Engineering Economic Analysis - Case Studies

The authors examined whether an IGCC facility that operates its gasifier continuously but stores the

syngas and produces electricity only when daily prices are high may be more profitable than an

IGCC facility with no syngas storage.

There are currently eight integrated coal gasification / combined cycle electrical turbine (IGCC)

facilities operating worldwide producing about 1.7 GW of electricity from coal or petcoke

feedstock, and in all of these facilities the syngas is used immediately after it is produced. There

are over one hundred coal gasification facilities producing chemical feedstocks, also without

storage. Without storage capabilities, the gasifier must be sized to fit the syngas end-use (such as

a gas turbine or chemicals process) and the operation of the two systems must be coupled.

Stored syngas may be used to produce electricity in gas turbines during periods of peak demand

when produced electricity is most valuable and prices are highest, while operating the gasifier at

the most efficient sustained production rate. Stored syngas may be a means to enhance the

reliability and availability of IGCC power plants, by increasing the availability of syngas during

planned and unplanned outages. Without storage, the coal gasification facility must be sized to

the gas turbine or other facility that uses the gas. Storage allows the two units to be sized and

run separately, thus gaining valuable flexibility. For IGCC designs where the air separation unit

is not fully integrated with the turbine (Farina 1999; Maurstad 2005), adding the capability to

store syngas can allow the gasifier and turbine to be sized and operated independently, thereby

providing valuable flexibility in the way the facility is configured and operated

The goal of this two year research project was to conduct a detailed study of syngas storage

options. The analysts performed an engineering-economic analysis of storage to inform the design of coal

gasification facilities as well as energy policy. The project collected the relevant syngas data

from gasification processes; explored the technical issues of storage such as hydrogen

embrittlement, leakage and energy loss from syngas storage; and performed an engineeringeconomic

analysis of storage options. In a parallel and complementary approach, they analyzed

the benefits and costs of syngas storage options under a variety of scenarios, sampling the

uncertainties in commodity prices, technical options, and regulatory policies.