Solar Powered Thermochemical Energy Storage

As considerable energy is consumed by UK buildings, not surprisingly, the Government targets for reducing carbon emissions require an 80% energy reduction in this area by 2050. Thermochemical (i.e. water sorption-based) heat storage (THS) can play a pivotal role in synchronizing energy demand and supply in buildings. Transformation of the existing British building stock towards net zero energy buildings requires effective integration and full use of the potential yield of renewable energy. Thermal storage is a key priority to make such a step, particularly for the energy renovation of the existing stock, where compact building level solutions are required. Thermal energy storage can be accomplished using sensible heat storage (SHS), latent heat storage (LHS) or THS. Over these methods THS has approximately 6-10 times higher storage density than SHS, and two times higher than LHS materials when compared on a like for like storage volume basis. In THS, thermochemical energy can be stored independent of the time without any heat loss, permitting solar energy storage during the summer to meet heating demand in winter. Achieving this by other heat storage methods is both complex and expensive. The proposed project will deliver an advanced solar powered THS system, which has stable long term performance in multi-cyclic seasonal use of at least 20 years. The system will contain environmental friendly and safe materials and will be compact, enabling installation in the limited space available in the existing housing stock and as well in the new buildings. Although seasonal storage of solar energy is intended within the proposed project (e.g. V=3-4 m3), it is also possible to design it as short term storage (3-4 days) only with resizing the THS reactor (e.g. V=0.1-0.2 m3). The proposed thermal storage system will lead to significant energy savings (greater than 50%) and CO2 emissions reduction, with a maximum payback of 5 years compared to the current state-of-the-art.

The project integrates multiple units of THS with solar air collectors to optimise the performance of these technologies providing seasonal heat storage in both the new and existing UK buildings that has: (a) low cost; (b) higher performance; (c) higher availability; (d) higher durability; (e) improved on-site health and safety; (f) efficient sorption and desorption processes (g) high solar contribution and (f) implementation of the computer design tools. The target is the development of an innovative, highly efficient thermochemical energy storage system with the following technical advantages:
* The theory and methodology of the THS reactor incorporating multiple sorption beds with hollow fibre membranes in a unique design that increases efficiency and reliability, thereby improving the current technologies and increasing system energy performance. Fundamental heat/mass transfer formulation and model for membrane fibre/reactor system.
* Theory and methodology for the novel evaporative humidifier integrated with heat pipe model for utilizing ground energy to ease evaporation of water and enhancing energy input to the system.
* Theory and methodology for the highly efficient solar air collectors to drive the system and achieve efficient sorption and desorption processes.
* The characterisation and adaptation of new and safety improved nano-composite sorbents, reducing barriers associated with new energy storage concepts.
* The theory and methodology for the advanced ICT optimized control, data/performance monitoring and energy management system

The project provides an opportunity for UK industries to pioneer the development of a new advanced energy storage technology. It will deliver a sustainable, environmental and cost-effective solution to significantly reduce energy consumption and CO2/GHG emissions. The project will contribute to UK excellence in terms of addressing fuel poverty and improving the quality of life for its citizens.

The domestic sector in the UK currently accounts for about 30% of national energy consumption and around 25% of greenhouse gas (GHG) emissions, as a result of dependency on fossil fuels particularly for space and water heating. In centrally heated homes natural gas provides 85% of the heating load with only 8% coming from electricity (7% from others). In non-centrally heated homes 50% is provided by natrual gas and 40% by electricity. Solar thermal systems, one of the most established renewable energy technologies, could help reduce UK space heating associated GHG emissions. Solar thermal is already well establlished in the UK with more than 100k units installed to date but this is still significantly lower than in countries such as Germany, which has over 1 million units in operation. Seasonal THS systems, integrated to solar thermal systems have the potential for the UK to increase its utilisation of solar energy, with an increased scale of manufacture reducing the cost of such systems and enabling them to penetrate into more price sensitive markets.

Thermochemical heat storage (THS) is a progressive technology for storing thermal energy that can alleviate environmental influences and contribute to producing more efficient and cleaner energy systems. The proposed project aims to develop a cost-effective solar powered thermochemical heat storage (SPTHS) system having: low cost, high efficiency, ease of production and installation. The outcomes of the project will provide a good combination of energy efficiency, cost and environmental sustainability involving fossil fuel energy saving, carbon emission reduction, as well as pollutant (haze) control. It will also contribute to the growth in the nations' industrial economy, accessing the UK's building and energy technology market, thus creating more employment opportunities and improving its strategic role in UK economy. Meanwhile, it will also foster multi-disciplinary research which will raise the nations' standard in the global context. The proposed research matches well with the EPSRC's research portfolio of boosting energy efficiency and reducing energy demand in cities
(http://www.epsrc.ac.uk/research/ourportfolio/researchareas/energyefficiency/).

This project, focused on numerical modelling, laboratory testing of system components and field trial of the full scale SPTHS prototype, will bring about substantial benefits (impact) to the government, industries and end users in the UK. The Government will benefit from the increased economy, decreasing GHG emissions to prevent environmental pollution, as well as enhanced investment. Industries (especially those in the HVAC, construction and heat storage sectors) will contribute to improving market competitiveness, growing business opportunities and increased profits. The new technology will offer valuable teaching and learning education materials for undergraduate and postgraduate students. Moreover, researchers and postgraduate students will participate in the project by means of assessing, modelling and testing the developed prototype experimental unit at the laboratories of the Sustainable Research Building at the UNOTT.