The energy supply network is facing dramatic change. Renewable energy sources challenge traditional energy supply networks which have been based on fossil fuels. There is a growing interest in renewable energy among households, but people desperately need more information on the available options and on how to efficiently utilize their existing energy structures. The share of renewable energy has increased significantly in the last ten years: in the European Union it reached 14.1 % in 2012, up from 8.3 % in 2004 . Renewable energy sources mainly cover solar thermal and photovoltaic energy, hydro, wind, geothermal energy, biomass, waste and landfill gas.
What actions can increase energy efficiency connected to energy supply? How should you communicate? Read about what to consider when choosing actions to increase energy efficiency below.
Solar power from photovoltaic systems is limited by the area that is usable for PV modules. For cities the most efficient way to use solar power is to integrate the modules into the roofs or facades of buildings. The electricity which is produced in this way can either be fed into the grid or can be used to supply just the respective building by using smart energy management systems (EMS) to maximize energy self-consumption. A city should quantify the renewable energy potential of their city, in the case of solar, to know the potential surface area from building rooftops, and their respective inclination angles. Parking lots also offer great potential for installing PV modules, especially if they are combined with EV charging stations to maximize self-consumption.
The solar irradiation is used for producing heat directly. In countries with existing low-temperature heating networks, solar collectors could be connected directly to the network or can be used together with other heating systems, like ground-sourced heat pumps to maximize the use of renewable energy of the heating system. During summer months, these collectors and heat pumps can be used to supply heat to the ground, for seasonal storage.
In the city context, small wind turbines are the most applicable and suitable technology. Small wind turbines can be mounted on roof tops as this is the most area efficient opportunity for cities. These turbines are mostly equipped with vertical rotor blades for reduced noise and shadow emission. Turbines with vertical rotor blades are usually visually less intrusive and therefore more suitable for city use.
Combined heat and power plants
Combined heat and power plants offer a very efficient way of providing with reliable power. By supplying both electricity and heat, the energy conversion efficiency ranges between 60 and 80%. Additionally, they can also offer the possibility of burning different types of fuels, for instance, organic waste from the cities can be used to produce biogas to fuel the power plant, likewise, other types of waste, with a valuable residual calorific value could be used as well.
Challenges with solar and wind energy are daily restrictions of availability due to sunrise and sunset as well as cloudy days limit the power generation by solar systems. Wind is a strongly fluctuating source and not exactly predictable (storms vs. windless days, change of wind speed etc.). One way to solve this challenge is to combine several renewable technologies with storage capacities. This approach is applied in virtual power plants which are controlled centrally while the energy is generated decentralized (where the conditions are suitable). In this way, the occasional lack of energy generated from fluctuating sources can be compensated with energy generated from non-fluctuating resources – like biomass – or covered by storage capacities.
For more technologies to improve energy efficiency please read PLEEC WP3 Technical State of the art innovative solutions (D3.1) and WP3 Improving energy efficiency through technology – Case studies (D3.2).
Contact: Erik Dahlquist, Technical University of Mälardalen, Sweden
Although a major part of energy consumption happens in cities, contemporary energy generation is less obvious connected to the urban structure. Energy consumed in transportation, based on fossil fuels, is produced at global scale; energy for electricity is usually distributed through a national or continental grid; energy for heating, if related to district heating systems or the use of local/regional resources for generation (e.g. biomass, waste), has a more local or at least regional character. In the latter, electricity might be a by-product of combined-heat-power plants, but still feeding into the grid. On the other hand, the focus on sustainable and efficient use of resources and energy at the local level, the mainstreaming of renewable energy production and ideas of urban energy harvesting put energy generation again on the local agenda. The role of the municipality can be twofold: (1) The municipality as a producer and (2) the municipality as an enabler or promoter. In the WP4 Thematic Report (D4.3) we review how planning can support sustainable urban energy generation (Chapter 5).
A widely employed technology in dense built-up areas is the cogeneration of heat and power (CHP plants and excessive heat producing companies) and heat distribution in local grids, while in sparsely built up areas heat pumps are getting more diffused. In smaller urban settlements, like the new urban development of Skanssi in Turku, joint heat pumps and a local grid can integrate energy producers and consumers on site. However, it will still be necessary to designate local areas suitable for large-scale energy production. Especially renewables as hydro/wind/solar/geothermal have special spatial requirements.
Becoming energy independent in Tartu
Despite sustainability, renewable energy might also solve issues of energy independency, which is a major issue in Tartu and Estonia. The current electric energy supply is mainly based on oil shale from the north of Estonia (see WP4 Case study report on Tartu (D4.2)). The implementation of heat pumps whenever excess heat energy is available in public works (e.g. waste water) or in private companies (e.g. excess heat from cooling) is one way to reduce energy demand from external sources. Furthermore, the implementation of planning guidelines to optimise solar access in built environment can increase opportunities for energy production.
For cities, focusing on renewable energy isn’t only an administrative requirement coming from national and EU levels but it should be seen beneficial to the city brand and marketing. By raising the profile of energy issues, better results will be achieved as principles of energy efficiency and clean energy are integrated into decision-making processes and city structures.
Eskilstuna, Turku and Jyväskylä – aiming high
Eskilstuna has become well-known both nationally and internationally for its eco-friendly city planning and energy efficiency campaigns. Eskilstuna started producing biogas from food waste in the 1080’s and was the first city to use optical waste sorting. The city of Turku has set plans to be carbon-neutral in year 2040 which is a very ambitious goal. Jyväskylä will become carbon neutral in heat and power production by 2030 and fossil free and carbon neutral in energy production and transport by 2050.
Research made in PLEEC clearly pointed to three solutions which should be the focus of increasing motivation when making the necessary changes in efficient supply of energy. These are:
Increasing the availability of non-biased practical information. Behavioral change and motivation grows from correct and reliable information. The municipalities and NGOs have a crucial role in breaking motivational barriers.
Increasing the amount of new affordable technologies. Incentives and policies supporting the renewable energy market and research are needed in municipal, national and EU levels.
Introducing basic financial incentives supporting adoption of renewable energy solutions. It is also effective to make actively fossil fuels less attractive financially for example by taxation and by showing the real costs of using fossil fuels.