Distributed Energy Systems
James L. Kirtley Jr.
Massachusetts Institute of Technology
November 17, 2006
J.L. Kirtley Jr. Room 10-098
617 253 2357, kirtley@mit.edu
Distributed Energy Systems
J.L. Kirtley Jr.
Power Systems
Engineering Group (PSEG)
Electric Power
Systems Engineering
Lab (EPSEL)
Lab for Electromagnetic
and Electronic Systems
(LEES)
1
Model Power System
Micro Machines
Real Time Control Simulator
Transmission System Simulator
Superconducting Generator
Monitoring Systems
Non-Intrusive Load Monitor
Transformer Monitor
Advanced System Control
State Estimation
Bounded Control
Selective Modal Analysis
Participation Factors
Advanced Motors
Reluctance Machines
Induction Motors
Micro (MEMS) Generators
Automotive Systems
Integrated Starter-Generator
Architecture (42 V)
Valve Lifters
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• Distributed Generation
– Is How the Electric Utility System got started
– Edison’s DC system WAS distributed
• Stations had to be within blocks (city blocks) of the
loads
– Distributed Generation also distributed side
effects
• Pollution
• Noise
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Modern Utility Systems
• Are still highly distributed
• But development has been away from distributed
generation
• Economies of scale (large power plants)
• Removing side effects from population centers
• Perceived Safety issues cause Nukes to be remotely
sited
• High Voltage Transmission allows efficient transfer of
electric power
• “Coal by wire”
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• Current Utility Systems Work Well…
– Generation/Transmission/Subtransmission/
Distribution is the power systems model
– Interconnection aids reliability
– Wide variety of sources
• Thermal Generation (Coal, Oil, Gas, Nuclear)
• Hydroelectric
– System can accommodate new sources
•
•
•
•
Wind
Solar
Geothermal
Others?
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Drivers for distributing (thermal) generation
– Heat Engines reject ‘waste heat’, which is still
useful
– Transmission lines are getting harder to build
– New technologies may result in generators that
are inherently small
• Microturbines
• Fuel Cells
• Rooftop solar cells
– Perception of reliability
– “There is a lot of Natural Gas around”
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• Status of Distributed Generation
– Industrial and Commercial CHP is Already established
• Diesel and/or Gas Turbine Engines
• Generally in MW sizes
– Microturbines (sub MW)
• Are on the market
• Have not achieved a great market share
• Yet…
– Rooftop Solar
• Also on the market, but unlikely to make much of an impact
– Micro-Hydro
• Limited number of sites, but perhaps valuable where it is
applicable.
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Total Cost of Generated Power
Large Combined Cycle Power
Plant
Source of Data: Congressional
Budget Office, Sept 2003
Combustion Turbine CHP
Combustion Turbine
Large Wind Turbine
Type
Small Wind Turbine
Solar Photovoltaic
Fuel Cell CHP
Gas ICE CHP
Gas ICE
Microturbine CHP
Microturbine
0.000
0.050
0.100
0.150
0.200
0.250
$/kWh
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0.300
• A few observations on the cost data:
– Solar photovoltaic appears to be substantially more
expensive than other alternatives (but these costs may
fall with aggressive development)
– CHP cuts the cost of electricity for Combustion
Engines (ICE and Gas Turbines)
– Small Wind Turbines are probably limited
– But Big Wind Turbines may turn into players
– Fuel Cells appear to have a cost disadvantage with
respect to microturbines
– Unless something else happens, DG is unlikely to
supplant central stations
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Will D-G relieve the need for transmission?
– Transmission is required to allow areas distant from
one another to support each other
– Large numbers of small generators will be a
challenge to control
– So does the presence of non dispatchable generation
(solar, wind)
– D-G, being smaller, reduces the size of lost unit
contingencies
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• Other observations on Distributed
Generation Technologies
– Some DG’s are dispatchable
• Microturbines,
• IC Engines,
• Fuel Cells
– Some DG’s have very low environmental
impact and represent renewable resources
• Small Wind Turbines,
• Solar,
• Micro-Hydro
– These are largely exclusive sets
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Some technologies called ‘Distributed’ are not really
so
– Large Wind Turbines
– Large Scale Solar Converters
And the non-dispatchable DG technologies will still
require, for when the wind doesn’t blow or the
Sun doesn’t shine:
– Transmission
– Redundant Generation
– Energy Storage
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• Reliability impact of D-G
– Supply with utility backup is at least as reliable
as the local utility
– Supply without utility backup is probably not as
reliable (utilities are pretty good)
– Cost of utility backup may be substantial
– Emergency backup systems can be less
expensive than D-G intended to run
continuously
– Meaning D-G is unlikely to have much of a
reliability impact
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• Distributed Generation for peaking?
