Future GB Research Articles

Transformation of a three‐phase double‐circuit overhead transmission line into a six‐phase feeder to increase power transfer capability

The UK net-zero target requires the integration of significant renewable energy resources into the electrical grid. This, together with the projected growth in electricity demand imposes practical challenges on the power transfer capability of existing transmission feeders. For environmental and planning reasons, construction of new overhead lines is problematic, and where possible upgrading of existing substations and lines is preferred. This paper investigates the feasibility of transforming an existing three-phase (3Φ) double-circuit 400 kV line into a six-phase (6Φ) feeder for a simulated future GB scenario. Results indicate a 6Φ feeder, operating at a ‘phase-adjacent phase’ voltage of 400 kV can effectively solve the constraints of boundaries in transmission networks. When considering the various operating contingencies, associated with an important UK network boundary and its expected near-future winter-peak power transfer requirements, the thermal overload issues are mitigated by transforming a feeder from 3Φ to 6Φ. The paper demonstrates upgrading to 6Φ technology is a potential solution to certain future boundary constraints and in these cases avoids the need to build new underground or overhead AC/DC lines.

Evaluation of Intraoperative Surgical Adjuncts and Resection of Glioblastoma (ELISAR GB): A UK and Ireland, multicentre, prospective observational cohort study

Abstract Aims Extent of resection is associated with better survival in patients with glioblastoma. Numerous surgical adjuncts can be used to achieve maximal safe resection - including fluorescence-guidance with 5-aminolevulinic acid (5-ALA), neuronavigation, intraoperative ultrasound (IoUS), intra-operative MRI (iMRI), tractography, electrophysiological monitoring and awake surgery. We evaluated the availability, use and operative aim and success associated with these adjuncts. Method This is a prospective cohort study of 27 of 31 neurosurgical centres in the UK and Ireland from 6 January to 19 March 2020. Consecutive cases were identified through neuro-oncology multidisciplinary meetings. Eligible cases included adults with a supratentorial histopathologically confirmed glioblastoma with pre/post-operative reported T1-weighted MRI with contrast deemed suitable for resection. Outcomes included the availability and usage of surgical adjuncts, and the percentage of operations that achieved their aim of complete resection, defined as complete resection of enhancing tumour (CRET) on post-operative T1-MRI. We present the initial descriptive statistics from this national study. Results 232 patients with glioblastoma were included. In 142 patients (61.2%) the surgical aim was CRET. 5-ALA and neuronavigation were available in all centres (Figure 1). The most commonly used neurosurgical adjunct was neuronavigation (88.2%) (Figure 2). The proportion of patients receiving 5-ALA in CRET and debulking-only groups was 65.0% and 48.9%, respectively. 35 different combinations of adjuncts were found in total, with 13 unique combinations only used in one instance (Figures 1 & 2). CRET was achieved in 69/142 (45.8%) patients in which was the aim. 9/90 (10%) patients in the debulking-only group achieved CRET, of which 7/9 (77.8%) had received 5-ALA. Of the three most frequently used combination of adjuncts for patients deemed feasible for CRET, the most successful in terms of achieving CRET was the combined use of neuronavigation, 5-ALA and IoUS, with post-operative CRET at 47.4% (Figure 3). Conclusion ELISAR-GB has collated prospective data to demonstrate the current use of intraoperative adjuncts in the UK and Ireland. There is marked heterogeneity with regards to combinations of adjuncts used. A CRET of 47% is lower than would be expected compared to previously published literature, possibly due to a more stringent definition of complete resection in this study. Based on these early descriptive results, there is no clear combination of adjuncts that shows superiority and use of 5-ALA does not always result in CRET when it is the surgical aim. Of interest, 5-ALA is being used for operations that do not aim for complete resection, a change in indication. The FUTURE GB trial will provide more conclusive evidence on the efficacy of surgical adjuncts to maximise extent of resection.

