NODA Intelligent Systems discusses how district heating and cooling systems are cost-effective solutions that contribute to developing smart cities
Around 66% of Earth population will live in cities in 2050 while in 1950 was 30%1. This foreseen evolution of human settlement has the challenge of keeping the COP21 agreement adopted in December 2015 in Paris by 195 members of the UN Framework Convention on Climate Change. This mainly consists of providing a framework for combating global warming worldwide with the key objective of limiting the rise in global temperature to below 2ºC. In that sense, cities will need to improve its efficiency in resource consumption and use of urban services.
One strategy of several cities around the world to face this challenge is to evolve to become smart cities. What does it mean? A smart city is an urban development vision that integrates connectivity between infrastructures, facilities and citizens by means of data-driven solutions to manage needs of urban areas. The main objective of smart cities is the use of information and communication technology (ICT) to improve quality of life of citizens and to provide real-time response to challenges2.
The smart city is a broad concept that aims to empower citizens to interact with its environment, to create community between cities and the public government, to promote fun activities, to improve mobility and security, to foster tourism, to provide health service, to contribute to developing low-income sectors, as some examples. However, there are some detractors about the benefits of the smart city concept, related to the fact that smart technologies could be used in a way that infringes upon people’s privacy3.
Despite this wide concept of a smart city, one specific challenge that cities are facing today is how to manage the increase of population, global warming and the rise of resource demand, as well as the need of security in energy supply. In that sense:
- Transport has to be decarbonised, improving urban flows using sensors and communication and reducing emissions of vehicles.
- Lighting infrastructures have a large potential for energy savings by use of ICT.
- Energy refurbishment of existing buildings has maximum priority including building structure and heating and cooling supply facilities. Buildings account for over one-third of total final energy consumption and equally important source of CO2 emissions.
- Infrastructures of energy supply, power grids and district heating and cooling networks, must be cost-effective and sustainable energy systems, where fossils fuels can be massively replaced for a solution with lower carbon impact.
To be more concrete, this article focuses on how district energy or district heating and cooling networks (DHC) as a part of smart cities, are crucial infrastructures to decarbonise cities, by means of generating new business opportunities and economic growth.
In comparison with individual systems on each building or apartment, DHC systems have several advantages that permit the creation of cost-effective solutions to develop urban areas, thus minimising carbon emissions:
- High capacity chillers or boilers placed in centralised facilities perform with better efficiency than individual small capacity systems.
- Waste heat recovery can be implemented in central plants, for instance, by taking profit of cogeneration plants, waste heat from solid urban waste treatment plants or industrial parks, data centres, malls or public transport stations.
- The use of renewable energy source (RES) by means of highly efficient technologies, such as biomass, biofuel, solar thermal energy or geothermal energy can be used, also reaching 100% RES coverage.
- Thermal storage systems can be implemented in DHC in a more efficient way and higher capacity than in individual systems. In the same way, heating and cooling networks are virtual storage systems themselves. Innovative district heating & cooling network controllers such as NODA Smart Heat Grid, will increase the use of waste heat and renewable energy sources and boost energy efficiency at a district level. The real application of these solutions is demonstrated in the H2020 STORM project. ( https://storm-dhc.eu/ )
In a distributed energy system, where penetration of renewables into the grid is very high (expected to grow 30% from 2014 to 20204, DHC infrastructures can be used as thermal storage to move the thermal energy production by heat pumps, electrically driven, shifting demand over time. In that sense, heating or cooling can be generated by efficient heat pumps driven by photovoltaic or wind farms when a renewable resource is available.
Another suitable technology to reach 10% RES in DH is the combination of biomass and solar thermal energy. Biomass boilers reduce its efficiency during summer time when demand is only required for domestic hot water and not for space heating. In this season, biomass boilers can stop most of the time and the energy can be obtained completely from the solar thermal field.
Nowadays, networks are designed to minimise losses. They include high-performance insulation with the optimised piping flow to reduce frictional losses. Besides that, they are designed to use lower temperatures to reduce heat losses. This feature is suitable for refurbished or new nearly net zero energy buildings (low heating/cooling loads)5.
Traditionally, some DHC base their business model on selling as much energy as possible. However, since the oil crisis in 1970’s when policies about energy efficient were a key component for reaching low carbon societies, the business of DHC in several countries is evolving towards highly efficient technologies. In that sense, the added value of a business is based on optimisation of the operation of plants, accurate maintenance and proper design to fit the energy demand avoiding oversizing plants and pipes.
In that sense, online access to buildings of smart cities will contribute to developing the optimal design of DHC infrastructures to maximise energy efficiency and to reduce greenhouse emissions. Knowing social patterns and behaviour related to energy use, together with the availability of renewable energy, these factors will drive towards an appropriate level of energy management that is suitable to cover citizens’ needs, with the lowest impact to the environment.
To sum up, district heating and cooling systems are cost-effective solutions that contribute to developing sustainable energy cities with low carbon emissions. These infrastructures permit to reuse waste heat and to increase the penetration of renewable energy source in urban environments. The centralised management of energy, with customer interaction by means of intelligent digital solutions in a smart city, is a great combination to optimise the energy use and to enhance the creation of decarbonised urban places.
1 World Urbanization Prospects. The 2014 Revision. United Nation, NY, 2015.
3 Just What is a Smart City, by Matt Hamblen. http://www.computerworld.com/article/2986403/internet-of-things/just-what-is-a-smart-city.html?page=2
4 Tracking clean energy progress 2016. Energy Technology Perspectives 2016 Excerpt. IEA Input to the Clean Energy Ministerial. International Energy Agency, Paris, 2016.
5 Transition to sustainable buildings. Strategies and opportunities to 2050. International Energy Agency, Paris, 2013.
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