Publications

This paper compares six (6) alternatives for green hydrogen transport at sea. Two (2) alternatives of liquid hydrogen (LH2) by ship two (2) alternatives of compressed hydrogen (cH2) by ship and two (2) alternatives of hydrogen by pipeline. The ship alternatives study having hydrogen storage media at both end terminals to reduce the ships’ time at port or prescinding of them and reduce the immobilized capital. In the case of the pipeline new models are proposed by considering pressure costs. One scenario considers that there are compression stations every 500 km and the other one considers that there are none along the way. These alternatives are assessed under nine different scenarios that combine three distances: 100 km 2500 km and 5000 km; and three export rates of hydrogen 100 kt/y 1 Mt/y and 10 Mt/y. The results show including uncertainty bands that for the 100 km of distance the best alternative is the pipeline. For 2500 km and 100 kt/y the top alternative is cH2 shipping without storage facilities at the port terminals. For 2500 km and 1 Mt/y and for 5000 km and 100 kt/y the best alternatives are cH2 or LH2 shipping. For the remaining scenarios the best alternative is LH2 shipping.

This paper delves into the critical role of tax credits specifically Sections 45Q and 45V in the financing and economic feasibility of low-carbon-intensity hydrogen projects with a focus on natural-gas-based hydrogen production plants integrated with carbon capture and storage (CCS). This study covers the current clean energy landscape underscoring the importance of low-carbon hydrogen as a key component in the transition to a sustainable energy future and then explicates the mechanics of the 45Q and 45V tax credits illustrating their direct impact on enhancing the economic attractiveness of such projects through a detailed net present value (NPV) model analysis. Our analysis reveals that the application of 45Q and 45V tax credits significantly reduces the levelized cost of hydrogen production with scenarios indicating a reduction in cost ranging from USD 0.41/kg to USD 0.81/kg of hydrogen. Specifically the 45Q tax credit demonstrates a slightly more advantageous impact on reducing costs compared to the 45V tax credit underpinning the critical role of these fiscal measures in enhancing project returns and feasibility. Furthermore this paper addresses the inherent limitations of utilizing tax credits primarily the challenge posed by the mismatch between the scale of tax credits and the tax liability of the project developers. The concept and role of tax equity investments are discussed in response to this challenge. These findings contribute to the broader dialogue on the financing of sustainable energy projects providing valuable insights for policymakers investors and developers in the hydrogen energy sector. By quantifying the economic benefits of tax credits and elucidating the role of tax equity investments our research supports informed decision-making and strategic planning in the pursuit of a sustainable energy future.

A thermodynamic model was developed for combustion performance and emissions with a reference diesel fuel a 10 vol% methanol blend with 90 vol% diesel a 10 vol% ethanol with 90 vol% diesel and a 4% hydrogen fumigating in the inlet port along with diesel direct injection. The diesel and two alcohol blends (10% methanol–90% diesel and 10% ethanol–90% diesel) was directly injected into the cylinder while hydrogen was fumigated at the inlet port. The model was developed by commercial GT-Suite software. Besides engine performance exergy and energy rates were estimated for the four fuels. Among the four fuels/fuel blends hydrogen fuel (4% fumigated hydrogen) shows the best performance in terms of exergy energy rates specific fuel consumption power and greenhouse gas emissions. Regarding greenhouse gases carbon dioxide was only considered in this investigation as it contributes to a significant detrimental effect on environmental pollution.

This is a time of enormous change for the gas industry as the UK and the world at large attempts to meet the challenges of decarbonisation in the face of climate change. Hydrogen is expected to play a vital role in achieving the government’s commitment of eliminating the UK’s contribution to climate change by 2050 with the industry creating up to 8000 jobs by 2030 and potentially unlocking up to 100000 jobs by the middle of the century. But despite the UK government’s huge ambitions hydrogen is just one piece of the puzzle and it will be necessary to seek solutions that bring the whole energy system together – including not just heat for buildings but hard-to decarbonise areas such as manufacturing road transport aviation and shipping. Here we bring you just a taste of some of the amazing work taking place across the energy sector to understand this fuel more clearly to comprehend its strengths and limitations and to integrate it into our current energy infrastructure. We hope you enjoy this special publication.

