United Kingdom

Carbon capture and storage is expected to play a pivotal role in achieving the emission reduction targets established by the Paris Agreement. However the most mature technologies have been shown to reduce the net efficiency of fossil fuel-fired power plants by at least 7% points increasing the electricity cost. Carbonate looping is a technology that may reduce these efficiency and economic penalties. Its maturity has increased significantly over the past twenty years mostly due to development of novel process configurations and sorbents for improved process performance. This review provides a comprehensive overview of the calcium looping concepts and statistically evaluates their techno-economic feasibility. It has been shown that the most commonly reported figures for the efficiency penalty associated with calcium looping retrofits were between 6 and 8% points. Furthermore the calcium-looping-based coal-fired power plants and sorption-enhanced hydrogen production systems integrated with combined cycles and/or fuel cells have been shown to achieve net efficiencies as high as 40% and 50–60% respectively. Importantly the performance of both retrofit and greenfield scenarios can be further improved by increasing the degree of heat integration as well as using advanced power cycles and enhanced sorbents. The assessment of the economic feasibility of calcium looping concepts has indicated that the cost of carbon dioxide avoided will be between 10 and 30 € per tonne of carbon dioxide and 10–50 € per tonne of carbon dioxide in the retrofit and greenfield scenarios respectively. However limited economic data have been presented in the current literature for the thermodynamic performance of calcium looping concepts.

As part of Work Package 2 (WP2) of the Hy4Heat programme DNV produced a substantive report regarding colourant within a potential hydrogen gas network within the UK. Considering the advances within the hydrogen industry over the past year this covering document provides an update to the results as presented by DNV based on current industry progress and research.

• Advancements have been made in the understanding of key topics:
• Flame visibility and supervision
• Health and safety of colourant additives
• Production of Nitrogen Oxides (NOx)
• Likelihood of ignition from domestic electrical installations
• Nature of gas escapes

The Hydrogen Colourant report was a study to determine if there is a requirement for adding a colourant to hydrogen to ensure that safe burning and user acceptance is achieved and to investigate the optimum solution if a colourant is required. The recommendation is that adding colourant to a future hydrogen gas network for use within buildings is not necessary if engineering measures are put in place to enable safe appliance operation."

Power to hydrogen (P2H) provides a promising solution to the geographic mismatch between sources of renewable energy and the market due to its technological maturity flexibility and the availability of technical and economic data from a range of active demonstration projects. In this review we aim to provide an overview of the status of P2H analyze its technical barriers and solutions and propose potential opportunities for future research and industrial demonstrations. We specifically focus on the transport of hydrogen via natural gas pipeline networks and end-user purification. Strong evidence shows that an addition of about 10% hydrogen into natural gas pipelines has negligible effects on the pipelines and utilization appliances and may therefore extend the asset value of the pipelines after natural gas is depleted. To obtain pure hydrogen from hydrogen-enriched natural gas (HENG) mixtures end-user separation is inevitable and can be achieved through membranes adsorption and other promising separation technologies. However novel materials with high selectivity and capacity will be the key to the development of industrial processes and an integrated membrane-adsorption process may be considered in order to produce high-purity hydrogen from HENG. It is also worth investigating the feasibility of electrochemical separation (hydrogen pumping) at a large scale and its energy analysis. Cryogenics may only be feasible when liquefied natural gas (LNG) is one of the major products. A range of other technological and operational barriers and opportunities such as water availability byproduct (oxygen) utilization and environmental impacts are also discussed. This review will advance readers’ understanding of P2H and foster the development of the hydrogen economy.

The opportunities and challenges to reducing industrial energy demand and carbon dioxide (CO₂ ) emissions in the Chemicals sector are evaluated with a focus on the situation in the United Kingdom (UK) although the lessons learned are applicable across much of the industrialised world. This sector can be characterised as being heterogeneous; embracing a diverse range of products (including advanced materials cleaning fluids composites dyes paints pharmaceuticals plastics and surfactants). It sits on the boundary between energy-intensive (EI) and non-energy-intensive (NEI) industrial sectors. The improvement potential of various technological interventions has been identified in terms of their energy use and greenhouse gas (GHG) emissions. Currently-available best practice technologies (BPTs) will lead to further short-term energy and CO₂ emissions savings in chemicals processing but the prospects for the commercial exploitation of innovative technologies by mid-21st century are far more speculative. A set of industrial decarbonisation ‘technology roadmaps’ out to the mid-21st Century are also reported based on various alternative scenarios. These yield low-carbon transition pathways that represent future projections which match short-term and long-term (2050) targets with specific technological solutions to help meet the key energy saving and decarbonisation goals. The roadmaps’ contents were built up on the basis of the improvement potentials associated with various processes employed in the chemicals industry. They help identify the steps needed to be undertaken by developers policy makers and other stakeholders in order to ensure the decarbonisation of the UK chemicals industry. The attainment of significant falls in carbon emissions over this period will depends critically on the adoption of a small number of key technologies [e.g. carbon capture and storage (CCS) energy efficiency techniques and bioenergy] alongside a decarbonisation of the electricity supply.

