Project SAVE-CAES is all about developing large-scale long-duration energy storage that will enable the UK to be powered largely (and possibly completely) from renewables. That energy storage must be affordable, sustainable and large-scale. Compressed air energy storage (CAES) has the potential to meet all these critically-important criteria. Developing such storage is probably the biggest single challenge standing in the way of "Net-Zero" for the UK by 2050. Offshore wind around the UK is a remarkable resource for a future zero-carbon UK electricity system. If we were to exploit all of the area that could feasibly be imagined, UK offshore wind could produce about 2000TWh of electrical energy every year - more than 5 times greater than the amount of electricity we presently consume in one year. Electricity usage will increase, of course, between now and 2050 - possibly increasing from ~350TWh each year to ~1000TWh annually. However, it is perfectly feasible that we can generate all of this electricity from wind. Solar power will also play a key role in powering the Net Zero UK but there are straightforward reasons why this will provide only about 20% of our power in the future. The strongest of those has to do with seasonality: solar on an average day in mid Summer is 9 times higher than on an average day in mid Winter, however our energy demand in Winter is higher than that in Summer. Happily the wind is also seasonal and it typically delivers 2.3 times more energy on an average mid-Winter day than it does on an average mid-Summer day. Nuclear power will also have some role. Opinions differ on how substantial that role will be but that is not very important for the purposes of understanding or justifying this research proposal. The key problem with having a country powered largely from inflexible low-carbon sources is that demand and supply must be matched and demand is relatively "inelastic". This means that proportionately small changes in the cost of electricity have very small influence on how much electricity that is consumed. Quantitative assessments of how much we will be paying for our electrical energy by 2050 suggest that less than half will be made up of the direct cost of generating the actual units of electrical energy. The larger cost will be connected with providing the flexibility - the ability to match up supply and demand. Different researchers predict different proportions, but the consensus is that flexibility costs will be the dominant ones. CAES is one of the most promising sets of options available in the UK for storing very large quantities of (wind or solar) energy over periods of tens of hours - possibly up to 100 hours. CAES has the potential to combine good performance (upwards of 70% round-trip efficiency) with relatively low costs (<£2/kWh). There are two different grid-scale energy storage plant which store compressed air in the world - one at Huntorf in Germany and the other in McIntosh, Alabama - however, these plants also store fossil fuel. Many commentators make the serious mistake of extrapolating from these to estimate what CAES can possibly do. Project SAVE-CAES sets out to apply fundamental engineering science to determine what a well-designed CAES plant without fossil fuel addition could possibly do. SAVE-CAES is a project filled with novelty. Pressurised air will be stored in salt caverns that are either offshore or at the coast. The project will explore the use of isobaric storage of the pressurised air and the management of concentrated brine (salt-water) for pressure regulation. It will also explore ultra-high-pressure air storage (for best value per cubic metre of cavern). It will also explore the potential for exploiting relatively mild geo-thermal heat during the re-expansion of the air and the possibility that some wind turbines might be deployed directly as last-stage compressors for charging the energy stores.

This proposal responds to a call from the Research Councils for a national Centre on energy demand research, building on the work of the existing six End Use Energy Demand Centres, for which funding ends in April 2018. Energy demand reduction is a UK success story, with a 15% fall in final energy consumption since 2004. Major further reductions are possible and will be needed, as part of a transformation of the energy system to low carbon, to deliver the goals of the Paris Agreement and the UK carbon budgets. Moreover, a low carbon energy system will be increasingly reliant upon inflexible and variable electricity generation, and therefore demand will also need to become more flexible. In short, changes in energy demand reduction will need to go further and faster, and demand will need to become more flexible. These challenges have far-reaching implications for technology, business models, social practices and policy. Our vision is for energy demand research in the UK to rise to these challenges. The Centre's ambition is to lead whole systems work on energy demand in the UK, collaborating with a wider community both at home and internationally. We aim to deliver globally leading research on energy demand, to secure much greater impact for energy demand research and to champion the importance of energy demand for delivering environmental, social and economic goals. Our research programme is inter-disciplinary, recognising that technical and social change are inter-dependent and co-evolve. It is organised into six Themes. Three of these address specific issues in the major sectors of energy use, namely: buildings, transport and industry. The remaining three address more cross-cutting issues that drive changing patterns of demand, namely the potential for increased flexibility, the impact of digital technologies, and energy policy and governance. Each Theme has a research programme that has been developed with key stakeholders and will provide the capacity for the Centre to inform debate, deliver impact and share knowledge in its specific area of work. The Themes will also undertake collaborative work, with our first joint task being to assess the role of energy demand in delivering the objectives of the UK Government's Clean Growth Plan. The Centre will also include Challenges that respond to cross-thematic questions for UK energy demand. These will mostly be developed in consultation over the early years of the Centre, and therefore only one is included in the initial plan: on the decarbonisation of heat. The Centre will function as a national focus for inter-disciplinary research on energy demand. In doing this it will need to respond to a rapidly evolving energy landscape. It will therefore retain 25% of its funds to allocate during the lifetime of the Centre through a transparent governance process. These funds will support further challenges and a 'Flexible Fund', which will be used to support research on emerging research questions, in particular through support for early career researchers. We are working closely with key stakeholders in business and policy to design our research programme and we plan detailed knowledge exchange activities to ensure that the work of the UK energy demand research community has broader societal impact.

