Handbook of Energy Storage for Transmission or ... - W2agz.com

EPRI Proprietary Licensed Material
4. Costs and Benefits
SMES Plant Costs
There are two approaches for developing SMES costs. One is to obtain prices from vendors and
use them directly or adjust them to fit the details of the application. This method is used below
for the System Stability and the Power Quality applications, which are based on vendor data.
The second is to carry out a “bottoms-up” calculation that begins with a design and applies cost
data for materials, labor, separate components and fabrication processes. It requires knowledge
of how a plant will be constructed. Bottoms up cost calculations are the fundamental method for
estimating projected costs for technologies that are not yet commercially available. It is used to
estimate costs for the load-leveling SMES application. This latter approach is discussed and
applied to estimates for load-leveling systems. This discussion is presented before presenting
commercial system costs because the information developed is instructive for understanding
SMES costs in general since the components are somewhat different from those of other
technologies.
The SMES system consists of the components discussed in section 1 of this chapter: i.e., a
superconducting coil, a refrigerator, a power conversion system, and a control system. The cost
of the control system is small for all SMES systems and is almost independent of size. That is,
controllers for a PQ system and one for a diurnal storage system would be in the range of
$20,000. PCS requirements, and thus their costs, depend on the power demands of the customer.
However, they can be estimated from known electronic converter costs from other applications.
The cost will depend somewhat on size, but is projected to be in the range of $125/kW to
$175/kW for nth of a kind (NOAK) installations. The cost for the refrigerator depends on
amount of cooling required. The cost is roughly proportional to the room temperature power
required for operation. Refrigerators with cooling capacities appropriate for each of the three
applications considered in this section are commercially available.
The cost of the superconducting coil is somewhat more complicated to determine. It includes
several components, each of which must be developed and integrated into a coherent, consistent
design. Here we discuss each of these components and then give a formula for calculating total
costs. The key to the operation of the SMES plant is the superconductor, which is available in
commercial quantities for other applications. The amount of conventional Nb-Ti conductor to be
purchased can be specified in several different units. Typically, the final user purchases the
conductor by the meter, which can carry a specified current (in kA) at a specified field (usually
about 5 T). This is referred to as the cost in $/kAm. This metric is convenient because it is a
natural output of the magnetic design of a SMES system. Whereas in most applications the
amount of material needed is linearly proportional to the stored energy, in the case of SMES, the
superconductor requirement is less than a linear function of the stored energy. Specifically, if
the total stored energy increases by a factor of 10, the amount of conductor only increases by a
factor of 5. As a result, the cost per unit if stored energy ($/kWh) decreases as the total amount
of stored energy increases.
SMES Page 17