Multi-scale modelling of integrated energy supply systems

Local energy systems are changing with the use of more distributed generation as well as the decarbonisation of heat and transport, but the impacts of these local changes on national scale energy supply systems are not well understood. The existing whole energy system models lack the spatial granularity to represent local energy systems and their interactions with gas and electricity transmission networks. This key limitation was addressed by the new CGEN+Energy Hubs model. The CGEN+Energy Hubs Model enables multi-time period operational analysis of integrated national and local energy supply systems. The CGEN+Energy Hubs model was developed by extending a well�established Combined Gas and Electricity Network model (CGEN) by adding the representation of local energy systems. Energy Hubs were used to represent local energy systems in different geographic areas of GB. The CGEN+Energy Hubs model also extended CGEN by including functions for bi-directional electricity interconnector flows, intermittent renewable generation, demand response, distributed injection of hydrogen and biogas, and vehicle to grid electricity supply. The application of the CGEN+Energy Hubs model was demonstrated using contrasting Energy Supply Strategies. The Energy Supply Strategies were defined to explore options to decarbonise heat supply in GB: i.e. 1) low-carbon electricity in the Electric Strategy 2) biomass and solid-waste fuelled CHP in the Heat Network Strategy, 3) hydrogen and biogas in the Green Gas Strategy, and 4) Unconstrained, which employs cost optimisation to choose the heating technology. The Energy Supply Strategies were first applied to the Oxford-Cambridge Arc region to investigate how each strategy would cost-effectively reduce CO2 emissions from the Arc’s energy system. The Electric Strategy was shown to be able to meet the CO2 emissions target in 2050 at the lowest annualised costs per dwelling (investment and operation). The study showed that additional investment is needed to increase the capacity of transmission electricity supply, distributed generation, and the electricity distribution network. The Energy Supply Strategies were then applied to all Energy Hubs in GB simultaneously. The Electric Strategy was again shown to be able to deliver the net-zero CO2 emissions target in GB at the lowest annual operating costs. It was shown that CCGT generator capacity is required to mitigate the impact on the electricity transmission network due to the variability of renewable generation. Battery storage systems are proposed to replace CCGT plants and further reduce the use of natural gas

Modelling of integrated local energy systems: low-carbon energy supply strategies for the Oxford-Cambridge arc region

The energy supply system is undergoing enormous change to deliver against cost, security of supply and decarbonisation objectives. Robust decisions on the provision of infrastructure requires integrated models to perform analytics across the entire energy supply chain. A national level combined gas and electricity transmission network model was upgraded to represent local energy systems. Multiple energy vectors including electricity, gas, hydrogen and heat were integrated within the modelling framework. The model was utilised for a study of the Oxford-Cambridge arc region. The study assessed how different energy supply strategies, from electrification of heat to use of ‘green’ gases or local heat networks, could affordably reduce carbon emissions from the Oxford-Cambridge arc region energy system whilst considering constraints from the national system. The modelling process generated a diverse range of options for energy supplies, the choice of supply networks and end use technologies. The analysis illustrated the cost effectiveness and emission reduction potential of electrification of heat despite the requirement for additional network and supply capacity. Additionally, insulation and other energy efficiency solutions were also analysed. Potential barriers to technological change such as upfront costs, lack of awareness and perceived technology shortcomings were discussed in the context of the strategies assessed

Simulating flexibility, variability and decentralisation with an integrated energy system model for Great Britain

Energy system models allow the development and assessment of ambitious transition pathways towards a sustainable energy system. However, current models lack adequate spatial and temporal resolution to capture the implications of a shift to decentralised energy supply and storage across multiple local energy vectors to meet spatially variable energy demand. There is also a lack of representation of interactions with the transport sector as well as national and local energy system operation. Here, we bridge these gaps with a high-resolution system-of-systems modelling framework which is applied to Great Britain to simulate differences between the performance of decarbonised energy systems in 2050 through two distinct strategies, an electric strategy and a multi-vector strategy prioritising a mix of fuels, including hydrogen. Within these strategies, we simulated the impacts of decentralised operation of the energy system given the variability of wind and across flexibility options including demand side management, battery storage and vehicle to grid services. Decentralised operation was shown to improve operational flexibility and maximise utilisation of renewables, whose electricity supplies can be cost-effectively converted to hydrogen or stored in batteries to meet peak electricity demands, therefore reducing carbon-intensive generation and the requirement for investment in expanding the electricity transmission network capacity

