Hydrogen-Fueled Power Systems

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1.3.1.3
Hydrogen-Fueled Power
Systems
1.3.1.3-1 Introduction
The concept of a hydrogen economy was introduced in the 1960s as a vision
for future energy requirements to replace the inevitable exhaustion of fossil fuels. In
the hydrogen economy, the storable and transportable hydrogen is envisioned to be a
dominant energy carrier. The hydrogen can also be exploited as a clean, renewable, and
nonpolluting fuel. The use of hydrogen as a fuel is attractive for a number of reasons:
• Hydrogen burns with 15-22% higher thermal effi ciency than that of
gasoline;
• From an environmental standpoint, hydrogen combustion with pure oxygen
results in no emissions of the greenhouse gases, CO, CO2, SOx, and NOx;
and
• It generates only steam and water.
Serious hydrogen-fueled turbine development program primarily comes from
the initiatives of the Japanese government in 1992, through its New Energy and Industrial
Technology Development (NEDO). It created the World Energy Network (WE-NET)
Program, a 28-year effort from 1993 to 2020, directed at research and development
of the technologies needed to develop a hydrogen-based energy conversion system1
.
Part of this effort is directed toward research and development of a hydrogen-fueled
combustion turbine system2 which can effi ciently convert the chemical energy stored in
hydrogen to electricity via a heat engine in which the hydrogen is combusted with pure
oxygen. Turbine manufacturers developing hydrogen-fueled power generation cycles
under the WE-NET program include Westinghouse, Toshiba and Mitsubishi Heavy
Industries3. The hydrogen-fuel power systems resulting from the WE-NET program
and others reported in the literature are summarized below.
Wen-Ching Yang
Department of Chemical &
Petroleum Engineering
University of Pittsburgh
Pittsburgh, PA 15261
(724) 327-3011
wcyang@pitt.edu
1.3.1.3-2 The High Temperature Steam Cycle (HTSC)
Power System
The High Temperature Steam Cycle (HTSC) power system, shown in fi gure
1 and reported by Kizuka et al.,, was based on that suggested by Jericha, et al.4. It has
two closed cycles: the topping and the bottoming cycles. The topping cycle consists
of a compressor, combustor, intermediate pressure (IP) turbine, steam cooler 1, and
steam cooler 2. The bottoming cycle includes a low pressure (LP) turbine, condenser,
preheater, high pressure (HP) turbine, combustor, and IP turbine. The key design
considerations are to increase the outlet temperature of the IP turbine to generate more
steam in the bottoming cycle and to increase the inlet temperature of the LP turbine to
obtain more power.
The HTSC power system makes use of the closed-loop cooling systems.
Closed-loop cooling techniques will be favored in advanced combustion turbines
because they (1) eliminate the disruption of the turbine fl owfi eld caused by coolant
ejection, (2) eliminate mixing losses caused by coolant ejection, (3) reduce the decrease
in gas path temperature caused by turbine cooling, and (4) return the turbine coolant to
the primary cycle5
.
The conceptual designs of the cooling systems were studied by Kizuka et al.,6
.
The three systems studied are (1) closed-circuit water cooling system for nozzle blades
and steam cooling system for rotor blade; (2) closed-circuit steam cooling system for
nozzle and rotor blades; and (3) open-circuit steam cooling system for nozzle and rotor
blades.
The main component parameters employed to evaluate the cycle performance
is summarized in table 1. The reported performance of three different types of cooling
systems for a 1700°C-class, hydrogen-fueled combustion gas turbine varies from 54.9
% to 61.3 % effi ciency based on HHV.
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