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Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University
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Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Dec 18, 2015

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Page 1: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Ensuring Reliable Electricity Supplies Using Distributed Generation

Gregory TressCarnegie Mellon University

Page 2: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Overview

• Introduction• The Power Grid• Power Disruptions• Infrastructure Issues• Distributed Generation• Solutions

Page 3: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Introduction

• What is distributed generation? – EPA definition:

“Small, modular, decentralized, grid-connected or off-grid energy systems located in or near the place where energy is used.”

• Goals for electricity generation and delivery– Reliable– Affordable– Efficient– Environmentally friendly

Page 4: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

• What is the problem?– We are addicted to electricity

Introduction

– We can consume any amount of power at any time– In most cases, this is not a problem– Under the right circumstances,

it can be a big problem

Page 5: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Introduction

• What is the problem?– Northeast Blackout, 14 Aug 2003– 50 million people affected

Before During

Page 6: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

The Power GridGeneration Transmission Distribution

substation

substation

substation

Page 7: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

The Power Grid

substation

substation

substation

Electricity

High power flowin transmission lines

The classic model

Page 8: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

The Power Grid

substation

substation

substation

Electricity

“Distributed”Generators

What can distributed generation do?

Page 9: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Power Disruptions

• Classification– Power shortages

• Blackout: complete loss of power• Rolling blackout: intentional, temporary shutoff• Brownout: voltage reduction, may be intentional

– Power quality issues• Voltage and frequency fluctuations

Page 10: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Power Disruptions

• Commercial and Industrial Impact– U.S. economy is losing over $100 billion / year

$0

$5

$10

$15

$20

$25

$30

$35

DigitalEconomy

ContinuousProcess

Manufacturing

Fabricationand Essential

Services

Billi

ons

of D

olla

rs

Power QualityIssues

Power Outages

Page 11: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Power Disruptions

• Commercial and Industrial Impact– Critical economic sectors are at risk

• Data storage, retrieval, processing• Research and development operations• Telecommunications• Financial operations• Precision and general manufacturing• Transportation• Utilities (e.g. water, natural gas)

Page 12: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Power Disruptions

• Residential consumer impact– Power-sensitive high-tech devices

• Possible equipment damage• Expensive to replace or repair• Possible irreversible data loss

– Essential devices• Refrigeration• Heating and cooling• Medical

Page 13: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Infrastructure Issues

• Why isn’t the system reliable now?– High peak demand– Delivery bottlenecks– Grid fragility– Power Loss

Page 14: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Infrastructure Issues

• The demand pattern– Higher during the day, lower at night– Higher in the summer, lower in the winter– Result: highest during the day in the summer

• Why does this matter?– We don’t know how much higher it will be

Page 15: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Infrastructure Issues

• The demand pattern– Sample residential area: winter vs. summer day

24120 24120

Maximum transmission capacity

Page 16: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Infrastructure Issues

• The bottleneck– “Inadequate investment in transmission infrastructure...

costs consumers tens of billions of dollars a year in higher energy costs and lost productivity”

-- National Commission on Energy Policy

Page 17: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Infrastructure Issues

• The bottleneck– Transmission loading relief events (TLRs) recorded when lines reach

full capacity– Quantitative indicator of transmission congestion

Page 18: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Infrastructure Issues

• The fragile grid– Equipment limitations

• Safety systems (e.g. circuit breakers) are designed to prevent dangerously high power flow

• Customers don’t know how high total demand is

– Cascading failure• A single equipment failure can cause a chain reaction• Lack of redundancy increases risk and severity

Page 19: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Infrastructure Issues

• Power loss– Transmission loss 6-8% during peak demand– Heat released into atmosphere

Page 20: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Distributed Generation

• Classification– Dispatchable

• Turned on and off when necessary• Fossil fuel, biofuel powered

– Intermittent• Not precisely controllable or predictable• Solar, wind

Page 21: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Distributed Generation

Clean power … but at what cost?

Page 22: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Distributed Generation

• The impact of intermittent generation– Reliability decrease

• Maximum generation doesn’t necessarily match up with maximum demand

– Transmission increase• Wind and solar have specific geographic requirements.

Delivering this power to other areas will add to existing transmission congestion.

Page 23: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Distributed Generation

• Dispatchable generators: the solution?– Can satisfy peak demand– Not susceptible to transmission bottlenecks– Increase grid stability and redundancy– Reduce atmospheric power losses

Page 24: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Distributed Generation

• Dispatchable generators: the solution?– High efficiency

• Up to 90% for combined heat and power generation

– Works well with intermittent generation• Operates when wind and solar can’t

– Flexible local fuel sources• Can use existing natural gas lines or locally-produced

biomass/biofuels.

– National energy security

Page 25: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Distributed Generation

• Dispatchable generators: the downside– Environmental impact– Public opposition– Additional points of failure– Capital cost

• $500-$1000 per kW to install typical generator unit• Average residence uses 1-2kW; more during peak• $500-$4000 or more per household over lifetime of the

generator, plus land, upkeep, etc

Page 26: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Solutions

• Combination of factors is at fault– Each problem can be fixed independently– Distributed generation can solve most at once

• Reliability is limited– Impossible to reach 100%

Page 27: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Solutions

• Standards already exist– FERC Order 888 & 889 (1996)

• Opens transmission lines to competition

– FERC Order 2006• Small generator interconnection agreements and

procedures

– IEEE Standard 1547• Standard for interconnecting distributed resources with

electric power systems

Page 28: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Solutions

• Government has spoken– Energy Policy Act 2005

• $800 million for distributed projects and research• Includes focus on reliability, efficiency, emergency

supply, effect on rates, advanced metering, residential grid connectivity, grid design and planning

– Environmental Regulations• EPA Clean Air rules in effect• National preference for clean, “green” power

Page 29: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Solutions

• A question of value– High cost for non-obvious increase in reliability– Desire for cheap power vs. desire for reliability – Some customers are already installing their own

systems (or backup supplies)

– Should we force all customers to pay for distributed generation?

Page 30: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Solutions

• Do we need distributed generation?• Other options:

– Add transmission capacity– Reduce consumption– Implement variable-rate billing– Deploy electricity storage units– Sell smart appliances– Do nothing

Page 31: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Conclusion

• There’s no clear winner– Distributed generation (both intermittent and

dispatchable) is already being adopted without much government intervention

– Many consumers may not want distributed resources or care about reliability (this must be assessed before making policy decisions)

– Environmental impact can still be significant, even with high efficiency and limited operating time

Page 32: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Conclusion

• Incentives can still be helpful– Potential market in individuals, groups, or

businesses for whom distributed resources would be cost-effective

– Directed incentives or financial assistance would enable adoption for specific economic sectors

– It may not be for everyone.

Page 33: Ensuring Reliable Electricity Supplies Using Distributed Generation Gregory Tress Carnegie Mellon University.

Thank you