Assessing the value of increasing GB interconnection

The liberalisation of electricity markets and increasing penetration of renewable generation are encouraging trading opportunities to be identified and developed. In Europe, the importance of interconnection is well recognised. Interconnections are particularly important for islanded nations, like Great Britain, which provides access to generation and demand across the national boundaries via sub-sea HVDC cables while providing means to share reserves enhancing the security of supply and reducing overall costs. There are plans in place to significantly increase the current 5 GW of interconnection capacity between GB and neighbouring European countries. The paper investigates the expected impacts that a large increase in interconnection capacity could have on key electricity market parameters such as marginal prices, carbon emissions and the nature of utilisation of existing and future GB interconnections. Several scenarios have been considered to model future uncertainty for the years 2020 and 2025.

Development of GB distribution networks with low carbon technologies and smart solutions: Scenarios and results

This is the second paper of the two-paper suite that describes development of future GB distribution networks integrating low carbon technologies (LCTs) and traditional and smart solutions for network reinforcement. The static and dynamic aspects of distribution networks development, as well as impact on the entire GB transmission system are investigated. The overall planning concept, planning assumptions and concepts, most important features of steady-state and dynamic studies, as well as traditional and smart solutions for the network development are presented in the first paper. This paper presents the energy LCT scenarios, projected LCT uptakes, modelling and profiles of different types of LCTs first. Results of the distribution network development studies are given next, which is followed by the results of studies that do not change development paths. The aggregated impact of all GB distribution networks on the entire electricity system is given through the analysis of system-wide frequency disturbances. Conclusions related to specific studies and networks are presented in the relevant sections, whilst the closing section gives generalized conclusions approved by the GB industry as answers to the key issues the future networks are faced with.

Preheating Quantification for Smart Hybrid Heat Pumps Considering Uncertainty

The deployment of smart hybrid heat pumps (SHHPs) can introduce considerable benefits to electricity systems via smart switching between electricity and gas while minimizing the total heating cost for each individual customer. In particular, the fully optimized control technology can provide flexible heat that redistributes the heat demand across time for improving the utilization of low-carbon generation and enhancing the overall energy efficiency of the heating system. To this end, an accurate quantification of the preheating is of great importance to characterize the flexible heat. This paper proposes a novel data-driven preheating quantification method to estimate the capability of the heat pump demand shifting and isolate the effect of interventions. Varieties of fine-grained data from a real-world trial are exploited to estimate the baseline heat demand using Bayesian deep learning while jointly considering epistemic and aleatoric uncertainties. A comprehensive range of case studies are carried out to demonstrate the superior performance of the proposed quantification method, and then, the estimated demand shift is used as an input into the whole-system model to investigate the system implications and quantify the range of benefits of rolling out the SHHPs developed by PassivSystems to the future GB electricity systems.

An initial assessment of the value of Allam Cycle power plants with liquid oxygen storage in future GB electricity system

The Allam Cycle is a novel oxy-combustion gas turbine power cycle with a reported net cycle efficiency of 58–60% LHV and near-zero operating emissions. An Allam Cycle process model is developed displaying a net cycle thermal efficiency (LHV) of 58.0%, a higher value than previously reported in the literature, due to the inclusion of a bypass stream heat source. Novel modes of operation are added to improve plant operational flexibility, including a temporary increase in cycle efficiency to 66.1%, with the use of liquid oxygen storage to shift the energy penalty of oxygen production. This facilitates decoupling oxygen and electricity production and operates as a form of energy storage. For the first time, a purpose-built Unit Commitment and Economic Dispatch (UCED) model is used to investigate the impact of Allam Cycle plants and of liquid oxygen storage on system costs and grid CO2 intensities, taking the illustrative case of the GB electricity system. Over a representative winter week with high net demand, a fleet of 5–15 Allam Cycle plants operates with a capacity factor of, respectively 97%-90%, reducing system costs by 2.6%–6.7% and reducing electricity grid average CO2 intensity by 7.9%–19.0%. Adding oxygen storage to these plants allows surplus renewable energy generation to be stored, thus avoiding wind curtailment. Our initial findings indicate that oxygen storage can be valuable to both to plant operators and the system operators, but also that further work is required to evaluate non-energy revenue streams from the ancillary service market to determine whether the capital expenditure of liquid oxygen storage could be justified without financial incentives.

