1. Achieving Energy Sustainability
Chapter 13

2. Current Energy Usage
US Energy Use
Global Energy Use

3. RENEWABLE ENERGY
The European Union aims to get 20% of its all energy from renewable sources by 2020
Costa Rica gets 92% of its energy from renewable resources.
China aims to get 10% of its total energy from renewable resources by 2020.

4. Electricity from RENEWABLE ENERGY
In 2014, Germany generated 75% of electricity with a combination of renewable sources
Denmark now gets 40% of its electricity from wind and plans to increase this to 100% by 2050.
In 2004, California got about 12% of its electricity from wind and plans to increase this to 50% by 2030.

5. Jobs & Economy: Renewable Energy
According to the American Council for an Energy-Efficient Economy (ACEEE), robust investment in energy efficiency:
could save $1.2 trillion by 2020, and the United States
could create 1.3 to 1.9 million jobs by 2050 through the deployment of energy efficient technologies
The International Renewable Energy Agency (IRENA) estimates that
5.7 million people worldwide were employed in the renewable energy sector, directly and indirectly, in 2012.
The largest number of jobs is found in biofuels and solar photovoltaic, 1.38 million and 1.36 million, respectively

6. Energy Use
Conservation - Reducing energy waste is quickest, cleanest, cheapest way to
provide more energy,
reduce pollution
reduce environmental degradation,
preserve our dwindling supply of resources
Evaluate efficiency
Incandescent light bulb: wastes 95%
Car motor: wastes 80%
Nuclear power plant: wastes 86%
Coal burning power plant: wastes 66%
Solution: Reduce waste & increase Efficiency

7. Wasted Energy Unavoidable: Avoidable:
41% of US Commercial energy is “lost” when energy changes form (2nd law of thermodynamics) usually heat lost to the environment
Avoidable:
43% of energy is wasted unnecessarily, by inefficient motors, appliances, wasteful usage
1st law of thermodynamics: conservation of energy – energy is neither created nor destroyed, just changes form
2nd law of thermodynamics: When energy changes form, energy quality decreases. We end up with less usable energy

8. Energy Efficient Appliances
Bulbs: To make same amount of light
Incandescent : 60 Watts
Fluorescent : 15 Watts
LED : 8 Watts
Heat pumps
40 % electricity to produce same amount of heat
Solar water heaters :
Reduce energy use by 50%

9. Living Roofs
Roofs covered with plants have been used for decades in Europe and Iceland.
These roofs are built from a blend of light-weight compost, mulch and sponge-like materials that hold water.
Figure 17-10

10. Saving Energy in Existing Buildings
About one-third of the heated air in typical U.S. homes and buildings escapes through closed windows and holes and cracks.
Figure 17-11

11. Efficient Design Example:
CA Academy of Sciences Building
Passive Solar Design
South-facing double-paned windows with adjustable shades
Overhang blocks summer sun, but winter sun enters windows
Heat absorbant floor: and heat is stored and slowly released in stone or concrete floors

12. Designing Buildings: Green Architecture
Other design features
Super insulate
Geothermal cooling / heating
Utilize breeze /wind for ventilation and cooling
Roof color: light colors reflect sunlight, dark colors absorb and store heat
Green roofs with soil and vegetation reduce cooling costs, create habitat, absorb runoff and improve air quality
Double paned windows and strong insulation to prevent heat loss
Recycled building materials
Trees for shade
Skylights and natural lighting
Radiant heating in floors
Energy efficient appliances

13. ENERGY EFFICIENCY: Cars
The government Corporate Average Fuel Economy (CAFE)
Enacted in 1977 after Arab Oil Embargo
Has not increased since 1985.
Stuck at 25 mpg for 30 years
Scheduled to increase to 35mph in 2016
Figure 17-5

14. How do we achieve energy sustainability?
Increase energy efficiency –
Fossil fuels will last longer and renewables will be able to support a larger portion of our energy needs.
Invest in a wide variety of energy sources –
Provides stability and diversity
Shift subsidies away from fossil fuels
to support research and development of renewables –
will make renewables more cost effective and
the transition away from fossil fuels less damaging
Full cost pricing – Externalities
include the social, environmental and health costs of an energy source in its price.
Will even the economic playing field between fossil fuels and renewables

15. Capacity and Peak Demand
We have to plan our energy capacity around peak demand
Capacity is the amount of energy a power plant can provide at any given moment
Peak demand – most energy used at one time: can be many times normal use
Reducing peak demand is a key component of energy sustainability
Options:
Increase energy efficiency
Conservation during energy transfers
Tiered pricing plans
Store energy (batteries, water uphill, solar heating)
Back up generators
Smart Grid: Smarter systems that automatically adjust energy usage to avoid blackouts and brownouts and that spread out energy usage

