The need for energy storage in Northern Ireland

Professor Neil Hewitt of Ulster University discusses Northern Ireland’s future energy system needs and the University’s role in the development of new technologies.

Innovation in renewable energy system development coupled with reduced costs of typically wind and PV systems has resulted in the wider deployment of renewable energy systems. Government supporting mechanisms have also facilitated deployment to contribute to carbon reduction targets for the region. However, the deployment of such renewable energy systems has challenged efficient flexibility management of the electricity transmission and distribution network. To date, curtailment of renewable energy systems has been effectively employed to ensure electricity network stability and safety.

While it is challenging to predict what the future energy system needs of Northern Ireland will be, the deployment of greater amounts of low carbon technologies that are likely to be non-dispatchable will require a greater amount of flexibility management. Such approaches may include greater interconnection to neighbouring energy markets, smart grids, greater energy storage and greater demand side response.

In addition, the electricity network is an aging system with limited flexibility and in the Northern Ireland context, may not be sufficiently funded to accommodate future flexibility needs. This is due in part, to competing challenges for limited public funding including fuel poverty and industrial energy costs. Therefore, to cost-effectively accommodate future renewable energy systems, energy storage and demand side response coupled intelligent systems and smart energy networks may provide best use of both existing electricity infrastructure and future limited yet targeted infrastructure investments.

Energy storage at Ulster University has become a strong research theme. It recognises that storage must become economically viable in these times of limited government financial support, although government will play a pivotal role in facilitating new project deployment through permitting and planning consents. Ulster recognises that many of the current generation of energy storage technologies are not designed to address both the quantity and rates of variability of renewably generated electricity. This is further challenged by decreasing spinning reserves and agreed ancillary service roles for energy storage.

Ulster also recognises that electricity is not the only stored commodity. Heat is considerably cheaper to store than electricity and is significantly more advantageous than curtailing wind or PV system outputs. Project SPIRE (Storage Platform for the Integration of Renewable Energy) (http://projectspire.eu/) was an INTERREG VA funded project examining three scales of energy storage i.e. large scale compressed air energy storage, intermediate site scale battery and thermal storage and domestic scale demand side management utilising heat pumps and thermal storage.

Project SPIRE not only developed new technologies in these areas but also incorporated such findings of the project into All-Ireland Single Electricity Market models. These models absorbed future capacity statements for electricity generation portfolios as well as looking beyond to 2030 and 2050 scenarios incorporating renewable energy and levels of storage for network stability.

The results from this project are encouraging. Compressed Air Energy Storage is potentially cost effective but requires use of deeper salt deposits to engineer a simpler cavern arrangement. Improvements in compressor-turbine efficiencies at the greater depths will also be required and Gaelectric Energy Storage Ltd is addressing these issues further. Autoproducer wind turbines delivering energy to a specific site illustrated the flexibility of flow batteries and in the case of Ulster’s partner in SPIRE, Dundalk Institute of Technology, ice banks, demonstrated greater levels of self-sufficiency and supply/demand integration. Ulster demonstrated successful heat pump and thermal storage displacement of gas boilers in its “Terrace Street” Victorian housing demonstrator and the utilisation of market electricity signals to cost-effectively operate the heat pump at low cost periods.

These results were then integrated at different levels (large-scale transmission connected and small-scale distribution connected) for the future (2020 and 2030) wind dominated Single Electricity Market.

Research was carried out by construction of 2020 and 2030 Single Electricity Market model with the PLEXOS software. The developed models considered current and future changes in thermal generation portfolios and accommodation of renewables, changes in market design and operation. The developed SEM model has been validated against historical market operation and exhibit good fit with real market outputs.

Techno-economic analysis of large-scale energy storage systems and its comparison with the traditional peaking generators showed exceptional technical benefits for operation of conventional thermal generators and gaining the most benefits from the renewable sources. Significant economic advantages were observed for market operation with any flexible technologies, whilst energy storage and advanced Combined Cycle Gas Turbines showed the best potential from economic point of view. Heat pumps and thermal energy storage could play a vital role in decarbonisation of heating market. Thermal energy storage systems could potentially reduce peak loads, which allow higher level of heat pump penetration and therefore achievements of higher decarbonisation targets. Heat pumps and thermal energy storage also showed significant benefits in comparison with the traditional resistive heating electrification. Cost-benefit analysis suggests potential investment viability of proposed technologies.

Heat pumps also play a significant role in the EU FP7 project EINSTEIN (Effective Integration of Seasonal Thermal Energy Storage Systems in Existing Buildings – http://www.einstein-project.eu/english/homepage) that utilises seasonal thermal energy storage. After a period of laboratory development, an advanced heat pump utilising R245fa as a refrigerant was used to upgrade heat from 800m3 insulated tank of water acting as a seasonal store, storing energy from a 150m2 solar thermal array.

The store heated a hospital administration building in Zabki, near Warsaw in Poland whose peak heating demand was in the order of 90kW. When the store’s temperature dropped below that required by the radiators of the building, the advanced heat pump developed by Ulster used the tank as a heat source and upgraded the heat to the necessary temperature of typically 75°C. Coefficients of performance of greater than 5.0 have been regularly achieved.

Advanced heat pumps also are a feature of i-STUTE (EPSRC Interdisciplinary Centre for Storage, Transformation and Upgrading of Thermal Energy-http://i-stute.org/) where new working fluids are utilised to optimally work with thermal storage solutions for domestic demand side management.

However research partnerships such as those described do not happen by accident. In addition to research excellence, Ulster provides the Horizon 2020 NICP Energy service, which aims to ensure that Northern Ireland companies, research institutions and other organisations are well informed when applying for Horizon 2020 funding for energy-related projects. We provide advice and support on accessing Horizon 2020 funding for research, development, demonstration, innovation and market transformation across the energy theme (http://h2020ni.com/supportcontacts/dominic-mclarnonenergy/).

For further information, please contact
Professor NJ Hewitt BSc DPhil CEng
CPhys MInstP MInstR MEI
Director
Centre for Sustainable Technologies
Ulster University
Email: nj.hewitt@ulster.ac.uk
Web: www.cst.ulster.ac.uk