How a smart electric grid will power our future
DOE/Pacific Northwest National Laboratory
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A
novel plan that offers partnership in keeping the United States electric grid
stable and reliable could be a win-win for consumers and utility operators.
The largest ever simulation of its kind, modeled on the Texas power grid, concluded that consumers stand to save about 15 percent on their annual electric bill by partnering with utilities.
In this system, consumers would coordinate with
their electric utility operator to dynamically control big energy users, like
heat pumps, water heaters and electric vehicle charging stations.
This kind of flexible control over energy supply and use patterns is called "transactive" because it relies on an agreement between consumers and utilities.
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| Graphic by Cortland Johnson | Pacific Northwest National Laboratory |
Hayden Reeve, a PNNL transactive energy expert and technical advisor, led a team of engineers, economists and programmers who designed and executed the study.
"Because
Texas's grid is quite representative of the nation's energy system, it not only
enabled the modeling and simulation of transactive concepts but provided a
reliable extrapolation of the results and potential economic impacts to the
broader United States grid and customers," he said.
The
simulation showed that if a transactive energy system were deployed on the
Electric Reliability Council of Texas (ERCOT) grid, peak loads would be reduced
by 9 to 15 percent. That savings could translate to economic benefits of up to
$5 billion annually in Texas alone, or up to $50 billion annually if deployed across
the entire continental United States. The savings would equal the annual output
of 180 coal-fired power plants nationally.
Cutting the brown out
By
now, most people have experienced or witnessed how weather extremes or natural
disasters can wreak havoc on our current power distribution systems. That
vulnerability is magnified by our reliance on a few centralized power sources
and a grid system that sometimes struggles to match supply with demand.
Further, decarbonization of the electric grid will mean that more and more
power will come from different kinds of renewable energy sources, like wind and
solar. So, avoiding sudden spikes or dips -- power brown or black outs --
becomes paramount.
The
study findings indicate that a transactive energy system would reduce daily
load swings by 20 to 44 percent. And as more electric vehicles come into use,
the study, perhaps counterintuitively, showed that smart vehicle charging
stations provide even larger electric peak load reductions because they offer
additional flexibility in scheduled charging times and power consumption.
"A
smart grid can act as a shock absorber, balancing out mismatches between supply
and demand," Reeve said. "Through our study, we sought to understand
just how valuable effective coordination of the electric grid could be to the
nation, utilities and customers. Working with commercial building owners and
consumers to automatically adjust energy usage represents a practical, win-win
step towards the decarbonization of the electrical, building and transportation
sectors without compromising the comfort and safety of participating homes and
businesses."
One
key component to this strategy is adoption of smart appliances and load
controls. These dynamic resources can learn how to consume energy more
efficiently, adjusting their use for brief periods to free up electricity for
other needs. For example, instead of charging an electric vehicle in the early
evening when energy demand and price is high, transactive energy participants
would rely on a smart load control to delay charging their vehicle until demand
is low and electricity cheaper. This approach not only reduces stress on the
existing grid infrastructure, it allows utilities more time to plan for
next-generation energy storage and distribution infrastructure that is
currently in development.
Transactive
Energy: A central component
In
a transactive energy system, the power grid, homes, commercial buildings,
electric appliances and charging stations are in constant contact. Smart
devices receive a forecast of energy prices at various times of day and develop
a strategy to meet consumer preferences while reducing cost and overall
electricity demand. A local retail market in turn coordinates overall demand
with the larger wholesale market. All parties negotiate energy procurement and
consumption levels, cost, timing and delivery in a dynamic pricing scheme.
While
this concept may seem futuristic, it is quite possible to accomplish and is
already being deployed in a demonstration project in the city of Spokane's
Eco-District. Here, the research team is developing and testing a transactive
energy coordination scheme and retail marketplace. The approach also includes
the use of PNNL-devised transactive software agents .
An
undertaking the size of Texas
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| A year ago, Texas's ERCOT utility failured spectacularly, killing at least 260 and as many as 750 people |
The analysis also included detailed representations of 60,000 homes and businesses, as well as their energy-consuming appliances.
Researchers used the models to conduct multiple simulations under various renewable energy generation scenarios. Each simulation demonstrated how the energy system would react to the addition of differing amounts of intermittent power sources, such as wind and solar.
The
research team also developed a detailed economic model to understand the yearly
cost impacts for operators and customers. Finally, they looked at upfront costs
associated with labor and software expenses, as well as the costs for buying
and installing smart devices in homes and businesses.
Another important goal of the study included evaluating the impact of a new kind of mediator in the grid economy. This entity, called a distribution system operator, would be required to manage a grid that has multiple energy sources owned and operated by distinct entities, all contributing energy to the grid at different times and amounts.
In addition, this distribution system operator
would negotiate the transactions with customers that allow flexible load
control. The goal would be to support efficient and reliable grid operation.
The study confirmed the value of establishing entities, such as a distribution
system operator, to manage transactive energy.
Overall,
the PNNL research showed clear benefits of reimagining how the electric grid
could accommodate a future where clean renewable energy is a much bigger contributor
and more of our transportation needs depend on ready access to electricity.
"These
findings make a strong case for investment in scaled deployments of transactive
energy systems," said Christopher Irwin, a program manager for the Office
of Electricity, Department of Energy, in its Smart Grid standards and
interoperability efforts. "As the nation moves towards a zero-carbon
future, a more adaptable energy system could help accelerate the broader
deployment of electric vehicles, solar energy and the conversion of homes and
buildings to clean electricity sources."
In
addition to Reeve, PNNL researchers Steve Widergren, Rob Pratt, Bishnu
Bhattarai, Sarmad Hanif, Sadie Bender, Trevor Hardy, Mitch Pelton, Ankit
Singhal, Fernando Bereta dos Reis, Ahmad Tbaileh, Matt Oster, Tianzhixi Yin,
Laurentiu Marinovici and Sarah Barrows all contributed to the research and
writing the final reports. The study was supported by the Department of
Energy's Office of Electricity.
Link
to "Distribution System Operation with Transactive (DSO+T) Study"
