Sustainable and energy efficient hydrogen production via glycerol reforming techniques: A review

Hydrogen-based energy solutions are among the alternative energy choices due to their clean emissions and high efficiency. H₂ is a highly convenient energy source, particularly if derived from sustainable feedstock. With the renewed emphasis on biodiesel production globally, large quantities of glycerol are expected to be produced as a major by-product. Reforming of this glycerol can provide a sustainable and H₂-rich feedstock. The study reveals that 7H₂ molecules were produced/molecule of glycerol in GSR, which is much higher than the commercially available SRM process. This also endorses the concept of circular economy and the 3Rs (Reuse, Reduce, and Recycle) by utilization of a by-product. This review highlights the recent advancements in different types of glycerol reforming technologies for H₂ production. The highly endothermic reaction and the coking of Ni-based catalysts are still the main limitations in its commercialization. It has been found that among different glycerol reforming techniques, the GSR is the finest with the least drawbacks. Hence, corresponding solutions to overcome these obstacles are deliberated.     

Trends in design of distributed energy systems using hydrogen as energy vector: A systematic literature review

Currently, a significant transformation for energy systems has emerged as a result of the trend to develop an energy framework without fossil fuel reliance, the concerns about climate change and air quality, and the need to provide electricity to around of 17% of world population who lacks the service. Accordingly, the deployment of power plants located close to end-users and including multiple energy sources and carriers, along with the growing share of renewable energies, have suggested changes in the energy sector. Despite their potential capabilities, the design of distributed energy systems (DES) is a complex problem due to the simultaneous goals and constraints that need to be considered, as well as to the high context dependence of this kind of projects. For these reasons, in this work a systematic literature review of DES including hydrogen as energy vector, was made analyzing 106 research papers published between the years 2000–2018, and extracted from Scopus^® and Web of Science databases. The aim was to identify how hydrogen is employed (technologies, uses) and the criteria that are evaluated (economic, technical, social and environmental) when these systems are designed, planned and/or operated. The results constitute a baseline information covering the type of technologies, equipment sizes and hydrogen applications, that could be valuable for the preliminary stages of research or project planning of DES involving hydrogen. Furthermore, other factors have also been identified, such as the focus on techno-economic issues, and the lack of considering socio/political aspects and the uncertainty about input data like weather conditions, energy prices and demands. Additionally, a more integrated approach is needed including all the hydrogen supply chain stages and project stakeholders, to tackle issues like safety of the energy systems that could produce consumer rejections.     

How the hydrogen production from RES could change energy and fuel markets: A review of recent literature

The goal that the international community has set itself is to reduce greenhouse gas (GHG) emissions in the short/medium-term, especially in Europe that committed itself to reducing GHG emissions to 80–95% below 1990 levels by 2050. Renewable energies play a fundamental role in achieving this objective. In this context, the policies of the main industrialized countries of the world are being oriented towards increasing the shares of electricity produced from renewable energy sources (RES).In recent years, the production of renewable energy has increased considerably, but given the availability of these sources, there is a mismatch between production and demand. This raises some issues as balancing the electricity grid and, in particular, the use of surplus energy, as well as the need to strengthen the electricity network.Among the various new solutions that are being evaluated, there are: the accumulation in batteries, the use of compressed air energy storage (CAES) and the production of hydrogen that appears to be the most suitable to associate with the water storage (pumped hydro). Concerning hydrogen, a recent study highlights that the efficiencies of hydrogen storage technologies are lower compared to advanced lead acid batteries on a DC-to-DC basis, but “in contrast […] the cost of hydrogen storage is competitive with batteries and could be competitive with CAES and pumped hydro in locations that are not favourable for these technologies” (Moliner et al., 2016) [1].This shows that, once the optimal efficiency rate is reached, the technologies concerning the production of hydrogen from renewable sources will be a viable and competitive solution. But, what will be the impact on the energy and fuel markets? The production of hydrogen through electrolysis will certainly have an important economic impact, especially in the transport sector, leading to the creation of a new market and a new supply chain that will change the physiognomy of the entire energy market.     

