wind energy - colorado state university

Wind Energy

Irene Shonle CSU Extension in Gilpin County

Parts of this were adapted from presentations by Tony Jimenez, NREL Mike Kostrzewa, CSU

Sarah Hamlen, MSU Extension Windpowering America

AWEA

Acknowledgements

Why wind?

• Emissions-free, non-depletable electricity

• Fuel cost will never increase

• Job creation/rural economic development

• Domestic power source

Energy in an arid land

• A typical 500-megawatt coal-fired power plant draws about 2.2 billion gallons of water each year. – This is enough water to

support a city of approximately 250,000 people.

• Wind needs no water

• EPA: Electricity generation uses more water than agriculture

westernresourceadvocates.org

1999-2013 installed wind capacities (2,500 MW- 61,108 MW)

Wind capacity • Wind power was the #1

new sources for electricity generating capacity in 2012 – wind power provided 42% of

all new generating capacity installed.

• In 2013, wind provided 30% of new US generating capacity – But for the first time, solar

outpaced wind in 2013 on global market

• Renewables currently produce about 13% of all electricity in US

Chart from U.S. Energy Information Administration

Wind power today

• Wind energy installations power the equivalent of more than 15.5 million homes.

• American wind power reached major power generation milestones in 2013 – 4% of U.S. electricity

National: 20% by 2030 (2008 report by DOE)

• US has affordable wind energy resources far in excess of those needed to enable a 20% scenario (no technological breakthroughs are needed)

• To implement: – new wind power installations would increase to

more than 16,000 MW per year by 2018 – continue at that rate through 2030

National: 20% by 2030

• The U.S. wind industry could support : – 500,000 jobs in the U.S.

• > 150,000 workers directly employed by the wind industry • > 100,000 jobs in associated industries (e.g., accountants, lawyers,

steel workers, and electrical manufacturing) • > 200,000 jobs through economic expansion based on local

spending;

– increase annual property tax revenues to more than $1.5 billion by 2030

– increase annual payments to rural landowners to more than $600 million in 2030.

Major challenges to 20% wind

• Transmission systems for the increased supply

• Developing larger electric load balancing areas on regional basis

• Significant growth in the manufacturing supply chain

• Addressing potential concerns about local siting, wildlife, environmental issues, public acceptance

Credit: Warren Gretz, NREL From EERE news

Growing public acceptance

• 10x as many positive attitudes towards wind energy than negative attitudes.

• Wind tourism on rise – People are paying to

tour wind farms, hotels/b&bs are advertising their proximity to farms

– (Ecotourism)

Birds and Bats

• Audubon Society supports properly sited wind power – the threat posed to birds by climate change is greater than turbines – Opposes new 30-year permits to kill and injure eagles

• Wind farms need to be planned, sited, and operated in ways that minimize harm to birds and bats

• 2.9 - 8 birds are killed per turbine each year • Bigger turbines may have more impacts. • Impacts may increase as # turbines increase

• Reducing “cut in speed” during high risk times for bats may reduce mortality 50-87%

Causes of bird mortality

http://www.sibleyguides.com

Cost of wind declining

• Turbine prices have fallen 26 percent worldwide since 2009, 90% since 1980 – wind power is within 5.5 percent of the cost of electricity from coal

(source: Bloomberg. MidAmerican Energy Holdings Co.)

Utility perspective: wind as hedge • “Wind prices are extremely competitive right now, offering lower costs

than other possible resources, like natural gas plants. These projects offer a great hedge against rising and often volatile fuel prices." - David Sparby, president & CEO of Xcel Energy’s Northern States Power announcing 600 MW of new wind power contracts on July 16, 2013.

• "The latest addition of 150 megawatts of low-cost wind energy provides AECC with a hedge against fluctuating natural gas energy prices […] We will continue to pursue energy options that allow AECC’s member cooperatives to provide reliable electricity at the lowest possible cost.” - Duane Highley, president & CEO of Arkansas Electric Cooperative Corporation after signing a 150 MW contract July 22, 2013

Onshore wind energy & natural gas most affordable options for new electricity generation

The Energy Information Administration

Production tax credit ended this year

• PTC was “predominant driver of wind energy development over the past decade.”

• Breaking news – may be retroactively renewed until 2015

PTC Impact on 2013

• Threat of loss stimulated more U.S. (MW) under construction than ever in 2013 – 12,000 MW under construction,10,900 MW

started construction activity during the fourth quarter.

