Unintended Consequences: The Impacts of Wind
Energy on Rural Alaska Diesel Power Systems
David Lockard and Alan Fetters, Alaska Energy Authority
Presentation Goals
• Describe impacts of wind turbines on rural
Alaska diesel power system operation (a
moving target)
• Assess significance of those impacts
• Discuss opportunities to optimize operation of
wind and diesel components of wind-diesel
power systems
Wind Impacts on Power Systems
Technology
Estimated Reduction
in Fuel Savings
Comments
Heat Recovery
10-25%
May be jacket-water, wet manifold, or
stack HR
Diesel Efficiency
?-30%
See genset manufacturer’s efficiency
curve. Also depends on penetration level.
Wind Turbine Station
Service
1-8%
Resistance heaters (controls,
powerhouses, transmissions), meters,
controls, startup power, etc.
Power Factor
Correction
1-3%
Sychronous converters, capacitors, “big
iron”, static VAR compensators, etc.
(Unalakleet PF < 0.4 at times)
Line and transformer
losses
2-5%
Typical losses based on design criteria
Wind energy used
for thermal purposes
50%
Oil heating efficiency is approximately
twice diesel generation efficiency
Cat 3456 w/ Custom Wet Manifold
Before
After
Chitina Stack Heat Recovery
Kotzebue Wind Impact on HR
• Kotzebue Heat Recovery:
– Water heating
– District heating
– Summer ice making with absorption refrigeration
– ORC/stack heat recovery
KEA goal of using 85% of energy in fuel.
Wind-powered Electric Boilers
10 in operation
6 in construction
6 in design
16 in feasibility
Nikolski Wind Example
• Wind Turbine: One 65 kW Vestas
• Gensets:
– One- 37 kW, mechanically fuel injected
– Two- 71 kW, mechanically fuel injected
•
•
•
•
Avg load = 30 kW
School closed
Electric heaters at school, lodge and powerhouse
Recent blackouts due to insufficient thermal
loads to absorb peak wind output (80 kW?)
Nikolski Diesel Dispatch Scenarios
Electric Load Scenario
Diesel Dispatch
Wind Dispatch
Low load 20 kW – 30 kW
Maximize diesel use to reduce
risk of wet stacking 37kWgenset
and improve diesel efficiency
Thermal purposes
30 kW – peak load (40 kW)
Maximize diesel use to reduce
risk of wet stacking 71kW genset
and improve diesel efficiency
Thermal purposes
John Deere Engine Recommendations
August 2004
Generator efficiency is also affected by power
factor. The inductive current in the generator
increases the resistive losses in the generator
and lowers efficiency. The highest generator
efficiency is at unity PF. A generator may
run at 92% efficiency at 1.0 PF and only 90%
efficiency at 0.8 PF.
Tier 4 Concern
• Tier 4 diesel gensets will have exhaust
emission equipment that requires minimum
stack temperatures for the oxidation catalyst
to work. At low genset loads, those
temperature requirements will be met by
burning additional fuel in the stack to meet
emission requirements.
• AEA has requested an EPA waiver for some of
the Tier 4 genset requirements
Conclusions
• Wind turbines have multiple impacts on the
performance and economics of diesel power systems.
• Wind-diesel economic analysis should include the
impacts on heat recovery, diesel efficiency, power
factor and quality, station power use, and
line/transformer losses.
• Wind energy used for heating purposes saves about
50% less fuel than when used for electrical purposes.
• Diesel power system technology is changing rapidly,
which makes it even more challenging to integrate
wind power.