United Kingdom

The UK government heat strategy is partially based on decarbonisation pathways from the UK MARKAL energy system model. We review how heat provision is represented in UK MARKAL identifying a number of shortcomings and areas for improvement. We present a completely revised model with improved estimations of future heat demands and a consistent representation of all heat generation technologies. This model represents all heat delivery infrastructure for the first time and uses dynamic growth constraints to improve the modelling of transitions according to innovation theory. Our revised model incorporates a simplified housing stock model which is used produce highly-refined decarbonisation pathways for residential heat provision. We compare this disaggregated model against an aggregated equivalent which is similar to the existing approach in UK MARKAL. Disaggregating does not greatly change the total residential fuel consumption in two scenarios so the benefits of disaggregation will likely be limited if the focus of a study is elsewhere. Yet for studies of residential heat disaggregation enables us to vary consumer behaviour and government policies on different house types as well as highlighting different technology trends across the stock in comparison with previous aggregated versions of the model.

A low pressure superheated hydrogen-steam system has been used to accelerate the oxidation kinetics while keeping the electrochemical conditions similar to those of the primary water in a pressurized water reactor. The initiation has been investigated using a Constant Extension Rate Tensile (CERT) test. Tests were performed on flat tapered specimens made from Type 316L austenitic stainless steel with strain rates of 2×10^-6 and 2×10^-8 ms^-1 at room temperature and at an elevated temperature of 350 °C. R = 1/6 was chosen as a more oxidizing environment and R = 6 was selected as a more reducing environment where the parameter R represents the ratio between the oxygen partial pressure at the Ni/NiO transition and the oxygen partial pressure. Different exposures (1 day and 5 days) prior to loading were investigated post-test evaluation by scanning electron microscopy.

The trial management philosophy of HyDeploy has been developed to enable the overall objectives of the project to be achieved; the safe demonstration of operating a Gas Distribution Network (GDN) on a blend of natural gas and hydrogen. This document provides an overview of the management and governance processes associated with the trial itself. The operational and safety related undertakings before during and after the trial are summarised within this report as well as the intrial experimental programme. The detailed operational procedures are covered in HyD-Rep09.<br/>The programme structure of HyDeploy consists of three phases: Phase 1: Enabling work for preparation of GS(M)R Exemption Phase 2: Construction and installation of process equipment and Phase 3: Safe injection of hydrogen – the trial.<br/>This report focuses on Phase 3 which has two parts; the Proving Trial and; the Trial. As Statutory Duty Holder Keele is accountable for operation of the network it owns over the course of the trial. Operation and maintenance of the network will be undertaken according to the provisions of the Exemption on the basis of agreed revised procedures (HyD-Rep09) by Keele and Cadent. A governance process is in place to manage the blending of hydrogen into the network. This isdescribed in Sections 2 and 3.<br/>Safety related undertakings will be actioned before during and after the trial to mitigate risks identified through the house-to-house testing (HyD-Rep06) procedural review (HyD-Rep09) and quantitative risk assessment (HyD-Rep02). This scope of the undertakings includes actions associated with the end appliances the network itself and the process equipment to be installed.<br/>The detail of these undertakings is given in Section 4.<br/>As part of the trial an experimental programme has been designed to provide further evidence relating to the interactions of a hydrogen blend on network materials and end appliances. The experimental programme is detailed in Section 5.<br/>Click the supplements tab to see the other documents from this report

Hydrogen is widely considered a clean source of energy from the viewpoint of reduction in carbon dioxide emissions as a countermeasure against global warming and air pollution. Various efforts have been made to develop hydrogen as a viable energy carrier including the implementation of fuel cell vehicles (FCVs) and hydrogen refuelling stations (HRSs). A good network of hydrogen refuelling stations is essential for operating FCVs and several hydrogen refuelling stations have been constructed and are in operation worldwide [1]. However despite the potential benefits of hydrogen its flammability creates significant safety concerns. Furthermore even though the energy density of hydrogen is lower than that of gasoline and there is no carbon present which means the amount of radiant heat flux released during combustion is relatively small hydrogen must be handled at high pressure in order to make the cruising range of a fuel cell vehicle (FCV) equal to that of gasoline-powered vehicles. Therefore it is essential to properly evaluate these safety concerns and take reasonable and effective countermeasures. Approximately 50 accidents and incidents involving HRSs have been reported globally [2]. Sakamoto et al. [2] analysed accidents and incidents at HRSs in Japan and the USA to identify the safety issues. Most types of accidents and incidents are small leakages of hydrogen but some have led to serious consequences such as fire and explosion. Recently there was a serious incident in Norway at Kjørbo where a strong explosion was observed [3] – indeed this was within a short time of two other serious incidents in the USA and South Korea showing that the frequency of such incidents may be higher as deployments increase. Use of hydrogen forklifts (and the associated refuelling infrastructure) is another challenge to consider. Hydrogen refuelling stations are often installed in urban areas facing roads and are readily accessible to everyone. Therefore a key measure to approve the hydrogen refuelling stations is safety distances between the hydrogen infrastructure and the surrounding structures such as office buildings or residential dwellings. Whilst a lot of work has been carried out on safety distances (see e.g. [4-6) the accident scenario assumptions and safety distances varied widely in those studies. As a result no consensus has yet emerged on the safety distances to be used and efforts are still needed to bridge the gap between international standards and local regulations (see e.g. [7-8]). The paper analyses this issue and provides guidance on the way forward.

