© 2010 Pearson Education Canada

17New Renewable Energy Alternatives

PowerPoint® Slides prepared by Thomas Pliske, Heidi Marcum, and Nicole Lantz

This lecture will help you understand:

•The major sources of renewable energy •Solar energy •Wind energy•Geothermal energy •Ocean energy •Hydrogen fuel cells

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Housekeeping Item: If you haven't already referenced your life-cycle analysis, use APA.See http://libguides.viu.ca/content.php?pid=47063&sid=399090

HOUSEKEEPING ITEMS

For those of you in Section 2, today is the Urban Issues Film Fest, starting at 3:30 in Building 355, Room 203, with Jim Green, Downtown East Side activist from Vancouver. Films will follow, along with free food, in Building 356, Room 109, around 5:00 or 5:30. We can always use volunteers so show up at 4:45 and help if you can!

The life cycle analyses are due today. Read the rest of the notes on Chapter16

(Conventional Energy Alternatives) on your own. Today, we will cover Chapter 17. In Section 2, I will show a video next Wednesday that is relevant to waste issues, but because of the holiday I won't be able to show it on Thursday.

Harnessing tidal energy at the Bay of Fundy

• The Bay of Fundy has the largest vertical difference between high and low tide in the world

• One of three tidal power plants in the world

• Nova Scotia Power is working on in-stream tidal power technologies for 2010 that would eliminate the need for a dam or sluice

“Not only will atomic power be released, but someday we will harness the rise and fall of the tides and imprison the rays of the sun.”

– Thomas A. Edison, 1921

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© 2010 Pearson Education Canada

“New” renewable energy sources

• “New” renewables are a group of alternative energy sources that include

- Energy from the Sun, wind, geothermal heat, and movement of the ocean water

• They are commonly referred to as “new” because:

- They are not yet used on a wide scale

- Their technologies are still in a rapid phase of development

- They will play a much larger role in our energy use in the future

The “new” renewables currently provide little of our power

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FIGURE 17.1

© 2010 Pearson Education Canada

The new renewables are growing quickly

• Solar power has grown by 28% each year

• Wind power has grown by 48% each year

FIGURE 17.2

• Manufacturing, installing, and servicing renewable energy is more labour-intensive than for fossil fuel

A switch to renewable energy should increase employment

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FIGURE 17.3

© 2010 Pearson Education Canada

Our transition must begin soon

• Federal funding for energy research and development has plummeted in Canada over the past 20 years

FIGURE 17.4

© 2010 Pearson Education Canada

Solar energy

• Passive solar energy = the most common way to harness solar energy

• Buildings are designed to maximize direct absorption of sunlight in winter and keep cool in summer

• Active solar energy collection = uses technology to focus, move, or store solar energy

• Solar energy has been used for hundreds of years

Passive solar heating is simple and effective

• Low south-facing windows maximize heat in the winter - Overhangs on windows block light from above in

the summer• Thermal mass = construction materials that absorb,

store, and release heat• Planting vegetation in strategic locations• By heating buildings in winter and cooling them in

summer, passive solar methods conserve energy and reduce costs

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Active solar energy collection can heat air and water in buildings • Flat plate solar collectors

(solar panels) = one active method for harnessing solar energy

- Water, air, or antifreeze pass through the collectors, transferring heat throughout the building

- Heated water is stored and used later

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FIGURE 17.5

Concentrating solar rays magnifies energy

• Power tower = mirrors concentrate sunlight onto receivers to create electricity

• Solar-trough collection systems = mirrors focus sunlight on oil in troughs

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FIGURE 17.6

Photovoltaic cells generate electricity directly

• Photovoltaic cells = collect sunlight and convert it into electrical energy

- These are used with wind turbines and diesel engines

• Photovoltaic (photoelectric) effect = occurs when light strikes one of a pair of metal plates in a PV cell, causing the release of electrons, creating an electric current

• A PV cell has two silicon plates, the n-type layer (rich in electrons) and the p-type layer (electron poor)

- Sunlight causes electrons to flow from the n-type to the p-type layer, generating electricity

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A typical photovoltaic cell

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FIGURE 17.7

Solar power is little used but fast growing

• Solar energy was pushed to the sidelines as fossil fuels dominated our economy

• Solar energy use has grown by 28% worldwide

• Canada lags behind solar energy use in Germany, Japan and elsewhere

• Attractive in developing countries

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Global production of PV cells grew sixfold