– Requires costs to be reflected in prices
• Costs are higher than central station machines
• Coordination of CHP with other uses is challenging
• CHP units cold be used in non-CHP peaking, with a
cost hit.
– Some distributed sources are hard to dispatch,
and so would not be good for peaking
• Wind
• Solar
• Micro-Hydro (run of river)
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• Interesting Possibilities
– Gas Turbines
• Well established at MW levels
• ‘Microturbines’ at 10’s to 100’s of kW (CHP for
commercial buildings)
• Under development are much smaller microturbines
(10’s of kW)
• Mass production of these engines could sharply
reduce capital expense.
– Rotating elements are similar to automotive turbocharger
components
– Need regeneration: heat exchangers have been difficult
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• Fuel Cells
– Several technologies are under development
– High temperature, molten carbonate “direct
conversion” cells burn natural gas directly
• Possibly suitable for commercial CHP
– PEM cells come in sizes consistent with
residential DG but require Hydrogen
• Chemistry looks very difficult
– Lifetime of all fuel cell technologies appears
problematical
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• Challenges for distributed generation
– Cost of natural gas is volatile and has been
increasing
– Push for Utility System reliability may result in
strengthening of the Transmission System
– Costs and Efficiencies for Gas Turbine and
Combined Cycle (Brayton + Rankine Cycle)
are a tough and improving target
– Advanced Nuclear plants may also be highly
competitive
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• So how to make money on all of this?
– Wind is not ‘distributed’ but may be viable
– Uninterruptible power supplies in distributed
locations can improve reliability where it
counts.
– Transmission is important and will remain so.
– Widely dispersed generation, particularly wind,
requires a strong network and robust voltage
control. (VARS don’t travel well)
– Advanced control, perhaps similar to
responsive load control, is key to making DG
work.
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Dual-Use Electronics
Steven B. Leeb
Massachusetts Institute of Technology
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Talking Lights Optical Communication
Ballast
Receiver
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Talking Lights Enables Context-Aware Computing
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Lamps as proximity and security sensors in buildings
Out in a monitored hallway near
offices 109 and 110:
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Real-time report in a
security area:
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How Does it Work?
The Lamp as a Capacitive Sensor
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E-Field Simulations
Lamp
Target
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E-Field Simulations
Lamp
Target
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E-Field Simulations
Lamp
Target
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E-Field Simulations
Lamp
Target
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E-Field Simulations
Lamp
Target
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E-Field Simulations
Lamp
Target
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E-Field Simulations
Lamp
Target
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Lamps as proximity and security sensors in buildings:
Empirical Data
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Non-intrusive Load Monitor
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Typical screen
interaction:
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Typical screen
interaction:
Research in Teaching:
Hands-on lab stations:
Take-home microcontroller kit:
Lab kits:
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Teaching Robot:
The robot has two drive
wheels at the rear of the
machine.
It tracks the magnetic fields
surrounding a low-voltage,
current carrying wire taped to
the floor.
The wire can be quickly run to
form a path almost anywhere,
making it easy to set up
experiments for the machine.
(For reference, the floor tiles in
the photo are nine inches on a
side.)
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Go-Cart experiments:
Students work with
electric go-carts how
hard a prime mover,
e.g., a person, horse, or
gas or electric motor,
has to work to push a
person on that vehicle.
Students compare the
energy density and
range of gasoline
versus electrochemical
storage based on their
experiments and
measurements:
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Combustion:
Students built a
combustion chamber
of their own design.
They use a thermal
imaging camera to
characterize the
performance of their
combustion
chambers, and
compute the efficiency
of their chamber in
extracting heat from
alcohol-based fuel in
order to heat water.
Teams compete to win
a prize for the most
efficient chamber.
Sterling Engine Power Plant:
Students use their combustion
chambers in a following week to
fire a power plant of their own
design, which consists of a
sterling engine prime mover and
a DC generator:
Induction flashlight: Students
construct an “shake-magnet”
induction powered flashlight of
their own design. They learn
basic principles like Lorentz
force law and Lenz!s law, and the
basic operating principles of
electromagnetic actuators:
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