– Rules changed so that wind farms only had to be “under construction” by the end of the year

Where wind power has shone

• Winter 2013-14 – record cold, natural gas shortages, power plant failures due to cold, record winter electricity demand – wind energy filled in supply

gaps in regions with large wind energy capacity

– At peak demand in late January, wind energy was saving $1.5 to $2 million per hour

Times when wind energy has flagged

• Texas heat 2011, 2012: record electrical demand (air conditioning) – high pressure systems

stalled winds – Wind provided just 1.3%

of demand, despite a 10% capacity

Wind and solar complementary

• Wind is often more productive in winter and at night

• Solar more productive in summer and during the day

Grid integration

• Wind energy can be ramped up or down to enhance system reliability – using wind farms to provide active power control

is economically beneficial, negligible damage to the turbines

• Power plants can also be ramped up and down – The increase in plant emissions from cycling to accommodate variable

renewables are more than offset by the overall reduction in CO2, NOx, and SO2. In the high wind and solar scenario, net carbon emissions were reduced by one third. (NREL Western Wind and Solar Integration Study)

Distributed wind

• 68 % (69,000 turbines, 812 MW) of all wind turbines in U.S. between 2003-2012 were distributed wind turbines

• 33% (3,800 turbines, 175 MW)of all wind turbines installed in the U.S. in 2012 were distributed wind turbines

• 50 % decrease in distributed turbine installations but increase in power production of 62%

-- Shift to larger turbines

Storage – will be game changer when feasible on large scale

• Harvard University developed a new type of battery --1/3 cost – store a couple of days of

electricity – based on plant

molecules called Quinones

Colorado – RE Bill 30% by 2020

• Colorado -- large utilities must obtain 30% of

their power from renewable sources by 2020 (March 22, 2010)

• Electric cooperatives and municipal utilities (over 40,000 customers) must provide 10 percent of their retail electricity sales from renewables by 2020.

Colorado wind power 2013

• Currently online: 2,392 MW at 10 farms (870,000 homes) • Percentage of electricity from wind 13.8% (up 2%) • 10th highest % of power in US (down from 6th last year, wind

resource is 13th) • Total direct and indirect jobs support in 2012: 4000-5000. • Capital investment: over $4.2 billion dollars • Annual land lease payments: over $7,500,000 • 19 manufacturing facilities

Wind energy basics

Power from the wind

•Power in the wind • Effect of air density, ρ • Effect of swept area, A • Effect of wind speed, V

R

Power in the Wind = ½ρAV3

Wind Speed (V)

• Most important part of equation

• Power is a cubic function of wind speed – V X V X V – 20% increase in wind speed

means 73% more power – Doubling wind speed means 8

times more power

power =½ρAV3

Effect of wind speed on production

• Same turbine, two different wind regimes: – Yampa (8.3 mph)

• 1200 kWh/year – Sheep Mtn: (18.4 mph)

• 6,500 kWh/year

Take home lesson: put turbines in areas with a good wind regime

Mountains have strong winds, but…

• Viewshed issues • Roadless areas • Forest Service issues • Severe winter weather • Costly to connect • Difficult to access for

maintenance

Economically viable projects: Utility-scale projects: class 4+ Residential scale: class 2+

On-grid vs off grid needs

• On-grid: should have winds of 9-12 mph • Off-grid 6 or 7mph

Estimating your wind resource

• People make very poor anemometers. • Use projected or real data

Sources of Projected Wind Data Wind Maps (Static and interactive)

• State wind maps: http://www.windpoweringamerica.gov/windmaps/residential_scale.asp

•Wind map US 30 m http://www.nrel.gov/gis/images/30m_US_Wind.jpg •US wind map 80m http://www.nrel.gov/gis/images/80m_wind/USwind300dpe4-11.jpg

Sites that charge:

•3TIER First Look: http://firstlook.3tiergroup.com/

•AWS Truewind Wind Navigator: http://navigator.awstruewind.com/

The values assume good exposure to the wind

New! Wind speeds at lower hub heights for residential scale

Realities of wind assessment with free projected data

• They use publicly available data – Accuracy varies – Difficult to know which data were used – May not know hub height of collection – Seasonality calculations can be off for

mountainous regions • Provide a “guesstimate” --uncertainties in the

average wind speed values are significant! • could be off by a wind class or two (viable not viable)

Sources of real data

• Anemometer loan program in Colorado run by CSU

• On-site “reality check” with an anemometer recommended if your project is 50-100kW

Colorado ALP program has data from 104 sites

46

Colorado ALP Data • Data collected by the ALP is run through a

software program called Windographer • Windog provides an estimate of the all-

important bottom line -- kWh

Capacity factor

Capacity factor is the ratio of the actual energy produced in a given period, to what the turbine would produce if it were running full time at rated power.