Hydrogen in energy transition: A review

The energy transition is not something that awaits us in the next decade. On the contrary, it is a process in which we are already deeply enrolled. The main step towards the creation of a carbon-neutral society is the implementation of renewable energy sources (RES) as replacements for fossil fuels. Given the intermittency of RES, energy storage has an essential role to play in this transition. Hydrogen technology with its many advances was recognized to be the most promising choice. As multiple hydrogen applications were researched relatively recently, the current development of its technology is not yet on the large-scale implementation level. With the increasing number of studies and initiated projects, the utilization of hydrogen's immense ecological potential is to be expected in the next few decades. New innovative solutions of hydrogen technology that includes hydrogen production, storage, distribution, and usage, are permeating all industry sectors. In a rapidly changing world, technological advances bring forth public discussions, that are a deciding factor whether society will be able to adapt and accept those new contributions or reject them. Currently, hydrogen is the best associated with fuel cell electric vehicles which emit only water vapour and warm air, producing no harmful tailpipe emissions. As various scientists are stressing the gravity of climate change effects that are reaching the physical environment, ecosystems, and humanity in general, concern for the future is becoming the main global topic. Consequently, governments are implementing new sustainable policies that promote RES as a substitute for fossil fuels. Increasing progress in hydrogen technology instigated nations worldwide to incorporate hydrogen in their energy legislations and national development plans, which resulted in numerous national hydrogen strategies. This work shows the progress of hydrogen taking its place as a key factor of the future green energy society. It reviews recent developments of hydrogen technologies, their social, industrial, and environmental standing, as well as the stage of transitioning economies of both advanced and beginner countries. An example of the ongoing energy transition is Croatia, which is in the process of implementing a hydrogen strategy with the ambition to be able to one day equally participates in the rapidly emerging hydrogen market.     

Towards sustainable energy systems: The related role of hydrogen

The role of hydrogen in long run sustainable energy scenarios for the world and for the case of Germany is analysed, based on key criteria for sustainable energy systems. The possible range of hydrogen within long-term energy scenarios is broad and uncertain depending on assumptions on used primary energy, technology mix, rate of energy efficiency increase and costs degression (“learning effects”). In any case, sustainable energy strategies must give energy efficiency highest priority combined with an accelerated market introduction of renewables (“integrated strategy”). Under these conditions hydrogen will play a major role not before 2030 using natural gas as a bridge to renewable hydrogen. Against the background of an ambitious CO₂-reduction goal which is under discussion in Germany the potentials for efficiency increase, the necessary structural change of the power plant system (corresponding to the decision to phase out nuclear energy, the transformation of the transportation sector and the market implementation order of renewable energies (“following efficiency guidelines first for electricity generation purposes, than for heat generation and than for the transportation sector”)) are analysed based on latest sustainable energy scenarios.     

An economic survey of hydrogen production from conventional and alternative energy sources

A source of hydrogen is needed in the developing hydrogen economy, and many technologies are available for producing hydrogen from both conventional and alternative energy resources such as natural gas, coal, atoms, sunlight, wind, and biomass. The following paper summarizes the economics of producing hydrogen from each of these sources and gives an overview of the energy resource for each feedstock. The results of the analysis show that the most economical sources of hydrogen are coal and natural gas, with an estimated cost of 0.36–1.83 $/kg and 2.48–3.17 $/kg for each energy source, respectively. Alternative energy provides hydrogen at a higher cost; however, fossil fuel feedstock costs are increasing as technology enhancements are decreasing the cost of alternative energy sources, and therefore alternative energy sources may become more economical in the future.     

Renewable and hydrogen energy integrated house

The residential sector accounts for about a third of the total world energy consumption. Energy efficiency, Renewable Energy Sources and Hydrogen can play an important role in reducing the consumptions and the emissions and improving the energy security if integrated (Efficiency, Res, Hydrogen) systems are developed and experimented. The paper analyzes a real residential 100 square meters house, where energy efficiency measures and RES technologies have been applied, sizing a hydrogen system (electrolyzer, metal hydrides and fuel cell) for power backup, taking into consideration its dynamic behavior, experimentally determined. The technologies used are already available in the market and, except hydrogen technologies, sufficiently mature. Through energy efficiency technologies (insulation, absorbers, etc), the maximum electrical and thermal power needed decreases from 4.4 kW_e to 1.7 kW_e (annual consumption from 5000 kWh to 1200 kWh) and from 5.2 kW_t to 1.6 kW_t (annual consumption from 14,600 kWh to 4500 kWh) respectively. With these reduced values it has been possible to supply the consumptions entirely by small photovoltaic and solar thermal plants (less than 10 m² each). The hydrogen backup even if remains the most expensive (versus traditional batteries and gasoline generator), satisfying all the electric needs for one day, increases the security and allows net metering. Moreover the low-pressure hydrogen storage system through metal hydrides guarantees system safety too. Finally the system modularity can also satisfy higher energy production.     

