Chap. 14: Renewable Chap. 14: Renewable EnergyEnergy

By: Beth Theve Reggie McMillian Kim Curry Letta Johnson Eugene Mackey

Key TopicsKey Topics

• Putting Solar Energy to Work– How do you harness the sun?

• Indirect Solar Energy– Putting the wind in your sails.

• Renewable Energy for Transportation– What will we do when the oil runs out?

• Additional Renewable Energy Options– Ride a wave, anyone?

• Policy for a Sustainable Energy Future– Key Recommendations of the National Energy

Policy

What should you walk away What should you walk away with? with?

• A greater understanding of the potential for sustainable energy from sunlight, wind, biomass, and other sources.– Sun and wind are rapidly

becoming cost effective, reliable energy solutions that don’t pollute the air or depend on limited fossil fuel supplies.

– 6% of US energy use in 2002 were from renewable resources – we can use it, and we should!

Renewable Energy Use in the United States

Geo-thermal

5%Solar1%

Wind2%

Biomass Energy46%Hydro-

power46%

14.1: Putting Solar Energy to Work14.1: Putting Solar Energy to Work

• Some general solar energy concepts:– Solar energy originates from the sun.

• Fantastic! All the chemical and radioactive wastes stay there, light years away from us!

– Solar energy reaching the earth is radiant energy called the solar constant.

• 1,370 watts per square meter – that’s a lot of power!– Only about half of the energy that reaches the top of the

Earth’s atmosphere actually gets to the surface.• 30% is reflected, 20% is absorbed.

– At full sunlight, we can get about 700 watts per square meter with the sun directly overhead.

• That’s the same output as a large power plant!

General Concepts General Concepts continuedcontinued

• 40 minutes of solar energy striking the land surface of the United States yields the equivalent of a years’ expenditure of fossil fuel.

• The Sun delivers 10,000 times the energy actually used by humans today.

• Using solar energy does not hurt the energy balance of the biosphere.– Solar energy is eventually converted into heat

and is lost into outer space.

So why not use it for So why not use it for everything???everything???

• Solar energy is a diffuse source, meaning it’s widely scattered.– How do you collect it and turn it into readily

accessible, constant fuel sources for cars, computers, machinery, homes and offices?

– What if it’s cloudy one day? Or for a week? Or a month?

• The problems of utilizing solar energy involve collection, conversion, and storage.

Solar Heating of WaterSolar Heating of Water

• Flat-plate collectors– Faced toward the sun, the black

bottom gets hot and the clear cover prevents heat from escaping.

• Active system– Uses pumps to move heated water.

• Passive system– Relies on natural convection currents.

• In climates where water might freeze, a heat exchange coil is placed in the hot water tank.

– Antifreeze is circulated in the coil to keep the water from freezing when not heated.

• Only a small portion of the US uses solar water heaters.

– Cheaper to use, but more expensive to buy.

– Mostly used to heat pools.

Solar Space HeatingSolar Space Heating

• Can use flat plate collectors just like with water, but the greatest efficiency is achieved when the building acts as its’ own collector!– Windows facing the sun.

• In the winter, the sunlight can come in and heat the building.

• At night, insulated window coverings keep heat from escaping.

• Awnings can be used in summer to shield the windows to keep heat from entering.

LandscapingLandscaping

• Along with design, positioning and good insulation, landscaping can contribute to heating and cooling efficiency.– Deciduous trees or vines

on the sunny side of a house block excessive summer heat while letting winter sunlight pass through.

Earth Sheltered HousesEarth Sheltered Houses

• Uses earth as a form of insulation.– Earth has a high capacity for heat storage.– Walls are built with concrete or masonry so at night, they radiate stored heat.– In the summer, being “underground” helps keep the building cool.

• Humidity can be a problem.• Faces the house toward sunlight for passive solar energy collection.

– Large south-facing windows expose the interior to heat that can be stored in the earth and bricks.

But don’t you still need a But don’t you still need a backup?backup?

• What if it’s cloudy and cold for a week? Won’t my house freeze? How will I get warm water???– Good insulation works

wonders. When good insulation is used, little more than a small wood stove or gas heater is needed.

• But this question misses the point completely. – The point is to reduce our

dependency on limited fossil fuels. Even if it doesn’t replace the usage of these fuels completely, utilizing solar power still reduces the dependency greatly – and all the pollution fossil fuels cause.

Energy StarsEnergy Stars

• Created by the EPA in 2001– The Energy Star label is awarded to

public and corporate buildings that use at least 40% less energy than others in their class.• In 2 years, 1,000 buildings earned the label,

saving $130 million and reducing carbon dioxide emissions by 2.6 billion pounds.