Small turbines usually have a capacity factor of

0.1-.25 Big turbines (wind farms): 0.2-.45

Ways to wring out maximum kWh at a specific site

Increase V by going higher

“Micro-Siting” to maximize generation at a site

“

Pay attention to prevailing wind direction when micro-siting

Minimum tower height • The entire rotor of the

wind turbine must be at least 30 feet above anything within 500 feet of the tower. Min 30’

500’

Two minute activity

• What would be the minimum tower height at your house/or a site you’re interested in?

• Where would you best place it (consider prevailing winds, trees, etc)

Go beyond the minimum height for best results “ More tower, more power” - Steve Wilke of Bergey Windpower

Tower height (feet)

Wind speed (mph)

kWh/ year

60 7.3 2,709

80 9.3 6,136

100 10.7 9,338

Analysis from Mick Sagrillo, RenewWisconsin

Does the expense of a taller tower negate the increased power?

Tower height (feet)

Wind speed (mph)

kWh/year System cost

Incremental cost from 60’

Incremental energy output from 60’

60’ 7.3 2,709 $48,660 -- ---

80 9.3 6,136 $49,841 $1176 or 2.4%

226% (94:1 ROI)

100 10.7 9,338 $51,346 $2681 or 5.5%

344% (63:1 ROI)

From Mick Sagrillo, RenewWisconsin.org

Indiana – class 3 to class 5

Micrositing: wind speeds strongest on hilltops, ridges, turbulent on lee side

Bigger turbines produce more power

• A= π x Radius²

– Doubling the rotor diameter increases swept-area by four times.

Remember: P= ½ρAV3

This is why utility scale turbines keep getting bigger!

Betz’s law

• No turbine can capture more than 59.3% of the kinetic energy in wind. The factor (0.593) is known as Betz's coefficient.

• Practical utility-scale wind turbines achieve at peak 75% to 80% of the Betz limit

The effect of air density - ρ

•Humid >dry

•Lower elevations > higher elevations •Wind energy in Denver about 14%

less than at sea level

P= ½ρAV3

Technology basics

TURNING WIND ENERGY INTO ELECTRICITY

This is the “hub” or “hub height”

02770329

Load

Meter

Inverter AC

Wind turbine

On-Grid Wind System without Storage

Off-grid systems

Also require batteries, inverter

Towers are a critical component

Guyed Tower Tilt-Up Tower Monopole Guyed-Latticed Tilt-up Latticed

Types of turbines

Horizontal Axis Wind Turbines • Rotors are usually

Upwind of tower • Most common,

most reliable

Source: KidWind

Vertical Axis Turbines

Advantages • Components usually

mounted at ground level – Ease of service – Lighter weight towers

• Can theoretically use less materials to capture the same amount of wind

Disadvantages • Rotors generally near ground

where wind poorer • Centrifugal force stresses blades • Poor self-starting capabilities • Requires support at top of

turbine rotor • Requires entire rotor to be

removed to replace bearings • Overall poor performance and

reliability – Have never been commercially

successful Source: KidWind

Darrieus Savonius

More on VATs

• None have been certified by Small Wind Council

• Most have dramatically underperformed marketing claims – no one has

produced a VAWT that is more cost effective than a conventional wind turbine

– “Can take wind from any direction.” So does any conventional wind turbine.

– “No tower required” Remember, less wind at lower hub height

– • “Allows for ease of maintenance on the generator.” The components that need attention are usually the blades, rotor bearings, and governing device- more difficult to access with many vertical axis designs than their horizontal-axis counterparts.

– • “Small rotor profile.” Small rotor= small energy output

The Myths & Mysticism of Vertical Axis Wind Turbines --Mick Sagrillo

“Urban turbines”

• Seem like a good idea – small, distributed wind on buildings

• Disappointing reality – too much turbulence,

not enough wind, potential vibration/structure integrity issues

• See paper on the Warwick Wind Trials

Comparing turbines

• Standardization coming with advent of Small Wind Certification Council; not yet widespread (only 8 certified so far)

Rated power: “Size” or power produced by turbine at rated wind speed

Small (≤10 kW) • Homes • Farms • Remote Applications

(e.g. water pumping, telecom sites, icemaking)

Intermediate (10-1000 kW) • Village Power • Hybrid Systems • Distributed Power

Large (1 MW+) • Distributed Power • Community Wind • Utility wind

Wind speed for rating not fully standardized

– Two generators, both rated at 1,000 watts (1 kW) • Generator 1 – rated at 16 mph • Generator 2 – rated at 32 mph • At 32 mph, both produce 1,000 watts • But at 16 mph, Generator 1 is producing 1,000 watts,

but Generator 2 is producing 1/8th of that amount or 125 watts

– (based on power from wind)

• It tells you nothing about how much energy it produces at YOUR site!

