Wind Power: The Smart Energy For Local Heating Networks As Well

Wind-based thermal energy storage facilities use wind power from neighbouring wind fields for a carbon-free local heat supply. Synergies are created here by coupling the energy industry segments of electricity and heat. This useful example of sector coupling can be ground-breaking for numerous North German municipalities and cities, which have copious amounts of wind energy locally available.

The unique feature of the wind-based thermal energy storage facility is the connection of a local heating network and wind turbines on site with an electrically operated heat storage facility. The variable electricity from production peaks serves to heat the water in the storage tank.

The slogan "Use instead of Shutdown" refers to the use of production peaks, for which there is no use in the grid, to instead supply heat. Instead of curtailing wind turbines, or in extreme cases shutting them down completely, water is heated in the heat storage tank by the use of the electricity, allowing wind power to be stored as thermal energy. This energy is then available in the local heating network to heat the connected houses and can replace old fossil heating systems. This cost-effective and highly efficient local heating can thus be combined with carbon-free wind power. In doing so, a highly efficient heating system based entirely on renewable energy is created. In the following real-life example of sector coupling, locally generated carbon-free electricity is used directly to heat an entire village.

Nechlin - A Village Full Of Energy

The Brandenburg village of Nechlin has been working on an intelligent and sustainable energy supply for several years now. Citizens participated in the construction of a network with several regenerative energy sources including photovoltaic systems. In addition, a local heating network has been built in recent years.

The wind turbines of the Nechlin wind field nearby generate around 70 million kilowatt hours of electricity per year. A small part of this (approx. 5 percent) is generated on particularly windy days. This amount of energy cannot be fed into the grid completely, but has great value for local use. Since the beginning of 2020, Nechlin uses wind energy from a neighbouring wind field for heat supply and heats the entire village with the help of a wind-based thermal energy storage facility. The wind-based thermal energy storage facility is heated only with electricity for which there are no consumers or grid capacity. The heating elements in the wind-based thermal energy storage facility are automatically switched on by the ENERTRAG PowerSystem control system. As soon as the transmission system operator gives a curtailment signal, the heating in the wind-based thermal storage facility is automatically switched on. This means that the wind energy heats the water in the new storage tank in exactly these windy periods when wind production would have otherwise been curtailed.
The new, large wind-based thermal energy storage facility has a capacity of around one million litres of water and has a diameter of 18 metres. The thermal energy is stored in this water tank as hot water and supplies the surrounding buildings with heat in the connected local heating network. Depending on weather conditions, the storage tank can supply Nechlin with heat for up to two weeks without the need for further curtailment and recharging. Both efficient and economical, this wind-based thermal energy storage tank is a reliable energy source for the local heating network of Nechlin.


The new, large wind-based thermal energy storage facility has a capacity of around one million litres of water and has a diameter of 18 metres. The thermal energy is stored in this water tank as hot water and supplies the surrounding buildings with heat in the connected local heating network. Depending on weather conditions, the storage tank can supply Nechlin with heat for up to two weeks without the need for further curtailment and recharging. Both efficient and economical, this wind-based thermal energy storage tank is a reliable energy source for the local heating network of Nechlin.


In autumn 2019, ENERTRAG began the construction of the wind-based thermal energy storage facility in Nechlin. As the storage tank does not contain any seals or screws, it is almost entirely maintenance-free and has a particularly long service life.


The Idea

The technical implementation is ingeniously simple: The wind turbines are directly connected to a 2-megawatt instantaneous water heater by a 20,000-Volt medium-voltage cable. There, water is heated up to 93 degrees Celsius and is released into the wind-based thermal energy storage facility.
From there, the hot water is delivered to the local heating network as required.
The wind-based thermal energy storage facility has a capacity of around one million litres of water. On windy days, the storage tank heats up within a few hours. The storage tank then releases its energy as required to the local heating network, which supplies 35 houses with an annual thermal energy demand of 720,000 kWh. The wind-based thermal energy storage facility has a total capacity of 38,000 kilowatt hours.
Once heated and charged, it can supply Nechlin with heat for up to two weeks. Because of the great wind conditions locally, the wind-based thermal energy storage facility can provide the village with completely renewable heating.

