Using heat off a CHP unit

[D14]

Nothing to stop you using waste heat to generate electric and claiming the electric subsidy. But the RHI scheme specifically excludes paying out the RHI subsidy on heat that is used to generate electric, so its not an "available subsidy". The efficiency of ORC systems is very low, especially on low temperature water off an engine, so he wont generate much electric at all, and at best will only get the FIT or Rocs for that small amount of extra electric. If he can use all of the heat for a useful heating purpose then RHI will pay for all of that use. Hence the OP question.

The RHI tariff for this is the biogas tariff; now in very heavy degression. Mainly due to AD plants retrospectively fitting equipment to claim that RHI. Somewhat galling for those of us working with biogas plants other than AD, the AD plants were mostly already built or committed to on the basis of the electric. RHI was just the icing on the cake and an unexpected bonus.

This is very confusing info. What about a biomass boiler already installed and claiming rhi for heat to a farmhouse for example. The rhi is paid off a meter that records heat sent to heat returned doesn't it?

Then the smoke from the boiler goes up out of the chimney and is wasted. If that smoke could pass through a machine where by it turned a turbine which in turn created electricity surely that electricity could be used to power the biomass boiler which then becomes self sufficient as well as making use of the smoke so reducing emissions?

 

[renewablejohn]

This is very confusing info. What about a biomass boiler already installed and claiming rhi for heat to a farmhouse for example. The rhi is paid off a meter that records heat sent to heat returned doesn't it?

Then the smoke from the boiler goes up out of the chimney and is wasted. If that smoke could pass through a machine where by it turned a turbine which in turn created electricity surely that electricity could be used to power the biomass boiler which then becomes self sufficient as well as making use of the smoke so reducing emissions?

Welcome to the government world of red tape.

 

[Fowler VF]

This is very confusing info. What about a biomass boiler already installed and claiming rhi for heat to a farmhouse for example. The rhi is paid off a meter that records heat sent to heat returned doesn't it?

Then the smoke from the boiler goes up out of the chimney and is wasted. If that smoke could pass through a machine where by it turned a turbine which in turn created electricity surely that electricity could be used to power the biomass boiler which then becomes self sufficient as well as making use of the smoke so reducing emissions?

Absolutely OK. You have claimed the RHI on the measured heat that went to the farmhouse, you didn't measure and didn't claim on the heat that went up the chimney. So do what you want with it, including make electric from it. But what you could also do is to stick a heat exchanger in the chimney and make more hot water. You can do what you want with that hot water. you could even stick a meter on it, send it to the farmhouse and claim RHI on it. (of course you would have to alter your RHI accreditation, change schematics and add capacity). BUT you cant taken that hot water through a meter, claim RHI and then use the hot water to make electric. You can only make one subsidy claim on that energy, not two.

Same thing applies with that AD CHP engine. You claim on the electric you make under FIT or ROC, you can also make hot water off the engine block and engine exhaust and claim under RHI if you have an eligible use. OR you could use the hot water off the engine block and engine exhaust to make hot water and then use the hot water in an ORC to make electric and claim FIT or ROC on that electric. But you cant do both, you cant have FIT or ROC on heat that you have already clamed RHI. In general, the low efficiency of ORC means that if you have a direct eligible use for the heat then claiming RHI on the heat is worth more than making electric form the heat and claiming FIT or ROC.

 

[thesilentone]

When a power generating plant is established and commissioned, it needs accreditation to export to the grid and claim tarrif. (G59)

The plant has a ' installed capacity ' which includes a detailed calculation of max capacity and outputs. How this is achieved is important, however all other criteria must be met. So, if we have a 500kw electrical CHP generating @ 42% electrical efficiency, the max capacity is 500x8760 =4,380,000 kwhr/yr. If this figure is exceeded, you will be inspected, if you continue to exceed this figure you ,may be charged for fraud (by Ofsted)

 

[Fowler VF]

[QUOTE="thesilentone, post: 3344870, member: 6194". If this figure is exceeded, you will be inspected, if you continue to exceed this figure you ,may be charged for fraud (by Ofsted)[/QUOTE]

I might expect to be charged by Ofgem in this instance. But then again if my adding up wasnt correct I suppose that Ofsted might get involved !!!!!!

 

[D14]

Is there a list of installed capacities for all these renewable machines?

 

[thesilentone]

Most CHP companies provide a specification sheet, however OFGEM check the plating and specification of the installed unit to ensure no modifications to capacity. Most can specify to suit your needs eg: 499kw

You can look at some examples here: https://powergen.gepower.com/products/reciprocating-engines/jenbacher-type-3.html#resources