Renewable Short Version

Renewable Energy for a Sustainable World Biomass Geothermal Photovoltaics Solar Thermal Wind 2003

Sustainable and Practical

Biomass plant, Vermont

Geothermal plant, California

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Sustainable and Practical

Wind turbines, Minnesota

Rooftop photovoltaics, Boston

Sustainable and Emerging

Solar thermal troughs, California

Solar central receiver and dish/engine, California

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Sustainable and Emerging

Utility-scale photovoltaics, California

Concentrator photovoltaics, California

Renewable Energy Is: • Environmentally responsible • Virtually inexhaustible • Available around the world • Supportive of local economies • Often cost-competitive with • existing energy sources • In many cases the most practical power option available, particularly in areas lacking well-developed energy delivery infrastructure

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Installed Capacity (MW) s as m o Bi

t eo G

al m r he

vo to o Ph

s ic lta r la So

al m r e Th W

in

d

• United States • Europe • Asia • Other

10,000 5,500 21,300 2,300 3,100

2,200 980

680

360 450

4,700 10

3,100 1,700

680 220

<1 <1

2,100 1,000

Worldwide:

20,900

7,980

2,030

370

29,100

(Estimated as of 2002. PV data reflect module sales; installed capacity is likely similar in total, but geographically different. Wind data from Windpower Monthly, January 2003. Biomass includes municipal solid waste.)

RENEWABLES’ ROLE IN THE 2004 U.S. ENERGY SUPPLY

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Resource Potential WIND

GEOTHERMAL

BIOMASS

PV

Biomass Electricity from Life Power generated from the combustion or gasification of organic material such as agricultural waste, forestry products residue, urban waste streams, and municipal solid waste.

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Biomass Installed Capacity There are nearly 21 GW (21,000 MW) of biomass capacity in the world: United States 10,000 MW Europe 5,500 MW Asia 2,300 MW Other 3,100 MW (Estimated as of 2002; includes municipal solid waste.)

Biomass Technologies Three Options: ●Direct-fired Combustion Burning biomass to create hot flue gases that produce steam in conventional boilers ● Cofiring Mixing or injecting biomass with coal or other fuels for combustion in traditional steam turbine boilers ● Gasification Converting biomass to a gas used as fuel in a boiler or gas turbine

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Biomass Technologies Direct-fired Combustion • Predominant process in use • As in conventional fossilfueled boilers, wood fuel is oxidized with excess air, creating hot flue gases that produce steam • More than 500 U.S. facilities use wood or wood residue in direct-fired systems to generate electricity

49-MW Wheelabrator Shasta plant, California

Biomass Technologies Cofiring with Coal Most practical, economical option

• Biomass can be substituted for up to 10% of a boiler’s coal input with minor modification of burner and feed intake • Minimal decrease in boiler efficiency

Biomass cofiring -NIPSCO’s

• Some studies indicate potential success cofiring as much as 20% biomass

Bailey station in Indiana

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Biomass Technologies

Cofiring: Low-sulfur, Low-cost Wood and most other biomass contains negligible sulfur and less ash than most coals Cofiring may yield NOx reductions of up to 20% in some cases Dry heating value of biomass is more than half that of bituminous coal

Bailey biomass feed system

Biomass Technologies Combined-Heat-and-Power Most direct-fired plants are combined-heat-and-power (CHP) systems run by paper mills and paperboard makers. Combustion generates both electricity and process steam or hot water Fewer than 20 are operated by electric utilities Some have buyback agreements to sell net excess generation to local utilities

Pulp and paper mill, Alaska

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Fuel Sources Whole-Tree Energy™ A dedicated feedstock approach that integrates tree farming with efficient power plants at the 100MW scale. • Whole trees are harvested, transported, dried with waste heat, and burned in a deepbed combustor • Cost reductions and demonstrations needed to achieve commercialization