Project Figures Of Nechlin 

  • Water volume: 1 million litres (10,000 litres per inhabitant)
  • Diameter: 18 meters, height: 4 meters
  • Heat storage capacity: 38,000 kWh
  • Electrical input capacity of heating elements: 2,000 kW
  • Maximal heating output capacity to village: up to 300 kW
  • Power source: Nechlin wind field with an annual production of 70 million kilowatt hours
  • Heat demand for 35 houses: 720.000 kWh annually - 1 percent of wind power generation
  • Construction time for storage tank: 6 months, construction time for local heating network: 3 months
  • Heating network connection rate in Nechlin: 90 percent
  • CO2 avoidance: 20 tons per year compared to oil heating

A Role Model For Other Municipalities

Thousands of villages and small towns throughout northern Germany can be heated at low cost and without CO2 emissions. The only preconditions are the proximity of wind turbines and the shared willingness to use or build a heating network if one does not yet exist.

Overview Of the Advantages:

  • About half the price of oil heating
  • 100 percent climate-neutral renewable heat
  • Reliable and uncomplicated technology
  • Online data of the heat supply for each household

Get in touch with our experts for sustainable energy systems! Find out more about the opportunities for climate-neutral local heating solutions for your municipality too!


Mr. Stefan Käding, Head of the project »Wind-based Thermal Energy Storage«, marketing[at], Tel: +49 39854 6459-0.

Advantages Of Wind-based Thermal Energy For Local Heating Networks


Local heating is heat for space heating and hot water, which is produced together for several buildings in a settlement or district. Users save the cost of their own heating system, while at the same time the environmental balance is improved due to better energy efficiency and a better carbon footprint.
A local heating network consists of a central heating system, a system of connecting pipes and several house transfer stations. These houses receive heat for heating and hot water from a central heating system. The heat generated is transported to the connected houses through insulated underground pipes. Instead of paying for a fuel, users of the local heating system only pay for the heat actually transferred. Local heating networks can cover either a few buildings or also entire districts. 
Up until now, gas-fired, heat-driven combined heat and power plants have been common as an energy source, just as oil and woodchip heating systems. An innovative energy source for Nechlin is the new thermal energy storage tank, in which water is heated without CO2 emissions through wind energy. The connection to the local heating system reduces the costs for heating technology for users: Because home owners don’t need a chimney, an oil tank or gas connection in their own house.

Requirements For Carbon-free Heating With Wind Energy

A nearby wind field...
... whose energy peaks during strong winds can be used for wind-based thermal storage facility.


A dedicated local representative...
... such as Hartmut Trester from Nechlin, who understands the people in the village and takes them along on the way to a local heating network.

An energy company such as ENERTRAG...
...that builds the energy system and the heating network with expertise.

 New legal framework for sector coupling... enable the use of wind energy. In Germany it is currently regulatorily impossible to use curtailed electricity from renewable energies for heating. Therefore, the operation of wind-based thermal energy storage facilities should be legally recognised as a technical measure in the event of curtailment. This is the only way to ensure that citizens benefit from local energy.

Furthermore, a reform of taxes, duties and levies in the energy sector is necessary. The basis of assessment for all taxes, charges and levies in the energy sector must be designed in such a way that the carbon quantity of the energy source determines the amount of taxes, charges and levies. To compare: At present, climate-neutral renewable electricity, which costs 5 ct/kWh to generate, is subject to additional charges of up to 25 ct/kWh. Natural gas and heating oil, whose production costs are between 3 and 10 ct/kWh, have high CO2 emissions, but are hardly ever subject to charges. A conversion of the charges in relation to CO2 emissions would have a much greater impact on oil and gas, but not on wind energy.

