Building
Owners - Benefits
Many
benefits to building owners for deploying CHP systems for buildings
include the following:
Reduced
energy costs
Building
owners can reduce their energy costs by deploying CHP systems
because compared to conventional systems these systems provide
the following advantages:
-
Increased energy efficiency
-
Reduced demand charge
-
Reduced peak electric energy costs
As
discussed in the section on Basics,
CHP systems can offer much higher energy efficiency than conventional
stand-alone equipment items for similar degree of power reliability,
comfort cooling, heating and indoor air quality. Because of the
higher energy efficiency of the CHP system, it consumes nearly
40% less fuel than conventional systems. The reduced fuel consumption
can significantly reduce energy costs.
The
cost of electricity to buildings is generally based on power demand
(measured in kW) and electric energy usage (measured in kWh).
The power demand charge is generally a monthly charge ($/kW) based
on the peak/maximum power used during a month for a specified
period, generally 15 minutes to 30 minutes. Power demand charge
rates can vary with time-of-year. CHP systems reduce power demand
in two ways: 1) by generating some of the power at site, and 2)
by using thermal energy from power generation equipment, instead
of electricity, for operating cooling, heating and/or humidity
control equipment.
The
charge for electric energy usage generally varies with the time-of-year
and the time-of-day. This charge is the highest during peak periods,
generally from 9AM until 3PM, and the least during off-peak period,
generally from midnight until 7AM. Therefore, primary reduction
in electric energy cost savings for using CHP systems comes from
avoiding purchase of electric energy during peak periods.
Reduced
life-cycle costs
Even
though the initial cost of CHP systems for buildings is higher
than purchasing all electric power needs and using conventional
chillers and boilers for cooling, humidity control and heating
needs, the life-cycle cost of the CHP systems is often lower because
of the energy cost savings over its useful life of more than 20
years.
Attractive
return on investment
As
discussed above, on an overall basis, CHP systems can reduce energy
costs for buildings. If the incremental installed cost of CHP
systems over conventional systems is treated as an investment,
and the annual savings in its energy costs are treated as the
return on that investment, the return can be very attractive.
Improved
power reliability
Economic
losses due to power outages in the U.S. have cost American businesses
billions of dollars. The following table shows the economic impact of power outages on some industries.
| Industry |
Average Cost of Power Outage,
$/hr |
Brokerage Operations
|
6,480,000
|
Credit Card Operations
|
2,580,000
|
Airline Reservations
|
90,000
|
Telephone Ticket Sales
|
72,000
|
Cellular Communications
|
41,000
|
Since
CHP systems generate power on-site or near-site, these systems
improve power reliability by either
reducing or eliminating a building's dependence on the electric
power grid, and by providing an additional power option to
the
building. Also, because CHP systems are located at or near buildings,
power outages experienced because of losing a distribution
line
are improbable.
The
higher the number of buildings that use CHP systems, the lower
the demand on the electric grid will be. In areas where the grid
is at or near capacity, the reduced demand provided by CHP will
result in increased grid reliability.
Improved
economics for enhancing indoor air quality
Controlling
humidity of indoor air is an important aspect of enhancing indoor
air quality in building. It is important to keep humidity in the
indoor air to below 60% to prevent growth of mold, mildew and
bacteria.
Traditionally,
humidity reduction is accomplished using chillers that lower the
temperature of incoming air to below the dew point temperature
and condensing out the moisture and then sometimes reheating the
air to bring it back to a comfortable temperature. This approach
requires a lot more energy than using a desiccant system that
reduces humidity without reducing air temperature.
Desiccant
systems use a medium that directly removes the moisture from the
air and then uses low-energy heat to regenerate the medium so
that it can be reused. The heat available from the exhaust gases
of power generation equipment in the CHP system can be used to
regenerate the desiccant. Therefore, deployment of CHP systems
that incorporate desiccant systems, improve the economics of enhancing
indoor air quality.