DNV has carried out an investigation into potential uses for smart gas meter data as part of Phase 1 of the Modernising Energy Data Applications competition as funded by UK Research & Innovation. In particular a series of calculations have been carried out to investigate the possibility of differentiating accidental gas leaks from normal appliance use in domestic properties. This is primarily with the aim of preventing explosions but the detection of leaks also has environmental and financial benefits.

Three gases have been considered in this study:

• A representative UK natural gas composition.
• A blend of 80% natural gas and 20% hydrogen.
• Pure hydrogen.

An established method was used to calculate the gas outflow rate from leaks into buildings downstream of the meter regulator. These gas leak rates were compared with the gas use by typical domestic appliances and these leaks were considered in the context of the smart gas meter data that is currently available in 30-minute periods. A representative set of gas accumulation calculations was performed. It was found that the following three general cases apply to all three gases:

• Small holes of up to 1 mm rarely reach flammable gas/air concentrations for any gas except under the most unfavourable conditions such as small volumes combined with low ventilation rates. These releases would likely be detected within 6 to 12 hours.
• Medium holes between 1 mm and 6 mm give outflow rates equivalent to a moderate to high level of gas use by appliances. The ability to detect these leaks is highly dependent on the hole size the time at which the leak begins and the normal gas use profile in the building. The larger leaks in this category would be detected within 30 to 60 minutes while the smaller leaks could take several hours to be clearly differentiated from appliance use. This is quick enough to prevent some explosions.
• Large holes of over 6 mm give leak rates greater than any gas use by appliances. These releases rapidly reach a flammable gas/air mixture in most cases but would typically be detected within the first 30-minute meter output period. Again some explosions could be prevented in this timescale.

An event tree has been used to quantify the approximate success rate of detecting and preventing explosion events. Using the currently available 30-minute smart meter data and functionality it is estimated that around 7% of explosions could be prevented with a slight variation depending on the gas type in use. Additional functionality could be included in the meter to improve this performance. Typically one of the risk mitigation measures in isolation increases the explosion prevention rate to around 15%. If multiple improvements are made then the detection rate is predicted to increase to around 30%.

An examination of detailed historical incident information suggests that the explosions that lead to fatalities or significant damage to houses are typically of the type that would be more likely to be detected and prevented. It is estimated that between 25% and 75% of the more severe explosions could be prevented depending on which potential improvements are implemented.

Based on the conservative estimates of explosion prevention a cost benefit analysis suggests that it is justifiable to spend between around £1 and £10 per meter installed to implement the proposed technology. This is based purely on lives saved and does not take account of other benefits.

The present study seeks to select the most important articles and reviews from the Web of Science database that approached alternative fuels towards the decarbonization of the maritime sector. Through a systematic review methodology a combination of keywords and manual refining found a contribution of 103 works worldwide the European continent accounting for 57% of all publications. Twenty-two types of fuels were cited by the authors liquefied natural gas (LNG) hydrogen and biodiesel contributing to 49% of the mentions. Greenhouse gases sulfur oxide nitrogen oxide and particulate matter reductions are some of the main advantages of cleaner sources if used by the vessels. Nevertheless there is a lack of practical research on new standards engine performance cost and regulations from the academy to direct more stakeholders towards low carbon intensity in the shipping sector.

A series of more than 100 experiments with hydrogen-air mixtures at cryogenic temperatures have been performed in a shock tube in the frame of the PRESLHY project. A wide range of hydrogen concentrations from 8 to 60%H2 in the shock tube of the length of 5 m and 50 mm id was tested at cryogenic temperatures from 80 to 130K at ambient pressure. Flame propagation regimes were investigated for all hydrogen compositions in the shock tube at three different blockage ratios (BR) 0 0.3 and 0.6 as a function of initial temperature. Pressure sensors and InGaAs-photodiodes have been applied to monitor the flame and shock propagation velocity of the process. The experiments at ambient pressure and temperature were conducted as the reference data for cryogenic experiments. A critical expansion ratio for an effective flame acceleration to the speed of sound was experimentally found at cryogenic temperatures. The detonability criterion for smooth and obstructed channels was used to evaluate the detonation cell sizes at cryogenic temperatures as well. The main peculiarities of cryogenic combustion with respect to the safety assessment were that the maximum combustion pressure was several times higher compared to ambient temperature and the run-up-distance to detonation was several times shorter independent of lower chemical reactivity at cryogenic conditions.

