Why Wind Power Works for Michigan: A Brief Primer on How Wind Turbines Make Electricity

Why Wind Power Works for Michigan: A Brief Primer on How Wind Turbines Make Electricity Christopher Schilling, Ph.D. C. J. Strosacker Professor & Chair of Engineering Saginaw Valley State University

Outline

Windmill physics controls performance economy.

Engineering design choices.

Future prospects.

An imaginary cylinder of air passes through a 1 kW wind turbine. The cylinder weighs 2.8 tons. 1 m diameter = 54 m

Extractable energy is proportional to the mass of air in the cylinder.

How to increase the mass?

Enlarge the propeller

Lower the air temperature

.

cold wind = more power Air at 5 o F is 21% more dense than air at 95 o F.

Windmill design is primarily driven by 1 equation:

P = maximum extractable power

P = ½ x (swept area) x (air density) x (wind speed) 3

Main implication: Doubling the propeller diameter quadruples the power output.

Doubling the propeller diameter quadruples the power output. Today’s challenge: making bigger propellers that are lightweight, strong, and affordable. Source: ATV Enterprises, France http://atv.tm.free.fr/index.htm

Power scales with wind speed 3 Power Density (Watts per m 2 of swept area) Doubling the prop diameter increases power by a factor of 8 steep

Great Lakes, Great Winds

Now – 129 MW installed in MI

Includes Harvest Wind Farm – 48 MW

Central East Michigan

Wind speed increases with elevation above ground level (ground drag). Average wind speed Elevation above ground level Main design implication: build taller and taller towers

John Deere Harvest Wind Farm, Elkton, MI Key focus of newly engineered windmills: tall, strong, lightweight towers

Main problem: top of the tower is too heavy

Heaviest parts:

Propeller

power transmission

alternator

Source: windmillsusa.com

Windmill casing manufactured by Cast-Fab Technologies of Ohio Large parts of a wind turbine are made by metal casting.

Consequence of too much weight on top of a tall tower: concrete foundation is a major component of installation cost. Source: Edinburgh Napier University www.sbe.napier.ac.uk

nacelle is heavy massive concrete foundation is needed lightweight, slender tower turbulent wind

Source: www.four-winds-energy.com Avoid turbulence with proper siting

Turbulence creates large, vibrational stresses in windmill parts (e.g., blades, transmissions, tower components). Too much vibration leads to premature fracture. Big engineering challenge: advanced materials to cut the weight at the top of the tower…… …… .. while avoiding fracture during turbulent loading.

Key point: Windmill design is mainly driven by one equation:

Maximum extractable power

= ½ x (swept area) x (air density) x (wind speed) 3

cold weather (high air density)

bigger propellers (more swept area)

high winds (tall towers; proper siting)

avoid turbulence

2 design options horizontal axis vertical axis Affordable Green Energy LLC, Essexville, MI

Vertical axis wind turbine at Mauceri residence, Chicago, IL Source: www.aerotecture.com

Vertical axis wind turbines

They like turbulence (rooftop installation possible)

Heavy electric alternator and heavy power transmission are located at the bottom of the tower.

Less power output (at a given wind speed and air density) than horizontal axis machines.

How much power is needed?

Let’s compare windmills…

US Navy radar station is powered by 2 Bergey 10 kW wind turbines, each with a 22 foot diameter propeller

Elkton MI 48 MW total 32 turbines 1.5 MW each 246 feet dia propeller Trillium Project, Lake Ontario (proposed) 710 MW total 142 turbines 5 MW each 378 feet dia propeller Biggest in the world: REPower turbine in Cuxhaven, Germany John Deere, Elkton Michigan

Average daily household power consumption: 1 to 2 kW, with peaks of 4 and above.

Power (kW)

12 AM

6 PM

6 AM

US Navy radar station is powered by 2 Bergey 10 kW wind turbines.

10 kW / 2 kW = 5 homes per turbine?

48 MW total 32 turbines at 1.5 MW each 1.5 MW / 2 kW = 750 homes per turbine ? 750 x 32 = 24,000 homes ? John Deere Harvest Wind Farm, Elkton Michigan

Great Lakes, Great Winds

Now – 129 MW installed in MI

Includes Harvest Wind Farm – 48 MW

Installed Wind Turbine Capacity in Megawatts as of December 2008 Source: American Wind Energy Association 25,170 ½ % of US total

Installed Wind Turbine Capacity in Megawatts as of December 2008 Sources: American Wind Energy Association and European Wind Energy Association 511 Michigans 195 Michigans

2008 was a record year

United Kingdom: 836 MW added = = 6.5 Michigans

France: 950 MW added = = 7.4 Michigans

Italy: 1,010 MW added = = 7.8 Michigans

Spain: 1,609 MW added = = 12.5 Michigans

Germany: 1,665 MW added = = 12.9 Michigans

United States 8,300 MW added = = 64 Michigans

Europe total 8,484 MW added = = 66 Michigans

Europe offshore total: 357 MW = = 2.8 Michigans

Michigan rates highly in U.S. for turbine manufacturing

http://www.repp.org/articles/static/1/binaries/WindLocator.pdf

Overview of study

Based on 50,000 MW assumption (which would be about 10% of U.S. electricity needs)

Current US wind installations – just over 25,170 MW

Matched wind turbine components with NAICS codes, then looked at U.S. Census data to see where these components were already being built

State by State Results

Michigan’s assets:

High winds

Manufacturing infrastructure

Skilled workforce

The right schools for knowledge workers.

Questions ?

Why Wind Power Works for Michigan: A Brief Primer on How Wind Turbines Make Electricity

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