The depletion of fossil fuels and climate change have led to international, European and national agreements. In recent years much effort has been given to lowering residential, commercial and industrial energy use through improved insulation and more efficient appliances. In urban renewal it is a very costly affair for an individual house or building to try to achieve the same energy savings as that of a ‘passive house’. A neighbourhood approach to energy production and distribution is more efficient. A more efficient and decentralised approach also has consequences for the national energy strategy. In this chapter a concise explanation will be provided in the field of this complex topic.

Dutch and European policy

On a European level it has been agreed that CO2 emissions should be reduced by 40% by 2020 as compared to 1990 levels. Energy use needs to be reduced by 20%, and the share of renewables in the total energy mix needs to increase 20% by 2020. [Erhorn-Kluttig et al., 2011]

The International Panel on Climate Change (IPCC 2007) states that developed countries need to reduce their greenhouse gas emissions by 80 to 95% with respect to 2000 emission levels in order to limit the increase of the average global temperature to 2°C. It further states that stabilisation of the emissions of greenhouse gases is not sufficient, but that between 2070 and 2100 negative emissions of global greenhouse gases will need to be achieved. [Hohmeyer, 2010]

Global energy demand is rising rapidly, though energy consumption in Europe has stabilised and is even declining in some countries due to improved energy efficiency. Of all energy used globally, 80% is from fossil fuels, oil, coal and gas. In Europe, this percentage is 75%.

Currently over 50% of the total energy used in Europe is imported. [EU Directorate-General for Energy, 2011]

Energy mix in EU Member States in 2009 (distribution of gross inland consumption by product). * = coal and other fuels © EU directorate-general for energy, 2011, by Eurostat

Each European country has a specific ‘energy mix’. This is the distribution of the various energy sources. The Dutch energy mix stands out because of its large share of gas and relatively small share of renewable energy sources. Austria, Finland and Sweden, for instance, all had sustainable energy shares of over 20% in 2009.

The European target of a 20% share of renewable energy in 2020 is an average. For each member state a goal has been set based on enlarging its original share of renewable energy. For example, Sweden had a percentage of renewable energy of around 40% in 2005 and will aim to be at around 50% by 2020. For the Netherlands the target is to reach a level of 14% renewables by then; in 2009 this was 4%. [EU Directorate-General for Energy, 2011]

EU Energy targets 20-20-20 by 2020: Increase the share of renewable energy sources in energy consumption to 20% © EU directorate-general for energy, 2011, by Eurostat and European Commission

As every European country has a specific energy mix and target percentage for renewable energy sources, there are various ways of making the countries more sustainable, and a particular national policy has been developed in each country.

Compared to that of its neighbouring countries, the share of renewable energy in the Netherlands is very small at 9-10%. About half of this energy comes from the incineration of household waste, yet according to the EU definition this in not a renewable source. Forty percent of the national sustainable energy production comes from wind turbines. Hydropower and solar power contribute only marginally to the total national energy production. [Wikipedia, duurzame energie 2012]

Working towards this common goal of making energy production more sustainable has become visible by means of wind turbines and solar panels in many European countries.

A 2009 EU guideline (EPBD) requires that as of 2021 all newly constructed buildings must be low-energy buildings which must cover their minimal energy needs by using renewable sources. For public buildings this requirement will come into force in 2019. [Erhorn-Kluttig et al., 2011]

A major portion of energy is consumed in the built environment. The switch must therefore take place in cities.

The legal requirements regarding building insulation are regularly tightened. The technology required to reach the European targets, for instance by realising zero-energy buildings, is already available, but it is only marginally used and still very costly. Data shows that energy use per square metre of living area is decreasing, but in order to reach the set objective there needs to be a major acceleration of improvement, and this is difficult to finance, especially for areas which require urban restructuring. [Erhorn-Kluttig et al., 2011]

Neighbourhood approach

It is feasible to have passive houses in newly constructed neighbourhoods, but to reach the same level of efficiency within the renovation sector a disproportionate increase of funds is necessary. Neither the annual percentage of newly built buildings nor the quality of renovation is sufficient to reach the abovementioned European objectives.