Canadian Wind Power Atlas

Power Curves used for energy output estimation – need to be run through a calculator spread sheet

CUT-IN SPEED

• Wind speed at which generator begins producing power – Wind speeds below 6-7

mph provide little to no usable energy

• Some new equipment have controllers which “store” some of the small amounts of energy produced a low wind speeds

• Wind speed at which generator governor kicks in to reduce exposure to wind – Some turbines will keep

producing at rated power in high winds (Jacobs), some will all but shut down.

• Survival wind speed: maximum wind speed that the wind turbine is designed to withstand safely.

CUT-OUT SPEED

Cut-in and cut-out

• Easy to measure and not subject to differing definitions or standards – Provides easy

comparisons between machines

– “New” technology may influence production, but overall square footage is greatest determining factor.

“What we really want to

know is kWh per month, but until we get more independent testing done, swept area is a good guide.”

» Mike Kleman

Better to compare rotor diameters than rated power

Energy output curves

Annual Energy Output

• Best measure and most easily compared – Many are provided by manufacturers in a range of

average annual wind speeds of 8 to 14 mph

• Determining calculations can be difficult for a consumer – Highly dependent on accurately pegging the

average wind speed! – Some experts suggests that you multiply the AEO

provided by 75% to account for overstatement of actual

Small Wind Certification Council

• Certifies Small Wind Turbines: The SWCC is an independent

certification body created to serve the North American market.

• Issue Consumer Labels: SWCC issues certified turbines easy-to-understand labels for:

• Rated Annual Energy Output • Rated Power • Rated Sound Level. • The label also confirms that the turbine meets durability and

safety requirements.

• www.smallwindcertification.org

The Bergey Excel 10 was the first turbine to be issued a label 11/16/2011 (many more are in the works)

Calculating paybacks

Cost of small wind system

• Rough cost estimates of $4K-$8K per kW (installed)

• To off-set almost all consumption of average CO home (8982 kWh), would need a 5-11 kW system at $6K/kW=

$30,000- $66,000 • Insurance and financing (if even possible) will

increase costs

Turbine Cost Example

Turbine & Inverter $31,700Tower (100 ft Guyed) $14,145Wiring Kit $1,615Shipping $1,500Installation $8,000Other $250

$57,210

Bergey Excel-S (10kW)

Operations and maintenance costs • O&M costs can be estimated in terms of cost per kilowatt-

hour (kWh) of electricity production. – Some estimates use $0.005 to $0.05 per kWh.

• Other methods estimate the cost of O&M based on the initial turbine cost. – For example, one percent of the initial purchase cost (one percent of a

$50,000 system would result in an annual O&M estimate of $500). • O&M costs will vary on the type of equipment. As the number

of “moving parts” increase, so should your estimates of O&M expense. – Newer, smaller, simpler turbines may need very little maintenance

Value of electricity produced

Colorado average retail energy rate: $.095

Depending on wind resource, an

Excel-S turbine could produce 9,600-27,000 kwh/yr, or

$912 - $2650 per year

Net Metering of Renewable Energy

Energy consumed immediately: retail rate

Excess energy used to offset consumption at another time: retail rate Net excess energy

(determined monthly or annually): wholesale rate, or given to the utility

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Don’t buy a bigger turbine than you need

• Yearly excess energy gets sold back to the utility at a much lower cost

Wind Turbine Economics Simple Payback (no rebates)

Simple Payback = Turbine Capital Cost / Annual Net Savings

Capital installed cost: $57,000 • Value of energy: (9,600 to 27,900) kWh x $0.095/kWh = $912-2650 • O&M (.01 average): 16,500 kWh x $0.01/kWh = $165

• Payback low wind= $57,000/($912 - $165) =76 yrs • Payback good wind= $57,000/($2650-165) =22.9

Net savings = value of wind energy – O&M

This method tends to be conservative because it does not account for the escalation in electricity prices

Alternative: Cost of energy

• Divide system cost by total predicted lifetime kWh • Lower wind: 9,600 kwh x 25=240,000 kwh • High wind: 27,900 kwh x 25 = 697,500 kwh

$57,000/240,000 or $57,000/697,500 kWh

• Lower wind: 0.24/kWh (incl. O&M= .25/kWh) • High wind: 0.08/kWh (incl. O&M =.087/kWh)

Wind rebates • Federal tax credit: 30%, expires 2016 • CO State: Currently no rebates May be local utility incentives : • United Power: $0.50/W up to 3kW • Xcel: none for wind at this time

Find rebates at: • Rechargecolorado.com • www.dsireusa.org

Payback with rebates • $57,210 install, Bergey Excel-S 10kW – $17,163 (federal) – $1,500 United Power $38,547 • Payback low wind= $38,547/ ($912 - $165) = 51.6

yrs • Payback good wind= $38,547/($2650-

$165) =15.5 yrs (shorter if electricity prices go up)

Economy of scale

• Payback is quicker with larger turbines, larger electricity bills (or higher electricity rates)

• (Cost per kWh goes down as size goes up)

Operations and maintenance

• “The life expectancy of a turbine is directly related to your involvement with the machine.”