16. Power Grid/Smart Grid

17. Renewable Energy

18. Biomass Biomass is organic material from plant and animal
Direct burning :
Wood, manure, MSW, crop residue, charcoal, etc
Convert to different forms:
methane (natural gas) – decomposing organic waste
ethanol (gasohol) - fermenting organic material
from corn, sugarcane, switchgrass, or agricultural residue
biodiesel - oil extracted or collected
from waste oil, soybeans, algae, etc

20. Biomass Potentially renewable Carbon neutral
Rate of harvesting < rate of growth
Max Sustainable Yield
Otherwise: Deforestation
Carbon neutral
Biomass is part of current carbon cycle
Stored & released in short time frame
Theoretically, no net increase in atmospheric carbon
Fossil fuels:
Carbon has been locked away for millions of years
Rapidly releasing what has been slowly accumulating
Results in Net increase in CO2 in atmosphere

21. Biomass Low-tech High-tech Solid Biomass: wood, charcoal, manure
heating & cooking
 Indoor Air Pollution
High-tech
Liquid & Gas Biomass
Biofuels: Ethanol, Biodiesel, Biogas
vehicles & electricity generation

22. Gas Biofuel: Biogas
Organic wastes go in  bacteria convert to methane  biogas harvested for use.

23. Biogas from Methane Digestion
Biogas (methane) is an important renewable gas fuel made by fermenting organic wastes, (animal dung), in a digester but can contribute to climate change. Biogas uses less land than other biofuels and thus reduces the amount of deforestation, runoff, soil erosion, and energy consumption.
Biogases occur in things like landfills or agriculture and produces a strong smell but with methane digestion the amount of methane released to the atmosphere is reduced. If the waste is not going to landfills then there is a reduction in the amount of waste as well.
Saprophytic bacteria (facultative anaerobes) break down fats, proteins, and polysaccharides
Biogas
What is the source of methane digestion?
Other environmental benefits of methane digestion: reduction of runoff from manure into waterways, reduction of manure form that needs to be disposed of in landfills, reduction in the use of fossil fuels for electricity.
Acid forming bacteria break down these monomers to short chain organic acids
Digester
BIOGAS
Methane
50-80%
CO2
15-45%
Water 5%
Methanogen bacteria (strict anaerobes) produce methane gas

24. Liquid Biofuel Types: Ethanol (fermented sugar) Corn (US )
Sugar cane (Brazil leads)
Switchgrass (promising on marginal land)
Biodiesel (extracted oil)
Soybeans
Palm Oil (Southeast Asia)
ALGAE!!!
WINNER!!

25. Algae Grow Fast Have High Biofuel Yields Consume CO2 Don’t Compete With Agriculture Microalgal Biomass Can Be Used or Fuel, Feed and Food Can Be Grown in the Sea Can Purify Wastewaters Can Be Used to Produce Many Useful Products The Algae Industry is a Job Creation Engine

26. Biofuel Downsides  crops for fuel vs. crops for food
(takes food away from people)
Agricultural expansion  land footprint  deforestation
(esp. soy & palm in the tropics)
Crops have fossil fuel input
(mechanized monoculture uses lots of fuel/fertilizer/pesticide)

27. http://c1gas2org. wpengine. netdna-cdn

28. Biomass: Environmental Impacts
Use of crops and crop land for fuel – creates competition for land and increases food prices
Growing crops for fuel creates all the problems associated with commercial agriculture
Fossil fuel dependent, fertilizer runoff, pesticides, soil degradation, etc
Impacts can be decreased by
Growing less intensive grasses on marginal land
Using waste material (trash, crop residue or logging waste)
Using algae which can be grown in brackish
water, on rooftops, or other non-traditional
agriculture spaces and creates more fuel per area

29. Large potential supply in some areas
Trade-Offs
Solid Biomass
Advantages
Disadvantages
Large potential supply in some areas
Nonrenewable if harvested unsustainably
Moderate to high environmental impact
Moderate costs
No net CO2 increase if harvested and burned sustainably
CO2 emissions if harvested and burned unsustainably
Low photosynthetic efficiency
Plantation can be located on semiarid land not needed for crops
Soil erosion, water pollution, and loss of wildlife habitat
Figure 17.24
Natural biomass capital: making fuel briquettes from cow dung in India. The scarcity of fuelwood causes people to collect and burn such dung. However, this practice deprives the soil of an important source of plant nutrients from dung decomposition.
Plantations could compete with cropland
Plantation can help restore degraded lands
Often burned in inefficient and polluting open fires and stoves
Can make use of agricultural, timber, and urban wastes
Fig , p. 405

