Energy Storage

Energy storage and sharing

Storage technologies analysis

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The group talked about energy storage and sharing in different meetings, the main discussions are explained below.

Storage technologies

Several storage technologies are available on the market, some of them have been analyzed by the group and the results are here resumed:

  • Battery storage “behind the meter”: could be used for many purposes: shifting consumption between peak and non-peak hours, storing surplus PV-energy, backup power, participate in demand-response and flexibility markets, etc. However there are concerns whether batteries are the best solutions to these issues.
  • Battery storage at “district level”: in communities with high amounts of local energy production (mainly photovoltaic) having a larger battery commonly used as an energy pool could be a way to decrease the dependency on the electricity grid.
  • Thermal inertia in buildings: is in many ways an unused energy storage resource. One use case is to lower heating power peaks by “charging” the buildings with energy during low-demand periods and then using the thermal inertia as a buffer during high-demand periods. Vice versa could be applied to cooling.
  • Vehicle2Building: the electrification of the transport sector will likely make housing buildings an important part of the charging infrastructure. Both being able to manage the power demand for charging as well as utilizing the batteries in the vehicle as a resource in the building energy system are interesting areas.
  • Thermal storages: several participants had experiences of various forms of thermal storages such as ice storage, rock storage and other types of ground storage. This applies primarily for seasonalenergystorage.

Energy sharing strategies

Another way to better use energy, renewable one in particular, is the energy sharing. Some different energy sharing strategies have been analyzed:

  • Solar power surplus generated at a site/building level with good conditions for solar power could be shared with other sites with a net demand for electricity. Different models for this and the legislative landscape around it was discussed.
  • Physical transmission in a local area: most of European electricity network tariff structures are not favorable for transmitting energy from one site to another within a small distribution area. DC transmission networks between closely located buildings could be an alternative solution.
  • Netting/Clearing by partnering with an actor (i.e. electricity provider) that allows surplus electricity being
  • Feed in tariffs:in some markets provide a good financial case also for solar power being fed to the grid.
  • Participation in flexibility markets:building automation/energy management systems allows non-critical electrical loads to be turned on/off automatically which could be used to participate in flexibility markets or demand response programs. This is an area that would be further leverage with energy storage or vehicle2grid solutions being deployed
  • Electric vehicle charging infrastructure installed at housing buildings could be provided as a service to multiple customer/user segments

Problems and barriers

The relatively low maturity of the technologies and legislation around it creates a number of uncertainties and barriers:

  • Business models needs to become more mature and new actors that provides attractive offers for building owners is needed. Many of these solutions are not within the scope of the typical business of a housing company and therefore strong partnerships are needed.
  • Alternative solutions for achieving the same net effect as an energy storage could be done with other measures such as demand response, feed in tariffs, physical transmission, etc.
  • Legislation and incentive structures have so far been key enablers (e.g. the solar power market in Germany) in many markets. So far, many technologies such as solar power, batteries, electric vehicles are financially feasible due to publicly financed subsidies. The uncertainties on the long-term viability of these creates risks for building owners to invest.
  • Dependency on energy market structure and tariffs: many of the discussed solutions are dependent on the cost of alternative energy sources, (e.g. electricity purchased from the grid). Therefore, the long term price development on the regional/European energy markets influences the viability of locally produced and stored energy.

Renewable energy and social housing sector

Concluding, the social housing sector could have some interesting opportunities to exploit, such as:

  • Technology shift: the general development in the energy sector with centralized fossil-based energy generation being replaced by de-centralized renewable energy sources influences the housing sector. Many opportunities come with this trend and makes possible for building owners to have a more active and proactive role in energy management increasing business value and sustainability.
  • Policy visions and harmonization: Even though today the legislation on energy related topics, especially regarding subsidies for renewables and storage, is rather fragmented around Europe, there are ongoing efforts to harmonize policies in the EU. A key step in this is the so called “winter package” which was launched by the EU in order to facilitate a “consumer centered clean energy transition”. This will set more clear legislative guidelines for how tomorrow’s energy system will be built up with the end consumer in focus. This will give more incentives for building owners to take an active part in energy storage and sharing solutions.


During the meeting in Darmstadt 2018 different companies presented different smart grid projects.

Power2U project


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Innoenergy presented a new project called Power2U.

Power2U is a new actor, a Local System Operator, which will design and operate sustainable local energy systems in building stock with focus on local, digital and renewable solutions.

