A quantitative assessment of the hydrogen storage capacity of the UK continental shelf

Increased penetration of renewable energy sources and decarbonisation of the UK's gas supply will require large-scale energy storage. Using hydrogen as an energy storage vector, we estimate that 150 TWh of seasonal storage is required to replace seasonal variations in natural gas production. Large-scale storage is best suited to porous rock reservoirs. We present a method to quantify the hydrogen storage capacity of gas fields and saline aquifers using data previously used to assess CO₂ storage potential. We calculate a P50 value of 6900 TWh of working gas capacity in gas fields and 2200 TWh in saline aquifers on the UK continental shelf, assuming a cushion gas requirement of 50%. Sensitivity analysis reveals low temperature storage sites with sealing rocks that can withstand high pressures are ideal sites. Gas fields in the Southern North Sea could utilise existing infrastructure and large offshore wind developments to develop large-scale offshore hydrogen production.     

Increasing biomass resource availability through supply chain analysis

Increased inclusion of biomass in energy strategies all over the world means that greater mobilisation of biomass resources will be required to meet demand. Strategies of many EU countries assume the future use of non-EU sourced biomass. An increasing number of studies call for the UK to consider alternative options, principally to better utilise indigenous resources. This research identifies the indigenous biomass resources that demonstrate the greatest promise for the UK bioenergy sector and evaluates the extent that different supply chain drivers influence resource availability.The analysis finds that the UK's resources with greatest primary bioenergy potential are household wastes (>115 TWh by 2050), energy crops (>100 TWh by 2050) and agricultural residues (>80 TWh by 2050). The availability of biomass waste resources was found to demonstrate great promise for the bioenergy sector, although are highly susceptible to influences, most notably by the focus of adopted waste management strategies. Biomass residue resources were found to be the resource category least susceptible to influence, with relatively high near-term availability that is forecast to increase – therefore representing a potentially robust resource for the bioenergy sector. The near-term availability of UK energy crops was found to be much less significant compared to other resource categories. Energy crops represent long-term potential for the bioenergy sector, although achieving higher limits of availability will be dependent on the successful management of key influencing drivers. The research highlights that the availability of indigenous resources is largely influenced by a few key drivers, this contradicting areas of consensus of current UK bioenergy policy.     

Research and deployment priorities for renewable technologies: Quantifying the importance of various renewable technologies for low cost,high renewable electricity systems in an Australian case study

This study aims to identify research priorities to enable low cost, high renewable power systems. An evolutionary program optimises the mix of technologies in 100% renewable energy portfolios (RE) in the Australian National Electricity Market. Various technologies are reduced in availability to determine their relative importance for achieving low costs. The single most important factor is found to be the integration of large quantities of wind; therefore wind integration is identified as a research priority. In contrast, photovoltaics are found to “saturate” the system at less than 10% of total energy (in the absence of storage or demand management, installation of further photovoltaics does not contribute significant further value). This indicates that policies to promote utility-scale photovoltaics should be considered in partnership with complementary measures (such as demand side participation and storage). Biofuelled gas turbines are found to be important; a complete absence of bioenergy increases costs by AU$20–30/MWh, and even having only 0.1 TWh per year of bioenergy available reduces average costs by AU$3–4/MWh. Limits on the non-synchronous penetration (NSP) are found to be relatively expensive, suggesting a significant research priority around finding alternative approaches to providing synchronous services, such as inertia. Geothermal and concentrating solar thermal technologies do not appear essential as long as sufficient wind and peaking bioenergy is available.     

Expected impacts on greenhouse gas and air pollutant emissions due to a possible transition towards a hydrogen economy in German road transport

Transitioning German road transport partially to hydrogen energy is among the possibilities being discussed to help meet national climate targets. This study investigates impacts of a hypothetical, complete transition from conventionally-fueled to hydrogen-powered German transport through representative scenarios. Our results show that German emissions change between ?179 and +95 MtCO₂eq annually, depending on the scenario, with renewable-powered electrolysis leading to the greatest emissions reduction, while electrolysis using the fossil-intense current electricity mix leads to the greatest increase. German energy emissions of regulated pollutants decrease significantly, indicating the potential for simultaneous air quality improvements. Vehicular hydrogen demand is 1000 PJ annually, requiring 446–525 TWh for electrolysis, hydrogen transport and storage, which could be supplied by future German renewable generation, supporting the potential for CO₂-free hydrogen traffic and increased energy security. Thus hydrogen-powered transport could contribute significantly to climate and air quality goals, warranting further research and political discussion about this possibility.     