The costs of increasing thermal insulation values are not proportional to the savings. Increasing the insulation value of a building using more technical measures is societally not feasible. More opportunities and efficiency can be obtained with a neighbourhood approach to energy and heat production using smart grids. [Erhorn-Kluttig et al., 2011]

Optimal neighbourhoods: sustainable coproduction, exchange and decentralised production

Many systems for the generation of energy, such as cogeneration (combined heat and power, or CHP), biomass, residual heat from industrial processes and heat from waste incineration, are more viable when they are available in large amounts.

These systems are well suited for a neighbourhood approach. Using the opportunities in a specific neighbourhood in combination with optimisation of the complete neighbourhood system can lead to output levels similar to those of low-energy buildings [Erhorn-Kluttig et al., 2011].

The challenge is that there are no standard solutions and that the solutions must always be attuned to the specific possibilities within a neighbourhood. The processes for optimising energy use within a neighbourhood are thus long and complex. The building blocks can be provided, but these need to be configured differently on a case by case basis. A neighbourhood approach is generally only feasible in combination with another transformative aspect such as change in use or when there is also a social drive to tackle a certain neighbourhood [Erhorn-Kluttig et al., 2011].

In addition to the approach to energy and heat production and the reduction of demand, optimising distribution will also become more important. Decentralised supply of energy, storage and distribution requires a more flexible grid. Smart grids will need to connect users, centralised and decentralised suppliers and storage locations with each other.

© Laure Itard, Olivia Guerra Santin, TU Delft, 2009

Sustainable, energy-neutral, or even better, energy-producing neighbourhood concepts are, as mentioned earlier, strongly dependent on the possibilities per neighbourhood. Density, functions within the neighbourhood, new or newly renovated construction, possibilities for geothermal and thermal energy, underground storage or available residual heat from enterprises are some of the aspects which determine the choice of a concept.

A future in which smart grids will play an ever increasing role and in which decentralised and centralised energy production must be optimally combined depends on the facilitating network structures. The social trend for citizens to take more responsibility for energy supply can be combined with the objectives for decentralised renewable energy generation.

This becomes clear with neighbourhood-oriented and citizen-owned power companies such as Thermo Bello in Culemborg and the Citizen Power Plants in Germany.

A transition from central to optimal

Further development of energy production using renewable sources will eventually conflict with existing systems. Coal-fired plants and nuclear power plants do not combine well with a transition to completely renewable power production. This is already apparent in Germany, where renewable energy has priority over fossil or nuclear sources. On some days up to 80% of the energy in Germany is provided by wind turbines. On those days the power stations sometimes need to be disabled. The discontinuity of wind and sun is difficult to combine with the slowness of nuclear and coal-fired plants. These plants were designed in the era before wind and solar power were used for base loads and medium loads. This means they need to be used as uniformly as possible throughout the year. Their investment costs are relatively high and operating costs are low, thus they need to run as many operating hours as possible to remain profitable. [Hohmeyer, 2010]

Daily load structure and subdivision in different load segments of electricity demand in the net. © Hohmeyer, 2010

Coal and nuclear power plants are considerably less flexible than for instance gas-fired power plants. For instance, it takes about 50 hours to restart a nuclear power plant that has been laid still, whereas the start-up time of a coal-fired plant is only 5 hours. Nuclear power plants cannot function at 50% capacity or less and need to then be switched off. [Hohmeyer, 2010]

Nuclear power plants therefore are unable to supplement the fluctuating supply of available renewable energy. Gas-fired plants are more suitable because of their short start-up time of 20 minutes for large plants and a few minutes for gas-fired cogeneration facilities for neighbourhoods or homes. Furthermore, gas-fired power plants can be converted to biogas power plants. [Hohmeyer, 2010]

Daily load structure and feed-in from not regulated renewable energy sources © Hohmeyer, 2010

Through increased use of wind power, for example in Denmark and Germany, there will be no continuous base load requested from 2020. A bridging form cogeneration facilities at home, block and district level with heat buffers that are centrally controlled to compensate for shortfalls in supply.Many small plants form a virtual work force. Gas-powered cogeneration plants have the advantage of high efficiency, rapid implementation of small projects in a few years as opposed to planning and construction of large work forces of 5 to 10 years. They are as large virtual work force smoothly and quickly adjustable to complement the renewable sources. Another advantage is the short decrease in value period of 10 to 15 years of smaller installations compared to large installations of 35 to 50 years. This allows flexibility to adapt to new developments. [Hohmeyer, 2010]

The grid structure will be adjusted and attuned more to decentralised generation. It is likely that more grid-like networks will need to be installed, deviating from the now common radial structures.

