Distributed Wind Energy
in Idaho
John Gardner
Professor & Chair
Mechanical & Biomedical Engineering
Boise State University
Today’s Talk
„ Some Preliminaries
„ Sources and Sinks of Power, US and Idaho
„ The Grid
„ Wind Energy
„ BSU Research
Laws of Thermodynamics
„ 1st Law: You can’t win
„ 2nd Law: You can’t even break even
„ Over-arching theme:
„
There is no free lunch
What’s Watt?
„ Typical household:~ 1.0 KW* = 0.001 MW
„ Average state if Idaho:2,570 MW**
„ Average USA: 463,000 MW***
„ Generating Capacity: 1,000,000 MW***
“The Physics Factbook”, http://hypertextbook.com/facts/
** DOE, EERE: http://www.eere.energy.gov/, 2003
***Energy Information Admin., http://www.eia.doe.gov/
*
Our energy uses by sector
„ Transportation
„ Industrial
„ Commercial/Residential
„ Electrical Generation
Our Energy Sources
„ Fossil Fuels
„ Coal, Petroleum, Natural gas
„ Biomass
„ Wood, Biodeisel, ethanol, etc.
„ Hydropower
„ Wind
„ Solar*
„ Wave/Tidal
„ Geothermal
„ Nuclear
Where we make it, where we use it
Source: http://www.eia.doe.gov/
US Electric Generation by Fuel Type
Source: http://www.eia.doe.gov/
Electrical Generation in Idaho
Actual Generation in state
Coal, 1%
Other
Renewable, 8%
Natural Gas,
25%
Hydro, 65%
Source: http://www.eia.doe.gov/
Idaho Electric Consumption by Fuel
Type
Other
Renewable
1%
Natural Gas
9%
Coal
42%
Hydro
48%
Source: 2007 Idaho Energy Plan
A bit about “The Grid”
„ Some claim it’s “the most complicated
machine ever built”
„ A huge system of wires, transformers,
switches, power plants and, of course,
consumers
A common misperception about the
grid
Power Plants ‘pour’
Electricity into the
grid, anytime,
anywhere
The grid is a ‘reservoir’
of power
Users take what they need, anytime, anywhere
But, it’s more like
•The allowable ‘level’ is a very narrow range
•Location matters
The Utility’s job
„ Put energy into the ‘tray’
„ Don’t let it overflow (damage to the system)
„ Don’t let it get ‘a little dry’ (brownout)
„ Don’t let any part of it go dry (blackout)
„ Under fluctuating load conditions
Seasonal Variations
Daily Demand Variations
“Nameplate” Capacity
Forecast/Actual Load
Imported
Source: http://currentenergy.lbl.gov/
How Generators View the Grid
Peak Load
Base Load
Power for Baseload
„ Coal
Days to start
„ Generally run at or near capacity
„
„ Nuclear
Also long startup time
„ Also, near capacity
„
„ Hydro
„
Inexpensive for baseload
Dispatchable Peak Power
„ Gas Turbines
„ Common for ‘peaking plants’
„ Short notice/quick start
„ Adjustable output
„ Mature technology
„ Hydro
„ Turbine flow can be
adjusted within limits but
environmental regulations
limit rate of change (ramp)
and overall range of flow.
What about Wind?
The Modern Wind Turbine
One of the 90 1.5 MW GE turbines at the
Judith Gap wind farm in Montana
Source: North American WindPower, March 2007
Inside the Nacelle
From: Windpower.org
But in reality…
Wind Research at Boise State
„ Wind/Irrigator Nexus
„ Innovative Generator Technology
„ Variable Speed to Maximize Energy Capture
„ Retrofit the Lewandowski Turbines
„ Blade Design for Low Speed Turbines
„ Local Energy Storage
Typical fixed-ratio gearbox
General Electric’s 1.5 MW Gearbox
What’s the issue?
„ AC generators run at constant (or nearly constant)
„
„
„
„
speed to generate 60 Hz electricity
Wind is variable
Fixed ration gearbox means that the rotor must
also run nearly constant
For a given wind speed, there is a ‘best’ rotor
speed and it pretty much scales with the wind
speed.
TSR = 5 (more or less)
Vwind
TSR =
ω Rotor RRotor
What are the solutions?
„ Variable speed generators
„ Rectify AC to DC and Invert DC to AC
„ Variable pitch blades
„ Adjust the pitch to be more ‘aggressive’ at low wind
speeds
„ Variable ratio transmissions!!
And Now for Something Completely
Differential
Differential Drivetrain:
Multiple inputs and/or outputs
From: http://auto.howstuffworks.com/differential1.htm
Planetary Gear Trains
Ring
Carrier
Sun (hidden)
Planets
Nr
Nr
ω s = (1 + )ωc − ωr
Ns
Ns
Proposed Gearbox
Output shaft (connected
to generator)
Two stages of planetary reduction
First ring gear, fixed to case
Input shaft (connected
to rotor)
2nd ring gear, driven by motor/generator
First Step: Computer Model
Controller
Vwind
Wind
Speed
Taero
Rotor
aerodynamic
forces
ωrotor
Rotor
dynamics
ωgen
Differential
Transmission
Tload
Induction
Generator
Tgen
Sample Output
Main Generator
Rotor Power
Power (W)
Ring Gear
Time (s)
Now what?
„ Implement automatic control to constantly
adjust ring gear speed
Maintain constant generator speed
„ Maintain constant TSR
„ Other adaptive behaviors
„
„ Secondary goals
Minimize torque transients
„ Improve power quality
„
Future Work: Dispatchability
„ Wind puts power on grid when it’s blowing
„ Takes power off when it stops
„ Both events are problematic for the grid
operator
„ What if….
Local Energy Storage: Compressed
Fluid
wind turbine
wind
compressor
generator
water
turbine
H2O
storage
tanks
Local Energy Storage: Flywheel
Intelligent Power Controller
differential
fixed-mesh
gearbox
From Turbine
To Grid
electric
generator
flywheel energy
storage
subsystem
Local Storage: Benefits
„ Store power mechanically when wind blows
„ Generate electricity when needed
„ Utilities could see a constant, or near
constant load
„ Turbine operators could save power and
deliver it when price is highest.
Just this week…
The Idaho Statesman, Monday, 12 March 2007
“Integration issues”
„ Idaho Power just published an interconnect
study claiming it will coast approximately
$10/MWhr to integrate wind to the grid
„ They’re seeking approval from the IPUC to
discount their payments to wind farm owners
by that much
„ There are real issues with integration but…
A Recent Minnesota Study
„ Cost for MN would be $4.5/MWhr with wind
comprising 25% of capacity
„ Currently wind is 6.1% of capacity in
Minnesota
„ Currently wind is 2.4% of capacity in Idaho
„ One of the main differences is policy
What about other western states?
From; North American Windpower, March 2007
“Local Optimization” vs. “Global
Optimization”
„ If each decision is made strictly to minimize
today’s cost, tomorrow’s cost will be higher
„ We need to invest today, for a better future
The Future
„ Wind energy needs to overcome barriers
„ Some technical, some political
„ Legislature, Utilities and producers need to
work together
„ If carbon cap-and-trade becomes common
practice, then alternate energies become
much more viable and likely
..is blowin’ in the wind….
With special thanks to….
„ Todd Haynes, Project Engineer
„ Co: PI’s
„ James Ferguson
„ Said Ahmed-Zaid
„ Anthony Paris
„ Paul Dawson
„ Students
„ Nathaniel Haro
„ Vanessa Wood
„ Xander Harmon
„ Tim Ross
„ Mike Quinn
„ Haley Adams