UK homes are primarily heated by fossil fuels and contribute 13% of UK’s carbon footprint (equivalent to all the UK’s 38.4m cars). The report says this is incompatible with UK climate legislation targeting net-zero economy by 2050. New polling finds that consumers are open to cleaner greener ways to heat their homes into the future but that they are “still in the dark about smarter greener heating solutions and lack access to independent advice to help them make better decisions for their homes pockets and the planet”.<br/><br/>The report – Uncomfortable Home Truths: why Britain urgently needs a low carbon heat strategy – says a bold new national roadmap is needed by 2020 which puts consumers and households at the heart of a revolution in green heat innovation. It recommends the creation of an Olympic-style delivery body to catalyse and coordinate regional innovation and local leadership tailored to different parts of the UK and the nation’s diverse housing stock.<br/><br/>This report is the third in the Future Gas Series which has explored the opportunities and challenges associated with using low carbon gas in the energy system and is backed by cross-party parliamentary co-Chairs

We demonstrate a new approach for producing highly dispersed supported metal phosphide powders with small particle size improved stability and increased electrocatalytic activity towards some useful reactions. The approach involves a one-step conversion of metal supported on high surface area carbon to the metal phosphide utilising a very simple and scalable synthetic process. We use this approach to produce PdP₂ and Pd₅P₂ particles dispersed on carbon with a particle size of 4.5–5.5 nm by converting a commercially available Pd/C powder. The metal phosphide catalysts were tested for the oxygen reduction hydrogen oxidation and evolution and formic acid oxidation reactions. Compared to the unconverted Pd/C material we find that alloying the P at different levels shifts oxide formation on the Pd to higher potentials leading to greater stability during cycling studies (20% more ECSA retained 5k cycles) and in thermal treatment under air. Hydrogen absorption within the PdP₂ and Pd₅P₂ particles is enhanced. The phosphides compare favourably to the most active catalysts reported to date for formic acid oxidation especially PdP₂ and there is a significant decrease in poisoning of the surface compared to Pd alone. The mechanistic changes in the reactions studied are rationalised in terms of increased water activation on the surface phosphorus atoms of the catalyst. One of the catalysts PdP₂/C is tested in a fuel cell as anode and cathode catalyst and shows good performance.

Numerical experiments are performed to understand different regimes of hydrogen non-premixed combustion in an enclosure with passive ventilation through one horizontal or vertical vent located at the top of a wall. The Reynolds averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) model with a reduced chemical reaction mechanism is described in detail. The model is based on the renormalization group (RNG) k-ε turbulence model the eddy dissipation concept (EDC) model for simulation of combustion coupled with the 18-step reduced chemical mechanism (8 species) and the in-situ adaptive tabulation (ISAT) algorithm that accelerates the reacting flow calculations by two to three orders of magnitude. The analysis of temperature and species (hydroxyl hydrogen oxygen water) concentrations in time as well as the velocity through the vent shed a light on regimes and dynamics of indoor hydrogen fires. A well-ventilated fire is simulated in the enclosure at a lower release flow rate and complete combustion of hydrogen within the enclosure. Fire becomes under-ventilated at higher release flow rates with two different modes observed. The first mode is the external flame stabilised at the enclosure vent at moderate release rates and the second mode is the self-extinction of combustion inside and outside the enclosure at higher hydrogen release rates. The simulations demonstrated a complex reacting flow dynamics in the enclosure that leads to formation of the external flame or the self-extinction. The air intake into the enclosure at later stages of the process through the whole vent area is a characteristic feature of the self-extinction regime. This air intake is due to faster cooling of hot combustion products by sustained colder hydrogen leak compared to the generation of hot products by the ceasing chemical reactions inside the enclosure and hydrogen supply. In general an increase of hydrogen sustained release flow rate will change fire regime from the well-ventilated combustion within the enclosure through the external flame stabilised at the vent and finally to the self-extinction of combustion throughout the domain.