Some folks don’t like solar Some folks don’t like solar energy…energy…

• Especially the ones making money off of fossil fuels.– In the 1980’s, utility and oil companies ran massive anti-

solar energy campaigns saying solar energy was expensive and impractical.

– They also lobbied to end incentive programs encouraging renewable energy usage.

• A solar tax credit program was ended that had increased solar powered water heater usage.

– In the 1990’s, fuel costs were low and the public had no reason to look for renewable fuel sources.

– In 2002, the World Summit gave in to pressure from fossil-fuel industries, and ended with a weak, watered down call to increase renewable energy.

Solar Power is Electric!Solar Power is Electric!

• Solar power can be used to create electricity, providing a safer, healthier alternative to coal and nuclear power.

Photovoltaic CellsPhotovoltaic Cells

• No moving parts, solar cells convert light energy directly to power with an efficiency of about 20%.

• Life span of around 20 years.

• Made with silicon, one of the most abundant resources on earth.

• Cost lies in intricate design and construction.

How are PV Cells used?How are PV Cells used?

• Today they are commonly used in calculators, watches, and some toys.

• Panels of PV cells provide power for rural homes, irrigation pumps, offshore oil-drilling platforms (ironic!) and more.

• Arrays placed in roof shingles provide power for some homes in the US.– Rooftop electrical output is

subtracted from customer’s use of power from the power grid, reducing energy costs.

Putting consumers to work to Putting consumers to work to harness more powerharness more power

• PV Pioneers in California– A local utility company pays homeowners $4 a month to

maintain a 2 to 4-kw PV system on their roof. These systems feed 3,600 kwhr/year back to the grid.

– Similar programs have begun in Japan.• Million Solar Roofs campaign

– A Federal initiative encourages installation of solar energy units on residential and commercial rooftops.

– The goal is one million rooftops by 2010.• Few financial incentives, but hopes to encourage grassroots efforts.

• The cost of PV Power is still more expensive than traditional electric harnessing methods.– In order for solar power to become routinely used, the

government needs to institute tax incentives and the price of PV power needs to drop.

Concentrating Solar PowerConcentrating Solar Power

• Government funding has developed several technologies for converting solar power into electricity using reflectors such as mirrors to focus concentrated sunlight into receivers that transfer heat to a turbogenerator.– Works well only where there is abundant

sunlight.

Methods of CollectingMethods of Collecting

• Solar Trough– Trough shaped reflectors tilted toward the sun with a pipe in

the center. A heat absorbing fluid is run through the pipe, heated to high temperatures, passed through a heat exchanger that creates boiling water which creates steam which feeds a turbogenerator.

• Power Tower– An array of sun-tracking mirrors that focus sunlight from

several acres of land into a receiver tower. The tower transfers heat to a molten salt liquid, which flows to either a turbogenerator or a tank for usage later.

• Dish Engine– A parabolic concentrator dish that focuses sunlight onto a

receiver. Fluid in the receiver is transferred to an engine that generates electricity directly.

The Promise of Solar Energy The Promise of Solar Energy Vs. Its DisadvantagesVs. Its Disadvantages

• Available solar technologies are still more expensive than conventional energy sources.

• However, the Available technologies:– Create air pollution– Destroy the earth through

strip mining– Create greenhouse

emissions – Create nuclear waste

• Is expensive to dispose of and has, in the past, been disposed of unethically in order to save money.

• Poisons our water, our land, and creates fatal and devastating illness in people, vegetation and wildlife.

The Promise of Solar Energy The Promise of Solar Energy Vs. Its DisadvantagesVs. Its Disadvantages

• Solar power only works in the daytime, and requires a backup energy source or storage battery for evening use.

• 70% of electrical demand occurs during daytime hours, when offices, industries and stores are open.– Using solar panels only

for daytime energy would drastically reduce our need for fossil fuels.

– Nighttime needs could be addressed by indirect solar energy, like wind or hydropower.

14.2: Indirect Solar Energy14.2: Indirect Solar Energy

• Indirect solar energies are:– Dams– Firewood– Windmills– Sails

• Why are these considered solar energies?– The sun is the driving force behind all of

these energy sources.

What is Hydropower?What is Hydropower?

• Hydropower is created by huge hydroelectric dams, where water under high pressure flows through channels, driving turbogenerators.– The amount of power generated depends on

the height of the water behind the dam. The water behind the dam provides pressure and controls the volume of water flowing through.

Hydropower FactsHydropower Facts

• About 6.7% of electric power that is generated in the U.S. comes from hydroelectric dams.