30. Hydropower
Using the potential energy of flowing water to generate electricity
Renewable / Nondepletable
suitable sites are limited and we are maxed out in terms of conventional dams
There is little room for expansion in the U.S. – Dams and reservoirs have been created on 98% of suitable rivers.
new technologies emerging for using tides and waves

31. The kinetic energy of water can generate electricity
Hydroelectricity- electricity generated by the kinetic energy of moving water.
This is the second most common form of renewable energy in the world.
7% of the electricity in the US…more than ½ of this is in the states of CA, WA, OR
China is the world’s leader in hydroelectricity followed by Brazil and the US.

32. Captures kinetic energy and uses it to turn a turbine.
Amount of electricity depends on the distance it falls or the flow rate or both.
Biggest dam:
In US: Grand Coulee Dam in Washington
In China: Three Gorges Dam on Yangtze River

33. Hydroelectric Dam Dam Transformer Sluice gate Powerhouse Generator
Reservoir
Penstock
Turbine
Dam
Afterbay

34. Types of Hydropower Water wheels Run of the river Systems
used to grind grain or cut wood
ancient practice
Run of the river Systems
Water runs through a channel and dam to create a small amount of electricity (water turns turbine)
Subject to flooding and drought so electricity production can vary as river flow changes
Water Impoundment Dams
Dam a river to create a large water gradient and water storage area (lake)
Falling water turns a turbine  electricity
Major up and downstream impacts

35. Types of Hydropower Pumped Storage Systems
excess electricity is used to pump water upstream (storing potential energy)
can then be used to generate extra electricity during peak hours

36. Types of Hydropower Tidal Energy
Uses the changing tides to turn a turbine
Tides are a very reliable source of energy
Energy captured both directions
Need to protect fish

37. Types of Hydropower Wave Power
Use the movement of waves to run a generator
Concerns about ocean habitat disruption
Not as reliable as the tides

38. Wave Power Power module 145 m
Each module produces 250 kW of electricity
3.5 m
145 m
Wave tube
Anchor
Power cable Feeds electricity back to land
Each power module is connected by hinges and attached to hydraulic rams. As the wave tube moves up and down, the rams shift hydraulic fluid in the power module and drive a turbine and generator.

40. Dams: Environmental Impacts
Upstream
Major reservoir is created upstream to provide drinking water, irrigation, recreation and flood control
Massive flooding changes habitat entirely and displaces native plants, animals and people
Siltation: Sediment build up behind the dam requires dredging
Standing water holds more heat, have less oxygen and more water is lost to evaporation
Downstream
Reduced water flow may alter riparian, wetland and estuary habitats which alter flora and fauna
Lack of nutrients from blocked sediments reduces soil fertility
Loss of seasonal water flow (changes estuaries and flooding patterns)
Dam itself
Fragments habitat
Disrupts fish migration
Increased anaerobic decomposition (decomp under water) creates methane and CO2
Blocks fish migration (can be helped with fish ladders)

41. Trade-Offs Large-Scale Hydropower Moderate to high net energy
Advantages
Disadvantages
Moderate to high net energy
High construction costs
High environmental impact from flooding land to form a reservoir
High efficiency (80%)
Large untapped potential
High CO2 emissions from biomass decay in shallow tropical reservoirs
Low-cost electricity
Long life span
Floods natural areas behind dam
No CO2 emissions during operation in temperate areas
Converts land habitat to lake habitat
Figure 17.20
Trade-offs: advantages and disadvantages of using large dams and reservoirs to produce electricity. QUESTION: Which single advantage and which single disadvantage do you think are the most important?
May provide flood control below dam
Danger of collapse
Uproots people
Provides water for year-round irrigation of cropland
Decreases fish harvest below dam
Decreases flow of natural fertilizer (silt) to land below dam
Reservoir is useful for fishing and recreation
Fig , p. 400

42. Geothermal
Energy stored below the earth’s surface can be harvested for heat and energy
Nondepletable although some sites can be temporarily depleted of hot water
Can be used directly as a source of heat/hot water or indirectly to produce electricity.
Direct use can happen almost anywhere, but sites for electricity production are limited.
Common in Iceland and currently practiced in the western US

43. Earth’s internal heat produces geothermal energy
Geothermal energy- using the heat from natural radioactive decay of elements deep within Earth as well as heat coming from Earth.
Wherever magma comes close enough to ground water, the ground water is heated. Where it does not rise to the surface naturally (Yellowstone geysers, etc.) humans may be able to reach it by drilling.
US, China, and Iceland have substantial geothermal resources and are the largest producers of geothermal energy.
Iceland: 87% of their home heating, 20% of it’s electricity.
US 5% of its renewable energy.

