Is it possible to use the words “sexy” and “cost effective” in the same sentence? It is, if you are talking about modern district energy. Three district energy champion cities – Saint Paul (USA), Malmö (Sweden) and Gothenburg (Sweden) took the stage to show how “hot” this topic is for achieving a climate-smart, resilient and green economy, during a session held at the Cities & Regions Pavilion, co-hosted by ICLEI, IDEA, Euroheat&Power and Empower at COP21 on 3 December at 18:00. These cities are not alone in exploring modern district energy, as over 30 cities worldwide participated in a recent joint call to action on building efficiency and district energy in preparation for COP21, as reported by Maryke van Staden, Director of the carbonn Center at ICLEI.
District energy systems produce steam, hot water or chilled water at a central plant. The steam, hot water or chilled water is then piped underground to individual buildings for space heating, domestic hot water heating and air conditioning. As a result, individual buildings served by a district energy system don’t need their own boilers or furnaces, chillers or air conditioners.
The advantages of this on conventional systems are significant. The way conventional thermoelectric power plants generate electricity is very inefficient, and a big portion of the energy is lost as heat. US power plants produce more waste heat each year than the total annual energy used in all but three countries – China, the USA and Russia. “Waste heat from power plants is 36% of total USA energy use, equivalent to the total energy used in buildings and industry. Clearly, recovering and using waste heat through district energy is an important near-term opportunity to cut emissions.” said Robert Thornton, President and CEO of IDEA.
In addition to enabling use of waste heat, district energy also enables economies of scale through demand aggregation. “If we are serious about climate change and energy security we have to get rid of the 100 million oil and gas boilers and as many chimneys that go with them. In cities – a key piece of the puzzle, as we all know – there is no better means of achieving this than District Energy,” said Paul Voss, Managing Director of Euroheat & Power.
In Malmö, 90% of houses are connected to district heating and 60% of the heat used comes from waste heat. The Mayor of the City of Mälmo, Katrin Stjernfeldt Jammeh, briefly presented Hyllie, the largest development Malmö currently has. Hyllie aims to be the most climate-smart city district in the region and a global benchmark for sustainable urban development, which includes making this area 100%RE by 2020. Biogas generated from food waste, smart grids, electric vehicles and district energy are key infrastructure solutions for this area.
In Saint Paul, Minnesota, district heating has been in use for 30 years, serving 80% of the businesses in the downtown district. The conversion from coal to biomass has had tremendous impact: “District Energy Saint Paul’s conversion from coal to biomass uses 300,000 tons annually of clean tree waste and reduces 106,000 tons of greenhouse gas emissions annually” said Anne Hunt, Environmental Policy Director of the City of Saint Paul.
In Gothenburg 70-90% of the heat in the District Heating (DH) system originates from waste heat from industry, depending on how cold the winter is. Peter Krahl Rydberg, Environmental Strategist of the City of Gothenburg, mentioned some innovative aspects being explored: ships in harbor also connect to DH, as do washing machines, and heat is also used to generate district cooling. The City of Gothenburg, in addition to having endorsed the Global District Energy in Cities Initiative, coordinates the Celsius Smart Cities project and is looking forward to connecting with other European Cities to further exchange and share good practices.
H.E. Ahmad Bin Shafar, CEO of Empower, shared the advantages of district cooling in the City of Dubai. Dubai has made district cooling a pillar of the strategy to 2020. Some distinct characteristic of the system include the use of treated waste water to address the unavailability of potable water to serve the system, and the use of thermal energy storage as chilled water, making the system more efficient. 854MW of electricity have been saved through the use of district cooling.
District energy is having a major impact in cities around the globe, as this session made clear. The goal now is to spread the word, coordinate and upscale, to ensure that cities are no longer wasting energy that can be put to use.