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The Good News
2017 October/November
Pg 3 - The Sunshine Express
1/10 to 1/40 the cost of batteries or pumped
hydroelectric systems Firebricks offer
low-cost storage for carbon-free energy
September 6, 2017: Firebricks, designed to with-
stand high heat, have been part of our technologi-
cal arsenal for at least three millennia, since the
era of the Hittites. Now, a proposal from MIT re-
searchers shows this ancient invention could play
a key role in enabling the world to switch away
from fossil fuels and rely instead on carbon-free
energy sources.
The researchers¡¯ idea is to make use of excess
electricity produced when demand is low ¡ª for
example, from wind farms when strong winds are
blowing at night ¡ª by using electric resistance
heaters, which convert electricity into heat. These
devices would use the excess electricity to heat
up a large mass of firebricks, which can retain the
heat for long periods if they are enclosed in an
insulated casing. At a later time, the heat could be
used directly for industrial processes, or it could
feed generators that convert it back to electricity
when the power is needed.
The technology itself is old, but its potential use-
fulness is a new phenomenon, brought about by
the rapid rise of intermittent renewable energy
sources, and the peculiarities of the way electricity
prices are set. Technologically, the system ¡°could
have been developed in the 1920s, but there was
no market for it then,¡± says Charles Forsberg, a
research scientist in MIT¡¯s Department of Nuclear
Science and Engineering and lead author of a re-
search paper describing the plan, that appears this
week in the Electricity Journal.
Forsberg points out that the demand for industrial
heat in the U.S. and most industrialized regions is
actually larger than the total demand for electric-
ity. And unlike the demand for electricity, which
varies greatly and often unpredictably, the de-
mand for industrial heat is constant and can make
use of an extra heat source whenever it¡¯s avail-
able, providing an almost limitless market for the
heat provided by this firebrick-based system.
The system, which Forsberg calls FIRES (for FIre-
brick Resistance-heated Energy Storage), would in
effect raise the minimum price of electricity on the
utilities market, which currently can plunge to al-
most zero at times of high production, such as the
middle of a sunny day when solar plant outputs
are at their peak.
Electricity prices are determined a day in advance,
with a separate price for each one-hour segment
of the day. This is done through an auction sys-
tem between the producers and the distributors
of power. Distributors determine how much power
they expect to need during each hour, and suppli-
ers bid based on their expected costs for produc-
ing that power. Depending on the needs at a given
time, these prices can be low, if only baseload nat-
ural gas plants are needed, for example, or they
can be much higher if the demand requires use of
much more expensive ¡°peaking¡± power plants. At
the end of each auction, the distributors figure out
how many of the bids will be needed to meet the
projected demand, and the price to be paid to all
of the suppliers is then determined by the highest-
priced bid of all those accepted for that hour.
But that system can lead to odd outcomes when
power that is very cheap to produce ¡ª solar, wind
and nuclear power, whose actual operating costs
are vanishingly small ¡ª can supply enough to
meet the demand. Then, the price the suppliers
get for the power can be close to zero, rendering
the plants uneconomical.
But by diverting much of that excess output into
thermal storage by heating a large mass of fire-
brick, then selling that heat directly or using it to
drive turbines and produce power later when it¡¯s
needed, FIRES could essentially set a lower limit
on the market price for electricity, which would
likely be about the price of natural gas. That, in
turn, could help to make more carbon-free power
sources, such as solar, wind, and nuclear, more
profitable and thus encourage their expansion.
The collapse of electricity prices due to expansion
of nonfossil energy is already happening and will
continue to increase as renewable energy instal-
lations increase. ¡°In electricity markets such as
Iowa, California, and Germany, the price of elec-
tricity drops to near zero at times of high wind or
solar output,¡± Forsberg says. Once the amount
Low-Tech Firebrick Thermal
Storage System Proposed
Strong Growth Expected
of generating capacity provided by solar power
reaches about 15 percent of the total generating
mix, or when wind power reaches 30 percent of
the total, building such installations can become
unprofitable unless there is a sufficient storage
capacity to absorb the excess for later use.
At present, the options for storing excess elec-
tricity are essentially limited to batteries or
pumped hydroelectric systems. By contrast, the
low-tech firebrick thermal storage system would
cost anywhere from one-tenth to one-fortieth as
much as either of those options, Forsberg says.
