Combined
Heat and Power: Frequently Asked Questions FAQs
What is combined heat and power (CHP)? An efficient and
clean approach to generating electric power and useful thermal energy from a single
fuel source. CHP is used either to replace or supplement conventional separate
heat and power (SHP). Instead of purchasing electricity from the local utility
and burning fuel in an on-site furnace or boiler to produce thermal energy, an
industrial or commercial facility can use CHP to provide both energy services
in one energy-efficient step.
How Does CHP Work?
o
CHP involves the
recovery of otherwise-wasted thermal energy to produce useful thermal energy or
electricity, configured either as a topping or bottoming cycle.
o
In a typical
topping cycle system, fuel is combusted in a prime mover such as a gas turbine
or reciprocating engine to generate electricity. Energy normally lost in the
prime mover’s hot exhaust and cooling systems is instead recovered to provide
heat for industrial processes, hot water, or for space heating, cooling, and
dehumidification.
o
In a bottoming
cycle system, also referred to as “waste heat recovery,” fuel is combusted to
provide thermal input to a furnace or other industrial process and heat
rejected from the process is then used for electricity production.
Why is CHP more efficient than conventional
electricity generation? CHP
is a form of distributed generation, which is located at or near the
energy-consuming facility, whereas conventional generation takes place in large
centrally-located power plants. CHP’s higher efficiency comes from recovering
the heat normally lost in power generation or industrial processes to provide
heating or cooling on site, or to generate additional electricity. CHP’s
inherent higher efficiency and elimination of transmission and distribution
losses from the central power plant results in reduced primary energy use and
lower greenhouse gas (GHG) emissions.
Is CHP widely used in the United States?
·
The existing 82
GW of CHP capacity at almost 3,600 facilities represents 8 percent of current U.S.
generating capacity and 12 percent of total electricity generated.
·
CHP is used in
every state, and is primarily found in areas with high concentrations of
industrial and commercial activity, high electricity prices, and policies
favorable to CHP.
What kinds of facilities use CHP?
CHP can be utilized in a variety of
applications that have significant electric and thermal loads. Eighty-eight
percent of existing CHP capacity is found in industrial applications, providing
electricity and steam to energy-intensive industries such as chemicals, paper,
refining, food processing, and metals manufacturing. CHP in commercial and
institutional applications is currently 12 percent of existing capacity,
providing electricity, steam, and hot water to hospitals, schools, university
campuses, hotels, nursing homes, office buildings and apartment complexes.
What are the benefits of CHP for the energy user?
Ø CHP reduces energy costs for the user.
Ø CHP reduces the risk of electric grid disruptions and
enhances energy reliability for the user. This is particularly useful for
hospitals, research institutions, or industrial facilities where electric power
outages are particularly disruptive and costly.
Ø CHP provides predictability in the face of uncertain
electricity prices.
What are the benefits of CHP for Your Community?
o
CHP reduces
emissions of GHGs and other air pollutants by as much as 40 percent or more.
o
CHP consumes
essentially zero water resources in generating electricity (a typical coal
fired power plant consumes 0.2 to 0.6 gallons of water per kWh).
o
CHP offers a
low-cost approach to adding new electricity generation capacity.
o
On-site electric
generation reduces grid congestion and improves the reliability of the
electricity distribution system.
o
CHP defers the
need for investments in new central generating plants, transmission and
distribution infrastructure, helping to minimize increases in electricity
costs.
o
CHP uses highly-skilled
local labor and technology.