Biomass Technologies Gasification A promising future • Converting biomass to a synthesis gas used in a combined-cycle gas turbine • New technique, not widespread • Potential advantages could make it a commercial workhorse of the future

Gasifier and loader, McNeil Station, Vermont

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Biomass Technologies Gasification: High Efficiency Combined-cycle system promise nearly twice the efficiency of older, smaller direct-fired combustion: • 37% vs. 20% efficiency • With combined-heat-andpower, where waste heat is captured and used, total efficiency could reach 80% Gasifier system, McNeil Station

Biomass Technologies Gasification: Cleanup Development of effective, economical gas cleanup process would open the door for gasification used with extremely efficient energy technologies: • Combined-cycle power plants • Electrochemical fuel cells

Gas sampling station on scrubber

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Biomass Fuel Sources Practical and Economic Issues • Feedstock type and diversity • Availability and cost • Location • Collection and transportation • Markets for potential byproducts Hybrid cottonwoods farmed as dedicated biomass

Biomass Fuel Sources

Short rotation hybrid poplars in Oregon, harvested for fiber and fuel

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Future of Biomass Near-term Improvements Next-generation of standalone biomass plants will be more cost-effective and efficient. • Expanded cofiring in coal plants • Improvements in direct-fired combustion technology

NREL Alternative Fuel Users research facility

• New high-efficiency gasification combined-cycle plants

Future of Biomass By 2010 Lower Cost, Expanded Use • Cofiring biomass with coal could generate 7 to 15 GW in the U.S. • Direct-fired combustion costs could drop to $1,300/kW or less • Gasification costs may fall to about $1,400/kW or less State University of N.Y. biomass research farm

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Future of Biomass 2010 and Beyond Mature and Productive • Cofiring will be widespread domestically and abroad • Gasification and/or advanced direct combustion will become a mature option, with costs nearing $1,000/kW • Dedicated feedstocks will contribute to stable energy price and supply

Geothermal Tapping the Heat of Earth’s Crust

The Geysers geothermal complex, California

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Hot springs in Steamboat Springs area. Source: National Renewable Energy Laboratory,

Resource Potential Energy from the Core

Subterranean heat is generated by friction from continental plates sliding against each other as well as natural radioactive decay. Geothermal power is most viable in areas that are geologically active, such as the “Ring of Fire” rimming the Pacific Ocean.

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Geothermal Tapping Earth’s Heat Electricity generated using high-pressure steam or hot water from within the Earth’s crust to— either directly or via a secondary working fluid—drive a steam turbine.

Geothermal Installed Capacity Used Internationally

Worldwide installed geothermal capacity is about 8,000 MW: • United States • Europe

2,200 MW 980 MW

• Asia

3,100 MW

• Other

1,700 MW

(Estimated as of 2002)

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Geothermal Resource Potential USGS estimates known, accessible hydrothermal (hot water/steam) resource to be about 23,000 MW for 30 years. Another 95,000 to 130,000 MW may yet be undiscovered.

Geothermal Technology Two Types: Hydrothermal Uses steam or hot water to power an electric generator Two techniques: Flash and Binary Well-developed technology used worldwide Hot Dry Rock Water is pumped through hot rock and returned to surface Still in early stages of development Ultimately promises much greater potential

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Hydrothermal Relatively Shallow Wells tap into permeable underground reservoirs of steam, hot water, or both. Resources include hightemperature steam, hightemperature water, and moderate-temperature water. Flashed-steam plant near Brawley, California

Hydrothermal: Flash High-Temperature Steam Water hotter than 200°C (392°F) “flashes” into steam as it is brought to surface and its pressure drops. This clean steam is used to directly drive a turbine. Steam jet at The Geysers

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Hydrothermal: Binary Moderate-Temperature Water The energy of water heated to 130-200°C (266-392°F) is transferred to a secondary working fluid with a lower boiling point. The working fluid vaporizes and drives a steam turbine. It is then cooled, condensed, and recirculated to be used again.