Biomass-based hydrogen production: A review and analysis

In this study, various processes for conversion of biomass into hydrogen gas are comprehensively reviewed in terms of two main groups, namely (i) thermo-chemical processes (pyrolysis, conventional gasification, supercritical water gasification (SCWG)), and (ii) biological conversions (fermentative hydrogen production, photosynthesis, biological water gas shift reactions (BWGS)). Biomass-based hydrogen production systems are discussed in terms of their energetic and exergetic aspects. Literature studies and potential methods are then summarized for comparison purposes. In addition, a biomass gasification process via oxygen and steam in a downdraft gasifier is exergetically studied for performance assessment as a case study. The operating conditions and strategies are really important for better performance of the system for hydrogen production. A distinct range of temperatures and pressures is used, such as that the temperatures may vary from 480 to 1400 °C, while the pressures are in the range of 0.1–50 MPa in various thermo-chemical processes reviewed. For the operating conditions considered the data for steam biomass ratio (SBR) and equivalence ratio (ER) range from 0.6 to 10 and 0.1 to 0.4, respectively. In the study considered, steam is used as the gasifying agent with a product gas heating value of about 10–15 MJ/Nm³, compared to an air gasification of biomass process with 3–6 MJ/Nm³. The exergy efficiency value for the case study system is calculated to be 56.8%, while irreversibility and improvement potential rates are found to be 670.43 and 288.28 kW, respectively. Also, exergetic fuel and product rates of the downdraft gasifier are calculated as 1572.08 and 901.64 kW, while fuel depletion and productivity lack ratios are 43% and 74.3%, respectively.     

Explaining hydrogen energy technology acceptance: A critical review

The use of hydrogen energy and the associated technologies is expected to increase in the coming years. The success of hydrogen energy technology (HET) is, however, dependent on public acceptance of the technology. Developing this new industry in a socially responsible way will require an understanding of the psychology factors that may facilitate or impede its public acceptance. This paper reviews 27 quantitative studies that have explored the relationship between psychological factors and HET acceptance. The findings from the review suggest that the perceived effects of the technology (i.e., the perceived benefits, costs and risks), and the associated emotions, are strong drivers of HET acceptance. This paper does, though, highlight some limitations with past research that make it difficult to make strong conclusions about the factors that influence HET acceptance. The review also reveals that few studies have investigated acceptance of different types of HET beyond a couple of applications. The paper ends with a discussion about directions for future research and highlights some practical implications for messaging and policy.     

Control of vehicular emission using innovative energy solutions comprising of hydrogen for transportation sector in Pakistan: A case study of Lahore City

Energy, either from non-renewable or renewable sources, is of paramount importance as the progress of a country is gauged on economic development. However, with the use of non-renewable energy resources, the environmental degradation is exacerbating with every passing day in developing countries including Pakistan. On the contrary, the developed countries are resorting to sustainable and renewable energy resources to achieve sustainable development goals. The primary consumer of the non-renewable energy sources is transportation sector in Pakistan, with the total consumption amounting to almost two-third of the total utilization. Keeping in view the existing energy expenditures and its share in environmental pollution by transportation sector, Lahore Metropolitan area has been selected for this research paper. This research analyzed the environmental data collected from multiple road junctions of Lahore City. In light of the existing data, the research exhibited improvements in overall environmental quality by comparing the existing and proposed energy solutions comprising of Hydrogen in transportation sector. The comparison carried out by utilizing International and National Environmental quality standards. Additionally, research also addresses the energy savings with the transition from non-renewable energy sources to renewable and innovative energy solutions.     

