Page 54 - North American Clean Energy March April 2016

rom electricity generation.
ehydrogen.com
gure 2.
UL Recognized Component
wind power
antage
e a battery storage system t offer the potential to store
gy in today’s wind farm echnology is inherently
ecause of its high cost. The ice is far too much for the
r in the long run, especially ing world.
c to calculate is the capital
att-hour. Battery technology s $500 per kilowatt-hour to about $10 per kilowatt-hour ogen’s magnesium slurry
e nancial impact on
his amounts to an estimated
tt-hour consumed for a
e system, compared to just ilowatt-hour for magnesium ogy.
Line
the right storage solution,
wind farms can be built. il fuel plants can be retired. n can run on electricity or
m electricity. Buildings can h electricity and hydrogen.
from the generation of
be a thing of the past.
n’s slurry is proving to be the
echnology with the cost- needed to give staying power ble energy resources.
Hydrogen and a
gure 1.
by Ken Brown
A NEW PARADIGM IS NEEDED FOR ELECTRICITY STORAGE IN THE WIND ENERGY MARKET.
Today, what passes for “grid storage” are technologies providing, at most, eight to 12 hours of discharge time. If electricity generation is to be successfully weaned from fossil fuels, storage must have more than 1,000 hours of discharge time to back up renewables when they are intermittent. Sometimes the wind does not blow and the sun does not shine for long periods of time. Long discharge time provides reliability.
e good news is the low-cost storage technologies required to accomplish this transformation are being developed.
Strong need for storage
It’s clear that renewable energy from wind farms, as well as solar energy installations, remains intermittent and frustratingly dependent on fossil fuels. Because of the variable nature of the energy output, a generation plant must be available to be turned up or down. In general, natural gas- red turbine generator plants accomplish this task for wind farms.
e renewable energy industry faces a dirty dilemma: behind every wind farm sits a fossil fuel plant to provide backup power when the skies are still. More wind farms mean more fossil fuel plants with more carbon emissions. Building more wind farms will not lead to full energy generation from wind.
To integrate this intermittent energy source, dispatchable plants of the same output must be ready to take over whenever wind production falls, as it does some 80 percent of the time, to keep the amount of generation constant. Some of the energy harvested by spinning wind turbines must be stored so it can be used when the wind isn’t blowing. at way, a wind farm becomes a dispatchable plant controlled just like a fossil fuel plant.
State of storage technology
To understand where we need to go, it’s important to look at how far we’ve come. What types of storage technologies are available or under consideration today and what are some of their attributes?
Batteries
Lead acid is a tried and true technology, and there have been developments to improve the cycle life. Lithium-ion, a newer technology, provides higher power density and the cycle life is longer compared to lead acid. ese technologies would need a cost reduction of 98 percent to economically store 1,000 hours of output.
Flow batteries have a di erent construction. An electrolyte liquid ows from tanks through a casing containing the electrodes. Because the electrolyte is separate from the electrode case, ow batteries can be signi cantly cheaper in cost. e cost still must be reduced by 95 percent to economically store 1,000 hours.
Metal air batteries involve the oxidation of metals with the oxygen from air. Using inexpensive metals, they can be cheaper as well but have limitations in their cycle life. e cost must come down 80 percent to economically store 1,000 hours.
Beyond batteries
Some other storage technologies are in the mix. First, ywheels are very quick to respond and are good for frequency and voltage control. Although high in power, they are low in energy and not suitable for long duration discharge.
Pumped storage is the only signi cant storage technology in use today. e idea is to pump water uphill when electricity is inexpensive and to harness gravitational energy by releasing the water back down through a hydroelectric turbine when power is needed. New pumped storage facilities are expensive to build and di cult to permit.
Another technology, Compressed Air Energy Storage, or CAES, consists of a compressor that pumps air into a pressure chamber. When electricity is needed, the air is heated and expanded via an air turbine generator. e lowest-cost CAES utilizes underground caverns. However, good caverns are in short supply.
Hydrogen on the horizon
In addition to the aforementioned storage solutions, a patented slurry technology is emerging as a contender to prevent wind farms from having a carbon footprint of their own. e projected costs make this technology economically viable.
New Paradigm for
Electricity Storage
•
• • • • • •
FOAM DUCT SEALANT MULTI-USE CARTRIDGE
Seals Out Water, Sewer Gases, and Rodents From Conduits
Reenterable
Holds High Water-Head Pressures
Kit Seals Five 2” (or 5 cm) Conduits Compatible with Cables and Conduits Creates Airtight Watertight Seals
Exceeds U.S.A. NEC Sections
225.27, 230.8,300.5 (G) and 300.7 (A)
on Raceway Seals. www.polywater.com/ductseal2.html
54
MARCH/APRIL 2016 nacleanenergy.com
500 450 400 350 300 250 200 150 100
50 00
Wind with Fossil Fuel Backup
30 40
Fossil Fuel Plant Output to Grid
Wind Farm Output to Grid
10 20
50 60 70 80 90
100
FRACTION OF THE YEAR (%)
The chart above shows the current method of integrating a 500 megawatt (MW) wind farm. Because this is an intermittent generation source, energy from fossil fuel-powered plants must make up the difference in output when wind production declines at various times of the year. Under this scenario, with wind and fossil fuel each contributing about half the energy output, we will never get above 50% renewable generation – no matter how many wind farms we build.
500
450
400
350
Wind Storage with Hydrogen Slurry
300 Energy to Energy to
250 200 150 100
Storage
Energy from Storage
Energy Direct
to Grid
50
00 10 20 30 40 50 60 70 80 90 100
FRACTION OF THE YEAR (%)
The chart above shows the same 500 MW wind farm rmed by Safe Hydrogen’s slurry storage technology. With 100,000 MWh of storage, the wind farm can be converted to a base load or a dispatchable plant that can be controlled just like a fossil fuel plant. The storage availability means the average annual output for the wind farm is about 150 MW. More importantly, the wind farm becomes a reliable, constant source of energy.
ENERGY OUTPUT (MW) ENERGY OUTPUT (MW)