an internal combustion engine
Nuclear power plant
Coal-fired power plant

6. Solutions Improving Energy Efficiency Prolongs fossil fuel supplies
Reduces oil imports and improves energy security
Very high net energy yield
Low cost
Reduces pollution and environmental degradation
Buys time to phase in renewable energy
Creates local jobs
Fig. 16-4, p. 404

7. Flow of Commercial Energy through the U.S. Economy

8. Net Energy is the Energy That Counts

9. We Can Improve Energy Efficiency and Save Money in Transportation
Hidden prices in gasoline
Should be $12/gallon
Car manufacturers and oil companies lobby to prevent laws to raise fuel taxes
Build or expand mass transit and high speed rail
Encourage biking

10. High Speed Magnetic Train

11. More Energy-Efficient Vehicles Are on the Way
Superefficient and ultralight cars
Gasoline-electric hybrid car
Plug-in hybrid electric vehicle
Energy-efficient diesel car
Electric vehicle with a fuel cell

12. Internal combustion engine
Conventional hybrid
Fuel tank
Battery
Internal combustion engine
Transmission
Electric motor
Plug-in hybrid
Fuel tank
Battery
Internal combustion engine
Transmission
Electric motor
Stepped Art

13. We Can Design Buildings That Save Energy and Money
Green Architecture
Green Roofs (Living Roof)
Blue Roof
Superinsulation

15. Green Architecture

16. Green Architecture

17. Green Roof

18. Green Roof

19. Green Roof

20. Green Roof

21. Green Wall

22. Blue Roof

23. Los Angeles River

24. Houses out of bottles?

25. Houses out of bottles?

26. What is Renewable Energy?
Renewable energy is energy from sources that are constantly being formed.
Renewable energy includes
Solar
Wind
Geothermal
Hydroelectric
Biomass

27. Available Energy Flow (exajoules per year)
World energy use (2010)
527
Direct solar
>1,000
Wind
600
Geothermal
500
<250
Biomass
Hydropower 50
Ocean
<1
Fig , p. 412

28. Solar Energy
Passive solar heating - uses the sun’s energy to heat something directly.
Active solar heating – when energy from the sun can be gathered by collectors and used to heat water or to heat a building.

29. Solutions: Passive and Active Solar Heating for a Home

30. Passive or Active Solar Heating
Trade-Offs
Passive or Active Solar Heating
Advantages
Disadvantages
Net energy is moderate (active) to high (passive)
Need access to sun 60% of time during daylight
Very low emissions of CO2 and other air pollutants
Sun can be blocked by trees and other structures
High installation and maintenance costs for active systems
Very low land disturbance
Moderate cost (passive)
Need backup system for cloudy days
Fig , p. 415

31. Passive Heating and Homes
Passive solar buildings have large windows that face south.
Solar energy enters the windows and warms the house.
Must be well insulated

32. Active Solar Heating
Solar energy can be used to heat water and generate electricity.

33. Solar Thermal System

34. Solar Thermal System – Central Receiver

35. Photovoltaic (PV) Cells
Photovoltaic cells(PV) = solar cells
Convert the sun’s energy into electricity
Run on nonpolluting power from the sun.
Cons:
Produce only a little bit of energy
Expensive
Energy produced must be stored in batteries

36. Photovoltaic (PV) Cells

37. Photovoltaic (PV) Cells

38. Trade-Offs Solar Cells Advantages Disadvantages
Medium net energy yield
Need access to sun
Some designs have low net energy yield
Little or no direct emissions of CO2 and other air pollutants
Need electricity storage system or backup
Easy to install, move around, and expand as needed
Costs high for older systems but dropping rapidly
Solar-cell power plants could disrupt desert ecosystems
Competitive cost for newer cells
Fig , p. 419

39. Wind Energy Wind farms – large arrays of wind turbines
Reminder- wind caused by the uneven heating of Earth’s surface
Wind energy is the fastest growing source of electricity in the world

40. Gearbox Electrical generator Power cable Wind turbine
Fig. 16-1a, p. 402

41. Wind Energy Controversy: Cape Wind

42. Fig. 16-1b, p. 402

43. Trade-Offs Wind Power Advantages Disadvantages High net energy yield
Needs backup or storage system when winds die down
Widely available
Visual pollution for some people
Low electricity cost
Little or no direct emissions of CO2 and other air pollutants
Low-level noise bothers some people
Can kill birds if not properly designed and located
Easy to build and expand
Fig , p. 423

44. Advantages of Wind Energy
Easy and quick start up – new turbine takes about 3 months to put up
Wind energy is cheap and abundant
Have the potential to generate a LOT of energy
Turbines don’t take up much space so the land can be used for other things as well, such as farming.

