Sue Ellen Haupt: NCAR
powers up renewable energy forecasts
July 8, 2013
The National Center
for Atmospheric Research (NCAR), building on a pioneering wind energy
forecasting system that saved millions of dollars for Xcel Energy
customers in eight states, has entered into a new agreement with the
utility for even more sophisticated weather forecasts.
The new NCAR
forecasting system will predict sudden changes in weather and the
resulting impacts on wind and solar energy production.
In the next two years, NCAR scientists and engineers will develop custom
forecasting systems to predict sudden changes in wind, shut down
turbines ahead of potentially damaging icing events, and even predict
the amount of energy generated by private solar panels. The systems will
be used by Xcel Energy control centers in Denver; Minneapolis; and
The cutting-edge forecasts will help Xcel Energy, and potentially other
utilities, to provide reliable power to their customers and reduce costs
while moving to greater use of wind and solar.
"This is pushing the state-of-the-art still further, using the latest
science to enable Xcel Energy to generate energy from the atmosphere
more effectively," says NCAR program director Sue Ellen Haupt, who is
overseeing the new project. "Every improvement to the forecasts results
in additional savings."
Xcel Energy officials say the more accurate forecasts are critical as
they increase their use of renewable energy.
"The importance and value of accurate renewable energy generation
forecasts increases with the size of our renewable energy generation
portfolio," says Ben Fowke, chairman, president, and CEO of Xcel Energy.
"Xcel Energy has been the largest utility provider of wind energy for
the last nine years and we are continuing to grow our renewable energy
The new project represents the latest venture by NCAR into renewable
energy. In addition to the lab's earlier work with Xcel Energy, NCAR is
also spearheading a three-year, nationwide project to create
unprecedented, 36-hour forecasts of incoming energy from the Sun for
solar energy power plants.
"By creating more detailed and accurate forecasts of wind and Sun, we
can produce a major return on investment for utilities," says Thomas
Bogdan, president of the University Corporation for Atmospheric
Research, which manages NCAR on behalf of the National Science
Foundation. "This type of cutting-edge research helps make renewable
energy more cost competitive."
Reliable forecasts needed
Xcel Energy has been utilizing increasing amounts of energy from
renewable sources, especially wind. But this shift means relying on
resources that are challenging to predict and manage.
Energy generated by a wind turbine, solar panel, or any other source
must be promptly consumed because large amounts of electricity cannot be
stored in a cost-effective manner. If an electric utility powers down a
coal or natural gas facility in anticipation of wind-driven energy,
those plants may not be able to power up fast enough should the winds
fail to blow. The only option in such a scenario is to buy energy on the
spot market, which can be very costly.
In order to help utility managers anticipate wind energy more reliably,
NCAR began designing a wind energy prediction system for Xcel Energy in
2009 that saved the utility's customers more than $6 million in 2010
alone. The specialized system relies on a suite of tools, including
highly detailed observations of atmospheric conditions, an ensemble of
powerful computer models, and artificial intelligence techniques to
issue high-resolution forecasts for wind farm sites.
Following up on that work, NCAR has entered into a two-year agreement
with Xcel Energy to focus on the following areas:
•Forecasting "ramp" events. A new system under development at NCAR can
provide utility managers with advance notice of a major change in wind
energy over a few hours due to a passing front or another atmospheric
event. The system, known as VDRAS (Variational Doppler Radar Analysis
System) relies on techniques that combine observations from radars and
other tools with computer simulations to create more accurate forecasts
for particular wind farms.
•Predicting ice and extreme temperatures. To keep aircraft safe from
potentially lethal icing conditions while aloft, NCAR has created
state-of-the-art ice forecasting systems that use computer models and
specialized algorithms. Applying similar technology, researchers at NCAR
and Pennsylvania State University will develop a 48-hour forecasting
system at designated wind farms to predict the impacts of freezing rain
and fog on wind turbines, which cannot operate when coated in ice. The
team also will forecast extreme low and high temperatures, which can
cause wind farms to temporarily shut down.
•Generating solar forecasts. Xcel Energy customers who have their own
solar panels draw far less energy from the grid while the sun is out,
and can even sell excess energy back to the utility. To help Xcel Energy
better anticipate when their customers are getting power from their own
panels, NCAR will create a solar energy forecasting system, using a
combination of computer models and specialized cloud observing tools.
Some of these new systems will provide "probabilistic forecasts,"
estimating the chances that a particular weather event will occur. This
means that utility managers will be able to make decisions based on
whether there is an 80 percent chance of certain weather events at a
wind farm the next day, or a 20 percent chance.
"We're taking our expertise in critical areas, such as keeping airplanes
safe from icing, and applying it to obtaining as much energy as possible
from the atmosphere," says NCAR program manager Marcia Politovich, who
is overseeing the development of icing and extreme temperature
forecasts. "This is cutting-edge science."
Once the systems are finalized, they will be turned over to Xcel Energy
or a utility contractor for ongoing operation. NCAR researchers will
publish the results in peer-reviewed journals, enabling other utilities
and forecast providers to learn about the technologies.
Energy is recognized by the energy industry as a national leader in
proactively moving forward with the utilization of renewable energy,"
says William Mahoney, deputy director of NCAR's Research Applications
Laboratory. "This new project is an example of how improved
understanding of the atmosphere can provide significant benefits to
The University Corporation for Atmospheric Research manages the National
Center for Atmospheric Research under sponsorship by the National
Science Foundation. Any opinions, findings and conclusions, or
recommendations expressed in this publication are those of the author(s)
and do not necessarily reflect the views of the National Science