Life cycle assessment of three types of hydrogen production methods using solar energy

A comprehensive life cycle assessment (LCA) is carried out for three methods of hydrogen production by solar energy: hydrogen production by PEM water electrolysis coupling photothermal power generation, hydrogen production by PEM water electrolysis coupling photovoltaic power generation, and hydrogen production by thermochemical water splitting method using S–I cycle coupling solar photothermal technology. The assessment also contains an evaluation of four environmental factors which are global warming potential, acidification potential, ozone depletion potential, and nutrient enrichment potential. After conducting a quantitative analysis of all three methods with environmental factors being considered, a conclusion has been drawn: The global warming potential and the acidification potential of the thermochemical water splitting by S–I cycle coupling solar photothermal technology are 1.02 kg CO₂-eq and 6.56E-3 kg SO₂-eq. And this method has significant advantages in the environmental impact of the whole ecosystem.     

A hydrogen economy and its impact on the world as we know it

An assortment of governmental, technological, environmental, and economic factors has combined to spur renewed interest in alternatives to petroleum, and especially in hydrogen. While there is no clear consensus on the viability of the technology, governments and corporations alike have vigorous hydrogen research programs. The result is that hydrogen may stand on the verge of becoming a true successor to oil. A transition from oil to hydrogen would alter familiar global economic and political structures in profound ways. The ramifications will influence developed and developing nations, oil importers, and exporters alike. New alliances among governments, corporations, and other groups may challenge existing notions of governance. Although a hydrogen-based economy may be decades away, the vision for it requires near- and mid-term thinking to manage the transition smoothly. Further, hydrogen is only a metaphor; any change from the current oil economy will entail dramatic changes to the global status quo that must be planned for now.     

Wind energy and the hydrogen economy—review of the technology

The hydrogen economy is an inevitable energy system of the future where the available energy sources (preferably the renewable ones) will be used to generate hydrogen and electricity as energy carriers, which are capable of satisfying all the energy needs of human civilization. The transition to a hydrogen economy may have already begun. This paper presents a review of hydrogen energy technologies, namely technologies for hydrogen production, storage, distribution, and utilization. Possibilities for utilization of wind energy to generate hydrogen are discussed in parallel with possibilities to use hydrogen to enhance wind power competitiveness.     

Dynamic and energy analysis of a liquid piston hydrogen compressor

Liquid piston compressor is the most promising compressor to be used for hydrogen-refueling stations. However, their energy transfer and the energy dissipation processes of are poorly studied and not well understood. In this paper, a new energy analysis method for an ionic-liquid type liquid piston compressor is proposed. In the compressor section, porous media is used to promote heat transfer from the hydraulic oil during the compression process. A mathematical model has been formulated considering the heat transfer and damping effects of the porous media on the compressor performance. Moreover, the compressibility of the hydraulic oil and its overflow loss on the compressor performance were also established. In the model, the seven stages of the entire working cycle of the compressor were look into in detail, alongside with its energy efficiency. The results show that the key parameters governing the energy efficiency of the compressor are the heat transfer efficiency of the compressor and the overflow losses of the hydraulic oil.     

Role of hydrogen storage in renewable energy management for Ontario

Effective energy storage and management is needed to manage intermittent renewable energy systems. Several jurisdictions around the world are planning to reduce or close their coal power plants to allow for renewable energy expansion, such as Ontario, Canada. Hydrogen storage, which is a promising energy storage option, is capable of meeting energy requirements that will arise from the shutdown of coal plants. In this paper, both economic and environmental feasibility of a hydrogen system linked with wind and hydroelectric plants in Ontario will be investigated. The Princefarm wind power plant and Beck1 hydro plant with production capacities of 189 MW and 490 MW, respectively, are analyzed in a case study for comparison purposes. The environmental analysis demonstrates the advantageous role of hydrogen storage and energy conversion. The overall system life-cycle yields 31.02 g CO₂ eq per 1 kW h power output of the system when hydrogen energy storage is adopted. The payback periods of the systems linked with the Princefarm and Beck1 are also analyzed and found to be about 17 years.     

Metal hydride hydrogen compressors: A review

Metal hydride (MH) thermal sorption compression is an efficient and reliable method allowing a conversion of energy from heat into a compressed hydrogen gas. The most important component of such a thermal engine – the metal hydride material itself – should possess several material features in order to achieve an efficient performance in the hydrogen compression. Apart from the hydrogen storage characteristics important for every solid H storage material (e.g. gravimetric and volumetric efficiency of H storage, hydrogen sorption kinetics and effective thermal conductivity), the thermodynamics of the metal–hydrogen systems is of primary importance resulting in a temperature dependence of the absorption/desorption pressures). Several specific features should be optimised to govern the performance of the MH-compressors including synchronisation of the pressure plateaus for multi-stage compressors, reduction of slope of the isotherms and hysteresis, increase of cycling stability and life time, together with challenges in system design associated with volume expansion of the metal matrix during the hydrogenation.     