• Most of the hydro power comes from 300 large dams in the northwest and southwest of the country.

• Hydroelectric dams have a generating capacity of 780,000 m.w.

• Hydropower generates 17% of electric power worldwide.

The Hoover Dam in Westerville, Ohio.

The Advantages vs. The Advantages vs. The Disadvantages of The Disadvantages of

HydropowerHydropower• Eliminates the cost and

environmental effects of fossil fuels and nuclear power.– Non-polluting renewable resource.

• Equipment life expectancy is longer than traditional fuel-fired generators.

• Provides flood control on rivers in addition to supplying power.

• Provides irrigation water for agriculture.

• Reservoirs behind the dams provide recreational and tourist opportunities.

• Reservoirs behind dams can drown farmland, wildlife habitats and can destroy towns of historical, archaeological or cultural value.

– Glen Canyon Dams (located on the border of Arizona and Utah) drowned one of the worlds’ most spectacular canyons.

• Dams and large reservoirs often displace rural population.

– 40 to 50 million people have been displaced by dams in the last 50 years.

• Dams prevent the migration of fish according to Federal surveys.

• Because the flow of water is regulated according to the need for power, dams create ecological problems downstream.

– Water may go from flood levels to complete dryness in a single day.

• Dams cannot be increased due to a lack of space.

– U.S. has 75,000 dams 6’ high and 2 million smaller ones.

Where else are dams being Where else are dams being built?built?

• Laos built a dam 50 meters high.– Nam Theun Dam –

1,060 MW– Project on a tributary of

the Mekong River

• China is building a dam 185 meters high.– Three Gorges Dam –

18,200 MW– Built on the Yangtze

River, will be the largest hydroelectric dam in the world.

– The dam itself was completed in May, 2006. Scheduled for completion in 2009.

What is Wind Power?What is Wind Power?

• Wind power is the kinetic energy of wind, or the extraction and use of this energy.

– The most popular design for harnessing wind is the wind turbine. The propeller shaft is geared directly by a generator.

• Wind power usage has increased 28% per year in the last five years to 59,000MW in 2006.

– Supplies 1.3% of global electricity.– Will be supplying 12% of the world’s

electricity by 2020.– It already supplies 20% of the

electricity in Denmark.• Wind is the second fastest

growing energy source in the world (behind solar PV cells).

The Advantages vs. The Advantages vs. Disadvantages of Wind PowerDisadvantages of Wind Power

• Pollution free, sustainable power.

• Inexpensive at 5 cents per kilo-watt hour.

• Amount of wind that could be tapped is immense.– American Wind Energy

Association says wind farms located throughout the Midwest could meet the electrical needs for the entire country, with land below still used for farming.

• Farmers paid handsome royalties to install wind turbines on their farmland – $2-3,000 per turbine per year.

• Wind is an intermittent power source.– Storage or backup could

become an issue.• Wind turbines are not very

attractive.– Creates a gaudy, unpleasant

landscape.• Windmills are a hazard to

birdlife.– Windmills located on

migratory routes or near endangered species could cause serious problems.

An example: Offshore WindAn example: Offshore Wind

• The Nantucket Sound is located south of Cap Cod.– It is a body of water which

has continuous windy days. • Cape Wind Associates

purposed an offshore wind farm in that location. – 130 turbines each 417 feet

tall would spread over 24 square miles.

– Would be able to provide 75% of electricity to Cape Cod.

• But the people objected!– The turbines would threaten

tourism, navigation, fishing industry and migrating birds.

• Proponents for the project claim this is a classic case of “NIMBY”…– “Sure, I want clean energy

from renewable resources, but not in MY backyard!”

• The project has passed numerous reviews, and now awaits license from the U.S. government.

Biomass EnergyBiomass Energy

• Definition: Energy derived from present-day photo synthesis. – Burning wood in a stove– Burning municipal wastepaper and other

organic waste– Generating methane from the anaerobic

digestion of manure and sewage sludge– Producing alcohol from fermenting grains and

other starchy materials. Sounds Sounds Yummy, Yummy, right?!?!right?!?!

Firewood as an Energy Firewood as an Energy SourceSource

• Firewood is a primary source of energy for 2.6 billion people.– It accounts for 7% of total

energy used worldwide.• 5 million homes rely

entirely on wood for heating.

• 20 million people use wood for some heating.– Extra winter heat.– Nighttime heat.

• A Pellet Stove is a device that burns compressed wood pellets made from wood waste.

• Fuelwood Crisis– Two ways forest resources

will be exploited:• Consumptive use– in

developing countries people gather wood for daily needs, destroying forests.