45. Biomass
Biomass fuel - Plant material, manure, and any other organic matter that is used as an energy source
Wood and dung (both biomass fuel), are major sources of energy in developing countries.

46. Biomass Fuel

47. Trade-Offs Solid Biomass Advantages Disadvantages
Widely available in some areas
Contributes to deforestation
Moderate costs
Clear-cutting can cause soil erosion, water pollution, and loss of wildlife habitat
Medium net energy yield
No net CO2 increase if harvested, burned, and replanted sustainably
Can open ecosystems to invasive species
Increases CO2 emissions if harvested and burned unsustainably
Plantations can help restore degraded lands

48. Methane Methane can be burned to generate heat or electricity.
In China, more than 6 million households use biogas digesters to ferment manure and produce gas used for heating and cooking.

49. Hydroelectricity Hydroelectricity - energy produced from moving water,
Accounts for about 20 percent of the world’s electricity
Dams are expensive to build, but inexpensive to operate

50. Hydroelectricity

51. Benefits of Hydroelectricity
Do not release air pollutants that cause acid precipitation.
Last longer than fossil fuel powered plants.
Dams also provide other benefits
flood control
water for drinking, agriculture, industry, and recreation.

52. Disadvantages of Hydroelectricity
Dams can alter the flow of a river, disrupting downstream ecosystems
Can disrupt fish migration (salmon)
Not enough water downstream to support ecosystems
Example: Three Gorges Dam in China
Present a flood risk if the dam leaks or breaks

53. Large-Scale Hydropower
Trade-Offs
Large-Scale Hydropower
Advantages
Disadvantages
High net energy yield
Large land disturbance and displacement of people
Large untapped potential
High CH4 emissions from rapid biomass decay in shallow tropical reservoirs
Low-cost electricity
Low emissions of CO2 and other air pollutants in temperate areas
Disrupts downstream aquatic ecosystems

54. Modern Trends Hydroelectricity
Micro-hydropower - electricity produced in a small stream without having to build a big dam.
Uses a small turbine floating in a stream or river, does not disrupt the flow of the water

55. Micro-hydropower

56. Micro-hydropower

57. Geothermal Energy
Geothermal energy - energy from heat in the Earth’s crust
This heat can be used to generate electricity
Geothermal power plants pump heated water or steam from rock formations and use the water or steam to power a turbine that generates electricity.

58. 2. Heat from underground spins a turbine to power a generator and produce electricity
Geothermal Energy
Generator
Steam turbine
Heat exchanger
3. Steam from turbine condenses to water and is pumped back down to geothermal reservoir
Production well
Injection well
1. Hot water or steam is pumped under pressure to the surface from underground
Geothermal reservoir
Fig a, p. 428

59. Geothermal Heat Pump System

60. Trade-Offs Geothermal Energy Advantages Disadvantages
Medium net energy yield and high efficiency at accessible sites
High cost except at concentrated and accessible sites
Lower CO2 emissions than fossil fuels
Scarcity of suitable sites
Low cost at favorable sites
Noise and some CO2 emissions
Fig , p. 430

61. Alternative Energy and Conservation
Section 2

62. What is alternative energy?
Alternative energy - describes energy sources that are still in development.
The source must be proven to be cost effective.
The environmental effects of using the energy source must be acceptable.

63. Tidal Power
Tides are the movement of water in the oceans and seas caused by gravitational attraction between the sun, Earth, and moon.
A tidal power plant works much like a hydroelectric dam.
As the tide rises, water flows behind a dam
When the sea level falls, the water is trapped behind the dam

64. Tidal Power

65. Potential Problems with Tidal Power
The cost of building and maintaining a tidal power plant is high
There are few locations that are suitable.
May have negative impacts on fragile coastal ecosystems.

66. Hydrogen Fuel Cells
Hydrogen, the most abundant element in the universe, can be burned as a fuel.
When burned, water vapor is the byproduct
Hydrogen gas (H2) can be produced by using electricity to split molecules of water (H2O).

67. Polymer electrolyte membrane
Electrons
Hydrogen gas (H2) in
Anode
Polymer electrolyte membrane
Cathode
Water vapor (H2O) out
Protons
Air (O2) in
Fig , p. 430

68. Potential Problems with Hydrogen Fuel
Takes a lot of energy to split water – not energy efficient by today’s standards
Water vapor is still a GHG

69. Trade-Offs Hydrogen Advantages Disadvantages
Can be produced from plentiful water at some sites
Negative net energy yield
Fuel cell
CO2 emissions
if produced from carbon-containing compounds
No CO2 emissions if produced with use of renewables
Good substitute for oil
High costs create need for subsidies
Needs H2 storage and distribution system
High efficiency in fuel cells
Fig , p. 432

70. Fig , p. 434