Energy storage: UK viability of energy storage from renewable sources and energy re-introduction into the grid or as fuel for transport

Lead Research Organisation: University of Oxford
Department Name: Engineering Science

Abstract

The balancing of supply and demand for electricity is arguably harder now than it ever has been. This is because of rising demand and a drastic change in the supply mix of most networks. Conventional methods for planning how to manage this are reliant on dispatchable fossil fuel generators, particularly large power plants running at low capacity or diesel generators. The variability of renewable energy sources (RES) is unlike what the system has seen before and due to the emissions targets conventional planning methods and solutions are not applicable. Many decision makers given the substantial year-on-year challenges are turning to using current economics and technical analyses as ''tools to support predetermined technology choices''.

This research has the potential impact to better inform decision makers as to the strategic decisions that they should be making to practically enable high penetration RE in an electricity supply mix. Specifically it determines how the size and duration of storage required, to balance supply and demand, changes with multiple variables (such as RES penetration and demand side management).

The research proposal can easily be separated into three key deliverables:
1. Quantifying (having developed the methodology) the relationship between RES and storage requirement.
2. A model which determines the technical and economic optimal renewable energy (RE) supply and storage system to meet a given demand profile.
3. A dynamic model of the Haber-Bosch (HB) process with novel catalysts to facilitate quantification of the back-up required.

Deliverables 2 and 3 will then be combined to provide a methodology to determine the optimal RE supply and storage system, including the production of ammonia by the HB process using conventional and novel catalysts, for a demand profile of a micro-grid or smaller.


In facilitate quantification and understanding of the relationship between RES and storage requirement this we have set up the Storage Duration Index (SDI) to enable the quantification of the storage duration and size required. This novel methodology is enabling us to identify the impact that key variables have on the storage requirements. The SDI has shown that seasonal storage is potentially undervalued at present particularly with high PV penetration networks. Unlike previous investigations this will enable us from first principles, without initially distorting the problem with constraints such as technology characteristics or current economics, to determine the technical and economically optimal supply and storage system to meet a given demand profile.

This understanding (and model) will then be used practically to determine the economically optimal RE supply and storage system for any given demand profile.

In parallel with this work we plan to develop a dynamic model of ammonia production from RE, using the HB process with conventional and novel catalysts, for use as an energy vector. This will allow us to determine more accurately than previous steady-state analyses the backup required for ammonia production from RES. The modelling of novel catalysts would enable planning a proof-of-concept plant which is at present not feasible. There is potential for us to be able to validate this model on a proof-of-concept plant at Harwell using conventional HB production from wind.

Having completed these two work-streams we will be able to determine the technical and economic optimal supply-storage system (including ammonia as a storage method) for a given demand profile. To conclude if we constrain the model's storage method to only using ammonia we would be able to build a business plan and identify its key sensitivities.

This project falls within the EPSRC energy research area and more specifically the sub-theme of energy storage (while facilitating high penetration renewable energy grid integration).

My Siemens-EPSRC iCASE Award has allowed me to work closely with Siemens.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509310/1 01/10/2015 30/09/2020
1658940 Studentship EP/N509310/1 01/10/2015 31/03/2019 Richard Nayak-Luke
 
Description Through my research to date I have developed two models: the storage duration index (SDI) and "green" ammonia production process design. More detailed descriptions of both of these models can be found in the "Research Databases and Models" section of this Researchfish submission. In short, the SDI model has quantified the need for electrical energy storage as a function of duration when integrating renewable energy (thereby highlighting the potential importance of seasonal storage) and the other has enabled the design of a "green" ammonia production plant and enabling the identification of its key variables and calculation of an LCOA estimate (thereby enabling the decarbonisation of ammonia production for fertiliser or seasonal energy storage).

Using the SDI model we have quantified the interaction that multiple flexibility methods have on the need for electrical energy storage and therefore have enabled the identification of "tipping points" (i.e. when the storage requirements require storage duration beyond current battery capabilities) that will be encountered as countries pursue emission targets. This has been employed at multiple locations in numerous countries including the UK and Japan.

Using the "green" ammonia model we have gained understanding of the impact that diurnal and seasonal intermittency of renewable energy has on the process design, operation and the achievable LCOA. We have identified the impact of key variables and simulated production of "green" ammonia at over 530 locations in 70 countries to identify the most favourable. Work is currently ongoing to incorporate uncertainty into both of these models to further develop their reliability and accuracy.
Exploitation Route Application of the SDI model can provide an improved understanding of the fundamental balancing problem that arises from integration of renewable energy (RE) for academia and government. It can provide a domain for techno-economic optimisation, thereby reducing run-time, to enable increased optimisation model complexity and therefore accuracy of their results. Application of the "green" ammonia model has enabled improved design of a proof of concept production plant in Harwell (Oxfordshire) and can be used to provide an initial plant design solution for any location globally. The model can be used to inform Haber-Bosch catalyst and electrochemical development by identifying the key variables and calculating how they (independently and in combination) impact the plant design and LCOA. Furthermore results from both models have been presented to key stakeholders in government, industry and academia across the globe (USA, Mexico, UK, Netherlands, India and Japan) and may inform policy / strategy.
Sectors Chemicals,Energy,Government, Democracy and Justice,Transport