The implications of ambitious decarbonisation of heat and road transport for Britain's net zero carbon energy systems

Decarbonisation of heating and road transport are regarded as necessary but very challenging steps on the pathway to net zero carbon emissions. Assessing the most efficient routes to decarbonise these sectors requires an integrated view of energy and road transport systems. Here we describe how a national gas and electricity transmission network model was extended to represent multiple local energy systems and coupled with a national energy demand and road transport model. The integrated models were applied to assess a range of technologies and policies for heating and transport where the UK’s 2050 net zero carbon emissions target is met. Overall, annual primary energy use is projected to reduce by between 25% and 50% by 2050 compared to 2015, due to ambitious efficiency improvements within homes and vehicles. However, both annual and peak electricity demands in 2050 are more than double compared with 2015. Managed electric vehicle charging could save 14TWh/year in gas-fired power generation at peak times, and associated emissions, whilst vehicle-to-grid services could provide 10GW of electricity supply during peak hours. Together, managed vehicle charging, and vehicle-to-grid supplies could result in a 16% reduction in total annual energy costs. The provision of fast public charging facilities could reduce peak electricity demand by 17GW and save an estimated £650 million annually. Although using hydrogen for heating and transport spreads the hydrogen network costs between homeowners and motorists, it is still estimated to be more costly overall compared to an all-electric scenario. Bio-energy electricity generation plants with carbon capture and storage are required to drive overall energy system emissions to net zero, utilisation of which is lowest when heating is electrified, and road transport consists of a mix of electric and hydrogen fuel-cell vehicles. The analysis demonstrates the need for an integrated systems approach to energy and transport policies and for coordination between national and local governments

Energy hub modelling for multi-scale and multi-energy supply systems

Current energy transitions towards the use of more distributed generation, as well as the decarbonisation of heat and transport, are changing the operation of local energy distribution systems. The impact of these local changes on a national scale energy supply system is not well understood. An energy hub approach was integrated into a national scale gas and electricity transmission networks model (CGEN), to represent local energy distribution systems. The energy hub models the integrated operation of electricity, natural gas and heat distribution systems. The distribution system within a region is described in terms of energy supply sources, conversion technologies and storage systems. Transmission supply points link the energy hubs with the gas and electricity transmission networks. A case study was conducted to investigate the impacts on model outputs by integrating energy hubs into the CGEN model. Preliminary results indicate that the operation of distributed generation and storage in energy hubs have a direct impact on electricity and natural gas supply in the transmission networks. The proposed methodology, therefore, extends the analytical capability of the CGEN model across multiple scales and vectors including heat

The implications of ambitious decarbonisation of heat and road transport for Britain’s net zero carbon energy systems

Decarbonisation of heating and road transport are regarded as necessary but very challenging steps on the pathway to net zero carbon emissions. Assessing the most efficient routes to decarbonise these sectors requires an integrated view of energy and road transport systems. Here we describe how a national gas and electricity transmission network model was extended to represent multiple local energy systems and coupled with a national energy demand and road transport model. The integrated models were applied to assess a range of technologies and policies for heating and transport where the UK’s 2050 net zero carbon emissions target is met. Overall, annual primary energy use is projected to reduce by between 25% and 50% by 2050 compared to 2015, due to ambitious efficiency improvements within homes and vehicles. However, both annual and peak electricity demands in 2050 are more than double compared with 2015. Managed electric vehicle charging could save 14TWh/year in gas-fired power generation at peak times, and associated emissions, whilst vehicle-to-grid services could provide 10GW of electricity supply during peak hours. Together, managed vehicle charging, and vehicle-to-grid supplies could result in a 16% reduction in total annual energy costs. The provision of fast public charging facilities could reduce peak electricity demand by 17GW and save an estimated £650 million annually. Although using hydrogen for heating and transport spreads the hydrogen network costs between homeowners and motorists, it is still estimated to be more costly overall compared to an all-electric scenario. Bio-energy electricity generation plants with carbon capture and storage are required to drive overall energy system emissions to net zero, utilisation of which is lowest when heating is electrified, and road transport consists of a mix of electric and hydrogen fuel-cell vehicles. The analysis demonstrates the need for an integrated systems approach to energy and transport policies and for coordination between national and local governments