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FIGURE 17.8

Solar power offers many benefits

• The Sun will burn for 4 - 5 billion more years

• Solar technologies are quiet, safe, use no fuels, contain no moving parts, and require little maintenance

• They allow local, decentralized control over power

• Developing nations can use solar cookers, instead of gathering firewood

• Net metering = PV owners can sell excess electricity to their local power utility

• New jobs are being created

• Solar power does not emit greenhouse gases and air pollution

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Location and cost can be drawbacks

• The yearly average of Canada’s populated areas exceeds that in both Germany and Japan

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FIGURE 17.9

Wind has long been used for energy

• Wind turbines = devices that harness power from wind

• Windmills have been used for 800 years to pump water to drain wetlands and irrigate crops and to grind grain into flour

• The largest wind power producer in Canada is the Le Nordais project in the Gaspé Peninsula

• Today, wind power produces electricity for nearly the same price as conventional sources

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Modern wind turbines convert kinetic energy to electrical energy• Higher is better to minimize turbulence and maximize wind speed

• Turbines rotate in response to wind direction

• Doubled wind velocity results in an eight-fold increase in power output

17-21FIGURE 17.10

Wind is the fastest-growing energy sector

• Wind power grew 26% per year globally between 2000 and 2005

• Only a very small portion of this resource is currently being tapped

• In Canada, wind power could meet 15% of the nation’s electrical needs

• Denmark is the leading manufacturer of wind turbines and derives 20% of its electricity from that source.

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Offshore and high-elevation sites can be promising

• Wind speeds are 20% greater over water than over land

• There is less air turbulence over water than land 17-23

FIGURE 17.12

Wind power has many benefits

• Wind produces no emissions once installed

• It prevents the release of CO2

• It is more efficient than conventional power sources

• Turbines also use less water than conventional power plants

• Farmers and ranchers can lease their land

- Produces extra revenue

- Landowners can still use their land for other uses

• Advancing technology is also driving down the cost of wind farm construction

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Wind power has some downsides – but not many

• We have no control over when wind will occur

• Companies have to invest a lot of research before building a costly wind farm

• Good wind sources are not always near population centres that need energy

• When wind farms are proposed near population centers, local residents often oppose them

• Wind turbines also pose a threat to birds and bats, which can be killed when they fly into rotating blades

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Wind and NIMBY

• If you could choose to get your electricity from either a wind farm or a coal-fired power plant, which would you choose?

• How would you react if the electric utility proposed to build the wind farm such that the turbines would be clearly visible from your living room window?

• Would you support or oppose the development? Why?

• If you would oppose it, where would you suggest the farm be located? Do you think anyone might oppose it in that location?

weighing

the issues

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Geothermal energy

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FIGURE 17.15

Geothermal energy

• Renewable energy is generated from deep within the Earth

• Radioactive decay of elements under extremely high pressures deep inside the planet generates heat

- This heat rises through magma, fissures, and cracks

• Geothermal power plants use heated water and steam for direct heating and generating electricity

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Geothermal energy is renewable in principle

• But if a geothermal plant uses heated water faster than groundwater is recharged, the plant will run out of water

- Operators have begun injecting municipal wastewater into the ground to replenish the supply

• Patterns of geothermal activity shift naturally

- An area that produces hot groundwater now may not always do so

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We can harness geothermal energy for heating and electricity

• Geothermal ground source heat pumps (GSHPs) use thermal energy from near-surface sources of earth and water

- The pumps heat buildings in the winter by transferring heat from the ground into buildings

- In the summer, heat is transferred through underground pipes from the building into the ground

- Highly efficient, because heat is simply moved

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Use of geothermal power is growing

• Currently, geothermal energy provides less than 0.5% of the total energy used worldwide

- It provides more power than solar and wind combined

- But much less than hydropower and biomass

• Commercially viable only in British Columbia

• In the right setting, geothermal power can be among the cheapest electricity to generate

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Geothermal power has benefits and limitations

• Benefits:

- Reduces emissions

- It does emit very small amounts of gases

• Limitations:

- May not be sustainable, as CO2 can be released

- Water is laced with salts and minerals that corrode equipment and pollute the air

- Limited to areas where the energy can be trapped

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Ocean Energy: We can harness energy from tides, waves and currents

• The rising and falling of ocean tides twice each day throughout the world moves large amounts of water

• Differences in height between low and high tides are especially great in long narrow bays

• These areas are best for harnessing tidal energy by erecting dams across the outlets of tidal basins