• Productive– People gather wood converting it into charcoal and selling the wood products.

– Both have potential to degrade local forest and woodlands.

14.3: Renewable Energy for 14.3: Renewable Energy for TransportationTransportation

• Due to the decline in the oil reserves in our economy and global climate, there is a critical need for sustainable energy to fuel our vehicles.

• Two types of renewable energy are being used for transportation:– Bio-fuels– Hydrogen fuel cells

Bio-FuelsBio-Fuels

• A bio-fuel is an organic matter that can be processed to make fuels for vehicles.– These fuels are

primarily made of plants, but some also use animal wastes.

Bio-FuelsBio-Fuels

Ethanol Fuel• Produced by

fermentation of starches and sugars

• Suitable substance for MTBE– A petroleum derivative

used as a fuel additive to make burning of gasoline cleaner.

– Methyl, Teriary, Bitul, Ether

Bio Diesel Fuel• Made from vegetables.

– Usually made with 20% soybean oil, 80% normal diesel fuel

– Can be made from any natural oil or fat

• Truck exhaust that smells like french fries!– Sometimes made with

recycled restaurant frying oil

Two types of fuel are currently providing for 2% of transportation fuel needs globally:

HydrogenHydrogen

• Another alternative fuel source for conventional cars.

• Hydrogen is not a fuel, but carries energy like electricity generated with some other types of energy source.– Produces neither carbon dioxide nor

hydrocarbon pollutants.• Sounds great, right?? BUT…

…there is virtually NO pure Hydrogen gas available on Earth.

So How Can We Get It??So How Can We Get It??

• Electrolysis– Pass electricity through

water to release water molecules and collect hydrogen at the negative electrode.

• Plants do it!– Photosynthesis– Research being done to

mimic the action of the plants.

• Solar Energy– Generate large solar

trough or PV cells– Use this electricity to

produce hydrogen by electrolysis

– Move hydrogen via underground pipelines

• Need Hydrogen burning cars!– Model U by Ford.

Fuel CellsFuel Cells

• An alternative to burning hydrogen in conventional internal combustion engines.– Hydrogen is chemically

recombined with oxygen that creates electricity rather than burning.

– The only emissions are water and heat!

• Fuel cells now power buses in Vancouver, Chicago and 10 European Cities

• Versions being made by DaimlerChrysler, GM,

FreedomCARFreedomCAR

• “Cooperativeooperative Automotiveutomotive Research”– Launched by President Bush

in 2003• Government partnered

with automobile companies to move toward fuel-cell-powered vehicles.

• $1.7 million dollar budget over five years.

• Make fuel-cell cars competitive in automotive market by 2010.

14.4: Additional Renewable 14.4: Additional Renewable Energy OptionsEnergy Options

Geothermal Energy• What is Geothermal

energy?– The word geothermal

comes from the Greek words geo (earth) and therme (heat).

– It is useful energy derived from water heated by the natural hot interior of the Earth.

What is Geothermal Energy What is Geothermal Energy Derived from?Derived from?

• Volcanic energy cannot be harnessed (controlled and collected), but in a few places heat from the earth, called geothermal energy, can be collected.– Engineers try to collect this heat in the

rare places where the Earth's crust has trapped steam and hot water.

– They drill into the crust and allow the heat to escape, either as steam, or as very hot water. Pipes carry the hot water to a plant, where some of the steam is allowed to "flash," or separate from the water.   That steam then turns a turbine - generator to make electricity.

Is Geothermal Energy Widely Is Geothermal Energy Widely Used?Used?

• Geothermal energy was first used to produce electricity in Italy in 1903. 

• At the end of 2004, there were 43 power plants producing electricity from geothermal energy in the USA.  – Most of these are located in California and Nevada; Utah has

two geothermal plants and Hawaii, formed by volcanic eruptions, has one. 

• Generating power from geothermal sources is "site specific," meaning it's only possible in a few places under unique geologic conditions.  – The Geysers in California, can produce almost as much

electricity as all the other geothermal sites combined.

Ecosystem Capital Derived Ecosystem Capital Derived from Geothermal Energyfrom Geothermal Energy

• Geothermal Energy can be used to heat homes and businesses, or to generate electricity via turbogenerators.– In the year 2000,

geothermal energy provided over 8,000 MW of electrical power

– That’s equivalent to the output of eight large nuclear or coal powered plants!

The Science Behind The Science Behind Geothermal EnergyGeothermal Energy

• Some Scientist feels that the potential for geothermal energy has barely been tapped.

• They predict that with today’s technology, an additional 80,000 MW of electricity could be generated.

