What is CHP?
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Click here to see a short animation about CHP
(contains sound).
Combined heat and power, or CHP, refers to generating electricity at or
near the place where it is used. The waste heat from the electricity
generation can be used for space heating, water heating, process steam for
industrial steam loads, humidity control, air conditioning, water cooling,
product drying, or for nearly any other thermal energy need. The end result
is significantly more efficient than generating each of these separately.
The average power plant in the U.S. is 33% efficient, and the average
overall efficiency of generating electricity and heat by conventional
systems is around 51%. CHP units are often more than 80% efficient. CHP is
sometimes called “energy recycling” because the same energy is used
twice—once for electrical energy and once for thermal energy.
CHP is also known as cogeneration. It sometimes goes by other related
terms— Building Cooling, Heating, and Power (BCHP), Integrated Energy
Systems (IES), and trigeneration.
CHP systems come in a range of sizes, from household-scale and up, but
they are most feasible in larger commercial buildings, multi-building
facilities such as colleges and universities, and industries.
CHP systems use one or more of the following prime movers: reciprocating
engines, turbines, microturbines, fuel cells, or Stirling engines. For
cooling and air conditioning applications, the waste heat can be used in an
absorption chiller, adsorption chiller, steam chiller, or a desiccant
dehumidification unit.
CHP units typically run on natural gas. They can also run on methane
(also known as biogas, bio-energy, or opportunity fuels) produced from landfills, wastewater treatment plants, concentrated livestock
operations, food and beverage processing waste, wood, or other organic
products, making CHP a renewable energy resource. They can also run on propane, diesel, or most other liquid or
gaseous fossil fuels.
To put CHP in the right perspective, think of the analogy of ice boxes.
Once upon a time, ice had to be made at a large central plant and delivered
by trucks to each household and business, where it would be kept ice boxes.
With the invention of the refrigerator, ice can now be made at each
household and business, right on-site where it is used. Computers offer
another analogy. Computers used to be large centralized mainframe units, and
now they’ve shrunk down to laptops and desktop units than can be sited
practically anywhere, right where they are needed.
- Lower energy bills. Many businesses can see significant cost
savings on their energy bills—especially during peak times.
- Protection from electric rate hikes. With CHP, your energy
costs can be more stable and more predictable.
- High-reliability power -> Fewer outages and reduced downtime. Consider the cost of
outages: lost computer data, lost productivity, and frustration from
customers. Having your own source of power on-site means that outages,
blackouts, and brownouts may hit the rest of your neighborhood—and your
competitors—but they won’t hit you.
- Improved power quality. Even momentary blips, surges, and dips
in electric power supply can wreak havoc on computer systems and sensitive
manufacturing processes. Many firms in fields such as bio-tech,
pharmaceutical, plastics manufacturing, financial, data processing and
storage, internet, and computer-related firms rely on CHP for high power
quality.
- Improved environmental quality. Customers and investors are
increasingly putting pressure on businesses to improve their environmental
profile. CHP is much more efficient than the electric grid and a separate
boiler/air conditioner—often more than twice as efficient. This means less
fossil fuel use, fewer greenhouse gas emissions, and fewer smog-forming
emissions for the same amount of energy. In addition to being more
efficient, more CHP systems also run cleaner than the average U.S. power
plant, which, again, means fewer smog-forming emissions.
- Improved indoor air quality and air conditioning. CHP can make
your building more comfortable for customers and employees. The waste heat
from cogeneration can be used to run an absorption chiller for air
conditioning, either replacing or supplementing an electric chiller. It
can also be used to run a desiccant dehumidification unit. Better control
of humidity reduces total air conditioning loads, prevents mold, mildew,
and rot damage, and protects moisture-sensitive manufacturing processes.
- PR and marketing benefits. Businesses that install CHP often
receive publicity for being innovative, technologically advanced, and
environmentally friendly.
- Hassle-free. Qualified CHP developers can perform the analysis,
site work, installation, and start-up of the CHP unit. A few CHP firms
will even own, operate, and/or maintain the CHP on your behalf.
- Free assistance from the Intermountain CHP Center.
The Center can provide you with neutral, objective and unbiased expert
opinions about if CHP is cost-effective and technically feasible for your
facility. If it is, we’ll walk you through the process, and answer any
questions you have along the way. If needed, we’d be happy to give
presentations to your company’s CEO, CFO, or other decision-makers.
