When
power plants are built, several factors influence the choice of fuels
and technologies that will ultimately generate electricity. Cost is one
of the most difficult factors to compare, as technologies can have
vastly different capital, fuel, maintenance, and financing costs, as
well as different utilization rates and access to fuel resources.
Two
measures, the levelized cost of electricity (LCOE) and the levelized
avoided cost of electricity (LACE), are widely used to make cost
comparisons across technologies. LCOE represents the
per-kilowatthour cost of building and operating a generating plant over
an assumed financial life and activity level (e.g., baseload, peaking,
seasonal). Key inputs used to calculate LCOE include capital costs, fuel
costs, fixed and variable operations and maintenance (O&M) costs,
financing costs, and an assumed utilization rate for each plant type.
These costs can vary by region and over time.
For example,
technologies such as solar and wind have no fuel costs for generation
and relatively small variable O&M costs, so their LCOE is mostly
determined by capital costs and financing costs. Capital costs include
things such as plant installation, labor, and grid-interconnection;
financing costs are the costs of servicing the debt incurred during the
lifetime of the plant. For generators that consume fuels such as coal
and natural gas, both fuel costs and capital cost significantly affect
LCOE.
LCOE values may also vary across regions because of
differences in construction, fuel, and transmission costs, as well as
differences in the quality of resource available for certain renewables
such as solar and wind. There are some attributes that LCOE does
not capture, such as environmental considerations and grid operation
constraints for maintaining system reliability. System reliability can
be important, as some technologies are not dispatchable, meaning they
cannot generate electricity on command at any time of day.
LACE, a
different but related concept, represents the value to the electric
grid (measured in per-kilowatt-hour terms) of adding generating capacity
using a specific technology to the system. LACE reflects the cost that
would be incurred to provide the same supply to the system if new
capacity using that specific technology was not added. A technology is
generally considered economically competitive when its LACE exceeds its
LCOE.
Comparisons between the LCOEs of different technologies will
not necessarily provide a good indicator of their economic
competitiveness. This is clearly evident where new capacity using one
technology competes against an existing plant using another technology.
Because the cost of the existing plant has already been incurred, the
new capacity addition will increase system cost unless its LCOE is lower
than the operating cost (fuel and maintenance) of the existing plant.
Many existing plants that were expensive to build but are cheap to
operate, such as large coal and nuclear plants, can therefore be very
economically competitive even though the LCOE for new plants of these
types may be higher than the LCOE for other technologies.
Even
when two new plants using different technologies are compared, LCOE may
not account for differences in the services that each technology
provides to the grid. For example, coal, nuclear, and natural gas
combined-cycle plants all provide baseload services to the grid, and
thus all have very similar LACE values, even where their LCOE values
differ. In some regions, wind plants often provide higher output during
the night when the demand for and the value of electricity is typically
low. Wind plants also provide energy intermittently, and they cannot be
ramped up and down by system operators to follow demand patterns. For
these reasons, in a situation where wind has a similar LCOE to a
combined-cycle plant, it typically provides less value to the system, as
measured by LACE. Solar plants tend to produce most of their energy
during the middle of the day, when the demand for and the value of
electricity is higher, resulting in a higher LACE.
As part of the analysis that determines capacity additions in the Annual Energy Outlook 2015,
EIA calculates LCOE and LACE for multiple technologies on an annual
basis through 2040 in 22 regions of the country. These calculations are
available in the full Levelized Cost and Levelized Avoided Cost of New Generation Technologies in the Annual Energy Outlook 2015 report.
http://theenergycollective.com/todayinenergy/2235636/levelized-cost-comparisons-help-explain-value-various-electric-generation-tech