44. Types of Geothermal Energy
Low Temperature – used directly for hot water or space heating
Hot water used for cooking or normal hot water uses – water may or may not go back into reservoir
Hot water is disseminated via a heat exchanger to heat buildings – water back into reservoir to be reheated and used again
Ground source heat pumps – constant temps underground transfer heat from underground . Requires energy to pump fluid.
Winter: heat from underground is used to heat a fluid which transfers heat to the house, fluid is then reheated
Summer: fluid cooled underground absorbs heat in the house and then transfers the warmer fluid underground where it loses heat
High Temperature – used to produce electricity
High pressure steam  turns turbine  makes electricity  water back into reservoir to reheated and used again
Just like a coal plant, but no burning required

45. Ground source heat pump
Can be installed anywhere regardless of whether there is geothermal energy

46. Geothermal Plant

47. Geothermal Suitability
Ground Source Heat Pumps can be used anywhere
Sites for direct use are somewhat limited
Sites for electricity generation are significantly limited to areas with high geologic activity 47

48. Geothermal in TX
According to a report by the Southern Methodist University Geothermal Laboratory, the hot water and pressure between 8,000 and 25,000 feet below Texas could supply more than 100 times the state's 2008 total electric consumption for well over a century.

49. Environmental Impacts
Geothermal heat and steam contain traces of gases (H2S, SOx, etc) that can be harmful to humans and the environment
Sulfur compounds from geothermal plants can lead to acid rain (but generally less than fossil fuel power plants)
Reduced by using scrubbers to clean out harmful gases or collecting the gases for useful purposes
Remote and pristine habitats can be fragmented or impacted by road construction, drilling, etc to access the geothermal reservoirs

50. Geothermal Power Advantages of geothermal power include:
high efficiency
moderate CO2 emissions
low cost (in suitable areas)
low environmental impact
Disadvantages of geothermal power include:
few suitable sites
noise and odor pollution
depleted easily if not managed
land subsidence due to extracted water

51. Solar Power
Capturing radiant energy from the sun to generate light, heat and electricity.
Cannot be depleted
Amount varies depending on latitude, cloud cover, time of day and season
Two Types
Active – using technology to capture the sun’s energy often changing the form
Examples: solar panels, solar water heating, concentrated solar plants
Passive - Using the sun’s energy to heat or cool without energy inputs, pumps or special technology
Examples: windows and blinds, solar oven

52. Solar Energy

53. Solar Power
FRQ 2006 #1: Describe one environmental benefit and one environmental cost of photovoltaic systems.

54. Solar Power
FRQ 2006 #1: Describe one environmental benefit and one environmental cost of photovoltaic systems.

55. Active: Photovoltaics
Photovoltaic cells convert radiant energy from the sun into electricity
Cells are composed of silicon with phosphorus and boron.
Photons strike the solar panel and
excite electrons to create a flow of electrons
Electrons flow through the semiconducting materials to create electricity
Electricity can be stored in batteries for use at night
Price of photovoltaic cellss is high, but dropping

56. Photovoltaic cell can be installed on roofs to provide electricity
Individual Solar cell
A solar cell converts light into electric current.
The energy that is generated is usually converted directly to electricity which is stored in a battery or used to heat water.
On their first tests the solar cells were only about 1% efficient (similar to photosynthesis). Since the increase in technology the percent efficiency has gone from 1% to 5% to 20% to 40% and now some designs are reporting 85% conversion efficiency.
Photovoltaic cell can be installed on roofs to provide electricity

57. Producing Electricity with Solar Cells
Single solar cell
Solar-cell roof – +
Boron enriched silicon
Roof options
Junction
Figure 17.17
Solutions: photovoltaic (PV) or solar cells can provide electricity for a house or building using solar-cell roof shingles, as shown in this house in Richmond Surrey, England. Solar-cell roof systems that look like a metal roof are also available. In addition, new thin-film solar cells can be applied to windows and outside walls.
Phosphorus enriched silicon
Panels of solar cells
Solar shingles
Photovoltaic (PV) cells can provide electricity for a house of building using solar-cell roof shingles.

58. Producing Electricity with Solar Cells
Solar cells can be used in rural villages with ample sunlight who are not connected to an electrical grid.
Figure 17-18

59. It is possible to get electricity from solar cells that convert sunlight into electricity.
Can be attached like shingles on a roof.
Can be applied to window glass as a coating.
Can be mounted on racks almost anywhere.

