Transmission, Distribution & Storage

Globally reducing CO2 emissions is an urgent priority. The hydrogen economy is a system that offers long-term solutions for a secure energy future and the CO2 crisis. From hydrogen production to consumption storing systems are the foundation of a viable hydrogen economy. Each step has been the topic of intense research for decades; however the development of a viable safe and efficient strategy for the storage of hydrogen remains the most challenging one. Storing hydrogen in polymer-based carriers can realize a more compact and much safer approach that does not require high pressure and cryogenic temperature with the potential to reach the targets determined by the United States Department of Energy. This review highlights an outline of the major polymeric material groups that are capable of storing and releasing hydrogen reversibly. According to the hydrogen storage results there is no optimal hydrogen storage system for all stationary and automotive applications so far. Additionally a comparison is made between different polymeric carriers and relevant solid-state hydrogen carriers to better understand the amount of hydrogen that can be stored and released realistically.

In the fast filling process in order to control the temperature of the vehicle-mounted storage tank not to exceed the upper limit of 85 ◦C it is an effective method to add a hydrogen pre-cooling system upstream of the hydrogenation machine. In this paper Fluent is used to simulate the heat transfer process of high-pressure hydrogen in a shell-and-tube heat exchanger and the phase change process of refrigerant R23. The accuracy of the model is proven by a comparison with the data in the references. Using this model the temperature field and gas volume fraction in the heat transfer process are obtained which is helpful to analyze the heat transfer mechanism. At the same time the influence of hydrogen inlet temperature hydrogen inlet pressure and refrigerant flow rate on the refrigeration performance was studied. The current work shows that the model can be used to determine the best working parameters in the pre-cooling process and reduce the operating cost of the hydrogen refueling station.

Electrical power generation is changing dramatically across the world because of the need to reduce greenhouse gas emissions and to introduce mixed energy sources. The power network faces great challenges in transmission and distribution to meet demand with unpredictable daily and seasonal variations. Electrical Energy Storage (EES) is recognized as underpinning technologies to have great potential in meeting these challenges whereby energy is stored in a certain state according to the technology used and is converted to electrical energy when needed. However the wide variety of options and complex characteristic matrices make it difficult to appraise a specific EES technology for a particular application. This paper intends to mitigate this problem by providing a comprehensive and clear picture of the state-of-the-art technologies available and where they would be suited for integration into a power generation and distribution system. The paper starts with an overview of the operation principles technical and economic performance features and the current research and development of important EES technologies sorted into six main categories based on the types of energy stored. Following this a comprehensive comparison and an application potential analysis of the reviewed technologies are presented.

Through the integration of multiple energy carriers with related technologies multi-energy systems (MES) can exploit the synergies coming from their interplay for several benefits towards decarbonization. In such a context inclusion of Power-to-X technologies in periods of excess renewable electricity supply removes the need for curtailment of renewable electricity generation. In order to achieve the environmental benefits of MES without neglecting their economic feasibility the optimal design problem is as crucial as challenging and requires the adoption of a multi-objective approach. This paper extends the results of a previous work by investigating hydrogen-based non-conventional storage for PV power in the eco-energetic optimization of an MES. The system under study consists of a reversible fuel cell (r-SOC) photovoltaic (PV) electric heat pump absorption chiller and thermal storage and allows satisfying the multi-energy needs of a residential end-user. A multi-objective linear problem is established to find the optimal MES configuration including the sizes of the involved technologies with the goal of reducing the total annual cost and the fossil primary energy input. Simulation results are compared with those obtained in previous work with a conventional nanogrid where a combined heat and power (CHP) system with gas-fired internal combustion engine and a battery were present instead of an r-SOC. The optimized configuration of the non-conventional nanogrid allows achieving a maximum primary energy reduction amounting to 66.3% compared to the conventional nanogrid. In the face of the environmental benefits the non-conventional nanogrid leads to an increase in total annual costs which compared to the conventional nanogrid is in the range of 41–65%.

Hydrogen-microvoid interactions were studied via unit cell analyses with different hydrogen concentrations. The absolute failure strain decreases with hydrogen concentration but the failure loci were found to follow the same trend dependent only on stress triaxiality in other words the effects of geometric constraint and hydrogen on failure are decoupled. Guided by the decoupling principle a hydrogen informed Gurson model is proposed. This model is the first practical hydrogen embrittlement simulation tool based on the hydrogen enhanced localized plasticity (HELP) mechanism. It introduces only one additional hydrogen related parameter into the Gurson model and is able to capture hydrogen enhanced internal necking failure of microvoids with accuracy; its parameter calibration procedure is straightforward and cost efficient for engineering purpose