 
Description My initial findings from the SDI modelling have provided a quantitative rationale for electrical energy storage beyond the duration that conventional batteries can operate. Therefore at conferences I have been approached on numerous occasions by members of industry who have developed / are developing technologies that aim to provide a range of electrical services from STOR to seasonal balancing and brown start. It has also provided initial solutions for the "tipping point" for renewable energy (RE) penetration at which there would be a technical imperative for such alternative storage methods. My work therefore is enables the identification of a potential timeline for business opportunities and initial technical specifications that will be required. My initial findings from the "green" ammonia modeling, particularly the identification of key variables and their impact on LCOA, has twice been discussed with members of industry and Dutch Government at the NH3 Event in Rotterdam. The were interested in the findings given that they are aiming to adapt a CCGT so that ammonia could be used as an alternative fuel source. More recent results have been used in discussions with stakeholders in industry and government in Mexico, UK, India and Japan, thereby informing them as to the likely timeline for the economic viability of the 'green' production process and its key drivers. My work therefore is helping to inform location specific design of the process for "green" ammonia production to inform scale-up and further necessary work.
First Year Of Impact 2017
Sector Chemicals,Energy
Impact Types Economic,Policy & public services

 
Description Citation in the International Energy Agency "Renewable Energy for Industry" publication
Geographic Reach Multiple continents/international 
Policy Influence Type Citation in systematic reviews
Impact This IEA publication is one of the first initial reviews of renewable energy (RE) integration in industry. Their publications are often of high quality, are read extensively (in and outside of academia, including government) and provide a good review of the existing body of work.
 
Description National priorities for research, technological development and human resources training for the Mexican energy sector
Geographic Reach National 
Policy Influence Type Participation in a national consultation
URL https://www2.ineel.mx/taller_almacenamientoenergia/en/
 
Description New College Postgraduate Research Grant (Oxford University)
Amount £1,125 (GBP)
Organisation University of Oxford 
Department New College Oxford
Sector Academic/University
Country United Kingdom
Start 07/2018 
End 07/2018
 
Description Newton Bhabha PhD Placement Programme
Amount £2,140 (GBP)
Funding ID 429278172 
Organisation Indian Institute of Technology Delhi 
Sector Academic/University
Country India
Start 01/2019 
End 06/2019
 
Description Oxford University, Department of Engineering Conference Grant
Amount £700 (GBP)
Organisation University of Oxford 
Sector Academic/University
Country United Kingdom
Start 07/2018 
End 07/2018
 
Description Siemens-EPSRC iCASE Studentship
Amount £88,275 (GBP)
Funding ID 397671 
Organisation Siemens AG 
Sector Private
Country Germany
Start 10/2015 
End 03/2019
 
Title "Green" ammonia production plant design 
Description The model that we have constructed is a method to calculate a first estimate for the optimum size of a "green" ammonia production plant (at the process level), the required renewable energy (RE) supply, and the levelised cost of ammonia (LCOA) for islanded operation with a hydrogen buffer. The particular novelty with this method is that it enables the use of an intermittent power source (such as RE) to design a production process and therefore provides a manifold of feasible plant designs from which an economic optimisation can be achieved. As importantly it identifes the plant designs that are not feasible which provides insight as to the current limiting variables. 
Type Of Material Computer model/algorithm 
Year Produced 2017 
Provided To Others? No  
Impact The model has identified key production process and cost variables and their impact on the levelised cost of ammonia (LCOA). When applied to Lerwick, Scotland it identified these key variables and their impact the LCOA (relative to a ±10 GBP/Tonne change in LCOA): levelised cost of electricity (±0.89 GBP/MWh), electrolyser CAPEX (±65 GBP/kW), minimum Haber-Bosch (HB) load (±12% of rated power), maximum rate of HB load ramping, and RE supply mix. Using 2025/2030 estimates results in a LCOA of 588 GBP/Tonne. Application of the model at other geographic locations has informed us of the impact of location (RE profiles) on the plant design and LCOA. The application of this model will facilitate and improve the production of carbon-free ammonia in the future. This is sorely needed given that it is essential for fertilizer production, currently accounts for ~1.3% of global carbon dioxide emissions and could be used for seasonal electrical energy storage. 
 
