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Compact REtrofit Advanced Thermal Energy storage

Periodic Reporting for period 2 - CREATE (Compact REtrofit Advanced Thermal Energy storage)

Reporting period: 2017-04-01 to 2018-09-30

The recent first global conference on energy storage in Paris, 2014 , concluded that to achieve the European goal of an energy-neutral built environment in 2050, harvesting, converting and storage of seasonal solar energy is essential. The 2020 climate and energy package calls already for a substantial increase in renewable energy by 2020. The buildings sector accounts for the largest share of energy consumption (Europe wide approx. 37 % ). As two third of the building stock in 2050 is made up of currently existing buildings, the solution should be realised with the current building stock. The CREATE project aims to tackle this challenge by developing a compact heat storage module. This “heat battery” allows for better use of available renewable energy sources in two ways: (1) Considering that solar and wind energy are abundant, but inconsistently available, proper use requires storage to bridge the gap between supply and demand, i.e. the intermittent nature of renewables. (2) Heat storage can also increase the efficiency in the energy grid by converting electricity peaks into stored heat to be used later. In this way heat storage increases the energy grid flexibility (e.g. the seamless exchange of energy in different forms, giving options for tradability and economic benefits). Heat storage is therefore considered an indispensable element to facilitate flexibility in the energy grid.

The main aim of CREATE is to develop and demonstrate a heat battery, i.e. an advanced thermal storage system based on Thermo-Chemical Materials (TCMs), that enables economically affordable, compact and loss-free storage of heat in existing buildings.

The heat battery targets three breakthrough elements, addressed by the CREATE consortium consisting of all relevant partners in the future knowledge and value chain,

• Economical affordability: for the existing building stock we will reach at least a reduction of 15% of the net energy consumption with a potential Return-On-Investment shorter than 10 years. This is achieved by (1) using renewable energy that would otherwise be lost and (2) the reduction of investments in upgrading the electricity grid. Detailed ROI calculations are presented in section 2.3.3;
• Compactness: novel high-density materials will be used in order to limit the use of the available space to a maximum of 2.5 m3 thermochemical material. On a system level, 1.5 GJ/m3 (417 kWh/m3) is the targeted system energy storage density; on a material level 2-3 GJ/m3 (555-833 kWh/m3)
• No heat losses during storage: this is an intrinsic material property of thermochemical storage technology, thereby enabling long-term storage.
CREATE will target the following sub-objectives, to overcome the main technical and non-technical barriers regarding thermal storage technology:
• To develop stable & compact materials with an energy density of more than 1.5 GJ/m3 (420 kWh/m3). The thermo-chemical storage materials (TCM) developed within CREATE will have a storage density of more than 6 times that of water and exceed storage density of existing technologies such as PCM’s with a factor of 3 or more. The low storage density of these technologies is the current barrier to technology break-through in view of longer term storage (>daily to seasonal). The CREATE solution will require less than 2.5m3.
• To ensure efficient and high power energy discharge of as high as 5kW for a single family home, avoiding necessity of a short term buffer and thus allowing for a simpler and more cost-effective system.
• To ensure long lifetime by the preparation of TCM/stabilizer composite materials and the prevention of unwanted side-reactions, e.g. by corrosion or through material impurities. Over 20 years, the modules should perform for over 100 cycles (i.e. 2-10 cycles per annum) with maximum 5% loss in storage capacity.
• To ensure safe and reliable operation, through full validation and testing against failure modes and effect analysis and by demonstration of compliance.
• To develop an affordable technology. The total storage system needs to be affordable to allow for rapid market uptake. The CREATE project will focus on low-cost and maintenance-free concepts for heat storage (e.g. no moving parts in the storage module, and using cheap active materials – salt and water – as a starting point).
• To develop the future value chain. No current supply and value chain exists for the ‘heat battery’ from the material level up to the system level and grid. CREATE will create just that by having all the required key players in the consortium
A lot of valuable results have been achieved in the project. However, the switch to a new baseline storage material (K2CO3 instead of Na2S) has caused some delays in progress and deliverables as some activities have/had to be redone. A plan to deal with the impacts of this switch has been formulated and agreed with the Commission, which will be formalized in a contract amendment. Major concern for the project is to fall not further behind on the timeline.

The main objectives per work package and their results are described in the attached pdf file.
1.3 Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)
The project is still in its early stage (M18 compared to project duration until M48). The expected impacts from the proposal are still guiding the project during its on-going developments.