Binary plant, Heber, California

In Early Development Surface water is pumped into hot underground strata fractured by highpressure water injection.

Hot Dry Rock

Water heats as it flows through the rock, and is extracted as hot water or steam from a nearby well. Requires very deep wells; cost and risk currently high.

DOE hot dry rock research facility, New Mexico

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Geothermal Markets Cost-Competitive • The cost of hydrothermal power is often comparable to that of conventional electric generation today • Future hydrothermal plants will benefit from improved exploration, drilling, and reservoir risk management Heber Geothermal Power Station, California

The Future of Geothermal By 2010: Progress depends on many variables: • Steady technological improvement • Advances in finding new resources • Private and public R&D support • Economics of the energy industry Advanced drill bit developed by Sandia National Laboratories

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The Future of Geothermal Mid-21st Century: Nearly Boundless Reserves Cost of Hot Dry Rock systems may drop from $5,500/kW today to a still-high $2,700/kW by 2030. But: Some analysts estimate that mature Hot Dry Rock technology could ultimately produce millions of megawatts and provide enough electricity to meet the needs of the U.S. for centuries to come.

Photovoltaics (PV) Harnessing Sunlight Electricity generated by solid-state semiconductor devices with no moving parts, no noise, and no waste or atmospheric emissions of any kind while in operation.

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PV Resource Potential Across the U.S., annual incident solar energy varies from the national average by less than 40% PV can be useful virtually everywhere.

History Decades of Development PV technology advanced rapidly through the 1960s and 1970s. Space exploration drove demand for power sources that were simple, reliable, and able to operate in extreme environments.

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History Modern Applications Today’s PV uses show a wide range of size and power, including: • Solar-powered consumer goods such as calculators and watches • Remote communications equipment • Distributed generation for homes and businesses • Utility-scale bulk power generation

PV Technology How It Works Charges build up on PV semiconductor layers as they absorb the energy of photons, producing current. Individual solar cells typically generate just a few watts. But when combined into large arrays, they can comprise a substantial power plant.

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PV Technology Crystalline-Silicon • Monocrystalline Thin wafers sliced from large single crystals of silicon. The most efficient type of PV available. • Polycrystalline Ribbons or wafers containing many silicon crystals fused together. Less efficient than monocrystalline, but also less expensive.

PV Technology Thin-Film Newer technique in which layers of semiconductor material thinner than a human hair are built up on a low-cost rigid or flexible substrate. • Larger and potentially lighter • Automated production • Economical use of materials • Nearing commercialization

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PV Modules Two Types: Flat-Plate and Concentrator Flat-plate modules can use both direct and diffuse sunlight. They are the most common PV system design. Concentrator modules focus direct sunlight onto a PV cell. They currently serve niche markets.

Distributed Generation Residential, Commercial & Industrial Distributed generation is energy produced independently of the power grid, typically near its point of use. Features include: • Assured electricity supply and quality • Possible economic and environmental benefits • May operate either off-grid or interconnected to the grid as supplementary power

Residential rooftop PV

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Distributed Generation Remote Power

PV can provide reasonably priced electrification for areas lacking infrastructure. Often used when small electrical loads (less than 100 kWh/month) cannot be conveniently or economically connected to the grid. PV-powered water pump

Distributed Generation Building-Integrated PV Thin-film PV can be incorporated into building materials such as glass, siding, or roof shingles. • Helps reduce cost impact • Adds relatively little to overall cost of construction • Market expected to grow tremendously

New York skyscraper with thin-film PV windows

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Distributed Generation Energy Storage Many distributed PV systems use batteries to store electricity for later use. However, increasing numbers of utility “net metering” programs allow PV owners to feed excess power they generate into the grid, essentially using it as a 100%-efficient battery while reducing their electric bills.