Title Storage duration index (SDI) methodology 
Description The model enables the user to quantify the flexibility requirement for any given electrical network. I.e. the required reserve, renewable energy (RE) curtailment, demand side management (DSM) and energy storage that is required. The user specifies the location, RE penetration and RE mix (i.e. Wind:Solar photovoltaic) and the model calculates the required energy storage as a function of storage duration. This information is condensed down to form the SDI, two non-dimensional numbers: the magnitude of the energy that has to be stored as a fraction of total demand, and the normalised variance of the storage profile from uniform duration storage. The SDI therefore allows us to quickly identify the impact that any variable has on the magnitude and variance of energy storage required. With multiple free variables the results from the model are two multi-dimensional manifolds. This significantly improves the fundamental impact that RE integration has on electrical network balancing and improves the foundations for techno-economic optimisation (MP-IAMs) to inform government energy policy. 
Type Of Material Computer model/algorithm 
Year Produced 2015 
Provided To Others? Yes  
Impact This work has improved the design of the proof of concept "green" ammonia production plant at Harwell and also helped to inform discussion about the RE and flexibility methods that should be implemented (to achieve the ambitious national emission targets) at the national consultation in Mexico. 
 
Description Proof of concept plant at Harwell: "Green" ammonia production and conversion back to electricity 
Organisation Siemens AG
Country Germany 
Sector Private 
PI Contribution We have assisted Siemens CT in the modelling of the "green" ammonia process to better inform the design and operation of the plant. This has facilitated the design, construction and future operation of the 0.3MW proof of concept plant at Harwell, Oxfordshire. We have subsequently performed sensitivity analyses on 100MW plants to inform them of the impact that PEM electrolyser development (particularly CAPEX) would have on the feasible levelised cost of ammonia (LCOA). This work has assisted them in their technological development of electrolysers by providing targets, enabled the initial design of an 100MW plant and identified the impact on LCOA if the operation schedule is inefficient.
Collaborator Contribution Siemens CT (and in particular Ian Wilkinson) has provided industrial limitations and evaluation to the modelling of the process. This has helped to inform the modelling that has been conducted so that it is relevant to industry and real world applicable.
Impact 0.3MW proof of concept plant at Harwell, Oxfordshire. Ian Wilkinson has co-authored a journal paper that has been submitted to Industrial and Engineering Chemistry Research. Ian has presented the sensitivity analysis and initial modelling results internally at Siemens and at multiple international conferences.
Start Year 2015
 
Description Engineering Education Scheme - Year long project (Harrow School) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact I was a mentor to one Engineering Education Scheme team of six students for the 2015/16 academic year and a new team for the 2016/17 year. This was a year long project for the students guided by myself as a mentor from industry / academia and a teacher at the school. I would often visit the school every two or three weeks on average to provide assistance and guidance to the project and their questions about engineering in general. Both teams were awarded the CREST Gold award and the Investec Platinum Award and the majority of the students have subsequently pursued engineering degrees at university. Despite being asked to mentor again this year (2017/18), I unfortunately did not have the time due to research and teaching commitments.
Year(s) Of Engagement Activity 2015,2016,2017
 
Description Engineering Education Scheme - Year long project (North London Collegiate School) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact I founded the Engineering Education Scheme at North London Collegiate School with their Head of Mathematics after finding out that very few girls were pursuing engineering from the school. I mentored two teams of six/seven students for the 2015/16 academic year. This was a year long project for the students guided by myself as a mentor from industry / academia and a teacher at the school. I would often visit the school every two or three weeks on average to provide assistance and guidance to the project and their questions about engineering in general. Both teams were awarded the CREST Gold award and the some of the students have subsequently pursued engineering degrees at university. They have subsequently employed additional staff to facilitate such activity in the future.
Year(s) Of Engagement Activity 2015,2016
 
Description Interview with BBC Shetland 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact I was interviewed by Ewan Murrie at BBC Radio Shetland to discuss the difficulties that Shetland has as an islanded energy system and whether ammonia is a potential solution to the problem. This was also picked up by the Shetland Times on 13th October 2018.
Year(s) Of Engagement Activity 2018
URL http://www.bbc.co.uk/programmes/m0000s9g
 
Description Renewable Hydrogen for Industry and Beyond 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact The CEEW-IEA Workshop on 'Renewable Hydrogen for Industry and Beyond' aimed to strengthen the National Hydrogen Energy Roadmap launched by the Government of India and to find conformity with India's ambitious renewable energy targets.

Green hydrogen, generated via renewable energy, has the potential to be a complementing energy vector at certain locations and with specific applications. The workshop focussed on applications in and around three potential end-use sectors: ammonia, methanol, and steel manufacturing.

The Workshop brought together several national and international experts in the sector to deliberate on the possibility of using ammonia, methanol and green hydrogen as feedstock and fuel, and discuss potential challenges and drivers.
Year(s) Of Engagement Activity 2018
URL http://www.ceew.in/events/renewable-hydrogen-industry-and-beyond