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Page first featured October 30, 2008
Modified Stirling Engine to Harness Industrial Waste Heat
ReGen Power Systems, Inc. is pioneering development of industrial sized (250kW-2MW), low temperature Stirling engines to convert excess process heat and steam energy at industrial plants into electricity.
They have completed the design of two low-temperature, modified Stirling engines. The first is a 250C engine which utilizes heat from high temperature waste heat streams. This system will be able to convert this waste heat at 25% thermo electric efficiency. The second engine (100C) utilizes low pressure steam as the heat source. Post process steam sources are routed to the engine's hot side heat exchanger where it condenses, releasing the latent heat into the engine. This engine converts 13% of the heat energy into electricity.
This power is combustion and emission free.
ReGen determined that the minimum power output for the industrial markets should be 200kW to keep the cost/kW in a competitive range. Engines having output up to 2,000kW appear feasible. Several such engines ganged together would serve the “sweet spot” of the market, 3-10MW.
Unlike other Stirling engines of the past 50 years, ReGen's was designed solely for the needs of the stationary power generation market. Little or no consideration was given to such factors as physical size or power-to-weight ratio, for example, which were key factors in the design of Stirling engines for automotive use. Instead, the following goals, considered to be of primary importance for power generation, were adopted as the guiding design parameters:
Good electrical efficiency (13% for steam, 25% for industrial heat)
Long life (>100,000 hours)
Low maintenance costs ($0.006/kWh)
Competitive capital cost ($1200-2000/kW installed)
As of Oct. 30, 2008, the company is in process of building their initial 10 kW prototype engine. The next prototype will be a 500 kW beta unit. Commercial product exptected in middle of 2010.
An independent agency has estimated that if all waste heat was harnessed, it could provide 20% of the entire power generation portfolio in the Western world.
Executive Overview - 2-page PDF.
One configuration, for example, will employ two engines operated as a combined cycle power system, as shown in the diagram below. This condition assumes availability of a hot gas exhaust with a temperature in excess of 600°F. In the first stage, a high temperature heat transfer fluid is converted to a vapor by passing through a heat exchanger in the exhaust flue. The vapor carries the heat away from the flue and delivers it to the first-stage engine heat exchanger. There, the vapor condenses, and its latent heat is used to drive the first-stage engine at an efficiency of 25%. Once condensed, the 490°F fluid returns back to the exhaust flue and the cycle is repeated.
The second cycle utilizes a separate heat exchanger, placed in the exhaust duct, which produces low pressure steam. The low pressure steam is delivered to the low temperature Stirling engine heat exchanger where it condenses and, again, the latent heat is used to drive the second stage engine at an efficiency of 13%. The 210°F water is then returned to the heat exchanger, and that cycle is repeated.
A second example of how the system would work is shown in the second diagram. Here, low pressure steam from an industrial process such as a paper or chemical plant is directed to a low temperature ReGen engine. In this case the steam is condensed on the hot side heat exchanger of the engine and the condensate is returned to the plant boiler system. The engine extracts the latent heat from the steam and converts it into electricity at 13% efficiency.
VANJ: ReGen Power Systems - 2.18 minutes.
The combination of low temperature operation and maintenance features of the Stirling engine produce a package with a very low life cycle cost. O&M costs are projected to be $0.006/kWh which includes all scheduled and unscheduled visits and overhauls. Stirling engines do not have spark plugs timing systems or require lubrication within the engine cylinder. Overhauls can be performed on site reducing downtime and cost.
ReGen power systems will be installed on site for $1,200-$2000/kW depending on size and application. This will allow a 2-3 year payback on the investment, depending on the avoided cost of electricity at the facility.
The cost above works out to btween $1.20 to $2.00/watt, that is a reasonable deal. Compared to a 1 kw solar panel which cost $4.00/watt, a 1 kw solar panel system would be $4000/kw, plus the cost of an inverter, and installation costs. This technology is a keeper.
Reduce an industrial company's effective cost of gas, which is used to create the process heat, by the value of power produced.
Produce power with zero emissions
Fast economic payback
Produce clean power using industrial waste heat and steam
Produce solar energy using concentrated thermal energy to heat the engine
Produce power from biomass materials, either combusted or gasified
Produce power from municipal solid waste and landfill mining through gasification
Produce power from gasified livestock, dairy and human solid waste
Initial 10kW prototype due for completion Q1 2009
One patent has been granted (U.S. Patent 6,568,169), and several additional patents are being applied for.
Another patent will be filed in Nov. 2008.
A prior idea. It was a Stirling cycle engine. The present design is a modified Stirling.
Abstract : An external combustion engine comprises a mass of compressible working fluid a fluidic piston in fluid communication with the working fluid and a second piston in hydraulic communication with the fluidic piston and in fluid communication with the working fluid.
Private company was founded in 1995. As of Oct. 30, 2008, a press release will be issued shortly regarding investment options.
Ricardo Conde is the inventor of the ReGen technology. A mechanical engineer with a manufacturing process specialty, he became interested in the Stirling cycle engine in 1998 and began modifying existing designs to meet the needs of a power generation system: 1) long life (100,000+ hours), 2) large scale (250kW-2MW), 3) low operating costs ($0.006/kWh), and 4) high efficiency. The first engine was a Phillips Stirling cycle designed to operate at 525C at 40% efficiency. Increasingly, however, he saw that waste heat was a very large opportunity and that lowering the operating temperature could open up large parts of that market to the company. In 2005, he was able to modify the engine in such a way as to significantly reduce the power loss due to dead space inside the engine. This opened the way to the much lower temperatures that are planned today.
list hereLatest: Directory:Stirling Engines / Directory:Waste to Energy >Directory:ReGen Power Systems - ReGen Power Systems is developing two engines: one to harness discarded heat in the 250ºC range (25% thermo electric efficiency), such as what emerges from steam turbines and the other in the range of 100ºC (13% efficiency). They can be arranged in tandem. A test 10kW prototype is being built. (PESWiki Oct. 30, 2008)
On March 8, 2007, Congress:Advisor:Kenneth M. Rauen wrote:
This is a commercial Stirling engine is worth putting on NEC for a vote for Top 100. It is a very practical interrim technology for waste heat
conversion into electricity, plus low grade solar heat. It might be cheaper than the solar collector project in San Diego.
113 Michael Lane
New Salem, MA 01355
E-Mail: [mailto:firstname.lastname@example.org?subject=ReGen%20Power%20Systems%20featured%20at%20PESWiki.com email@example.com]
700 Canal Street
Stamford, CT 06902
Dick Meloy, Chairman and Treasurer,
ReGen Power Systems LLC
E-Mail: [mailto:firstname.lastname@example.org?subject=ReGen%20Power%20Systems%20featured%20at%20PESWiki.com email@example.com]
Directory:Traveling-wave Engine - Adaptation of Stirling engine uses heat differential and acoustics.