• “Wind turbines are not toasters. You can’t just plug them in and walk away.”

» Mick Sagrillo

Operation and Maintenance • Small wind turbines require at least annual maintenance. • Maintenance requirements are different for each system. • If you are not willing to maintain your system or hire

someone to perform maintenance work on a regular basis – wind is not for you.

From ground

– Check rotor for symmetry

– Watch how the turbine changes directions as the wind shifts

• Check for smooth or abrupt yawing

– Check that the tower is still vertical

In air (or with turbine lowered)

• Check for cracks, worn fittings

• If the turbine has a gearbox (larger turbines), , check for excessive grease or oil, change oil regularly.

• Check that all bolts on turbine and tower are snug.

• The more complex the turbine, the more that can go wrong

Batteries

• Batteries for off-grid or

grid-tied with battery back up bring a whole new level of maintenance (check voltage, fluid levels, connections, corrosion)

http://www.dep.state.pa.us

Zoning

Solar access laws extend to wind • Colorado's solar access laws, which date back to 1979,

prohibit any residential covenants that restrict solar access. HB 1270 of 2008 extended the law to protect installations of wind turbines that meet the state's interconnection standards, and certain energy-efficiency measures including awnings, shutters and other shade structures, garage fans, energy-efficient outdoor lighting, retractable clotheslines, and evaporative coolers. Some exceptions are made to allow for aesthetic requirements that do not significantly increase the cost of the device or decrease its performance. HB 1270 further protects owners of solar or wind-energy systems by awarding reasonable attorney fees to the prevailing party in any court case involving the significant increase in the system's cost based on aesthetic requirements.

Zoning • Does your area allow wind turbines?

– Some areas do not allow wind turbines or have special permitting for small wind turbines.

– Check with your county –varies widely • Some have use-by-right, others have condition use, others have special use

permitting after a certain height • Special use permitting usually requires public hearing

– There are often set-backs to ensure that a falling tower would not fall outside the property

• Other zoning restrictions may address noise, tower placement, and tower type.

• Zoning or ordinances may require one-half acre to over five acres of available space based on the size of wind system

• Check with your electrical utility to see what utility company rules you must follow if you intend to remain connected to your electrical utility.

Noise? • Modern turbines are

relatively quiet • Rule of thumb – stay

about 3x hub-height away from houses

• If possible, find a turbine or two and listen

Source: KidWind

Overall summary

• Wind energy might be right for you IF: – You have a good wind resource (10-14 mph)

• Don’t overestimate your wind resource

– An energy-efficient home – Space and permits to install a tall tower – Ability and mindset to do maintenance or pay for

it

Additional resources • Wind website on CSU Extension page: http://www.ext.colostate.edu/energy/wind.html • Includes many links and some Webinars • 20 by 2030 report: http://www.20percentwind.org/ • Anemometer Loan Program sites and data: www.engr.colostate.edu/ALP/ALP_Sites.htm • Wind Maps (Static and interactive) • State wind maps: http://www.nrel.gov/gis/wind.html • 3TIER First Look: http://firstlook.3tiergroup.com/ • AWS Truewind Wind Navigator: http://navigator.awstruewind.com/ • Renewable Energy Atlas of the West: http://www.energyatlas.org/ • Small Wind Certification Council: www.smallwindcertification.org • Small wind toolbox from Mick Sagrillo:www.renewwisconsin.org/wind/windtoolbox.htm • Is wind power right for me? http://homepower.com/view/?file=HP143_pg52_Woofenden • Physics of small wind turbines webinar: http://vimeo.com/58394314 • Birds and bats fact sheet: nationalwind.org/research/publications/birds-and-bats-fact-sheet/ • Books • Wind Power for Dummies - Ian Woofenden 2009 • Wind Power, renewable energy for home, farm and small business—Paul Gipe 2004 • Magazines • Home power www.homepower.com

DIY Wind Assessment tool

• www.ext.colostate.edu/energy/wind-assess.html

• We’ll now go through how to use it….