Energy models provide essential quantitative insights into the 21st Century challenges of decarbonisation, energy security and cost-effectiveness. Models provide the integrating language that assists energy policy makers to make improved decisions under conditions of pervasive uncertainty. Whole systems energy modelling also has a central role in helping industrial and wider stakeholders assess future energy technologies and infrastructures, and the potential role of societal and behavioural change. Despite this fundamental underpinning role, the UK has not had a national strategic energy modelling activity. Models have been developed on a fragmented, reactive and ad-hoc basis, with a critical shortfall in the continuity of funding to develop new models, retain human capacity, and link modelling frameworks in innovative ways to answer new research questions. The whole systems energy modelling (wholeSEM www.wholesem.ac.uk) consortium is explicitly designed to enable the UK to make an internationally leading research impact in this critical area, and hence to provide cutting-edge transparent quantitative analysis to underpin public and private energy systems decision making. Following a rigorous selection process, the wholeSEM consortium encapsulates leading and interdisciplinary UK capacity in quantitative whole systems energy research. The key aims of the interdisciplinary wholeSEM consortium are: 1. Undertake internationally cutting edge research on prioritised energy system topics; 2. Integrate whole energy systems modelling approaches across disciplinary boundaries; 3. Build bilateral engagement mechanisms with the wider UK energy systems community in academia, government and industry. The wholeSEM consortium will prioritise on key modelling areas of high relevance to interdisciplinary energy systems. Internationally leading research will focus on: 1. How does energy demand co-evolve with changes in practice, supply, and policy? 2. How will the endogenous, uncertain, and path dependent process of technological change impact future energy systems? 3. How can the energy supply-demand system be optimised over multiple energy vectors and infrastructures? 4. What are the major future physical and economic interactions and stresses between the energy system and the broader environment? The consortium, will employ extensive integration mechanisms to link and apply interdisciplinary models to key energy policy problems. This will take place across the conceptualisation and development of innovative modelling approaches, model construction, and through an integrated set of use-cases. A key element of the wholeSEM is substantive bilateral engagement with stakeholders in academia, government and industry. Multi-layered integration mechanisms will include: - A high-profile advisory board, with key policy/industry representation plus wider academic experts; - An innovative fellowship programme to enable bi-directional UK academic, policy and industrial and international experts to work with wholeSEM research teams; - A range of workshops including four internationally high profile annual UK energy modelling conferences, technical workshops focused on key modelling issues, and non-technical stakeholder workshops on model conceptualisation, development and use-cases; - Detailed and transparent documentation for all of the consortium's new energy models; - Model access, based on collaborative agreements with an expert model user group. This will ensure best-use of models, accountability and two-way flows of information from/to model developers, users and critics; - Collation and curation of energy modelling data sources (building off and working with the UKERC Energy Data Centre); - Provision of training in modelling techniques and software platforms, to train and develop the next generation of energy systems modellers, including interactions with centres for doctoral training (CDTs); - Interactive web-based information dissemination

There has been a huge investment in micro generation from both customers and small scale providers, particularly in residential PV. Individual participation of these assets (offers to buy/sell/store energy) by micro/domestic scale agents in local, distributed electricity markets is currently a significant business and technological challenge in the UK's large-scale energy systems. A solution to enable energy trading between small scale generators and consumers that provides a compelling business case for storage and further penetration of embedded renewables is essential. New aggregators, that is, new market players who are highly adaptable in terms of dynamically organising Distributed Energy Resources (DERs), are emerging to provide a retail service to distributed groups of customers who could not manage to act in the energy market on their own. These aggregators would deal with requirements of the wider energy system by utilising diverse and multiple low carbon and renewable technologies for generation and storage to provide local/micro-grid solutions. However, there are significant barriers to the emergence of such entities which can be overcome by adoption of contemporary digital technologies. Our AGILE proposal sets out an integrated digital solution which can deliver suitable mechanisms to allow aggregators to offer the wider energy market bundled DER services of particular duration and value. To allow this, the preferences and descriptions of DERs, which form smart, micro contracts, will be articulated using an agent based model. Bids and offers will be enabled through integration with Distributed Ledger Technologies (DLTs) which will provide a trustworthy implementation of the scheme through a distributed database trusted by all agents. AGILE will examine the synergies between several permissioned, public, and hybrid DLTs as there are key questions about which type of ledger and related services is best for this elastic aggregator approach. An optimisation model will recommend particular configurations of DERs satisfying several portfolio optimisation strategies (financial, environmental and social welfare). The validation of preferred configurations of DERs is an essential step to ensure the feasibility of DER incorporation and a digitised, stylised IEEE network will be integrated into the digital solution to achieve this. Validation using a range of realistic network topologies will be performed to evaluate the effect on aggregator business models.

The global energy sector is facing considerable pressure arising from climate change, depletion of fossil fuels and geopolitical issues around the location of remaining fossil fuel reserves. Energy networks are vitally important enablers for the UK energy sector and therefore UK industry and society. Energy networks exist primarily to exploit and facilitate temporal and spatial diversity in energy production and use and to exploit economies of scale where they exist. The pursuit of Net Zero presents many complex interconnected challenges which reach beyond the UK and have huge relevance internationally. These challenges vary considerably from region to region due to historical, geographic, political, economic and cultural reasons. As technology and society changes so do these challenges, and therefore the planning, design and operation of energy networks needs to be revisited and optimised. Electricity systems are facing technical issues of bi-directional power flows, increasing long-distance power flows and a growing contribution from fluctuating and low inertia generation sources. Gas systems require significant innovation to remain relevant in a low carbon future. Heat networks have little energy demand market share, although they have been successfully installed in other northern European countries. Other energy vectors such as Hydrogen or bio-methane show great promise but as yet have no significant share of the market. Faced with these pressures, the modernisation of energy networks technology, processes and governance is a necessity if they are to be fit for the future. Good progress has been made in de-carbonisation in some areas but this has not been fast enough, widespread enough across vectors or sectors and not enough of the innovation is being deployed at scale. Effort is required to accelerate the development, scale up the deployment and increase the impact delivered.