From an evaluation of the GB housing stock it is clear that a mosaic of low carbon heating technologies will be needed to reach net zero. While heat pumps are an important component of this mix our analysis shows that it is likely to be impractical to heat many GB homes with heat pumps only. A combination of lack of exterior space and/or the thermal properties of the building fabric mean that a heat pump is not capable of meeting the space heating requirement of 8 to 12m homes (or 37% to 54% of the 22.7m homes assessed in this report) or can do so only through the installation of highly disruptive and intrusive measures such as solid wall insulation. Hybrid heat pumps that are designed to optimise efficiency of the system do not have the same requirements of a heat pump and may be a suitable solution for some of these homes. This is likely to mean that decarbonised gas networks are therefore critical to delivery of net zero. 3 to 4m homes1 (or 14% to 18% of homes assessed in our analysis) could be made suitable for heat pump retrofit through energy efficiency measures such as cavity wall insulation. For 7 to 10m homes there are no limiting factors and they require minimal/no upgrade requirements to be made heat pump-ready. Nevertheless given firstly the levels of disruption to the floors and interiors of homes caused by the installation of heat pumps and secondly the cost and disruption associated with the requirement to significantly upgrade the electricity distribution networks to cope with large numbers of heat pumps operating at peak demand times - combined with the availability of a decarbonised gas network which requires a simple like-for-like boiler replacement - is likely to mean that many of these ‘swing’ properties will be better served through a gas based technology such as hydrogen (particularly when consumer choice is factored in) or a hybrid system. A recent trial run in winter 2018-19 by the Energy System Catapult revealed that all participants were reluctant to make expensive investments to improve the energy efficiency of their homes just to enhance the performance of their heat pump. They were more interested in less costly upgrades and tangible benefits such as lower bills or greater comfort. This means that renewable gases including hydrogen as heating fuels are a crucial component of the journey to net zero and the UK’s hydrogen ambitions should be reflective of this. The analysis presented in this paper focuses on the external fabric of the buildings further analysis should be undertaken to consider the internal system changes that would be required for heat pumps and hydrogen boilers for example BEIS Domestic Heat Distribution Systems: Gathering Report from February 2021 which considers the suitability of radiators for the low carbon transition.

The CCUS Advisory Group (CAG) established in March 2019 is an industry-led group considering the critical challenges facing the development of CCUS market frameworks and providing insight into potential solutions. The CAG brings together experts from across the CCUS industry finance and legal sectors.<br/>The CAG has examined a range of business models focusing on industrial CCUS power production CO? transport and storage and hydrogen production. It has considered how the proposed business models interact in order to minimise issues such as cross-chain risk and has considered issues such as delivery capability. The conclusions of the CAG can be found in this report.

Hydrogen presents an opportunity for Africa to not only decarbonise its own energy use and enable clean energy access for all but also to export renewable energy. This paper developed a framework for assessing renewable resources for hydrogen production and provides a new critical analysis as to how and what role hydrogen can play in the complex African energy landscape. The regional solar wind CSP and bio hydrogen potential ranges from 366 to 1311 Gt/year 162 to 1782 Gt/year 463 to 2738 Gt/year and 0.03 to 0.06 Gt/year respectively. The water availability and sensitivity results showed that the water shortages in some countries can be abated by importing water from regions with high renewable water resources. A techno-economic comparative analysis indicated that a high voltage direct current (HVDC) system presents the most cost-effective transportation system with overall costs per kg hydrogen of 0.038 $/kg followed by water pipeline with 0.084 $/kg seawater desalination 0.1 $/kg liquified hydrogen tank truck 0.12 $/kg compressed hydrogen pipeline 0.16 $/kg liquefied ammonia pipeline 0.38 $/kg liquefied ammonia tank truck 0.60 $/kg and compressed hydrogen tank truck with 0.77 $/kg. The results quantified the significance of economies of scale due to cost effectiveness of systems such as compressed hydrogen pipeline and liquefied hydrogen tank truck systems when hydrogen production is scaled up. Decentralization is favorable under some constraints e.g. compressed hydrogen and liquefied ammonia tank truck systems will be more cost effective below 800 km and 1400 km due to lower investment and operation costs.