WIND ENERGY SYSTEMS - Cd3wd

Chapter 8—Economics 8–18
The unit cost of electricity due to this fixed charge rate is then
C uf = L f
W = 144
2628 =$0.0548/kWh
Variable costs in Fig. 6 consist of fuel costs (if any) plus operation and maintenance (OM)
costs. The OM costs consist of both a fixed and a variable portion. The fixed portion is
defined as being invariable with energy generated, transferred, or used. The variable portion
depends on the amount of generated power. This would include water, limestone, filter bags,
and ash disposal costs for coal generators. Wind generators do not consume anything as they
generate electricity, but some maintenance functions will depend on the number of hours of
operation, so these functions would represent the variable portion. The variable costs are
normally expressed in mills/kWh, where 1 mill = $0.001 or one tenth of a cent. The fixed
OM costs are expressed in dollars per year per kW of rating. The levelized annual variable
costs would then be expressed as
L v = L fuel + L fom + L vom $/kW/yr (20)
where L fuel is the levelized annual fuel cost, L fom is the fixed OM cost, and L vom is the variable
OM cost.
We see that the levelized annual fuel cost L fuel is just the present cost of fuel to generate
one kWh, C fuel , times the number of kWh generated per year by each kW of capacity times
the levelizing factor.
L fuel =(C fuel )(W )(LF) $/kW/yr (21)
We may also define the levelized annual revenue requirements in dollars per kWh L ′ rather
than the dollars per year per kW of capacity L.
L ′ = L W
(22)
Similar expressions hold for the individual components of L, L f and L v .
We now want to present a major example of all these computations for a large coal plant.
These numbers were developed for the Electric Power Research Institute[3] and thus represent
typical utility values for end-of-year 1978.
Example
A large coal plant has the following data assumptions:
Wind Energy Systems by Dr. Gary L. Johnson November 21, 2001