Can a hierarchical ordering of alternative technological concepts for decarbonizing industrial energy systems minimize mitigation costs?

Integration of alternative technological concepts such as switching to alternative fuels, advanced energy efficiency, and carbon capture and storage in existing industrial energy systems can prove highly effective at minimizing emissions; however, their adoption is low since solutions using these concepts raise costs considerably. The hypothesis of this work is a hierarchical combination of these concepts can reduce mitigation cost. To this end a mixed method approach is applied combining energy simulation with a novel Mixed Integer Linear Programming model developed to explore 48 alternative solutions to make industrial energy systems more sustainable. The method was applied to the most common industrial energy systems configurations. Results show that the added cost of integrating alternative technological concepts are lowered when energy efficiency via direct heat recovery is explored first in an optimization-based hierarchy of options. The hierarchy is advanced energy efficiency before fuel and technology switching or integrating carbon capture and storage. This means process integration can pay for steeper reductions in carbon emissions. Integrating alternative technological concepts optimally and hierarchically reduced emissions by 61%, and costs by 55.7% compared to a partial integration for a heat-only business-as-usual industrial energy systems. Even though switching to an alternative fuel (blue hydrogen) reduces carbon emissions by 72%, costs increase by at least 3% compared to a system using fuel gas and fuel oil. A hierarchical integration of blue hydrogen reduces cost by 47% and carbon emissions by 88.7%. Partial integration of carbon capture and storage reduces carbon emissions by 36% but costs increase by 89%, with full integration using optimization and the hierarchy costs only increase by 6.3%. Therefore, the cost-effectiveness of integrating alternative technological concepts is highly influenced by the hierarchy which seeks to minimize demand for energy from industrial processes first, then increase the supply efficiency of industrial energy systems, and before switching to alternative fuels and technologies

A two-step optimization model for quantifying the flexibility potential of power-to-heat systems in dwellings

Coupling the electricity and heat sectors is receiving interest as a potential source of flexibility to help absorb surplus renewable electricity. The flexibility afforded by power-to-heat systems in dwellings has yet to be quantified in terms of time, energy and costs, and especially in cases where homeowners are heterogeneous prosumers. Flexibility quantification whilst accounting for prosumer heterogeneity is non-trivial. Therefore in this work a novel two-step optimization framework is proposed to quantify the potential of prosumers to absorb surplus renewable electricity through the integration of air source heat pumps and thermal energy storage. The first step is formulated as a multi-period mixed integer linear programming problem to determine the optimal energy system, and the quantity of surplus electricity absorbed. The second step is formulated as a linear programming problem to determine the price a prosumer will accept for absorbing surplus electricity, and thus the number of active prosumers in the market. A case study of 445 prosumers is presented to illustrate the approach. Results show that the number of active prosumers is affected by the quantity of absorbed electricity, frequency of requests, the price offered by aggregators and how prosumers determine the acceptable value of flexibility provided. This study is a step towards reducing the need for renewable curtailment and increasing pricing transparency in relation to demand-side response

Assessing Domestic Heat Storage Requirements for Energy Flexibility Over Varying Timescales

This paper explores the feasibility of storing heat in an encapsulated store to support thermal load shifting over three timescales: diurnal, weekly and seasonal. A building simulation tool was used to calculate the space heating and hot water demands for four common UK housing types and a range of operating conditions. A custom sizing methodology calculated the capacities of storage required to fully meet the heat demands over the three timescales. Corresponding storage volumes were calculated for a range of heat storage materials deemed suitable for storing heat within a dwelling, either in a tank or as an integral part of the building fabric: hot water, concrete, high-temperature magnetite blocks, and a phase change material. The results indicate that with low temperature heat storage, domestic load shifting is feasible over a few days. Beyond this timescale, the very large storage volumes required make integration in dwellings problematic. Supporting load shifting over 1–2 weeks is feasible with high temperature storage. Retention of heat over periods longer than this is challenging, even with significant levels of insulation. Seasonal storage of heat in an encapsulated store appeared impractical in all cases modelled due to the volume of material required

Domestic thermal storage requirements for heat demand flexibility

Future changes to the UK’s energy system, specifically radically increasing the deployment of renewable energy sources at all scales, will require much more flexibility in demand to ensure system stability. Using dynamic building simulation, this paper explores the feasibility of using thermal storage to enable flexibility in heat demand over a range of timescales: diurnal, weekly and seasonal. Time-varying space heating and hot water demand profiles for four common UK housing types were generated, accounting for different occupancy characteristics and various UK climates. These simulated heat demand profiles were used to calculate the necessary storage volumes for four heat storage options: hot water, concrete, high-temperature magnetite blocks and an inorganic phase change material. The results indicated that without first radically improving insulation levels to reduce heat demands, even facilitating diurnal heat storage would require low-temperature, sensible heat storage volumes well in excess of 1000L, in many cases. Storage of heat over more than a few days becomes infeasible due to the large storage volumes required, except in the case of dwellings with small heat demands and using high-temperature storage. However, for heat storage at high temperature, retention of heat over longer time periods becomes challenging event with significant levels of insulation

A mountain to climb? Tracking progress in scaling up renewable gas production in Europe

In the last couple of years there has been increasing recognition by key players in the European gas industry that to mitigate the risk of terminal decline in the context of a decarbonising energy system, there will need to be rapid scale up of decarbonised gas. This has led to several projections of the scale of decarbonised gas which could potentially be supplied by 2030, 2040 or 2050. This paper, joint with the Sustainable Gas Institute at Imperial College, London, considers the very significant rate of scale up and the significant cost reductions contemplated by such projections. Based on a database of actual announced projects (both committed and in earlier stages of development) for production of decarbonised gas, it then considers the extent to which project activity is consistent with meeting the ambitious projections. It identifies a significant gap in current levels of activity, largely because there is not yet sufficient economic incentive for investors to develop the required projects. It is intended that this paper will form the basis of continued tracking of the level of activity over the coming years, to help inform industry players of further actions which may be required