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# Combined heat and power plants

I've started an new wiki page Combined Heat and Power (CHP) Plants with a link to a calculator.

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1.
edited April 2013

Thanks, Jim! Nice page!

I'll change the title to match our conventions, which are also the Wikipedia conventions:

Combined heat and power plant

(singular, only first word capitalized unless there's a damned good reason), adding a redirect at the bottom of the page so that

CHP

and some other things also work, including your original title.

Comment Source:Thanks, Jim! Nice page! <img src = "http://math.ucr.edu/home/baez/emoticons/thumbsup.gif" alt = ""/> I'll change the title to match our conventions, which are also the Wikipedia conventions: [[Combined heat and power plant]] (singular, only first word capitalized unless there's a damned good reason), adding a redirect at the bottom of the page so that [[CHP]] and some other things also work, including your original title.
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2.

In Helsinki the energy company claims to reach 90% of overall efficiency with chp. Description of the cogeneration They have also added "district cooling" where the cooling of houses produces heat for heating.

In Helsinki area they are building a new chp plant that burns household waste. When burning waste they get about 18-25% of the input energy (fuel) as electricity and 60-70% as heat. In another plant using natural gas they get 41% as electricity and 50% as heat. In the country there is more demand on electricity than heat, so when burning waste the smaller electricity production must be compensated. The overall efficiency of the whole energy sector is extremely difficult to describe, understand and optimise.

Comment Source:In Helsinki the energy company claims to reach 90% of overall efficiency with chp. [Description of the cogeneration](http://www.helen.fi/ymparisto_eng/Yhteistuotanto.html) They have also added "district cooling" where the cooling of houses produces heat for heating. In Helsinki area they are building a new chp plant that burns household waste. When burning waste they get about 18-25% of the input energy (fuel) as electricity and 60-70% as heat. In another plant using natural gas they get 41% as electricity and 50% as heat. In the country there is more demand on electricity than heat, so when burning waste the smaller electricity production must be compensated. The overall efficiency of the whole energy sector is extremely difficult to describe, understand and optimise.
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3.

When burning waste they get about 18-25% of the input energy (fuel) as electricity and 60-70% as heat.

Do you know where the remaining 10-15 % ends up? (I assume 18+70 and 60+25, otherwise it's 5-22 %) Are there heat losses on the heat generation?

Comment Source:> When burning waste they get about 18-25% of the input energy (fuel) as electricity and 60-70% as heat. Do you know where the remaining 10-15 % ends up? (I assume 18+70 and 60+25, otherwise it's 5-22 %) Are there heat losses on the heat generation?
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4.
edited April 2013

When burning waste the steam does not become so hot. When the cold end is in constant temperature, the efficiency is higher, if the steam is hotter. (Carnot ia to blame) When burning natural gas the steam can be much hotter than when burning municipal waste.

In chp the steam goes first to the turbine (for electricity), then for district heating. When going to district heating, the water is somewhere near 100 degrees celsius hot, sometimes 115 (pressurised, 1 bar) in cold winter time. So the temperature difference of the turbine input and output is determined by the input heat. I guess, that the steam with natural gas is about 550 degrees and pressure about 200 bars and with waste about 500 and 150 bars. So the total efficiency with waste is lower.

Comment Source:When burning waste the steam does not become so hot. When the cold end is in constant temperature, the efficiency is higher, if the steam is hotter. (Carnot ia to blame) When burning natural gas the steam can be much hotter than when burning municipal waste. In chp the steam goes first to the turbine (for electricity), then for district heating. When going to district heating, the water is somewhere near 100 degrees celsius hot, sometimes 115 (pressurised, 1 bar) in cold winter time. So the temperature difference of the turbine input and output is determined by the input heat. I guess, that the steam with natural gas is about 550 degrees and pressure about 200 bars and with waste about 500 and 150 bars. So the total efficiency with waste is lower.
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5.

Thanks! So I suppose the waste does not get completely burned.

Comment Source:Thanks! So I suppose the waste does not get completely burned.
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6.

I believe that the waste gets completely burned but household waste contains water or biological waste containing water. It lowers the burning temperature. The plastics burn very hot, but some materials have lower burning temperatures.

Comment Source:I believe that the waste gets completely burned but household waste contains water or biological waste containing water. It lowers the burning temperature. The plastics burn very hot, but some materials have lower burning temperatures.