Energy system aspects of hydrogen as an alternative fuel in transport

Considering the enormous ecological and economic importance of the transport sector the introduction of alternative fuels—together with drastic energy efficiency gains—will be a key to sustainable mobility, nationally as well as globally. However, the future role of alternative fuels cannot be examined from the isolated perspective of the transport sector. Interactions with the energy system as a whole have to be taken into account. This holds both for the issue of availability of energy sources as well as for allocation effects, resulting from the shift of renewable energy from the stationary sector to mobile applications. With emphasis on hydrogen as a transport fuel for private passenger cars, this paper discusses the energy systems impacts of various scenarios introducing hydrogen fueled vehicles in Germany. It identifies clear restrictions to an enhanced growth of clean hydrogen production from renewable energy sources (RES). Furthermore, it points at systems interdependencies that call for a priority use of RES electricity in stationary applications. Whereas hydrogen can play an increasing role in transport after 2030 the most important challenge is to exploit short–mid-term potentials of boosting car efficiency.     

Hybrid energy management with respect to a hydrogen energy system and demand response

A Hybrid Energy System (HES) is a mechanism that combines multiple sources of energy connected together to achieve synchronised energy output. However, increased energy consumption, operator energy expenses, and the potential environmental impact of increased emissions from the exhaustion of non-renewable energy resources (fossil fuel) pose major challenges to HES. This research is to conduct energy management strategy based on a demand response (DR) program and a hydrogen storage system by designing a Program Logic Controller (PLC) unit. The hybrid system is evaluated by comparing different scenarios such as a hydrogen energy system and demand response. The purpose of this research is to reducing peak demand, minimise the cost of the system and also to extract surplus power generation out of the rate of the battery. This can be achieved by improving the system performances and by eliminating any degradation at the early stages. Organisations or companies must be sure their systems are working properly and that their investments will pay off.     

A comprehensive review on power-to-gas with hydrogen options for cleaner applications

This review presents the power-to-gas concept, particularly with hydrogen, from renewable energy sources to end-use applications in various sectors, ranging from transportation to natural gas distribution networks. The paper includes an overview of the leading related studies for comparative evaluation. Due to the intermittent/fluctuating phenomena of most renewables, power-to-hydrogen appears to be a promising option to offset any mismatch between demand and supply. It is a novel concept to increase the renewability of fuels and reach a sustainable energy system for future transportation, power and thermal process sectors. Comparisons of different hydrogen production methods fed by several energy sources are made regarding environmental impact, cost and efficiency. The present results show that hydrogen production (with power-to-hydrogen concept) via polymer electrolyte membrane electrolyser has lower environmental effects than other traditional methods, such as coal gasification and reforming and steam methane reforming. The geothermal energy-based system has the lowest levelized cost of electricity during hydrogen production, while natural gas has the highest value. The best option for the plant efficiency is found for high-temperature steam electrolysis fed from biogas, while the lowest efficiency value belongs to polymer electrolyte membrane electrolyser driven by solar photovoltaics, respectively.     

The competitiveness of Korea as a developer of hydrogen energy technology: The AHP approach

Korea's need for energy conservation and alternative energy is greater than for any other nation. Korea imports more than 97% of its total energy consumption and ranks 10th in the world in terms of energy consumption. Developing hydrogen energy technology has great potential to cope with Korea's energy security and to establish Korea's hydrogen economy. In this study, we analysed the potential of Korea to be competitive in development of hydrogen energy technology using the analytic hierarchy process (AHP) approach. In this paper, two scenario analyses are presented: in the first, the R&D budget is a criterion and in the second it is not. The results show that Korea is the sixth most competitive nation because of the low score for infrastructure required for hydrogen technology. In addition, compared with US results for both scenarios, patents, papers and proceedings, R&D budgets, and infrastructure for hydrogen technology are inferior to the US, which is ranked in first place for this sector. Korean policymakers have to concentrate on those sectors to strengthen Korea's competitiveness in the development of hydrogen energy technology.