Low-carbon hydrogen has the potential to play a significant role in tackling climate change and poor air quality. This policy briefing considers how hydrogen could be produced at a useful scale to power vehicles heat homes and supply industrial processes.

Four groups of hydrogen production technologies are examined:

Thermochemical Routes to Hydrogen

These methods typically use heat and fossil fuels. Steam methane reforming is the dominant commercial technology and currently produces hydrogen on a large scale but is not currently low carbon. Carbon capture is therefore essential with this process. Innovative technology developments may also help and research is underway. Alternative thermal methods of creating hydrogen indicate biomass gasification has potential. Other techniques at a low technology readiness level include separation of hydrogen from hydrocarbons using microwaves.

Electrolytic Routes to Hydrogen

Electrolytic hydrogen production also known as electrolysis splits water into hydrogen and oxygen using electricity in an electrolysis cell. Electrolysis produces pure hydrogen which is ideal for low temperature fuel cells for example in electric vehicles. Commercial electrolysers are on the market and have been in use for many years. Further technology developments will enable new generation electrolysers to be commercially competitive when used at scale with fluctuating renewable energy sources.

Biological Routes to Hydrogen

Biological routes usually involve the conversion of biomass to hydrogen and other valuable end products using microbial processes. Methods such as anaerobic digestion are feasible now at a laboratory and small pilot scale. This technology may prove to have additional or greater impact and value as route for the production of high value chemicals within a biorefinery concept.

Solar to Fuels Routes to Hydrogen

A number of experimental techniques have been reported the most developed of which is ‘solar to fuels’ - a suite of technologies that typically split water into hydrogen and oxygen using solar energy. These methods have close parallels with the process of photosynthesis and are often referred to as ‘artificial photosynthesis’ processes. The research is promising though views are divided on its ultimate utility. Competition for space will always limit the scale up of solar to fuels.

The briefing concludes that steam methane reforming and electrolysis are the most likely technologies to be deployed to produce low-carbon hydrogen at volume in the near to mid-term providing that the challenges of high levels of carbon capture (for steam methane reforming) and cost reduction and renewable energy sources (for electrolysis) can be overcome.

There is a growing conversation around the role that hydrogen can play in the future of the UK and how to best harness its potential to secure jobs show climate leadership promote industrial competitiveness and drive innovation. The Government’s ‘Ten Point Plan for a Green Industrial Revolution’ included hydrogen as one of its ten actions targeting 5GW of ‘low carbon’ hydrogen production by 2030. Britain is thus joining the EU US Japan Germany and a host of other countries seeking to be part of the hydrogen economy of the future.<br/><br/>A focus on clean green hydrogen within targeted sectors and hubs can support multiple Government goals – including demonstrating climate leadership reducing regional inequalities through the ‘levelling up’ agenda and ensuring a green and cost-effective recovery from the coronavirus pandemic which prioritises jobs and skills. A strategic hydrogen vision must be honest and recognise where green hydrogen does not present the optimal pathway for decarbonisation – for instance where alternative solutions are already readily available for roll-out are more efficient and cost-effective. A clear example is hydrogen use for heating where it is estimated to require around 30 times more offshore wind farm capacity than currently available to produce enough green hydrogen to replace all gas boilers as well as adding costs for consumers.<br/><br/>This paper considers the offer of hydrogen for key Government priorities – including an inclusive and resilient economic recovery from the pandemic demonstrating climate leadership and delivering for all of society across the UK. It assesses existing evidence and considers the risks and opportunities and how they might inform a strategic vision for the UK. Ahead of the forthcoming Hydrogen Strategy it sets expectations for Government and outlines key recommendations.

Titanium dioxide coatings have potential applications including photocatalysts for solar assisted hydrogen production solar water disinfection and self-cleaning windows. Herein we report the use of suspension plasma spraying (SPS) for the deposition of conformal titanium dioxide coatings. The process utilises a nanoparticle slurry of TiO₂ (ca. 6 and 12 nm respectively) in water which is fed into a high temperature plasma jet (ca. 7000–20 000 K). This facilitated the deposition of adherent coatings of nanostructured titanium dioxide with predominantly anatase crystal structure. In this study suspensions of nano-titanium dioxide made via continuous hydrothermal flow synthesis (CHFS) were used directly as a feedstock for the SPS process. Coatings were produced by varying the feedstock crystallite size spray distance and plasma conditions. The coatings produced exhibited ca. 90–100% anatase phase content with the emainder being rutile (demonstrated by XRD). Phase distribution was homogenous throughout the coatings as determined by micro-Raman spectroscopy. The coatings had a granular surface with a high specific surface area and consisted of densely packed agglomerates interspersed with some melted material. All of the coatings were shown to be photoactive by means of a sacrificial hydrogen evolution test under UV radiation and compared favourably with reported values for CVD coatings and compressed discs of P25.

