Grid-scale energy storage could play an important role in helping
unstable island grids integrate more intermittent wind and solar power.
On islands where electricity is generated from expensive, imported
fossil fuels, storage plus green power also makes good economic sense.
But creating the right technical, economic and regulatory frameworks to marry these two resources together isn’t easy. Just take Puerto Rico, where some long-awaited rules for pairing energy storage and renewable energy have finally been passed, after a year of wrangling that has kept new projects on the island in limbo until now.
Earlier
this month, the Puerto Rico Electric Power Authority (PREPA) and the
island’s main utility, the Autoridad de Energía Eléctrica (AEE), released a set
of minimum technical requirements (MTRs) that govern new power
projects. These MTRs apply to new solar or wind farm projects that are
seeking to interconnect to the island territory’s grid, to which PREPA
and AEE are hoping to add 600 megawatts of green power next year, to
bring its share from about 1 percent today to 6 percent by the end of
2014.
Under the new MTRs, all new green power projects must
include some minimum energy storage capabilities aimed at helping to
stabilize the island’s grid. First, each project must have enough energy
storage to provide 45 percent of the plant’s maximum generation
capacity over the course of one minute, for use in smoothing out the
“ramp rate” of power coming on and off with changes in sunlight or wind
speeds. That’s a lot like the minimum ramp rate requirements that Hawaii’s grid requires
for large-scale wind power projects, which has also made that island an
early test market for storage-backed green power projects.
Second,
each new Puerto Rico project must have enough storage to meet 30
percent of its rated capacity for approximately 10 minutes or less, to
be called on for frequency regulation, or for keeping the grid’s power
constant at 60 hertz. While other grid operators allow energy storage to play a role in frequency regulation,
it’s unusual to match that requirement to individual projects, making
Puerto Rico’s MTR an interesting example of how to merge several forms
of grid balancing into a single regulation.
For developers
targeting Puerto Rico, the decision finally opens up a path forward for
projects that have been awaiting clear guidelines for more than a year,
said Jim McDowall, business development manager at French battery giant
Saft, in an interview. Since August 2012, PREPA has known that it needed
to ask solar and wind power projects to provide some forms of balancing
to keep the island’s unstable grid under control, he said.
But
how to set those guidelines was a trickier issue. Specifically, project
developers wanted a “safe harbor” framework that would set guidelines
for how much storage needed to be included as part of a project’s
nameplate capacity.
“Then all you have to do is keep the storage system operational, and you’re good to go,” said McDowall.
But
some regulators wanted compliance to be based on tracking each
project's continuing ability to meet grid stabilization requirements in
real time, as well as for projects to face curtailment or penalties for
failing to do so, he said. That, in turn, was seen as a non-starter for
parties putting together financing for projects, who saw the threat of
non-compliance in the future as an overwhelming risk to future
profitability.
The new rules, created through negotiations between
renewable energy and storage advocates and regulators, could now serve
as a template for similar projects across regions that face challenges
in keeping older, centrally controlled grids running amidst increasing
amounts of intermittent wind and solar power, he noted.
“I think
there’s going to be a domino effect around the Caribbean, when these
systems start going in and they’re shown to be financeable,” said
McDowall.
While he wouldn’t name any specific projects, McDowall
did say that Saft has its first contract for adding storage to a
renewable power project, and is soon to land its second on the island.
Other
big companies involved in storage, power electronics or systems
integration for storage-backed green power projects in Puerto Rico
include Schneider Electric and ABB,
he said. One of the key challenges coming in 2014 will be designing
systems that can automatically manage the specific set of ramp-control
and frequency regulation functions that the island’s new MTRs call for.
Xtreme Power, the Texas-based startup that’s built the control systems for nearly 100 megawatts
of grid-scale energy storage systems around the country, is also taking
orders now for 2014 delivery of systems that are compliant with Puerto
Rico’s new MTRs, said Ryan O’Keefe, Xtreme Power’s vice president of
business development, in an email.
AES Energy Storage, which has
the largest individual fleet of commercial-scale grid energy storage
projects in the United States, also has its eyes on Puerto Rico. In
fact, its storage operating system software,
which manages the interplay of storage and grid-scale energy markets,
has long included a module designed to meet the island’s specific needs.
http://theenergycollective.com/jeffstjohn/321826/puerto-rico-mandates-energy-storage-green-power-mix
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