Citigen: heating and cooling solutions

Citigen energy centre is one of UK’s largest urban heating, combined heating and cooling tri-generation systems, located in central London. We provided unique solutions for combined heating and cooling.
E.ON's citigen energy centre providing low carbon district heating and cooling to London. Innovative heat pump solution
E.ON, one of Europe’s largest operators of energy networks and energy infrastructure, provides district cooling, heating and electricity to commercial and residential buildings in the City of London through its Citigen energy centre.
Located in the heart of London, near the Smithfield Market, Citigen primarily uses gas powered internal combustion engines.
Through a new decarbonisation project, E.ON has established Citigen as the largest urban heating and cooling tri-generation system in the UK, resulting in up to 50% fewer CO2 emissions.
E.ON commissioned Ramboll to design a heat pump solution and develop the concept through a feasibility study. Our contribution also spanned detailed design, mechanical and electrical design, and other services including energy modelling, air quality assessment, noise assessment, utility coordination, structural design, planning, CDM principal design, tender package support, and procurement.
The breakthrough: combined heating and cooling
The installation designed by Ramboll included three heat pumps with a capacity of 4 MW heating and 3 MW cooling, supplemented by three 200-metre-deep ground boreholes for energy balance.
The electrically driven heat pumps enable low-carbon heating and cooling to be generated, resulting in reduced use of the existing gas-fired boilers and the combined heat and power plant.
Extensive energy and techno-economic modelling indicated the optimal heat pump size and heat source prioritisation to meet Citigen’s energy needs.
A flexible heat pump concept can switch from ground source to combined heating and cooling, or waste heat recovery as required, at different periods. The heat pumps complement the existing combined heat and power boilers and electric chillers to provide heat and chilled water as necessary.
Ramboll closely supported E.ON with a team of experts throughout the project, which was completed in the summer of 2022.
Heat pumps are a safe, cheap, and clean alternative to fossil fuel-based systems. Explore below what are they key benefits of a heat pump solution for Citigen’s decarbonisation:
  • Reduces energy waste via recycling heat that would otherwise be rejected into the urban space. The heat pumps effectively recycle low grade waste heat from both the CHP generation - capturing the waste heat from the site's cooling towers - as well as from neighboring commercial buildings which require cooling into the district heating system, reducing carbon emissions, and running cost.
  • Heat pumps electrify Citigen’s plant, reducing dependence on fossil fuels.
  • Strengthens Citigen’s security of supply, while safeguarding space in the always congested city centre energy infrastructure.
  • Combines heating and cooling installations into one, limiting investment and operating costs. The district cooling abstracted heat (that would otherwise be dumped via cooling towers), can be stored in 200m deep ground boreholes and upgraded through heat pumps into useful heat, again saving cost and carbon.
  • Allows Citigen's district energy networks to extend to further customers, allowing greater take-up of low carbon energy in a densely populated area.
  • The multi heat source approach adds flexibility to the energy system paving the way to future innovations.

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