Renewable energy (solar and wind) sources have evolved dramatically in recent years around the globe primarily because they have the potential to generate environmentally friendly energy. However operating systems with high renewable energy penetration remain challenging due to the stochastic nature of these energy sources. To tackle these problems the authors propose a state machine-based energy management strategy combined with a hysteresis band control strategy for renewable energy hybrid microgrids that integrates hydrogen storage systems. By considering the power difference between the renewable energy source and the demand the battery’s state of charge and the hydrogen storage level the proposed energy management strategy can control the power of fuel cells electrolyzers and batteries in a microgrid and the power imported into/exported from the main grid. The results showed that the energy management strategy provides the following advantages: (1) the power supply and demand balance in the microgrid was balanced (2) the lifespans of the electrolyzer and fuel cell were extended and (3) the state of charge of the battery and the stored level of the hydrogen were appropriately ensured.

Underground Hydrogen Storage (UHS) has received significant attention over the past few years as hydrogen seems well-suited for adjusting seasonal energy gaps. We present an integrated reservoir-well model for “Viking A00 the depleted gas field in the North Sea as a potential site for UHS. Our findings show that utilizing the integrated model results in more reasonable predictions as the gas composition changes over time. Sensitivity analyses show that the lighter the cushion gas the more production can be obtained. However the purity of the produced hydrogen will be affected to some extent which can be enhanced by increasing the fill-up period and the injection rate. The results also show that even though hydrogen diffuses into the reservoir and mixes up with the native fluids (mainly methane) the impact of hydrogen diffusion is marginal. All these factors will potentially influence the project's economics.

The transition to cleaner energy sources including renewables introduces the need for versatile and transportable energy carriers such as hydrogen. This paper aims to quantify the hydrogen export competitiveness of all countries using a newly developed comprehensive index. The developed competitiveness index includes 21 indicators under four main categories: resource availability and potential economic and financial potential political and regulatory status and industrial knowledge. Expert interviews and surveys are conducted to properly identify choose and modify the categories and indicators and to calculate the appropriate weight for each. Top-ranking countries include the United States Australia Canada United Kingdom China Norway India Russia Netherlands and Germany and they are poised to be significant players in the hydrogen market. Policy recommendations for growing the hydrogen production and export sector are given based on each category.

As a manufactured fuel hydrogen can be produced in a decentralized way in most countries around the world. This means even in a net zero economy the global trade of hydrogen could look quite different to the current international trade in fossil fuels including natural gas. With further declines in the costs of renewable electricity and electrolyzers regions which have lower cost renewable electricity may develop an economic advantage in the production of low-cost hydrogen but for hydrogen to become a globally traded commodity the cost of imports needs to be lower than the cost of domestic production. Unlike oil or natural gas transporting hydrogen over long distances is not an easy task. Hydrogen liquefaction is an extremely energy-intensive process while maintaining the low temperature required for long-distance transportation and storage purposes results in additional energy losses and accompanying costs. The upside is that hydrogen can be converted into multiple carriers that have a higher energy density and higher transport capacity and can potentially be cheaper to transport over long distances. Among the substances currently identified as potential hydrogen carriers suitable for marine shipping liquid ammonia the so-called ‘liquid organic hydrogen carriers’ in general (toluene-methylcyclohexane (MCH) in particular) and methanol have received the most attention in recent years. This paper compares the key techno-economic characteristics of these potential carriers with that of liquified hydrogen in order to develop a better understanding of the ways in which hydrogen could be transported overseas in an efficient manner. The paper also discusses other factors beyond techno-economic features that may affect the choice of optimum hydrogen carrier for long distance transport as well as the global trade of hydrogen.

The hydrogen economy is one of the possible directions of development for the European Union economy which in the perspective of 2050 can ensure climate neutrality for the member states. The use of hydrogen in the economy on a larger scale requires the creation of a storage system. Due to the necessary volumes the best sites for storage are geological structures (salt caverns oil and gas deposits or aquifers). This article presents an analysis of prospects for large-scale underground hydrogen storage in geological structures. The political conditions for the implementation of the hydrogen economy in the EU Member States were analysed. The European Commission in its documents (e.g. Green Deal) indicates hydrogen as one of the important elements enabling the implementation of a climate-neutral economy. From the perspective of 2050 the analysis of changes and the forecast of energy consumption in the EU indicate an increase in electricity consumption. The expected increase in the production of energy from renewable sources may contribute to an increase in the production of hydrogen and its role in the economy. From the perspective of 2050 discussed gas should replace natural gas in the chemical metallurgical and transport industries. In the longer term the same process will also be observed in the aviation and maritime sectors. Growing charges for CO2 emissions will also contribute to the development of underground hydrogen storage technology. Geological conditions especially wide-spread aquifers and salt deposits allow the development of underground hydrogen storage in Europe.