Steam Costs Cogeneration

[illhp]

Anybody know how i can calculate the marginal costs of steam generated through cogeneration or have any rules of thumb? ($ per unit of usable heat energy)

 

[alehman]

What kind of cogeneration? Try posting a little more information about your proposed system. Clearly the cost of your fuel will be a factor.

 

[illhp]

The natural gas price is approximately $4/mmbtu and the pressure of the steam is about 125 psig. I don't know what the temperature of the feedwater would be.

 

[peebee]

If you're already burning gas to generate electricity, well, then the marginal cost of the steam is exactly zero.

Am I missing the point?

If you prefer to allocate costs to steam and electricity, then you could do something like this:

fuel charge x (kW of heat)/(kW of elec + kW of heat)= cost of heat

 

[ScottyUK]

Peebee,

"....exactly zero".

If only it were true! Demin water, feedwater treatment chemicals, cooling tower make-up water, more chemicals, etc all need to be factored in. Sadly none are free.

 

[jbartos]

Suggestion: Visit

http://www.linnhoffmarch.com/pdfs/Utility System Design.pdf

http://www.envirotechnet.com/pinchtechnology.com/PDF/revised_july_feature.pdf

http://www.prayaspune.org/energy/M25_cogenPPAJune02.pdf

etc. for more info