• See CBC clip: http://archives.cbc.ca/science_technology/energy_production/topics/1750-12014/

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Energy can be extracted from tidal movement

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FIGURE 17.16

Wave energy

• Can be developed at a greater variety of sites than tidal energy

• The motion of wind-driven waves at the ocean’s surface is harnessed and converted from mechanical energy into electricity

• Offshore or coastal

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FIGURE 17.17

Ocean currents• Harnesses marine kinetic energy by using the motion of ocean

currents, such as the Gulf Stream

• Underwater wind turbines have been erected in European waters to test this idea

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Source: Google

The ocean stores thermal energy• Each day, the tropical oceans absorb an amount of solar

radiation equal to the heat content of 250 billion barrels of oil

• The ocean’s surface is warmer than deep water

- Ocean thermal energy conversion (OTEC) is based on this gradient in temperature

- Closed cycle approach = warm surface water evaporates chemicals, which spin turbines

- Open cycle approach = warm surface water is evaporated in a vacuum and its steam turns turbines

- Costs remain high and no facility is commercially operational

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Hydrogen

• The development of fuel cells and hydrogen fuel shows promise to store energy in considerable quantities

- To produce clean, efficient electricity

• A hydrogen economy would provide a clean, safe, and efficient energy system

• 2004: Hydrogen Village (H2V) launched in the Greater Toronto Area

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A typical hydrogen fuel cell

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FIGURE 17.18

A hydrogen-fueled bus

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FIGURE 17.19

Hydrogen fuel may be produced from water or other matter

• Electrolysis = electricity is input to split hydrogen atoms from the oxygen atoms of water molecules

2H2O 2H2 + O2

- Produces pure hydrogen

- Will cause some pollution depending on the source of electricity, but less than than other processes

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Other ways of obtaining hydrogen

• Hydrogen can also be obtained from biomass and fossil fuels, such as methane (CH4)

CH4 + 2H2O 4H2 + CO2

- Results in emissions of carbon-based pollution

- Leakage of hydrogen could deplete stratospheric ozone

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Precaution over Hydrogen?

Some have recently warned about replacing fossil fuels with hydrogen fuel. An increase in hydrogen gas would deplete hydroxyl (OH) radicals, they hypothesize, possibly leading to ozone depletion and global warming.

• Do you think we should apply the precautionary principle to the development of hydrogen fuel and fuel cells?

• Or should we embark on pursuing a hydrogen economy before knowing all the scientific answers?

• What factors inform your view?

weighing

the issues

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Fuel cells produce electricity

• Once isolated, hydrogen gas can be used as a fuel to produce electricity within fuel cells

• The chemical reaction involved in that fuel cell is the reverse of electrolysis

2H2 + O2 2H2O

• The movement of the hydrogen’s electrons from one electrode to the other creates electricity

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Hydrogen and fuel cells have many benefits

• We will never run out; hydrogen is the most abundant element in the universe

• Can be clean and nontoxic to use

• May produce few greenhouse gases and other pollutants

• Can be no more dangerous than gasoline in tanks

• Cells are energy efficient

• Fuel cells are silent and nonpolluting and won’t need to be recharged

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Conclusion

• Many people are convinced that we need to shift to renewable energy

• Renewable sources include solar, wind, geothermal, and ocean energy sources and hydrogen fuel

• Renewable energy sources have been held back by inadequate funding and by artificially cheap prices for nonrenewable resources

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QUESTION: Review

Which of these is not a passive solar technique?

a) The use of thermal mass

b) Using flat-plate solar collectors

c) Installing low, south-facing windows that will maximize sunlight capture in the winter

d) Using strategically planted vegetation

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QUESTION: Review

We can harness power from wind by using devices called:

a) Wind turbines

b) Wind parks

c) Wind farms

d) Solar cells     

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QUESTION: Review

Turbines can be erected singly, but they are most often erected in groups called:

a) Wind turbines

b) Wind farms

c) Wind mills

d) Solar cells     

        

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QUESTION: Review

Which energy source may not be renewable, and is laced with minerals that corrode equipment?

a) Solar panels

b) Wind energy

c) Geothermal energy

d) Hydrogen fuel cells

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QUESTION: Interpreting Graphs and Data

What conclusions can you draw from this graph?• Production of PV cells grew

rapidly and price fell rapidly

• Production of PV cells fell rapidly and price fell rapidly

• Production of PV cells grew rapidly and price grew rapidly

a) Production of PV cells fell rapidly and price grew rapidly

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FIGURE 17.8