Evaluating the hydrogen storage potential of shut down oil and gas fields along the Norwegian continental shelf

The underground hydrogen storage (UHS) capacities of shut down oil and gas (O&G) fields along the Norwegian continental shelf (NCS) are evaluated based on the publicly available geological and hydrocarbon production data. Thermodynamic equilibrium and geochemical models are used to describe contamination of hydrogen, loss of hydrogen and changes in the mineralogy. The contamination spectrum of black oil fields and retrograde gas fields are remarkably similar. Geochemical models suggest limited reactive mineral phases and meter-scale hydrogen diffusion into the caprock. However, geochemical reactions between residual oil, reservoir brine, host rock and hydrogen are not yet studied in detail. For 23 shut down O&G fields, a theoretical maximum UHS capacity of ca. 642 TWh is estimated. We conclude with Frigg, Nordost Frigg, and Odin as the best-suited shut down fields for UHS, having a maximum UHS capacity of ca. 414 TWh. The estimates require verification by site-specific dynamic reservoir models.     

Development of a viability assessment model for hydrogen production from dedicated offshore wind farms

Dedicated offshore wind farms for hydrogen production are a promising option to unlock the full potential of offshore wind energy, attain decarbonisation and energy security targets in electricity and other sectors, and cope with grid expansion constraints. Current knowledge on these systems is limited, particularly the economic aspects. Therefore, a new, integrated and analytical model for viability assessment of hydrogen production from dedicated offshore wind farms is developed in this paper. This includes the formulae for calculating wind power output, electrolysis plant size, and hydrogen production from time-varying wind speed. All the costs are projected to a specified time using both Discounted Payback (DPB) and Net Present Value (NPV) to consider the value of capital over time. A case study considers a hypothetical wind farm of 101.3 MW situated in a potential offshore wind development pipeline off the East Coast of Ireland. All the costs of the wind farm and the electrolysis plant are for 2030, based on reference costs in the literature. Proton exchange membrane electrolysers and underground storage of hydrogen are used. The analysis shows that the DPB and NPV flows for several scenarios of storage are in good agreement and that the viability model performs well. The offshore wind farm – hydrogen production system is found to be profitable in 2030 at a hydrogen price of €5/kg and underground storage capacities ranging from 2 days to 45 days of hydrogen production. The model is helpful for rapid assessment or optimisation of both economics and feasibility of dedicated offshore wind farm – hydrogen production systems.     

The prospective of coal power in China: Will it reach a plateau in the coming decade?

Coal power holds the king position in China's generation mix and has resulted in ever-increasing ecological and environmental issues; hence, the development of the electric power sector is confronted with a series of new challenges. China has recently adopted a new economic principle of the “new economic normal,” which has a large effect on the projection electricity demand and power generation planning through 2020. This paper measures electricity demand based upon China's social and economic structure. The 2020 roadmap presents China's developing targets for allocating energy resources to meet new demands, and the 2030 roadmap is compiled based upon an ambitious expansion of clean energy sources. Results show that electricity demand is expected to reach 7500 TWh in 2020 and 9730 TWh in 2030. Coal power is expected to reach its peak in 2020 at around 970 GW, and will then enter a plateau, even with a pathway of active electricity substitution in place.     

How to analyse and maximise the forest fuel supply availability to power plants in Eastern Finland

The annual use of forest fuels has grown rapidly in Finland during the 21st century. In 2007 the annual use was 5.3 TWh (firewood use excluded), whereas the targeted growth by the year 2010 is 10.6 TWh, i.e. some 5 million m³. The purpose of this work was to evaluate the maximum availability of forest fuels to CHP plants in Eastern Finland. The total availability to the selected CHP plant population was 7 TWh at the maximum transport distance of 100 km. The main share came from logging residues, 3.3 TWh, and the rest from stumps, 1.8 TWh, and small diameter energy wood, 1.9 TWh. The highest plant-specific availability reached the level of 1.7-1.8 TWh, but the overlapping procurement areas reduced the availability for most plants to a level less than 1 TWh. In all plant sites peat fuel could be partially compensated with forest fuels according to availability, but not completely due to the boiler technology. Increasing the targeted national forest fuel use presupposes the use of new logistics supply solutions, such as other transport modes and regional buffer storage networks. This makes it possible to widen the traditional procurement area-based on truck transportation, which is less than 60 km because of a dense plant network.     