Firebrick itself is just a variant of ordinary bricks,
made from clays that are capable of withstand-
ing much higher temperatures, ranging up to
1,600 degrees Celsius or more. Virtually dirt
cheap to produce ¡ª clay is, after all, just a
particular kind of dirt ¡ª such high-temperature
bricks have been found in archeological sites
dating back to around 3,500 years ago, such as
in iron-smelting kilns built by the Hittites in what
is now Turkey. The fact that these bricks have
survived until now testifies to their durability.
Nowadays, by varying the chemical composition
of the clay, firebrick can be made with a variety
of properties. For example, bricks to be placed
in the center of the assemblage could have high
thermal conductivity, so that they can easily take
in heat from the resistance heaters. These bricks
could easily give up that heat to cold air being
blown through the mass to carry away the heat
for industrial use. But the bricks used for the
outer parts of the structure could have very low
thermal conductivity, thus creating an insulating
shell to help retain the heat of the central stack.
The current limit on FIRES is the resistance
heaters. Existing low-cost, reliable heaters only
go to about 850 C. Ultimately, Forsberg sug-
gests, the bricks themselves could be made
electrically conductive, so that they could act as
low-cost resistance heaters on their own, both
producing and storing the heat. A promising ma-
terial for these firebricks is silicon carbide, which
is already produced at massive scales for uses
such as sandpaper. China currently produces
about a million tons of it per year, Forsberg says.
Turning that heat back into electricity is a big-
ger technical challenge, so that would likely be a
next-generation version of the FIRES system, he
says. That¡¯s because producing electricity with
the conventional turbines used for natural gas
power plants requires a much higher tempera-
ture. While industrial process heat is viable at
about 800 C, he says, the turbines need com-
pressed air heated to at least 1,600 C. Ordinary
resistance heaters can¡¯t go that high, and such
systems will also need an enclosing pressure
vessel to handle the needed air pressure. But the
advantage would be great: Doubling the operat-
ing temperature would cut in half the cost of the
heat produced, Forsberg says.
The next step, Forsberg says, will be to set up
some full-scale prototype units to prove the
principles in real-world conditions, something he
expects will happen by 2020. ¡°We¡¯re finding the
right customers for those initial units,¡± he says,
which would probably be a company such as an
ethanol refinery, which uses a lot of heat, located
near a sizable wind-turbine installation.
¡°I believe that FIRES is an innovative approach
to solve a real power grid problem,¡± says Regis
Matzie, the now-retired Chief Technical Officer
at Westinghouse Electric, who was not involved
in this work. The way prices for electricity are
determined in this country produces a ¡°skewed
electricity market [that] produces low or even
negative market prices when a significant frac-
tion of electrical energy on the grid is provided
by renewables,¡± he says. ¡°A very positive way to
correct this trend would be to deploy an eco-
nomical way of storing the energy generated
during low electricity market prices, e.g., when
the renewables are generating a large amount of
electricity, and then releasing this stored energy
when the market prices are high. FIRES provides
a potentially economic way to do this, but would
probably need a demonstration to establish the
operability and the economics.¡±
The research team included MIT graduate stu-
dents Daniel Stack, Daniel Curtis, Geoffrey
Haratyk, and recent graduate Nestor Sepulveda
MS ¡¯14.
(source: David L. Chandler, MIT News Office,
news.mit.edu)
One proposed application of the firebrick
based thermal storage system is depicted in
this hypothetical configuration, where it is
coupled to a nuclear power plant to provide
easily dispatchable power. Image: Courtesy of
the researchers
State forecast shows increased momentum
DENVER: Sept 20, 2017: The Governor¡¯s Office of
State Planning and Budgeting (OSPB) released its
quarterly economic and revenue forecast.
After modest increases in the prior two fis-
cal years, General Fund revenue is forecast to
increase at stronger rates of 8.1% in FY 2017-18
and 4.9% in FY 2018-19.
¡°Our momentum remains strong thanks to the
strength of the state¡¯s technology sector, new
business start ups and the growth of our skilled
workforce,¡± said Governor John Hickenlooper.
¡°Still, the tight labor and housing market condi-
tions are raising costs for individuals and busi-
nesses and our rural communities continue to
experience lower job and income growth than our
urban areas. We are keeping on eye on these
issues so they don¡¯t curtail our success.¡±