April 2011 |
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Productive Load Banking
—as important as Efficiency and Demand Response? |
Toby Considine |
All the Smart Grid attention is on Demand Response (DR), that is, on
the half dozen times a year when the grid runs out of energy or has to
turn to expensive energy sources. All the building attention is on
efficiency, using the least energy inside the building possible.
Neither approach supports renewables, or distributed energy resources.
Efficiency may reduce the ability to respond to Demand Response
signals. Building owners and integrators should turn to productive load
banking instead.
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When I am at home, my smart thermostat turns my home temperature up and
down. In the winter, the temperature setting goes way down at night.
The house uses the least energy just as prices on the local wholesale power
market go negative. The price goes negative because it is expensive to
turn up and down the power generation; it is cheaper to pay to acquire
consumption than it is to turn off the generation. I don’t see
wholesale prices, so for now, I minimize use. In a better market, I
would increase my use at night, and turn the temperature down when I
get up. Instead, I use less energy but use it at the wrong time.
Load banks are familiar to those who test and install generators.
Generators can burn out the circuits they are on, or the equipment on
those circuits, if there is not adequate load on the circuits to
consume the power generated. Load banks are paired with generation to
use excess energy and to protect the generator. Most load banks do
little more than heat the air to burn off excess energy; the load bank
does not produce any service. If we can make our building systems
create value while load banking, creating productive load banking, we
will turn grid economics upside down.
Renewable energy, or rather intermittent generation, often generates
energy when there is no market for that energy. Wind farms often
produce far more energy than they can sell at that time. Just google
“wind farm Texas toaster” for description of the problem. The problem
is not, as many decry, subsidies for wind. The problem is a lack of
markets at the right time. With no place to sell enough power when the
wind is blowing, the great Texas toaster load banks wind power into
heat.
Building systems should look at what they can do to use more energy,
but at the right time. Ice Energy, which chills water at night to avoid
air conditioning during the day, is better thought of as a daily load
bank. The real impulse behind utility support of electric cars is that
if charged only at night, they provide load banking while expanding the
power market.
The most efficient place to store energy is in the middle of a process
you were going to do anyway. Ice Energy is effective because it stores
cold in the middle of the air cooling process. My home well would be a
great load bank if I had a means to store several days of water
pressure. A maker of home water heaters marshals thousands of home
units to provide fast 4-second load banking to meet the needs of the
gird—and radically changes the net cost of water heating. Productive
Load banking that performs a useful service creates value you can see
every day.
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The barriers to investments in renewable energy sources are expense and
a long payback. Each of these is dominated by capital costs rather than
by the incremental costs of generation. This means that increased sales
does not increase costs, reducing the market cost and the payback
period. The best wind farms can sell less than half of their output. If
the great wind farms could sell more than 40% of what they generate,
they would be instantly more economic, without waiting for new
technologies. If we can buy energy when it is cheap, and use it when we
need it, we can get economic benefits in the building beyond those of
efficiency. Productive load banking lets us do both.
I always laugh when I go to a conference “powered by wind”. I know that
they are paying un-economic fees to a power source that is not the
wind, which promises to buy wind at some later time. If you want to
encourage renewable energy, you need to buy it when it’s available and
cheap, not on some pretend market which sells you conventional power,
and promises to buy wind later when it is not needed. If we instead
bought energy when the wind is blowing, we would increase the value of
wind energy. Think of it as canning fresh tomatoes in summer. You don’t
can tomatoes in summer to heat the house; that would suggest canning in
winter. You can tomatoes in summer because that is when they are fresh
and cheap.
Look at your buildings, and ponder, what you can do in advance, and do
it when there is a load banking opportunity. Look for ways to
productively load bank your distributed energy resources rather than
sell excess to the grid. Look for ways to use more energy, right now.
Demand response happens now and then. For the last couple years, with a
down economy and lower industrial demand, it might not happen at all.
Load surplus opportunities happen every day. If your building systems
can take advantage of this surplus, consume energy when it is cheap and
plentiful, to provide service when it is expensive and scarce, you can
find new value streams from energy engineering, renewable energy, and
building systems.
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