A combined ultra-short-term wind power prediction strategy with high robustness based on least squares support vector machine (LSSVM) has been proposed in order to solve the wind abandonment caused by wind power randomness and realize efficient hydrogen production under wide power fluctuation. Firstly the original wind power data is decomposed into sub-modes with different bandwidth by variational modal decomposition (VMD) which reduces the influence of random noise and mode mixing significantly. Then dragonfly algorithm (DA) is introduced to optimize LSSVM kernel function and the combined ultra-short-term wind power prediction strategy which meets the time resolution and accuracy requirements of electrolytic cell control has been established finally. This model is validated by a wind power hydrogen production demonstration project output in the middle east of China. The superior prediction accuracy for high volatility wind power data is verified and the algorithm provides theoretical basis to improve the control of wind power hydrogen production system

With the rising threat of climate change green hydrogen is increasingly seen as the high-capacity energy storage and transport medium of the future. This creates an opportunity for low- and middle-income countries to leverage their high renewable energy potential to produce use and export low-cost green hydrogen creating environmental and economic development benefits. While identifying ideal locations for green hydrogen production is critical for countries when defining their green hydrogen strategies there has been a paucity of adequate geospatial planning approaches suitable to low- and middle-income countries. It is essential for these countries to identify green hydrogen production sites which match demand to expected use cases such that their strategies are economically sustainable. This paper therefore develops a novel geospatial cost modelling method to optimize the location of green hydrogen production across different use cases with a focus on suitability to low- and middle-income countries. This method is applied in Kenya to investigate the potential hydrogen supply chain for three use cases: ammonia-based fertilizer freight transport and export. We find hydrogen production costs of e3.7–9.9/kgH2 are currently achievable across Kenya depending on the production location chosen. The cheapest production locations are identified to the south and south-east of Lake Turkana. We show that ammonia produced in Kenya can be cost-competitive given the current energy crisis and that Kenya could export hydrogen to Rotterdam with costs of e7/kgH2 undercutting current market prices regardless of the carrier medium. With expected techno-economic improvements hydrogen production costs across Kenya could drop to e1.8–3.0/kgH2 by 2030.

Hydrogen addition can improve the performance and extend the lean burn limit of gasoline engines. Different hydrogen injection strategies lead to different types of hydrogen mixture distribution (HMD) which affects the engine performance. Therefore the present study experimentally investigated the effects of hydrogen injection strategy on the combustion and emissions of a hydrogen/gasoline dual-fuel port-injection engine under lean-burn conditions. Four different hydrogen injection strategies were explored: hydrogen direct injection (HDI) forming a stratified hydrogen mixture distribution (SHMD); hydrogen intake port injection forming a premixed hydrogen mixture distribution (PHMD); split hydrogen direct injection (SHDI) forming a partially premixed hydrogen mixture distribution (PPHMD); and no hydrogen addition (NHMD). The results showed that 20% hydrogen addition could extend the lean burn limit from 1.5 to 2.8. With the increase in the excess air ratio the optimum HMD changed from PPHMD to SHMD. The maximum brake thermal efficiency was obtained with an excess air ratio of 1.5 with PPHMD. The coefficient of variation (COV) with NHMD was higher than that with hydrogen addition since the hydrogen enhanced the stability of ignition and combustion. The engine presented the lowest emissions with PHMD. There were almost no carbon monoxide (CO) and nitrogen oxides (NOx) emissions when the excess air ratio was respectively more than 1.4 and 2.0.