Potential of renewable surplus electricity for power-to-gas and geo-methanation in Switzerland

Energy systems are increasingly exposed to variable surplus electricity from renewable sources, particularly photovoltaics. This study estimates the potential to use surplus electricity for power-to-gas with geo-methanation for Switzerland by integrated energy system and power-to-gas modelling. Various CO₂ point sources are assessed concerning exploitable emissions for power-to-gas, which were found to be abundantly available such that 60 TWh surplus electricity could be converted to methane, which is the equivalent of the current annual Swiss natural gas demand. However, the maximum available surplus electricity is only 19 TWh even in a scenario with high photovoltaic expansion. Moreover, making this surplus electricity available for power-to-gas requires an ideal load shifting capacity of up to 10 times the currently installed pumped-hydro capacity. Considering also geological and economic boundary conditions for geo-methanation at run-of-river and municipal waste incinerator sites with nearby CO₂ sources reduces the exploitable surplus electricity from 19 to 2 TWh.     

Exploring the competitiveness of hydrogen-fueled gas turbines in future energy systems

Hydrogen is currently receiving attention as a possible cross-sectoral energy carrier with the potential to enable emission reductions in several sectors, including hard-to-abate sectors. In this work, a techno-economic optimization model is used to evaluate the competitiveness of time-shifting of electricity generation using electrolyzers, hydrogen storage and gas turbines fueled with hydrogen as part of the transition from the current electricity system to future electricity systems in Years 2030, 2040 and 2050. The model incorporates an emissions cap to ensure a gradual decline in carbon dioxide (CO₂) levels, targeting near-zero CO₂ emissions by Year 2050, and this includes 15 European countries.The results show that hydrogen gas turbines have an important role to play in shifting electricity generation and providing capacity when carbon emissions are constrained to very low levels in Year 2050. The level of competitiveness is, however, considerably lower in energy systems that still allow significant levels of CO₂ emissions, e.g., in Year 2030. For Years 2040 and 2050, the results indicate investments mainly in gas turbines that are partly fueled with hydrogen, with 30–77 vol.-% hydrogen in biogas, although some investments in exclusively hydrogen-fueled gas turbines are also envisioned. Both open cycle and combined cycle gas turbines (CCGT) receive investments, and the operational patterns show that also CCGTs have a frequent cyclical operation, whereby most of the start-stop cycles are less than 20 h in duration.     

Storage of atomic hydrogen in multilayer graphene

The world is moving rapidly to embrace renewable energy sources. One energy carrier, hydrogen, is a growing player in this field. This study was motivated by a desire to find alternative hydrogen storage mechanisms using processes that are cost effective with low environmental impact and good energy storage efficiency. This paper presents initial research findings on the novel approach of employing the patented RMIT Proton Battery to store atomic hydrogen in a multilayer graphene electrode using an acid electrolyte. This is a very different approach to conventional hydrogen energy storage systems. The paper reveals that one supplier's product achieves a 0.35 wt% reversible hydrogen storage in a multilayer graphene material with 0.35 nm layer separation and a specific surface area of 720 m²/g.     

Experimental simulations of hydrogen migration through potential storage rocks

In the framework of future decarbonization of the energy industry, the safe and effective storage of hydrogen is an important approach to add to a climate-friendly energy system. Until the development of sufficiently large electrical storage systems, the storage of hydrogen in the order of GWh to TWh is envisaged in salt caverns or porous geological formations with a gas-tight covering of salt or claystone. In order to calculate gas losses from these H₂ storage facilities, the H₂ diffusivity of the storage and cap rocks must be known. To determine the hydrogen diffusion rates in these rocks, an experimental set-up was designed, constructed and tested. The set-up comprises two gas chambers, separated by the rock sample under investigation with an exposed area of approximately 7 cm². The driving force for gas migration through the rock sample from the hydrogen-containing feed gas chamber to the hydrogen-free permeate chamber is the chemical potential (concentration) gradient. With respect to hydrogen migration behaviour, hydrogen breakthrough times and hydrogen diffusion coefficients were determined for dry and wet Bentheimer sandstone, Werra rock salt and Opalinus clay samples. Breakthrough times varied between less than 1 h and 843 h. Based on concentration changes at the permeate side, hydrogen diffusion coefficients were derived ranging from 10⁻⁹ to 10⁻⁸ m²/s. The differences between the materials and the effect that wetted or water-saturated samples have higher hydrogen retention due to closed pores and microcracks were clearly shown. The experimental set-up proves to be a suitable approach to determine site-specific rock characteristics such as hydrogen diffusion coefficients and breakthrough times for natural geomaterials.     

