• Energy Research

Thermo-chemical networks using absorption and desorption to capture and valorise the potential of very low-grade residual heat (20 °C to 60 °C) to offer a reduction of end user costs and increased primary energy efficiency. The paper demonstrates the technical and economic potential of thermo-chemical networks by defining use cases and their related level of energy efficiency and technological feasibility. Furthermore, specific economic scenarios, including estimations on investment and operation costs, demonstrate the economic benefit of the technology. Simple payback periods between about 0.5 and 7.5 years indicate a good economic feasibility with end user costs below 4 €ct/kWh-equivalent and refunds of 0.5 to 1 €ct/kWh for the required residual heat. Due to the low-temperature characteristics of the relevant systems and services, detailed simulations are required to approve the functioning and viability of the new technology. For this purpose, the paper demonstrates the simulation outline using the example of space heating based on a low-temperature air heating system partially driven with thermo-chemical fuel.

The installed capacity, electricity generation from wind, and the curtailment of wind power in the UK between 2011 and 2021 showed that penetration levels of wind energy and the amount of energy that is curtailed in future would continue to rise whereas the curtailed energy could be utilised to produce green hydrogen. In this study, data were collected, technologies were chosen, systems were designed, and simulation models were developed to determine technical requirements and levelised costs of hydrogen produced and transported through different pathways. The analysis of capital and operating costs of the main components used for onshore and offshore green hydrogen production using offshore wind, including alternative strategies for hydrogen storage and transport and hydrogen carriers, showed that a significant reduction in cost could be achieved by 2030, enabling the production of green hydrogen from offshore wind at a competitive cost compared to grey and blue hydrogen. Among all scenarios investigated in this study, compressed hydrogen produced offshore is the most cost-effective scenario for projects starting in 2025, although the economic feasibility of this scenario is strongly affected by the storage period and the distance to the shore of the offshore wind farm. Alternative scenarios for hydrogen storage and transport, such as liquefied hydrogen and methylcyclohexane, could become more cost-effective for projects starting in 2050, when the levelised cost of hydrogen could reach values of about £2 per kilogram of hydrogen or lower.

Abstract The automotive industry is facing on-going challenges to improve the sustainability of its manufacturing processes and vehicle emissions due to economic, environmental, marketability and policy concerns. This review aims to evaluate steps that could be taken by automotive manufacturers to further reduce energy consumed during manufacturing processes, particularly focusing on thermal management of low-temperature heat sources that are extensively present in the whole plant and in the paint shop. Through an extensive literature review on the subject, this article presents vehicle production processes, the past and future drivers, and strategies towards sustainability. Firstly, the whole vehicle manufacturing process is explained focusing on the energy sources and their use in the plant. Then, the paint shop is described as being responsible for the highest energy consumption in the production process, focusing on components, paints and energy utilisation. After presenting the practice performed by automotive manufacturers to reduce the energy consumption of their production process in terms of energy efficiency and thermal management, the article is closed by future steps that could be undertaken by the automotive industry towards the realisation of a low-carbon sector. It is concluded that unexploited potential for heat recovery in the paint shop is present in the low-temperature range and this waste heat could be effectively exploited by liquid desiccant technology for energy consumption reduction and could increase paint quality of the painting process due to more efficient moisture control.

Managing the intermittency of renewable sources together with transient (hourly to daily to seasonal) energy demands is one of the principal challenges of delivering a net-zero energy system. Smart multifunctional thermo-chemical energy networks represent an alternative energy network and storage system, a solution based on the distribution of energy via thermo-chemical material rather than thermal energy, gas, fuels or electricity– an option that has scope for integrated short- and long-term energy storage. This is the first research work to realise such a system and demonstrate how it might operate using smart control strategies and how thermo-chemical fluids (TCFs) can be used as a medium for timely energy storage and distribution. The experimental study also describes the effect of steady and variable heat sources on TCF regeneration performance and estimates the potential of thermo-chemical energy networks, which would be particularly beneficial in buildings with high energy consumption for humidity control. This research proves the practicality of the design idea for such a network, which would be governed by centralised control, regenerated by steady or transient heat loads and capable of supplying a variety of demands in an experimental setting. The energy and economic potential of the network were also assessed, identifying temperature and humidity control application scenarios with energy savings of more than 60% compared to conventional operation and payback periods of 6.6–9.7 years.

Abstract The automotive industry is facing on-going challenges to improve the sustainability of its manufacturing processes and vehicle emission. Policies are one of the main drivers towards low-carbon manufacturing. In this work, the UK regulations in terms of environment, energy-efficiency and resources management and the ISO Standards concerning the automotive sector have been identified and described. The environmental benefits obtained in terms of energy consumption, waste production, water consumption, and air quality by a more efficient vehicle production for the UK manufacturers are presented. Current thermal energy management practice and strategies to increase the energy efficiency of the automotive manufacturing process are described. It is concluded that manufacturing processes and plants are both in need of modifications to achieve low-carbon manufacturing and produce low or zero emission vehicles.

Abstract In an effort to minimise electricity consumption and greenhouse gases emissions, the heating, ventilation and air-conditioning sector has focused its attention on developing alternative solutions to electrically-driven vapour-compression cooling. Liquid desiccant air-conditioning systems represent an energy-efficient and more environmentally friendly alternative technology for dehumidification and cooling, particularly in those cases with high latent loads to maintain indoor air quality and comfort conditions. This technology is considered particularly efficient in hot and humid climates. As a matter of fact, the choice of the desiccant solution influences the overall performance of the system. The current paper reviews the working principle of liquid desiccant systems, focusing on the thermodynamic properties of the desiccant solutions and describes an evaluation of the reference thermodynamic properties of different desiccant solutions to identify which thermodynamic, physical, transport property influences the liquid desiccant process and to what extent. The comparison of these thermodynamic properties for the commonly used desiccants is conducted to estimate which fluid could perform most favourably in the system. The economic factors and the effect of different applications and climatic conditions on the system performance are also described. The paper is intended to be the first step in the evaluation of alternative desiccant fluids able to overcome the problems related to the use of the common desiccant solutions, such as crystallization and corrosion to metals. Ionic liquids seem a promising alternative working fluid in liquid desiccant air-conditioning systems and their characteristics and cost are discussed.