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Combined Heat and Power Systems for Residential Use
An appliance which makes home-spun electricity and heat
Once available only to large commercial buildings, Combined Heat and Power generation (CHP) systems are now being produced on a scale that is safe, practical, and affordable to homeowners. CHP technologies sometimes referred to as cogeneration, have provided heat and electrical energy efficiently at commercial and industrial sites for many years. However, after hundreds of successful residential installations in Japan and Europe, several manufacturers are now offering models in the U.S.
A CHP system uses fuel such as natural gas to produce heat and electricity simultaneously. The electricity can be used for any household device such as lights and appliances. Simultaneously, the heat produced can be used for water heating and/or space heating. About 10% of the fuel used is lost as exhaust, much like a high efficiency furnace.
The engines used in the CHP units for producing electricity can be internal combustion or Stirling (also called external combustion) engines. Other types of generation technologies, such as fuel cells, have not reached the commercialization stage. Micro-CHP, as residential-sized CHP systems are usually called run on propane, natural gas, or even (in the case of Stirling engines) concentrated solar energy or biomass. The byproduct of electricity generation is waste heat—and plenty of it. One 6-kW unit provides 10 gpm of hot water at 140 to 150°F. This waste heat can be used to heat an entire home, water for domestic use, for swimming pools and spas, or even as an energy source for heat-driven (absorption) cooling systems.
CHP systems are extremely efficient, offering combined heat and power generating efficiency of about 90%, compared to about 30 to 40% for electricity from a central power station.
Micro-CHP units range in capacity from about 1 kW to 6 kW and are about the size of a major appliance. Installation may be performed initially by specialists and, after the technology matures, by an experienced plumber, electrician, or HVAC technician. Units come as grid-tied systems which connect to utility power as backup or as stand-alone systems for remote residences.
One unit with a new, small capacity engine simultaneously produces 1.2 kilowatts of electric power and 11,000 BTUs of heat in the form of hot water. The system is combined with a high efficiency, natural gas-fueled warm air furnace or boiler for supplemental space heating.
The small engines tend to burn very cleanly - exceeding all emissions requirements for CO2 and NOx. One unit claims to produce less CO and nitrous oxides than a single burner on a kitchen gas range.
The primary challenge for getting the highest efficiency and best economic return on CHP is to fully utilize all of the thermal energy produced when generating electricity. As the technology develops, various operating regimes will be tested to optimize the energy available based on variables such as the loads in the home, the climate and the season.
Benefits/Costs
Payback on investment varies with fuel cost, electricity cost, the availability of net metering (where the utility credits the customer for excess electricity placed onto the utility grid at the retail rate), and the need for the waste heat (e.g., a system heating a pool will provide useful heat and electricity in the summer and winter). Some units operate only when there is a need for heat and are therefore more cost-effective in cold climates. The best economics will be found in cold climates having high electric rates and low natural gas rates.
Combined heat and power systems produce electricity at a very high efficiency when there is a demand for heating. If net metering is available (where the utility credits the customer full retail rate for electricity sent into the grid), the systems can reduce annual energy costs, however, with current technologies and utility rates the payback period can be long. When there is no heating demand, no electrical generation ensues. Payback time decreases as electric rates and heating demand increase.
The extent of maintenance depends on the type of engine and the type of fuel. For a natural gas internal combustion engine, routine maintenance is required every 4,000 to 10,000 hours (about 1 to 3 years). At this interval, an oil and filter change, spark plug replacement, and minor adjustments are necessary. The servicing takes about one hour and costs about $200. It is imperative that internal combustion CHP systems have routine scheduled maintenance. Therefore, most manufacturers are offering systems through authorized installers who will also offer service contracts.
One manufacturer of a Stirling free-piston engine, expected on the market in 2008, touts its product as zero-maintenance because there is no contact between moving parts in the engine.
Another manufacturer will distribute, install, and service through authorized and certified contractors, only. While this will help ensure quality installations, it may be difficult to find qualified contractors in the early stages of the products' development except in specific markets. |
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Bath Fan Exhaust through Brick Wall
If you are doing a bathroom in your finished basement you can’t avoid to vent out a bath fan. Running bath fan exhaust through brick wall makes more questions then any other type of installation. So, here on this page all your questions are answered!
1.List of materials needed for the project:
1. 4” plastic wall cap 2. 4” pipes ...................................................................
1. Power drill 2. Cordless drill ............................................................
In order to better organize an explanation of execution of this project I would like to divide it in several steps:
Step #1 -Step #4
This is a parent page. If you would like to read more you can buy an access to the secondary page for only $2.50.You can pay right here on this page by using the Buy Now button below.
Installation on the paid page might not exactly describe your upcoming project. However, it will give you an important example of how this type of installation should be done. In addition, it will open the gates for as many questions as necessary to make sure that the job is done right.
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Finished Basement Edition is a new book designed just for you! In this book you can find answers to your most frequently asked questions about ductwork installation in basement and more.
For more information please visit “Finished Basement Edition” page.
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Please watch 11 video presentations. If you'll find out that you need any fan from the list below, please contact me on this page and you will get the lowest price guaranteed!
List of the videos:
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