Review and comparison of worldwide hydrogen activities in the rail sector with special focus on on-board storage and refueling technologies

This paper investigates hydrogen storage and refueling technologies that were used in rail vehicles over the past 20 years as well as planned activities as part of demonstration projects or feasibility studies. Presented are details of the currently available technology and its vehicle integration, market availability as well as standardization and research and development activities. A total of 80 international studies, corporate announcements as well as vehicle and refueling demonstration projects were evaluated with regard to storage and refueling technology, pressure level, hydrogen amount and installation concepts inside rolling stock. Furthermore, current hydrogen storage systems of worldwide manufacturers were analyzed in terms of technical data.We found that large fleets of hydrogen-fueled passenger railcars are currently being commissioned or are about to enter service along with many more vehicles on order worldwide. 35 MPa compressed gaseous storage system technology currently dominates in implementation projects. In terms of hydrogen storage requirements for railcars, sufficient energy content and range are not a major barrier at present (assuming enough installation space is available). For this reason, also hydrogen refueling stations required for 35 MPa vehicle operation are currently being set up worldwide.A wide variety of hydrogen demonstration and retrofit projects are currently underway for freight locomotive applications around the world, in addition to completed and ongoing feasibility studies. Up to now, no prevailing hydrogen storage technology emerged, especially because line-haul locomotives are required to carry significantly more energy than passenger trains. The 35 MPa compressed storage systems commonly used in passenger trains offer too little energy density for mainline locomotive operation - alternative storage technologies are not yet established. Energy tender solutions could be an option to increase hydrogen storage capacity here.     

Hydrogen supply scenarios for a climate neutral energy system in Germany

A climate neutral energy system in Germany will most likely require green hydrogen. Two important factors, that determine whether the hydrogen will be imported or produced locally from renewable energy are still uncertain though - the import price for green hydrogen and the upper limit for photovoltaic installations. To investigate the impact of these two factors, the authors calculate cost optimized climate neutral energy systems while varying the import price from 1.25 €/kg to 5 €/kg with unlimited import volume and the photovoltaic limit from 300 GW to unlimited. In all scenarios, hydrogen plays a significant role. At a medium import price of 3.75 €/kg and photovoltaic limits of 300–900 GW the hydrogen supply is around 1200 to 1300 TWh with import shares varying from 60 to 85%. In most scenarios the electrolysis profile is highly correlated with the photovoltaic power, which leads to full load hours of 1870 h–2770 h.     

A data‐driven approach to study the role of interconnectors in a future low‐carbon electricity supply system

This paper investigates the potential role of the electricity interconnectors in improving the security of supply in Great Britain (GB) in 2030. Real electricity demand and price data for GB and France in 2016 were used to understand the relationship between power exchange between the two countries and their wholesale electricity prices. A linear programming optimisation model was developed to find the economic power dispatch. Two interconnection links were considered; two‐way trade interconnector with a capacity of 5.4 GW and a 12.3 GW import‐only interconnector between GB and other states. The GB–France link transmits electricity from cheaper system to the more expensive one. The total electricity demand in 2030 will be 406 TWh. Gas‐fired power plants w/wo CCS will provide 83 TWh of the total electricity demand, whereas nuclear power plants will produce 74 TWh. In addition, wind farms and solar PVs are expected to deliver ~120 TWh electricity. CHP units will provide 88 TWh electricity in 2030. The electricity traded between GB and France in 2030 was found to be 33 TWh, which is 160% larger compared with 2016. The power import from France is about 27 TWh and occurs in 59% of the time. For 64% of the time, the interconnector with France is fully loaded. The electricity imported via the 12.3 GW interconnector in 2030 is 1 TWh and mainly occurs during winter‐time when the demand in GB is high. De‐rated capacity margin was calculated based on instantaneous electricity demand and varies between ?2% and 139%. The impact of the price of the imported electricity via the 12.3 GW link was investigated. Increasing the price of the imported electricity via the 12.3 GW link results in a higher capacity factor for all the generation options except the 12.3 GW interconnector link.     

Variability and phasing of tidal current energy around the United Kingdom

Tidal energy has the potential to play a key role in meeting renewable energy targets set out by the United Kingdom (UK) government and devolved administrations. Attention has been drawn to this resource as a number of locations with high tidal current velocity have recently been leased by the Crown Estate for commercial development. Although tides are periodic and predictable, there are times when the current velocity is too low for any power generation. However, it has been proposed that a portfolio of diverse sites located around the UK will deliver a firm aggregate output due to the relative phasing of the tidal signal around the coast. This paper analyses whether firm tidal power is feasible with ‘first generation’ tidal current generators suitable for relatively shallow water, high velocity sites. This is achieved through development of realistic scenarios of tidal current energy industry development. These scenarios incorporate constraints relating to assessment of the economically harvestable resource, tidal technology potential and the practical limits to energy extraction dictated by environmental response and spatial availability of resource. The final scenario is capable of generating 17 TWh/year with an effective installed capacity of 7.8 GW, at an average capacity factor of 29.9% from 7 major locations. However, it is concluded that there is insufficient diversity between sites suitable for first generation tidal current energy schemes for a portfolio approach to deliver firm power generation.     

