October 2010 |
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Load Shaping for Net Zero Buildings Load shaping prioritizes energy use by prioritizing systems, matching demand to supply within the microgrid. |
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Management of load shape will become a new source of value in Net Zero buildings. Smaller operating margins will increase the cost of overshooting energy budgets even briefly. New market models will create costs for undershooting as well as over-shooting energy use. Off-grid facilities will want to fix energy use to supply precisely. Storage management and even privacy create new incentives to precise energy use.
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Load shape is the chart over time of how much energy
is used. Each system in a building has a load shape. A refrigerator has a simple
recurring load shape. An air conditioning system cycle has a load shape that
will vary based on outside temperature and room occupancy. The building’s load
shape is the sum of all the load shapes of the systems within the building.
It is easiest to consider the value of managing load shape when considering an
off-grid scenario. There is a knowable and fixed amount of electricity
available. The building load is dynamic, composed of many systems each on its
own cycle. The peak load used by each system is less than available power. If
the peak load from two or more systems coincide, they can exceed the available
power, and damage the other systems on the internal grid. Top shape load, one
system can be delayed for a few minutes, or another can be accelerated,
maintaining service while never exceeding supply.
The electricity source is solar PEV providing a predictable yet intermittent
energy supply. It is necessary to store energy while the sun shines for times
when it does not. Storage management may involve managing battery charging, or
it may require pre-use. Pre-use may involve a variety of physical processes,
such as pre-cooling or pre-pumping water. Each pre-use scenario has its own load
profile.
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Load shaping manages the existing electrical supply for maximum utility while
storing all excess supply in some form or another. It avoids peaks, and uses the
troughs in energy use. Load shaping prioritizes energy use by prioritizing
systems, matching demand to supply within the microgrid.
As energy markets become dynamic, the most valuable customer is one whose load
is predictable. Today, load variance is statistical noise within the grids
operating margins. As we reduce the operating margins of our smart grids, they
will have less ability to absorb variability. Customers may have to purchase
variability on energy spot markets.
Some consumers today already protect themselves from price variability by making
committed purchases of energy. Customers using more than the committed load can
incur substantial costs. Using any less than a committed purchase is leaving
money on the table. Site-based storage as a complement to load shaping supports
customers on both sides of the committed load. Customers in more dynamic markets
with higher prices will benefit from load shaping just as do consumers in
off-grid facilities.
The approaches and technologies that enable a facility to manage its load shape
adapt naturally to shortages and outages. Facilities managers increase their
demand response capabilities when they know each load, how to move it in time,
and how to shape load for each level of use.
In today’s world, load shape arbitrage is a service provided by the energy
supplier. Under smart grids, the cost of that arbitrage will be unbundled and it
will increase. Many facilities will see opportunity in bringing that arbitrage
in-house.
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