How do you save clean energy? This company plans to pump it underground

New York. California. Hawaii. Colorado. Maine. All of these
states and a few others want to get their electric grids running
mostly if not entirely on renewable energy in the next few decades.
As they ramp up wind and solar farm projects, they’re also
looking for ways to store surplus energy to use when the wind
isn’t blowing and the sun isn’t shining.

Start-ups focused on energy storage are scrambling for the cash
and opportunities to demonstrate that their system will hold more
than a few hours worth of charge. Last week, Quidnet, a Houston,
Texas-based company, announced that it lined up a contract with the
New York State Energy and Research Development Authority to
construct a pilot project for its “Geomechanical Pumped
Storage” technology.

Quidnet’s system is a new take on pumped-hydro storage, which
takes excess energy from the grid during periods of low electricity
demand and uses it to pump water up a hill from a lower reservoir
to an upper reservoir. Later, when energy is needed, the water is
released back down to spin a turbine and generate electricity.
Pumped-hydro accounts for 95 percent of the existing energy storage
used by utilities in the U.S., but most of these systems were built
in the 1970s and 1980s. That’s because it’s expensive and
politically difficult to set aside enough land in the mountains to
build new pumped-hydropower reservoirs.

Joe Zhao, the CEO of Quidnet, said the company’s technology
depends on the same supply chains and expertise used by existing
pumped-hydro systems, but gets around those stickier land-use
problems by pushing the water underground. To “charge” the
battery, the system draws excess energy from the grid to suck water
from a holding pond into an underground well, where it’s stored
under pressure
in the rock. When the energy is needed, the
water is released and rushes back to the surface, spinning a
turbine similar to those deployed in traditional pumped-hydro
systems. The pilot project in New York aims to store 10 hours worth
of energy.

Zhou said that Quidnet, which is backed by Bill Gates’
Breakthrough Energy Ventures, could deploy these systems in roughly
60 percent of U.S. power markets today, based on the type and
structure of rock required for the wells. The conditions are
especially ripe in New York. “There’s a tremendous, tremendous
energy storage resource in New York. I think it can really help the
state advance its clean energy goals,” Zhou told Grist.

Quidnet is one of several companies piloting new energy storage
systems across the country. In Vermont, Highview Power plans to
build
the first liquid air storage project in the U.S
that would
store more than eight hours of energy, using power from the grid to
liquify air and store it in tanks. One of the most anticipated
projects is Form Energy’s “aqueous air battery system” in
Minnesota, aimed at storing and delivering 150 hours of power to
the grid, though how it works
remains a bit of a mystery
.

Today, with pilot projects that store just 8-10 hours, each of
these storage solutions are in hot competition with cheap,
efficient lithium-ion batteries, which average around 4 hours of
storage. “The closer you play to lithium-ion’s durations, the
more lithium-ion can compete,” said Dan Finn-Foley, head of
energy storage at the consulting firm Wood Mackenzie. “The reason
that all these alternative technologies think that they can catch
lithium-ion is due to how the different technologies scale.”

If you have a grid that depends on wind energy and the wind
slows down for weeks at a time, you might need hundreds of hours of
storage. Increasing the storage capacity of a lithium-ion system is
costly; to double it, you need to install another battery, hence
doubling the price. Quidnet’s technology, on the other hand,
might be able to scale up more cost-efficiently by increasing the
size of a surface pond or the volume of a well. That’s how
technology like Quidnet’s could ultimately differentiate itself,
Finn-Foley explained.

“The fact that they have a pilot program is encouraging,”
Finn-Foley said. “You need to be able to show your price point
and show your duration and show your efficiencies and demonstrate
it. So that’s the next big step, you know, it puts them into the
conversation.”

This story was originally published by Grist with the headline
How do you save clean energy? This company plans to pump it
underground
on Jun 30, 2020.

Source: FS – All – Ecology – News 2
How do you save clean energy? This company plans to pump it
underground