Power2U develops its services together with forward thinking costumers (building owners) and partners sharing the ambition and vision of a sustainable energy future. Their purpose is to increase the control and the system optimization.

This local system operator works on reduce, produce and share energy.

  1. Reduce energy cost and unlock flexibility: automation with minimal lock effect, optimization of local building microgrids.
  2. Produce and store energy: combine local energy production and storage, improve EV-charging management.
  3. Share flexibility: deliver district heating demand response, deliver frequency control services, participate in demand side management programs.

Power2U provides services both for building owners and for grid operators. They want to transform buildings in more efficient way and in the future different buildings will interact each other. Building should also help to reduce power peks thanks to batteries.

The CODES PROJECT is a pilot project, where they installed 6 batteries in 6 buildings (5 residential and one shopping centre). The aim is a cloud for energy system to store energy, peak demand management and TSO services. They are now developing the “brain” of the system, with a predictive algorithm that can help to optimize energy.

During the discussion we talked about the grid dimension: if the grid is small in the end it has to “feed” itself, instead if the grid is wider is possible to share electricity among different households. Another problem is the environmental footprint of battery production.

SWIVT project


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The aims of this project are:

  • Ensure >30% better energy balance than conventional renovation.
  • Network of actors and areas.
  • Use innovation in practice.
  • Develop new methods for energy management.

The activities to reach these aims are:

  • Develop renovation and energy production concepts.
  • Networking energy systems through conversion and storage technologies at district level.
  • Operational optimization through control stategy.


After the preliminary work phase at ETA factory, they analyzed different interests of different participants: the housing company (Bauverein AG) focus is on real estate, economics and rental space; the energy supplier (Entega) find business model for decentralized energy generation from renewable sources, focus on grid stability and balanced potential with fluctuating energy supply; users want maximum comfort at lowest possible cost. All the actors want a reduction of greenhouse gas emissions.

The pilot projects is an headquarter in Darmstadt  with existing buildings in Moltkenstasse 3-19, in non renovated condition, built in 1952 and a building, renovated in 2011, in Moltkenstasse 27.

They planned:

  • minimal intervention in existing buildings, double densification, trough highly efficient new living space;
  • local energy production;
  • networking through hybrid heat and power grids;
  • installation of heat and electricity storage in residential complex;
  • predictive energy management strategy for operational optimization.

After works they saw that even without insulation of the outer walls, the existing building can achieve a >30% better energy balance compared to a conventional renovation and densification scenario. GHG emissions do not decrease linearly with primary energy demand.

The vision of SWIVT concept is to create a district development model for residential buildings in Germany. They aim for increasing the renovation rate without invasive measures in existing buildings (no insulation); they want to reduce GHG emissions by evaluating scenarios according to a lifecycle GWP indicator, a more effective contribution to climate targets than current energy standards. They also want to create e cooperation model for a sustainable, long term investment for all involved actors, by linking synergies within today’s set of unilateral economic incentives.


The project became bigger in the implementation phase (SWIVT II): they increase the area, including other existing buildings. The core of this project is the SWIVT controller, the central tool for planning, dimensioning and later controlling the energy related components of the SWIVT district. The SWIVT controller has a modular structure and can be expanded. The results of the controller can be dispayed as load profiles or annual quantities, here is the achieved transparency in the overview of all occurring energy flows in the system.

The thus dimensioned amounts of energy and components are integrated in a parameterized overall balance with results of the structural design.

In later real operation, the energy components are then controlled in real time by algorithm based optimization.



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With Web2Energy In 2010 Entega started a research project to layout an intelligent energy supply net in southern Hessen, it was a first smart grid connecting different power plants (wind, hidro etc) and some storage to see how it works in a smart grid. Six different housing area were connected with power plants, there were panels on the roof, windmill on the top of the hill and also biogas. This production is connected with a storage; in winter time there is not enough energy production, so they opted for a district storage, that can be used flexibly by the final user. The energy storage can be commercialized.

Users become active actors in this energy efficiency project, they participate in the monitoring with some information. Entega usually communicate with housing company and not direct with the users, because is easier.

The company has to know when the user needs energy, to know if the costumer devices are smart and which are the energy production condition (weather).

Nobodies can calculate the needs for the next 40 year, is too difficult, so they storage the energy surplus now, because they can’t calculate how big will be the demand.

Nowadays we have small different production, not only a big one and sometimes they produce too much electricity that is not needed.

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