• Utilizing this natural energy would heat more homes and save thousand of dollars to consumers.

• It would also help eliminate dangerous pollutants.

Castle Geyser, Yellowstone Park

Tidal PowerTidal Power

• Tidal Power - Power achieved by capturing the energy contained in moving water in tides and ocean currents.

• There are two types of energy systems that can be used to extract energy:

– Kinetic energy - the moving water of rivers, tides as face ocean currents

– Potential energy – aquired from the difference in height (or head) between high and low tides.

• Kinetic Energy uses turbines. It is gaining popularity because of the lower ecological impact compared to potential systems that are similar to dams sometimes called barrages or tidal fences.

• Many coastal sites worldwide are being examined for the suitability to produce kinetic energy.

– Suitable Sites exhibit high water speeds which typically occur in channels such as the entrances to bays, rivers or between islands where water currents are concentrated

Kinetic Energy Turbines

The Global Impact of Tidal The Global Impact of Tidal PowerPower

• A tidal power scheme is a long-term source of electricity. – A proposal for the Severn

Barrage, if built, has been projected to save 18 million tons of coal per year of operation.

• Decreases the output of greenhouse gases into the atmosphere.

• Will help replace fossil fuel usage by the end of the 21st century.

Ocean Thermal Energy Ocean Thermal Energy Conversion (OTEC)Conversion (OTEC)

• OTEC harnesses the difference in temperature between surface waters to produce power.

• OTEC utilizes the temperature difference that exists between deep and shallow waters to run a heat engine.

– Done within 20° of the equator in the tropics.• The oceans are continually heated by the sun

and cover nearly 70% of the Earth's surface, so this temperature difference contains a vast amount of solar energy which could potentially be tapped for human use.

• If this extraction could be done profitably on a large scale, it could be a solution to some of the human population's energy problems.

– The total energy available is one or two orders of magnitude higher than other ocean energy options such as wave power.

– The small size of the temperature difference makes energy extraction difficult and expensive. Hence, existing OTEC systems have an overall efficiency of only 1 to 3%.

View of a land based OTEC facility at Keahole Point on the Kona coast of Hawaii

How Does That Work?!?How Does That Work?!?

• The concept of a heat engine is very common in engineering, and nearly all energy utilized by humans uses it in some form.

• A heat engine involves a device placed between a high temperature reservoir (such as a container) and a low temperature reservoir. As heat flows from one to the other, the engine extracts some of the heat in the form of work. – This same general principle is used in steam turbines and

internal combustion engines, while refrigerators reverse the natural flow of heat by "spending" energy.

• Rather than using heat energy from the burning of fuel, OTEC power draws on temperature differences caused by the sun's warming of the ocean surface.

14.5: Policy for a Sustainable 14.5: Policy for a Sustainable Energy FutureEnergy Future

• Global issues are social, political, economic and environmental issues that affect us all!– Fossil fuels, oil and natural

gases are being used at such a rapid rate that it will soon hinder production.

– An unhealthy daily dependence has been created that is increasing the atmospheric burden of carbon dioxide…the dreaded Greenhouse gasses.

Renewable EnergyRenewable Energy

• Renewable energy means sustainable energy.

• A sustainable energy future does NOT include significant fossil fuel usage.

• Globally, we should aim for:– Stable atmospheric levels of

greenhouse gasses, especially carbon dioxide

– An energy development and consumption pattern based on fuels that are renewable and safe to use.

National Energy PolicyNational Energy Policy

• The U.S. depends on importing over half of our oil, all of which is used for transportation.

• $200,000 leaves the U.S. every minute to pay for imported oil.– Enormous drag on our economy.

• Natural gas resources are being stretched thin to create electrical power.– Electricity prices tripled in 2002!

• Energy Security Problems– We are completely at the whim of OPEC and other oil

producers– Also vulnerable to terrorist attacks on various aspects of our

energy infrastructure.

Energy Policy ActEnergy Policy Act

“America must have an energy policy that plans for the future but meets the needs of today. I believe we can develop our natural resources and protect our environment”.

~ President George W. Bush

Renewable Energy & Efficiency Renewable Energy & Efficiency Hits and Misses of the Energy Hits and Misses of the Energy

Policy ActPolicy Act

Does:• Attempt to combat

growing energy problems

• Provide tax incentives

• Provides loan guarantees for energy production of various types.

Does Not:• Include a Federal

Requirement thato That utilities purchase a

certain percentage of electricity from renewable sources. o Wind, solar, bio-mass

o Address Global Warmingo Greater energy efficiency

and the use of renewable energy sources would reduce greenhouse gas emission in the U.S.

Questions?Questions?