investment, maintenance cost and environment impact will be significantly
reduced, and consequently the price of these products could be reduced as
well. Furthermore, because of the co-production, the “peak and valley” of
each product (especially power generation) could be adjusted more easily
according to the demand.
5. “Open” and highly flexible. Under the concrete circumstance of
China, in the coal abundant areas, polygeneration system is quite beneficial.
It could be implemented step-by-step or phase-by-phase according to the
technical advancement and the availability of capital investment. For
example, for the first phase, only power, heat and methanol could be co-
produced, some more other products could be arranged later when financial
situation is improved.
Fig. 3 only shows the preliminary framework of polygeneration. The
detailed material flow, energy flow, information flow and multi-target
(technology, economics, resources utilization, environment) optimization
for each related subsystems should be carried out in the future through
sophisticated study of complex systems and taking the local concrete
conditions into account.
A Quantitative Example of the Benefit of Polygeneration System.
The base case for comparison is the stand-alone production of power,
heat, methanol and syngas by conventional power plant, industrial boilers,
traditional technology for methanol production, and coal gasifiers corres-
pondingly. The outputs are respectively 400 MW
e
, 400 MW
th
and 400 MW
equivalent.
Compared with stand-alone production, quad-generation of these four
products leads to the following benefits: reductions of capital investment
by 38 percent, cost for unit energy by 31 percent and coal consumption by
22.6 percent [3] (see Fig. 4).
Fig. 4. Benefits of investment, energy consumption and environment for quad-
generation
ISSN 0236-3941. Вестник МГТУ им. Н.Э. Баумана. Сер. “Машиностроение”. 2006. № 1 115