The recommended minimum separation distances in IGEM/TD/1 were based on a research programme that studied the different ways in which a failure of one buried natural gas transmission pipeline can affect another similar pipeline installed adjacent to the first taking account of the initial pressure wave propagating through the ground the size of the ground crater produced and the threat of escalation from fire if the second pipeline is exposed. The methodology developed from the research was first published in 2010 and is implemented in a software program (“PROPHET”). The distances in IGEM/TD/1 are generally cautious and are essentially determined by the size of the ground crater produced by pipeline ruptures as predicted by the methodology.

To assess the impact of hydrogen transmission on the recommended separation distances the possibility of one pipeline transporting natural gas and the other transporting hydrogen was considered as well as both pipelines transporting hydrogen. The following steps were carried out to assess the impact of hydrogen transmission on parallel pipeline separation distances drawing on existing knowledge only:

• Estimate the ground pressure loading predicted from a hydrogen pipeline rupture.
• Consider the ground pressure effect on a parallel natural gas or hydrogen pipeline.
• Evaluate available ground crater formation models and assess if existing natural gas model is cautious for hydrogen.
• Consider effects of thermal loading due to hydrogen fires where recommended natural gas separation distances are not met.

The following conclusions were made as to whether the current methodology for natural gas is cautious when applied to hydrogen:

• Ground pressure loading: The current natural gas methodology is cautious.
• Ground pressure effects: The current natural gas methodology is applicable (no change for hydrogen).
• Ground crater formation: The current natural gas methodology is cautious for ruptures and applicable for punctures (almost no change for hydrogen).
• Thermal loading: The current natural gas methodology is cautious for the thermal loading from ruptures but not necessarily cautious for punctures. Calculations of the minimum flow velocity required to prevent failure of a natural gas pipeline are not cautious for hydrogen.

In summary the recommended minimum separation distances in IGEM/TD/1 for parallel natural gas pipelines should be cautious when applied to parallel hydrogen pipelines. However in cases where the recommended minimum separation distances are not met the calculations to predict the thermal loading and response of the exposed pipeline should take account of the properties of hydrogen as the natural gas results will not necessarily be cautious.

It is now well established that electrochemical systems can optimally perform only within a narrow range of temperature. Exposure to temperatures outside this range adversely affects the performance and lifetime of these systems. As a result thermal management is an essential consideration during the design and operation of electrochemical equipment and can heavily influence the success of electrochemical energy technologies. Recently significant attempts have been placed on the maturity of cooling technologies for electrochemical devices. Nonetheless the existing reviews on the subject have been primarily focused on battery cooling. Conversely heat transfer in other electrochemical systems commonly used for energy conversion and storage has not been subjected to critical reviews. To address this issue the current study gives an overview of the progress and challenges on the thermal management of different electrochemical energy devices including fuel cells electrolysers and supercapacitors. The physicochemical mechanisms of heat generation in these electrochemical devices are discussed in-depth. Physics of the heat transfer techniques currently employed for temperature control are then exposed and some directions for future studies are provided.

Heating and hot water within buildings account for almost a quarter of global energy consumption. Approximately 90% of this heat is derived directly from the combustion of fossil fuels primarily natural gas leading to the unabated emission of carbon dioxide. This paper assesses the environmental sustainability of a range of heating technologies and scenarios on a life cycle basis. The major technologies considered are natural gas boilers air source heat pumps hydrogen boilers and direct electric heaters. The scenarios use the UK as an example due to its status as a major economy with a legally-binding net-zero carbon target for 2050; they consider plausible future electricity and natural gas mixes including the potential growth of domestic shale gas. The environmental impacts are estimated using ReCiPe 2016. Current gas boilers have a climate change impact of 220 g CO₂ eq./kWh of heat which could fall to 64 g CO₂ eq./kWh for boilers fuelled by hydrogen derived from natural gas with carbon capture. Heat from electric air source heat pumps or hydrogen from electrolysis can achieve net zero with a decarbonised electricity mix but electrolysis has the highest energy demand of all options which leads to the highest impacts across 17 of the 19 categories. Despite their high carbon emissions gas boilers remain the lowest impact option across 12 categories as they avoid the impacts related to electricity generation including metal depletion toxicities and eutrophication. By 2050 the best performing scenario sees the climate change impact of the heating mix fall by 95%; this is achieved by prioritising electric air source heat pumps without hydrofluorocarbon refrigerants alongside demand reduction. The results show that if infrastructure and financial challenges can be overcome there are several viable decarbonisation strategies for heating with heat pumps offering the most environmentally sustainable option of those considered here. However increased renewable electricity demand may worsen some environmental impacts compared to natural gas boilers.