Operational reliability

Another reason for making the transition to more grid-like structures is that these are not as vulnerable. With centralised power production, the malfunctioning of a power plant can paralyse a huge area if there is no solid emergency power supply. Furthermore, power failures in the US have shown that when power is fed in from the surrounding network during a power failure, there can be a domino effect and the afflicted area can increase.

Vulnerability plays a role on a different level as well. With centralised power production, large power plants become possible targets of attack. [US Department of Energy, 2011]

Smart grids can reduce the abovementioned limitations and create a more robust and sustainable energy network.

Smart grids

A smart grid is a network in which all available possibilities are deployed to attune demand and supply as much as possible and to facilitate the use of renewable and local energy sources as well as possible. Information technology has much to offer in this respect. For instance, based on the current situation, energy production in power plants can be adapted to the anticipated amount of wind- and solar energy. Variable pricing can be introduced to steer the demand side. Electric appliances can be adapted in such a way that they only turn on when the price of electricity falls below a certain level.

In principle, with a smart grid, each consumer can also be a producer, and local renewable energy sources such as wind turbines and solar panels can be connected to this grid.

Further developments integrate alternative, often local forms of energy storage. Conventional batteries should not be the only medium considered; energy can also be stored in other places such as the ground, and electric batteries or fuel cells from cars can also be deployed. By applying smart grids the robustness of the energy system can be enhanced.

Denmark is working hard to realise such a smart grid. The objective in Denmark is to have an intelligent meter in each household by 2020, creating the possibility that certain appliances such as washing machines and dishwashers will turn on and batteries will start charging at times when energy is readily available [Danish Ministry of Climate, Energy and Building, 2011].

In the US the term “islanding” is already taking hold when explaining the workings of a smart grid. In this model, networks of city quarters or villages can be converted into independent local networks by being connected to local energy sources such as solar and wind power, or to the locally stored energy in car batteries, so that in the case of a power failure vital urban functions such as emergency response services and supermarkets will receive priority and remain in operation.

Smart grids consist of a great variety of technologies. They also cannot be ‘constructed’. Building a smart grid is a long-term, gradual process that has not only technical but also legal, administrative and social aspects. [US Department of Energy, 2011]

Framework for the transition from fossil fuels to renewable resources

A transition from fossil fuels to renewable resources can only take place within an integrated vision on sustainable, decentralised and centralised energy supply. Germany and Denmark are examples of neighbouring countries with more or less similar geographical conditions as in the Netherlands, creating conditions that lend themselves to the development of renewable energy.

Denmark aims to base 100% of its energy and heat production on renewable resources by 2050, while Germany’s goal is 80%. Toward this goal, both countries are focusing on on- and offshore wind farms. This wind energy is supplemented by local possibilities such as solar energy, hydropower and decentralised cogeneration plants. The two countries are also hard at work developing possibilities for electricity storage.

A German study stated that Germany’s electricity supply could consist completely of renewable resources by 2050. This same study states that renewable energy will be less expensive by 2035 at the earliest and 2045 at the latest. [Hohmeyer,2010]

Development of specific costs for the generation of electricity for renewable energy sources (including storage and national and international expansion of the High Voltage Direct Current (HVDC) grid) compared to possible development of costs for the generation of electricity from conventional sources in the future scenario (according to SRU Scenario 2.1.a / 509 TWh/a in 2050). © Hohmeyer, 2010

Besides the transition to renewable energy sources, policy development is also focusing on a reduction of CO2 emissions. Implementing CO2 storage now is being rejected both in Denmark and Germany so that this storage capacity will be available in the future, as the goal is to reach a negative CO2 balance by 2050. The storage possibilities for CO2 will be used in the winning and firing of biogas. [Hohmeyer, 2010]

Denmark also finds that the storage of CO2 is too costly and requires too much energy [Danish Ministry of Climate, Energy and Building, 2011].

