HOT|COOL NO. 1/2020 - "How to District Energize your City"

Cities in the USA Next we look at US cities, such as Cambridge or Sommerville, MA and University campuses (which are often like small cities) such as Dartmouth and Brown. These are looking to district energise to meet carbon neutrality or net zero targets which they have committed to. In addition, however DHC provides a resiliency component for energy supply in these cities. The transition to low carbon thermal supply in the US is often planned through electrification and supply to individual buildings. However, with electrification of thermal supply (which tends to be 50% of a city’s total energy consumption) comes increased dependence on the electrical grid to provide current, in addition to future, demands such as data centres and the transport sector. This will require extensive electrical system investment. DHC networks often provide a lower cost option by comparison in heat demand dense areas, while improving the resilience of the city’s energy supply. In these instances, the Cities and Universities are the project champions who drive these projects forward. This method of thermal energy delivery through hot water supply has shown to have the lowest possible long term costs but is not well known or common in the US. As a result, each has their respective barriers to address in order to realise the transition. Our work in the US decarbonisation projects has shown that to reach low carbon targets, this will almost always include district energy. This ensures a plug and play solution for potential future new technologies, improves resiliency, facilitates use of waste heat sources and is often the cost competitive solution when compared with electrification.

energy delivery is not well known or common in any of these countries. As a result, each city has their respective barriers to address in order to realise this transition, but these barriers are well-known in other countries with a developed DH sector and so are being addressed incrementally. What each of these cities have identified, which in line with larger studies such as the Heat Roadmap Europe studies funded by the European Union’s Horizon 2020 research and innovation programme, is that there is a lot of waste and ambient heat unutilised in Europe. If DH networks are available to distribute this heat, then these sources can be utilised economically to reduce fossil fuel consumption in their cities, thus decarbonising them. There are existing examples of this in Danish Cities, where the District Heating & Cooling (DHC) systems are not only capitalising on available waste and ambient heat, but also being used to utilise low cost electricity from intermittent energy sources through heat pumps, hot water storage accumulator tanks and electric heaters. In these Western European instances, the cities are district energising themselves and acting as the project champions by utilising an existing attractive low carbon heat source to supply an identified local heat demand. Starting to future proof themselves for a transition from fossil fuels to alternative heat sources for use in renewably (RES) driven heat pumps (waste heat e.g. from production of cooling or from sewage, ground source, sea water, ambient heat and deep geothermal), will then need to be distributed to consumers. These energy sources have been utilized in the Scandinavian countries for decades and obstacles have been overcome through extensive experiences.

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