| Abstract | Thermal Energy Storage (TES) has been planned as a load shifting device in the Thai
power sector. Its use can accrue benefits not only to the building owners but also to the electric
generating utility. In this study, the impacts of TES application in the conunercial sector were
assessed on the utility operation and planning. The previous research of the author and his advisor
reveals that the stocks of conunercial buildings suitable for TES applications in Thailand comprise
four main types, office, hotel, hospital, and retail store, then defined as the identified customer
groups for TES application. The target groups of TES application are medium and large buildings
having electric demands between 30-1999 kW and above 2000 kW respectively, in the utility's
customer categories. A building energy simulation package, DOE-2 is employed to develop the
reference building models and their load shapes. The development of the reference building
models and results of their load profiles agree with the load survey of the electric utility's.
_ Modes of operations of TES system; partial, full, and demapd-limited storage modes, can
be used in the commercial buildings. Selection of TES modes is depended upon several factors;
the tariff structure, the load shape of a customer, technical problems, and cost of the systems. A
multi-criteria decision analysis, called the Analytic Hierarchy Process (AHP), was introduced to
assess the potential adoption of TES by the building owners. The results from AHP model can be
used to develop the new building load shapes after an application of TES, and then the changes in
system load shapes. The change of load shapes of the identified customer groups after the
application of TES gives several effects to electric generating utility; impacts on operation, and
impacts on expansion planning.
A production cost simulation model, Electric Production and Financial Simulation model
(ELFIN), was employed to perform a comparative analysis of the power system production, using
the system configuration for the system load requirements corresponding to the base-case load
shape, and for the load shapes corresponding to the TES case. The ELFIN's reports includes annual
generation summary, annual plant factor, system reliability, and marginal cost of production for
each specified period of the day. In 2005, the TES case can reduce peak-time cost from $23.2/
MWh to $22.5/MWh and increase off-peak-time cost from $20.6/MWh to $20.8/MWh. The
significant benefits of TES are obtained in terms of decreased unserved energy, improved reserve
margin (RM), and the capacity released, for examples, in 2005 the TES case reduces LOLP from
0.054% to 0.031%, increases RM from 13.1% to 15.1%, and gives the capacity released of 1020
MW.
Finally, a generation expansion optimization model (WASP-III) is used to obtain the leastcost generation expansion plan which offers a comparison of the base case to the TES case. It
revealed that TES application in commercial buildings causes a substantial reduction in the
requirement of 1200 MW for addition of generating capacity in 2005. |