60. Active: Solar hot Water System
A heat collecting liquid is heated on the roof and transferred to the water storage tank where it heats the water. Fluid returns to the roof to be reheated.
Setup costs associated with buying and installing the system, but then you get free hot water (still have to pay the water itself though)
May require energy to pump the water around

61. Active: Concentrated Solar Thermal Systems
Power Towers
Rotating mirrors track and aim sunlight at a tower
Fluid collects heat to make steam to generate electricity
Parabolic Troughs
Reflective troughs focus sunlight on a fluid filled tube which heats up to make steam to generate electricity
Large land requirements: Usually placed in a desert habitat with no trees and year round sun
Some threats to fragile desert ecosystems
Do not produce electricity at night
Go To:

62. Passive Solar
Absorbs & stores heat from the sun directly within a structure
Window placement (under an overhang to let winter sun in and keep summer sun out)
Windows (double or triple paned with low e glazing to prevent heat loss)
Flooring (concrete or stone with good thermal inertia to absorb and store heat)
House orientation (south facing in the US)
Insulation (sufficient to keep heat in or out)
Albedo effect (dark colors to absorb heat, light colors to reflect it)
Green roof
Deciduous tree for shade in summer (no leaves in winter
Building into side of hill

63. Passive Solar

64. Solar Suitability

65. Passive or Active Solar Heating
Trade-Offs
Passive or Active Solar Heating
Advantages
Disadvantages
Energy is free
Need access to sun 60% of time
Net energy is moderate (active) to high (passive)
Sun blocked by other structures
Quick installation
Need heat storage system
No CO2 emissions
Very low air and water pollution
High cost (active)
Figure 17.14
Trade-offs: advantages and disadvantages of heating a house with passive or active solar energy. QUESTION: Which single advantage and which single disadvantage do you think are the most important?
Very low land disturbance (built into roof or window)
Active system needs maintenance and repair
Moderate cost (passive)
Active collectors unattractive

66. Wind Energy the most rapidly growing source of electricity
Nondepletable
convert wind (kinetic) into electricity
Wind turns a turbine directly to create a flow of electrons

67. Wind Turbines & “Wind Farms”
Best in rural areas with lots of wind
Must be near transmission lines
Requires lots of land, but land can be used for other things (farming, ranching, habitat) or they can be placed off shore.

68. Wind energy capacity: US has the largest capacity, followed by Germany, China, India, and Italy.
US only produces 1% of its electricity via wind.
Denmark: largest user at 21% of their electricity

69. Land Turbines Pros Cons
Clean, inexpensive energy source that runs off of a nondepletable energy source
Can share space with other land uses: ranching/farming
Cons
Requires lots of space
Noisy/eye sore
Threatens migrating birds and bats
Public resistance
Not suitable everywhere
Construction costs/metal
Requires a back-up source or
batteries for storage

70. Offshore Wind Farms Turbines located 3-20 miles off shore
Offshore winds are stronger and often more reliable
Concerns include
Impact on marine wildlife during construction and possibly operation
Impact on bird and mammal migration
Transfer of electricity (loss over longer distances)

72. Wind Suitability

73. Hydrogen and oxygen are combined to produce electricity
Hydrogen Fuel Cells
Hydrogen and oxygen are combined to produce electricity
2 H2 + O2 → energy +2 H2O
No pollution! Only water vapor
Continues to produce electricity as long as supplied with fuel

74. Hydrogen Fuel Cell Car Benefit: 80% efficient - H2O only waste product
Problem: H2 gas is rare in nature – Have to generate using energy (electrolysis) & explosive – dangerous for collisions with H2 tanks, have to build distribution network
Hydrogen for Cars -

75. The Economics of Renewable Energy

76. Future Energy Solutions
Energy use in the near future will be a mix of renewable and non renewable energies.
As technology improves, current renewable energy sources will become more efficient and more common.
A move away from large central power producers will see an increase in more efficient regional power producers.
Household energy production, such as home solar water heating or battery storage, will play a major part in meeting the world’s future energy demands.
Renewable energy technologies will continue to become more efficient and affordable.
Water heating and electricity needs will increasingly become the task of small home based solar power devices.

77. Energy Solutions Government strategies
Subsidize energy resources to encourage use: tax breaks, rebates, research grants, regulations to stimulate development
Raise price to discourage use: tax, eliminate subsidies, regulations to restrict development
Public education: advantages and availability
Develop long range policies to transition to more sustainable energy sources

78. Energy: Source vs Use

79. Good Study Resource for Energy