Inverter and battery storage for a PV system

Utility-Scale Generation Modular Capacity As Needed Large PV systems typically installed to provide substation support. • Output highest on hot, sunny days when demand is greatest • Could help defer costly infrastructure expansion • Usually competes with grid power at wholesale level

210-kW grid support at substation

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Future of PV By 2010: Cost Continues to Fall • Residential-scale PV systems may drop to about $3.50 per peak watt • Sales could rise to 1 GW (1,000 MW) per year • Cumulative total installed capacity could reach 6 to 10 GW • Market for building-integrated PV could equal or surpass that for traditional flat-plate systems.

PV roof shingles

Future of PV: Increasingly Competitive Global PV Module Price Experience $100,000

Average Module Sales Price, Year-2000 Dollars/Peak Kilowatt

1976 1977 1978 1979 1980

1982 1985

$10,000

1990 1995 2000

2010

$1,000

$100 0.0001

0.001

Data source: Strategies Unlimited

0.01

0.1

1

10

Cumulative Module Sales, GWP

100

1000

T.M. Peterson, EPRI

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SOLAR ENERGY

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Solar Thermal Power from the Heat of the Sun

Electricity generated by focused or reflected sunlight that typically heats a working fluid, which in turn powers an engine or steam turbine.

Solar Thermal Resource Potential

Good

Best

Fair

Unlike photovoltaics, solar thermal systems need direct sunlight and move on one or two axes to track the Sun’s apparent motion. Many regions in the nation and world are suitable for solar thermal technologies.

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U.S. SOLAR INSOLATION MAP

2004 SOLAR ENERGY STATUS • • • • • • • • • • •

Total U.S. installed PV and solar thermal capacity is 0.5 GW Total world PV capacity is 4 GW with 1.8 GW being grid connected The nine parabolic trough plants for concentra-ting solar power produce energy at 12 – 14 ¢/kWh PV systems at APS facility in Prescott, AZ The price of power from grid-connected PV systems is 20 – 30 ¢/kWh

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Solar Thermal Energy from the Heat of the Sun

Solar One central receiver, Southern California, 1988

Solar Thermal Power Is: Efficient and Clean • Emission-free • Available worldwide • Increasingly costeffective • Dispatchable in some situations • Primarily for utilityscale application

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Installed Capacity Most Solar Thermal Power is Generated in U.S.

Interest is growing in Europe and elsewhere: United States

360 MW

Europe

10 MW

Asia

<1 MW

Other

<1 MW

(Estimated as of 2002)

Solar Thermal Technology Three Types: Solar Trough In “commercial” operation over 10 years, now producing power below 15¢/kWh Central Receiver Can efficiently store heat for dispatchable power

Dish/Engine Modular, portable

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Concentrating Solar Power

Solar Trough Parabolic Reflectors Rows of parabolic troughs focus sunlight on a tube containing a working fluid. • Troughs move to follow Sun • Recirculating fluid heats to • 300-400°C (570-750°F) • Fluid creates high-pressure steam that drives a turbine Reflective troughs, with tube of working fluid suspended at focus

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Central Receiver Large-scale Reflection Thousands of sun-tracking mirrors (“heliostats”) focus light onto a tower • Focused light heats a working fluid, such as molten salt • Heat exchangers create highpressure steam • Hot molten salt can be stored onsite to power turbines for more than 12 hours • Dispatchable solar power Solar One Central Receiver

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Central Receiver Productive Prototypes • Solar One 10 MW, Operated 1982-88, California Working fluid: water-steam • Solar Two 10 MW, Operated 1996-99, California Working fluid: molten salt • Solar Tres 15 MW, Design underway, Spain Working fluid: molten salt Solar Two

Dish/Engine Mirrors Focus Light on Engine • Hot working fluid powers an engine mounted on arm • Entire unit rotates to follow the Sun • Typical size: 25 kW • Modular: Capacity can be added where needed

25-kW Dish/Engine

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Development Status Solar Trough • The only solar thermal technology with extensive commercial experience • Component development, O&M improvements have continued to lower costs • No new plants completed since 1989

Wind Energy of Moving Air Power captured by bladed wind turbines whose spinning rotors generate electricity, often at a cost competitive with fossil fuel generation.