- Lower vulnerability to terrorist attacks. A system that has
many smaller power plants is inherently more secure than one that has
several large plants.
- Reduced need for new power lines →
Preserves scenic views and property values. Communities fight new
transmission lines, in some cases stalling them for years though legal
wrangling. No one wants a new transmission line going through their
property. CHP reduces the need for new transmission and distribution
lines.
- Reduced line losses. An average of 5-10% of electricity
generated at a power plant never gets to its destination. Such “line
losses” are even higher the further the electricity has to travel, and the
higher the congestion on a power line. Since CHP is located right near
where the electricity is used, it doesn’t have any line losses. This
means, essentially, that CHP gains an extra 5-10% efficiency compared to a
central power plant.
- Increased energy supply → Reduced
vulnerability to brownouts and blackouts. Widespread outages like the
one that hit the northeast, and widespread shortages like the one that hit
California, can be mitigated by having a wide diversity of supply options.
Loss of a single plant or a few plants would have a far smaller effect on
the whole system. Each facility that has CHP could keep their business
running throughout the outage. Plus, depending on how the CHP units are
configured, utilities can use them to help bring up the rest of the grid
after an outage.
- Flexible and modular → A better way to
plan for new capacity additions. CHP units are smaller than central
power plants and come in a variety of sizes, so they can be added as they
are needed, and when and where they are needed. CHP units’ smaller size
means they have a shorter lead time to install. This reduces the risk of
over- or under-building (each of which have their own financial
consequences), and avoids the problem of excess capacity sitting idle
while waiting for demand to “grow into it.”
- Lower overall fossil fuel use. Conventional systems that
generate electricity and thermal energy separately require about 65% more
energy input than integrated CHP systems. Using CHP prolongs the
availability of our limited fossil fuel resources and reduces our
dependence on imported fossil fuels and on nuclear power.
- Lower greenhouse gas emissions. Because of its higher
efficiency, CHP produces less CO2 emissions than conventional centralized
power plants.
- Lower smog-forming emissions. CHP produces fewer NOx emissions
by two ways. First, CHP plants are more efficient overall than
conventional systems, so less fuel is burned in the first place to produce
the same amount of useful energy. Second, CHP units run cleaner than the
average U.S. power plant, so fewer emissions are produced when the fuel is
combusted.
- Option to use free, renewable waste fuels from landfills, wastewater
treatment plants, livestock operation, forest waste, and food and beverage
processing.
- Wastewater treatment plants that use anaerobic digestion
create methane, and that methane can be captured and used for CHP. The
heat from the CHP is fed back to the digester to maintain the process
temperature—replacing the natural gas boilers that would otherwise have
to be used.
- Landfills let off methane, which can be captured and used as
a fuel for CHP. Many mid-size landfills currently “flare” (burn) off the
methane, instead of using it for a useful purpose, like CHP. Smaller
landfills just vent the methane to the atmosphere—and methane is a
greenhouse gas 21 times more potent than carbon dioxide. Note, however,
that using the landfill methane for CHP requires a nearby business or
industry that can use the thermal energy, since landfills themselves
usually don’t have a high heat load.
- Concentrated livestock feeding operations, such as those for
cattle, hogs, or poultry—generate significant amounts of waste that
often sits in lagoons, causing odor problems for nearby neighborhoods
and significant water quality issues. Putting the waste into an
anaerobic digester instead, and capturing the methane for CHP,
eliminates both of these issues. The heat can be used in the digester to
maintain the process temperature, or used to heat the site’s buildings.
- Forest thinning and logging activities: Reducing accumulated
underbrush and slash reduces the risk of uncontrolled wildfires. This
waste material, combined with the leftover wood products from mills, can
be combusted, gasified, or anaerobically digested and used in a CHP unit.
- In food-processing industries and beverage production, the
organic material and wastewater left over from food-processing
industries and beverage production can be put in an anaerobic digester,
and the methane from the digester can run a CHP plant. The thermal
energy from the CHP can go towards the facility’s steam loads, heat
loads, or back into the digester to maintain its process temperature. A
number of breweries in the region are taking advantage of CHP.
** Note: CHP
is ideal for certain market sectors. Click here
to see sector-specific resources & reports for hospitals, campuses, agriculture
& livestock, food & beverage processing, ethanol plants, multi-family housing,
and others. |
