part 1: overview of cogeneration and its status in asia - Fire

80 Part II: Cogeneration experiences in Asia and elsewhere
Natural gas is used as the main fuel for which a long-term agreement has been signed with
the Petroleum Authority of Thailand. Distillate oil can be used as a back-up fuel.
In line with the incentive policies of the Board of Investment, certain privileges were granted to
this project, such as:
- import duty exemption or reduction on imported machinery;
- corporate income tax exemption for 8 years, and further reduction of 50 per cent for 5
more years;
- double deduction from taxable income of electricity, water and transport costs for 10 years
from the date of first sales;
- deduction from net profit of the costs of installation or construction of the project’s
infrastructure facilities;
- exemption of personal income tax on dividends to shareholders.
2.6.2 Choice of the cogeneration plant
The choice of technology is primarily based on the consideration that both steam and
electricity can be supplied with high efficiency and reliability. During the plant operation, there
is practically no SOx emission and the NOx level is reduced to 50 ppm (with 15 per cent O2)
with steam injection.
The major advantages of this configuration are:
- low capital cost: approximately three-fourth that of a conventional power plant of the same
output;
- short gestation period: two-third of the power available with gas turbines within 12 to 15
months, and remaining one-third is available with steam turbine within 18 to 20 months;
- low operating and maintenance costs; competitive operating costs and higher availability,
particularly in comparison with coal fired thermal steam power plants;
- higher efficiency: electrical efficiency of 45.14 per cent in combined cycle mode, and
global efficiency of almost 70 per cent in cogeneration mode;
- flexibility of operation: ensured by the modularity of the plant, gas turbine exhaust by-pass,
steam turbine by-pass system, and the option of auxiliary firing on HRSG which allows
some decoupling between power and steam generation.
The gas turbines are installed outdoor. The unit is capable of being operated at full load within
16 minutes. Each unit consists of the following components:
- air inlet module with filter, silencer and ducts;
- gas turbine and auxiliary equipment package;
- generator package with load gear, exciter and coolers;
- exhaust module with ducts, bypass stacks, silencer and expansion joints;
- control components with option for local operation;
- medium voltage compartment with circuit breakers and auxiliary transformers.