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Installed Capacity Wind Around the World

There are nearly 30 GW (20,000 MW) of wind power deployed in the world: United States

4,700 MW

Europe

21,300 MW

Asia

2,100 MW

Other

1,000 MW

(Estimated capacities as of January 2003)

NREL

2003 – 05 GLOBAL WIND 70000 CAPACITY 60000 11,769 50000 MW

8,207 40000 30000 20000 10000 0 2003

2004

2005

Source: Global Wind Energy Council

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GLOBAL INSTALLED WIND POWER CAPACITY (MW) – REGIONAL DISTRIBUTION Africa & The Middle East Asia Europe Latin America & Caribbean North America Pacific Region

Source: Wind Energy Fact Sheet, American Wind Energy Association, www.awaea.org

2005 INSTALLED WIND CAPACITY Asia 7,135 MW 12% Americas and Africa 10,979 MW 19%

total wind 59,322 MW

Australia 708 MW 1%

Europe 40,500 MW 68%

Source: Global Wind Energy Council

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Wind Turbine Design Wind turns a rotor linked to a generator to produce electricity. Key system components include gears, bearings, and brakes to control turbine movement. Transformers and control facilities are also necessary.

Applications Uses Tailored to Need: Windfarms Utility-scale power from large numbers of turbines Distributed: Clusters Medium level of power generated by a small group of turbines Distributed: Remote Small turbines used for offgrid or supplemental power Alta, Iowa

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Turbine Design Variable-Speed Turbines

Unlike traditional turbines that only rotate at one speed, a variable-speed machine spins at different rates in different wind conditions. • Makes more efficient use of wind energy • Reduces mechanical stresses NREL

• Prolongs turbine lifetime

Turbine Design Systems Growing Larger The size of wind turbines has grown steadily over the years. Today, individual turbine capacity is up to 2 MW, and is expected to soon reach 3 MW.

Worker entering hub of 1.5-MW turbine

NRE

L

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Applications Windfarms Scores of turbines acting as a single large power plant • Common approach in U.S. • Tens to hundreds of MW • Found in California, Texas, Minnesota, Iowa, Kansas • Electricity typically fed to grid via dedicated substation King Mountain, Texas

Expanding Markets Increasingly Cost-Effective As wind turbines become more efficient, the price of electricity they produce continues to drop: • 1985:

10-20¢/kWh

• 1990:

8-12¢/kWh

• 1995:

5-7¢/kWh

• Today:

2-4¢/kWh

Wind power is already competitive with bulk rates in many markets.

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Future of Wind By 2010 Wind will be an increasingly affordable source of bulk power • Low-speed direct-drive generators • Inexpensive sophisticated electronic controls • New advanced materials and components • Installed world wind capacity could exceed 140,000 MW

NREL

Future of Wind 2010 and Beyond Better cost, performance and reliability • Turbine size of about 1 MW will be optimal for large windfarm deployment in U.S. • Advanced short- and longterm wind forecasting will allow accurate capacity projections • Fully competitive wind power will grow via traditional market drivers NREL

Experimental turbine at National Wind Technology Center

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Environmental Impact As they operate, wind turbines:

• Consume no fossil fuels • Produce no greenhouse gases or other air emissions • Co-exist with other rural land uses such as ranching and farming

Kansas windfarm shares agricultural land

Environmental Impact Public Perception: Sight and Sound • Wind turbines are tall, often located atop hills and ridges • Plant layout, type of tower, and color can affect perception • Modern designs reduce noise with state-of-the-art blades and components

Community acceptance is vital to a wind power project’s success.

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Public Perception: Sight and Sound

Environmental Impact Another problem is that some environmentalists believe there is no good wind power, citing the turbines' noise and blaming them for the deaths of birds and other flying animals.

Community acceptance is vital to wind power success.

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