If delays emerge in the further development of renewable sources in Germany, consideration will be given to running the existing gas-fired power plants longer, as they still have lower CO2 emissions than coal-fired power plants. New construction will primarily be realised as smaller cogeneration plants, seeing that these are more adjustable and easier to regulate and that they can produce both electricity and heat.

A forced extension of high voltage power lines from the production areas in Northern Germany to the economic centres in Southern Germany is crucial.

For the storage of excess electricity from wind and solar power, Germany has opted for the production of hydrogen and methane. By adding CO2 to hydrogen, methane is produced which is then used in the existing gas network. Energy is also stored by pumping water up into a reservoir. [Klaus et al., 2010]

Both Germany and Denmark have the objective to generate 50% of their energy demand from renewable resources, mainly wind, by 2020. Currently Germany is building over 2000 new wind turbines in addition to the already existing wind parks and turbines. Applications have been submitted for permits for 84 wind parks with 3600 wind turbines in the North Sea and Baltic Sea. To speed up the process, procedures have been simplified, also for the construction of high voltage lines. The German government is investing 5 billion euros in wind parks.

Large investments have also been made in research relating to energy storage. Whereas contributions to solar panels are being reduced because of their increasing efficiency, the extension of decentralised cogeneration plants is being stimulated. [www.bundesregierung.de]

Energy and heat at the neighbourhood level

In the framework of sustainable energy and heat production in the Netherlands, the trias energetica is often used: 1) limit demand, 2) use renewable resources and 3) use fossil fuels efficiently. Here the trias is extended with an extra step (Van den Dobbelsteen 2011), namely the introduction of the use of waste streams. This strategy is called the New Steps Strategy, or Nieuwe Stappen Strategie (NSS).

We have expanded Step 4 to also include the efficient use of renewable resources.

  • Reduce demand,
  • Utilise waste streams,
  • Use renewable resources, and
  • Use sustainable and fossil fuels efficiently.

In this overview by Van den Dobbelsteen the opportunities in relation to limiting demand, utilising waste streams and sustainable generation have been depicted on the various levels of scale. In the overview of measures below, the technical measures at the block and neighbourhood levels have been merged.

Building Neighbourhood/district City/region
Reduce the demand Improve building envelope
Reduce cooling demand
Construction materials with a high albedo values and low emissivity value
Optimalisation daylight entry
Building component activation
Efficient and healthy ventilation
Efficient hardware
Efficient lights
Company optimalisation
Smart meters/thermostats
Education
Reduce heat loss
Orientation
Wind disturbance reduction
Reduce cooling demand
Pavement materials with a high albedo value and low emissvity values
Shading by green
Temperature reduction by green
Efficient lights
Reduce cooling demand
Pavement materials with a high albedo values and a low emissivity value
City ventilation
Temperature reduction by green
Reuse waste streams Air
• Ventilation air recovery
Water
• Shower heat recovery
Water
• Waste water
Organic waste/biomass
• Fermentation organic household
waste/biogas production
• Residual heat from production
processes
Water
• Waste water
Organic waste/biomass
• Fermentation organic household waste/biogas production
• Fermentation of waste/biogas production
• Residual heat from production processes
Use sustainable sources Sun
• Passive solar energy
• PV-panels
• Solar thermal collectors
Wind
• Small wind turbines
Ambient heat
• Surface water
• Drinking water
• Air
• Ground
CHP-biofuel
Sun
• Passive solar energy
• PV-panels
• Solar thermal collectors
Asphalt collectors
Wind
• Small wind turbines
Ambient heat
• Surface water
• Drinking water
• Air
• Ground
CHP-biofuel
Hydropower
Sun
• Passive solar energy
• PV-panels
Wind
• Wind turbines
Ambient heat
• Surface water
• Drinking water
• Air
• Ground
CHP-biofuel
Hydropower
Blue energy
Minimize the use of fossil sources CHP-fossil CHP-fossil CHP-fossil

REAP © Andy van den Dobbelsteen

Literature