Archive for June, 2009
Combined Heat and Power idea ….. would it work?
I had an idea for a simple combined heat and power system I could build from mostly scrap materials. (To keep it as simple as possible, this one *doesn't* feed back into the grid.) The idea was to use a small water-cooled diesel engine, powered from cooking oil, to turn two generators: a 230 volt alternator and a 24V truck or coach alternator. The latter would be used to charge a bank of lead-acid batteries, in conjuction with a modified computer UPS. The water jacket of the engine would be plumbed into my existing radiator circuit with a 3-port valve to select between it and the gas boiler, and the engine would be controlled by the thermostat.
When the thermostat calls for heat, the engine fires up and heats the radiators, but it also generates 230 volts AC (to run the house electrics) and 24 volts DC (to charge the batteries). When the thermostat is satisfied, the engine is stopped and the UPS switches over to battery power.
If I can get a donor vehicle with an air conditioner, I would use that to transfer the waste heat from the exhaust gases into the main living room of the house as blown warm air heating. The radiator in that room is already fitted with a TRV so would shut down automatically in the presence of extra heat.
Anytime necessary, the gas boiler can be run for heating, and/or the UPS input can be switched over to mains power from the grid.
Would this actually work in practice?
***** UPDATE *****
I intend to refine waste cooking oil for fuel. People will actually pay good money to get rid of the stuff …..
I will only need a two-position switch if I position it at the input of the UPS, to select "real" mains or the AC generator. Operation on batteries would be taken care of by the UPS's own electronics doing what they're meant to.
The idea of the separate 24 volt generator for battery charging is to ease the load on the 230-volt generator. The UPS's own charging circuit will only be rated for charging batteries of a few amp-hours anyway. I might add a third, 12 volt generator for my 12V electronics.
I'm thinking of using open-vented batteries; the air conditioning idea if used would provide me with a supply of de-mineralised water for topping-up. All of this would be located in a coal shed which is attached to my outside privy behind my house.
It may work, but the cost of fuel for the diesel would be high, unless you spend a lot of time collecting and filtering used cooking oil, and you get it free.
But the whole thing is very complicated. How will you switch between 230 volts from the power company and diesel generator and the output from the UPS? you will need a big three position relay. Is the relay switched manually?
And, it looks like it will never operate in the summer, as the only control you have is an air temperature thermostat.
I don't think you need two generators on the diesel. The 230 volt one can be used to charge the batteries via a charge controller, which you need anyway to avoid overcharging the batteries.
Do not use auto batteries indoors, they can leak poisonous gases.
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Organic Rankine Cycle: Infinity Turbine Presents the 10 kw Waste Heat to Power ORC Generator
The worlds first production Infinity Turbine IT10 5-12 kw waste heat to power generator, based on the Organic Rankine Cycle (ORC) turbine that generates electricity.
http://www.infinityturbine.com
This video shows our first prototype running on R134 refrigerant. The turbine is turning (no load) at about 20,000 rpm and with load at about 8,000 rpm. Most of the noise will be taken care of by use of a muffler system for the feed pump. The high pitch whine is the turbine. Design sound is about 45 dB.
The first production units will be with permanent magnet alternators. Custom AC units in 50 hz or 60 hz will be available shortly.
Used in geothermal, solar and waste heat (industrial waste heat, gas turbine waste heat, diesel engine waste heat). Excess heat from the system output can be used for CHP applications, including desalination, hot water, air conditioning, chiller and process heat.
The turbine will operate off low grade industrial waste heat. It will also operate from geothermal, hot springs, oil well producer water or solar collector heat in the 70-150 C range.
The evaporator and condenser exit may operate in conjunction with a secondary heat exchanger for CHP hot water or chiller applications. It may also be used in tandem with a CHP, air cooling tower, or ground based geothermal system.
The IT10 is a 5-12 kilowatt power producing unit which operates off of waste heat, by vaporizing and pressurizing a environmentally friendly refrigerant which spins a turbine generator.
The unit produces 48 Volts DC. A standard inverter can convert the VDC to AC power, stand-alone or grid connect, and in 50hz or 60hz.
The IT10 is a rack-mounte plug-and-play ORC unit which can be numbered up in series to 100 kw. For AC applications, we’re offering a fully enclosed silent generation unit.
For larger applications, we have the IT250 and IT500.
For Geothermal applications (Enhanced Geothermal System (EGS)), you may utilize oil and gas wells, or abandoned wells that reach depths to get temperatures greater than 150 deg. C. In general, you may sink a deep well anywhere in the continental USA around a depth of 15,000 ft to reach this temperature. The diameter of the well will determine the maximum power you can reach with this type of power generating system. Another example of utilizing geothermal resources is at Chena Hot Springs, in Alaska, or The Geysers in northern California, or Puna Geothermal Venture in Hawaii, or Mammoth-Pacific geothermal power plants at Casa Diablo in California.
For diesel generator sets (CHP), you can first use the heat to make additional power, then still use the leftover heat for CHP.
For Solar Options you can use resource heat from parabolic trough solar, tube solar, or other means of solar heated thermal liquid.
Evaporator Exit Heat: Can be used for saltwater desalination, fresh water maker, chiller, hot water or additional process heat, such as drying and other applications (lumber dry kiln, firewood dry kiln, hardwood drykiln, greenhouse, etc.).
Condenser Exit Heat: Can be used for the production of secondary energy products, like hot water, chilled water or district heating, such as in radiant floor heating, or greenhouse heat.
This system may be able to access renewable (green) energy credits, as well as CO2 offset credits, which are worth as much as 25 Euro a ton.
This system is similar in function to the system at Chena Hot Springs, where a organic Rankine cycle is used to produce power from a geothermal source.
For more information:
http://www.infinityturbine.com
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Used: Kohler 40 kW Fast-Response II Diesel generator set - Stock# 40785008
Used: Kohler 40 kW Fast-Response II Diesel generator set. Model 40REOZJB, serial #0764825. John Deere engine SN-PE3029T266713. Alternator model 4Q10, 1/60/120/240V. 175 amp main-line circuit breaker. 200 gallon sub-base fuel tank. 110V battery charger and block heater. Weather enclosure. 210 hours. Built 2003.
http://www.aaronequipment.com/UsedEquipment/Generators/Diesel - Gas Fueled/40785008.html
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