Joint Project WindNODE For Renewable Electricity

The wind-based thermal energy storage facility Nechlin is part of the WindNODE network and the SINTEG support programme. Without the creation of special legal regulations for the SINTEG showcase projects by The Federal Ministry of Economics, the economic operation of the wind-based thermal energy storage facility would be impossible. It is currently unclear what will happen to the wind energy in Nechlin after the end of the SINTEG programme at the end of November 2020.

WindNODE is researching a future with 100 percent renewable energy in northeastern Germany. More than 70 partners from industry, research and civil society have been working together since 2017 in this showcase project, which is supported by the Federal Ministry of Economics in the SINTEG programme. WindNODE deals with the question of how electricity grids can be kept stable if renewable energies cover 100 percent of the electric demand in the future. The project region of North-East Germany is particularly suited as a "real-life laboratory" for this question, given that even today, significantly more than 56 percent of the consumed electricity originates from renewable energies. Amongst other areas, WindNODE researches and advances large storage solutions and sector coupling technologies. Here, for example, renewable electricity is converted into gas or is directly used in the transport and heating sector.

WindNODE has dedicated a special website to our project, which is well worth seeing: (in German)

No Climate Protection Without Heat Recovery

At the Climate Change Conference in Paris, the United Nations agreed to combat climate change and limit the global temperature increase to 1.5 degrees. To achieve this goal, countries must set concrete targets to reduce their greenhouse gas emissions in all sectors. By 2050 Germany plans to reduce its national greenhouse gas emissions by 80 to 95 percent below 1990 levels. The building sector is responsible for around 25 percent of German CO2 emissions and 30 percent of final energy consumption. CO2 is generated primarily in heating, water heating and also in cooling. In addition to the conversion of electricity generation to renewable energies, climate-neutral heat supply is therefore one of the most important tasks of our time.


Example Of Sector Coupling

The consistent use of renewable energies in the electricity, transport, industrial and heating sectors is the key to effective climate protection and a successful energy transition. The chart shows the different areas in which we need climate-neutral electricity in our energy system. In addition to the electricity sector, we also need electricity from renewable energies in the industrial, transport (electro-mobility) and heating sector (heat pumps). We can either use electricity directly or convert it into hydrogen or heat using Power-to-X (PtX) technologies. Power-to-Heat (PtH) technologies are used to convert electricity from renewable energies into heat. For this purpose, water is heated by using heating coils and stored, as in Nechlin. This water is then used, for example, for heating and service water in housing developments.


Potential Of Wind Heat In 2050

Total electricity generation in 2050 will be around 1,200 TWh. This electricity will be generated exclusively by wind and solar energy. With the help of sector coupling, the energy flows into different sections (see diagram) and enables the decarbonisation of the entire energy system. A renewable energy system is highly efficient with an efficiency of more than 80 percent. The wind-based thermal energy storage facility is an important part of the sector coupling: energy peaks which were unusable before are used directly to heat entire towns and villages. As shown in the diagram, wind-based heating systems will have the potential of around 55 TWh in 2050. Therefore, the wind-based thermal energy storage facility in Nechlin is only the beginning.


Benefit Instead Of Curtailment In Detail

The energy contained in the wind has a cubic relationship to the average wind speed: a warm breeze of 4 m/s has hardly any energy, but 8 m/s already has 8 times the energy and 16 m/s wind speed brings 64 times the energy. As a result, there are energy peaks. In the case of very strong winds, a multiple of the energy is generated that cannot be fed completely into the grid. These energy peaks occur about 25 times a year for about 10 hours. Up to now, these energy peaks are curtailed by the grid operators and are not used. In 2018 alone, 5.4 billion kilowatt hours of electricity from renewable energies were curtailed in Germany. This could supply up to one million people with carbon-free space heating. The diagram above shows the increase of nationwide curtailment, which cost a total of 635 million euros in 2018. A part of this is the curtailment in the Nechlin wind field. The 0.7 GWh for the heating of the village are always available due to the frequent curtailment. Although the frequency of curtailment in Nechlin decreased in 2017 due to grid reinforcements, it will increase again as wind energy expansion increases. Therefore, the wind-based thermal energy storage facility is the perfect solution to the problem of curtailment.