Use of hydrogen as a seasonal energy storage system to manage renewable power deployment in Spain by 2030

Spain has presented a plan (known as PNIEC) to reduce conventional energy sources (shutting down 16 GW) and to increase the use of renewable sources (incorporating 65 GW). This generation portfolio leads to a situation in which there will be a surplus of electrical energy in spring and summer, which will be lacking in autumn and winter. The plan sets a target on batteries, but insufficient to manage more than 10 TWh over 6 months. This paper proposes the deployment of electrolysers to produce hydrogen with the surplus energy, using the already existing Spanish natural gas network to store it. The resulting gas (up to 15% blend of hydrogen in natural gas) could be used subsequently in turbines to alleviate the energy deficit. With this strategy, up to 7.27 TWh of the surplus renewable energy could be reused, and 2.54 million tons of CO2 equivalent would be avoided yearly.     

Offshore transmission for wind: Comparing the economic benefits of different offshore network configurations

It has been argued that increasing transmission network capacity is vital to ensuring the full utilisation of renewables in Europe. The significant wind generation capacity proposed for the North Sea combined with high penetrations of other intermittent renewables across Europe has raised interest in different approaches to connecting offshore wind that might also increase interconnectivity between regions in a cost effective way. These analyses to assess a number of putative North Sea networks confirm that greater interconnection capacity between regions increases the utilisation of offshore wind energy, reducing curtailed wind energy by up to 9 TWh in 2030 based on 61 GW of installed capacity, and facilitating a reduction in annual generation costs of more than €0.5bn. However, at 2013 fuel and carbon prices, such additional network capacity allows cheaper high carbon generation to displace more expensive lower carbon plant, increasing coal generation by as much as 24 TWh and thereby increasing CO₂ emissions. The results are sensitive to the generation “merit order” and a sufficiently high carbon price would yield up to a 28% decrease in emissions depending on the network case. It is inferred that carbon pricing may impact not only generation investment but also the benefits associated with network development.     

Prospects of green hydrogen in Poland: A techno-economic analysis using a Monte Carlo approach

The European Commission's plan to decarbonize the economy using innovative energy carriers has brought into question whether the national targets for developing electrolysis technologies are sufficiently ambitious to establish a local hydrogen production industry. While several research works have explored the economic viability of individual green hydrogen production and storage facilities in the Western European Member States, only a few studies have examined the prospects of large-scale green hydrogen production units in Poland. In this study, a Monte Carlo-based model is proposed and developed to investigate the underlying economic and technical factors that may impact the success of the Polish green hydrogen strategy. Moreover, it analyzes the economics of renewable hydrogen at different stages of technological development and market adoption. This is achieved by characterizing the local meteorological conditions of Polish NUTS-2 regions and comparing the levelized cost of hydrogen in such regions in 2020, 2030, and 2050. The results show the geographical locations where the deployment of large-scale hydrogen production units will be most cost effective.     

Hydrogen storage technology options for fuel cell vehicles: Well-to-wheel costs, energy efficiencies, and greenhouse gas emissions

Five different hydrogen vehicle storage technologies are examined on a Well-to-Wheel basis by evaluating cost, energy efficiency, greenhouse gas (GHG) emissions, and performance. The storage systems are gaseous 350 bar hydrogen, gaseous 700 bar hydrogen, Cold Gas at 500 bar and 200 K, Cryo-Compressed Liquid Hydrogen (CcH2) at 275 bar and 30 K, and an experimental adsorbent material (MOF 177) -based storage system at 250 bar and 100 K. Each storage technology is examined with several hydrogen production options and a variety of possible hydrogen delivery methods. Other variables, including hydrogen vehicle market penetration, are also examined. The 350 bar approach is relatively cost-effective and energy-efficient, but its volumetric efficiency is too low for it to be a practical vehicle storage system for the long term. The MOF 177 system requires liquid hydrogen refueling, which adds considerable cost, energy use, and GHG emissions while having lower volumetric efficiency than the CcH2 system. The other three storage technologies represent a set of trade-offs relative to their attractiveness. Only the CcH2 system meets the critical Department of Energy (DOE) 2015 volumetric efficiency target, and none meet the DOE’s ultimate volumetric efficiency target. For these three systems to achieve a 480-km (300-mi) range, they would require a volume of at least 105-175 L in a mid-size FCV.