Drive Systems: Options - Future / Stirling
engines are classed as external combustion engines. They are sealed systems with
an inert working fluid, usually either helium or hydrogen. They are generally
found in small sizes (1 - 25 kW) and are currently being produced in small quantities
for specialized applications.
engines were patented in 1816 and were commonly used prior to World War I. They
were popular because they had a better safety recordthan steam engines and used
air as the working medium (rather than steam). As steam engines improved and the
competing compact Otto cycle engine was invented, Stirling engines lost favor.
Recent interest in DER (Distributed Energy Resources), used by the space and marine
industries, has revived interest in Stirling engines and as a result, research
and development efforts have increased.
- ARES - Advanced Reciprocating Engine Systems
The mission of the ARES program (sponsored by the Department of Energy) is to
lead a national effort to design, develop, test and demonstrate a new generation
of reciprocating engine systems that are cleaner, more reliable, and more efficient
than products that are commercially available today.
activities for this program focus on the following performance targets for the
next generation of reciprocating engines:
- The target for fuel-to-electricity (low heating value) is 50% by 2010.
- Engine improvements in efficiency, combustion, strategy and emissions reduction
will substantially reduce overall emission to the environment. The NOx target
for the Advanced Natural Gas Reciprocating Engine is 0.1g/hp-hr (0.134 g/kwh).
- In the future, natural gas-fired engines are to be adaptable to firingwith dual
Cost of Power
- The target for total energy costs, including operating and maintenance costs,
is 10% less than current state-of-the-art engine systems while meeting projected
Reliability, and Maintainablity
- The goal is to maintain levels equivalent to current state-of-the-art systems.