Low carbon electricity systems for Great Britain in 2050: An energy-land-water perspective

The decarbonisation of the power sector is key to achieving the Paris Agreement goal of limiting global mean surface temperature rise to well below 2 °C. This will require rapid, national level transitions to low carbon electricity generation, such as variable renewables (VRE), nuclear and fossil fuels with carbon capture and storage, across the world. At the same time it is essential that future power systems are sustainable in the wider sense and thus respect social, environmental and technical limitations. Here we develop an energy-land-water nexus modelling framework and use it to perform a scenario analysis with the aim of understanding the planning and operational implications of these constraints on Great Britain’s (GB) power system in 2050. We consider plausible scenarios for limits on installed nuclear capacity, siting restrictions that shape VRE deployment and water use for thermal power station cooling. We find that these factors combined can lead to up to a 25% increase in the system’s levelised cost of electricity (LCOE). VRE siting restrictions can result in an up to 13% increase in system LCOE as the deployment of onshore wind is limited while nuclear capacity restrictions can drive an up to 17% greater LCOE. We also show that such real-world limitations can cause substantial changes in system design both in terms of the spatial pattern of where generators are located and the capacity mix of the system. Thus we demonstrate the large impact simultaneously considering a set of nexus factors can have on future GB power systems. Finally, given our plausible assumptions about key energy-land-water restrictions and emission limits effecting the GB power system in 2050, the cost optimal penetration of VREs is found to be at least 50%.

Challenges on primary frequency control and potential solution from EVs in the future GB electricity system

System inertia reduction, driven by the integration of renewables, imposes significant challenges on the primary frequency control. Electrification of road transport not only reduces carbon emission by shifting from fossil fuel consumption to cleaner electricity consumption, but also potentially provide flexibility to facilitate the integration of renewables, such as supporting primary frequency control. In this context, this paper develops a techno-economic evaluation framework to quantify the challenges on primary frequency control and assess the benefits of EVs in providing primary frequency response. A simplified GB power system dynamic model is used to analyze the impact of declining system inertia on the primary frequency control and the technical potential of primary frequency response provision from EVs. Furthermore, an advanced stochastic system scheduling tool with explicitly modeling of inertia reduction effect is applied to assess the cost and emission driven by primary frequency control as well as the benefits of EVs in providing primary frequency response under two representative GB 2030 system scenarios. This paper also identifies the synergy between PFR provision from EVs and “smart charging” strategy as well as the impact of synthetic inertia from wind turbines.

Benefits of Demand-Side Response in Providing Frequency Response Service in the Future GB Power System

The demand for ancillary service is expected to increase significantly in the future GB electricity system due to high penetration of wind. In particular, the need for frequency response, required to deal with sudden frequency drops following a loss of generator, will increase because of the limited inertia capability of wind plants. This paper quantifies the requirements for primary frequency response and analyses the benefits of frequency response provision from DSR. The results show dramatic changes in frequency response requirements driven by high penetration of wind. Case studies carried out by using an advanced stochastic generation scheduling model suggest that the provision of frequency response from DSR could greatly reduce the system operation cost, wind curtailment and carbon emissions in the future GB system characterised by high penetration of wind. Furthermore, the results demonstrate that the benefit of DSR shows significant diurnal and seasonal variation, whereas an even more rapid (instant) delivery of frequency response from DSR could provide significant additional value. Our studies also indicate that the competing technologies to DSR, namely battery storage and more flexible generation could potentially reduce its value by up to 35%, still leaving significant room to deploy DSR as frequency response provider.

Acoustic evaluation of classrooms in China—green campus workgroup

Armstrong, as a member of the China Green Building Council, has been working with the special subcommittee on Green Campus associated with Tongji University in Shanghai. The goal of this working group is to develop a green rating system for schools including acoustic design/performance in classrooms. In support of this rating development we have been pursuing research on classroom performance relative to meeting the current GB 50118-2010 and future GB 50099-2011 codes for schools. In conjunction with the Green Campus work group 10 schools were identified across China for study with pre/post architectural interventions. In this case a suspended acoustical ceiling was installed and both objective (sound) measurements, and subjective (student & teacher perception) surveys were conducted. Additionally it was desired to develop an objective assessment of student learning performance with changes in acoustical design and this was addressed through a joint development program with the University of Nebraska. Current results from these school evaluations are being presented.