Draft Greater Cambridge Energy SPD
Gas fired CHP is considered a low carbon technology and as such can be counted towards the 10% requirement. Once the infrastructure is installed, the type of fuel used can be altered more easily than the infrastructure being put in later, and therefore has the potential to be changed over to a renewable fuel. However, there are some important considerations that must be factored in to determining whether CHP will be feasible for a particular development. Applicants will also need to be mindful of Government’s intention to ban gas boilers in new homes from 2025 in a bid to tackle climate change.
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Coupled with the proposed changes to the carbon intensity of electricity in SAP 10, which takes into account the decarbonisation of electricity, a long terms view of the carbon emissions associated with gas CHP should be taken into consideration.
From my discussions with specialists in this field it seems electricity off the grid will be lower carbon that gas powered CHP by as early as 2021-2022, why therefore embed a sub optimal technology. CHP and district cooling might make sense but only where off a low carbon power source.
One possibility is to drive them with ground source heat pumps – see this DECC report from 2015. These are new to the UK but there are good European examples such as Helsinki city centre, which innovatively extracts heat from sewage.
The view of housebuilders is that this is just too experimental for their low risk business model, and why should they dig expensive networks when they can just superinsulate which the forthcoming Future Homes standard would require under part L anyway? There is also the concern that houseowners may resist being locked into high price future power contracts without chance of switching (the CHP market is correctly unregulated).
To my mind the current technology seems to offer little carbon advantage for the typical housebuilder site of 1-300 houses which will inevitable pug into existing networks. Where CHP may have a role is in new settlement scale areas where CHP might form part of a utility and network scale design solution integrating wastewater and power solutions.
Decisions, Decisions, Decisions 
” Gas powered CHP no longer makes sense”. Find some part of the current flight from fossil fuels which ‘makes sense.’ It becomes a contest to decide which part of a smorgasbord of false premises is least realistic. The ‘renewables’ meme is all by itself a comedy of errors. One cannot ‘replace’ a system which works with one which does not and expect better than a catalogue of failure.