Renewable hydrogen is hydrogen produced by renewable energy, including wind, solar, tidal energy and hydro. When used in fuel cells, renewable hydrogen can produce power while only emitting water. It can be used in several ways, including long-duration storage, which will be necessary, transportation and reducing the carbon footprint of heavy industry by using hydrogen instead of fossil fuels.
Hydrogen (H2) is presented as an essential alternative for clean energy and raw material in the modern world. Nevertheless, H2 application as a renewable fuel is the most promising application for the future. Its main advantage is its cleanliness and low greenhouse gas emissions, determined by the hydrogen production pathway. Therefore, the study and understanding of every path are essential for the development and advance of the so-called “hydrogen economy”, mainly focused on green hydrogen.
The level of cleanliness of the energy produced from hydrogen is related to the amount of carbon emissions produced during hydrogen production — an interesting approach for classifying carbon emission during hydrogen production is the use of colour labels. The colour codes of the hydrogen production process might be the statement of sustainability from the suppliers to the consumers.
The most straightforward proposed model for the classification is based on three colours, according to the CO2 emission. Grey H2 is produced through the steam reforming process and uses fossil fuels as raw material. In addition, there is no restriction to carbon emission, and it is considered “dirty” hydrogen. Blue hydrogen also uses fossil fuels but includes some kind of carbon capture, decreasing the CO2 emissions. Some people also believe hydrogen produced using electricity from nuclear power to be blue. Today, it is essential to note that by far, most hydrogen being produced is either grey or blue.
On the other hand, green hydrogen is considered renewable hydrogen due to water as a source of H2 and renewable energy in the electrolytic process (water splitting process), which fits with the zero-emission carbon approach. Furthermore, if the input energy is renewable, the process would be clean; thus, it can lower environmental impact .
1.2 A world of opportunities
Roughly 95% of hydrogen is fossil-based. So, is green hydrogen purely theoretical?
Strategies setting us on the path to meet our climate goals of becoming net-zero by 2050 will position renewable hydrogen and associated technologies in the spotlight. We are beginning to see serious investment and new technological development that will make green hydrogen successful beginning now. There are many compelling examples of green hydrogen use around the globe, but we want to highlight too in this introductory section.
The first is in the Orkney Islands in northern Scotland, where tidal and wind energy have been successfully captured and used to make hydrogen, stored, used to supply power on the island, and used in vehicles. Soon, they will begin using that hydrogen to power ferries and heat schools.
Another exciting example comes from Australia, and that is where the government is working to build the Asian renewable energy hub. The goal is to use abundant wind and solar assets in Western Australia to export green hydrogen to parts of Asia, looking for a clean fuel source. This project could see the installation of 26 gigawatts of wind and solar projects and the creation of at least 3,000 jobs. As you learn from this article, investment in this technology is also happening in many other countries, and we certainly believe more is coming.
Figure 2 shows the global production of hydrogen by energy source in 2018. The total global production of hydrogen back then was 144 Mt, in which 67% of production was deliberate, and 33% was produced as a by-product of industrial processes . Most of the hydrogen produced today is made from fossil fuels; 48% of total hydrogen produced worldwide was derived from natural gas, H2 production from coal, primarily due to its popularity as an energy source in China, accounted for 18% of production. Oil and electricity each contributed 0.48%, and the balance was produced as a by-product of another industrial process such as sodium chlorate and chlor-alkali production.
Global demand for hydrogen in 2018 was 115 Mt-H2. Applications utilising pure hydrogen accounted for 60% (69 Mt-H2) of that. Pure hydrogen for oil refining and ammonia production was the most common end-uses, accounting for a combined 60% of total demand. The remainder of pure hydrogen use included transport, metals, electronics, chemicals, and glass-making industries. Demand for mixed hydrogen covered the remaining 46 Mt-H2 of the market with other end-uses such as heat generation from steelworks arising gases and by-product gas from steam crackers. Other uses of mixed hydrogen included the production of methanol and direct reduced iron steel.
2 THE GREEN HYDROGEN VALUE CHAIN
Water as feedstock
The world is rich in feedstocks such as solar radiation, water, and biomass. Coupled with a skilled labour force and strategic energy assets, many countries are well-positioned to become top global producers of clean hydrogen. The scale of projected hydrogen demand requires the development of all low-carbon intensity pathways across the world. Each region will have a unique mix based on local resources and economic factors.
The search for clean, renewable and environmentally friendly hydrogen sources has made water an excellent feedstock candidate to produce hydrogen . The production of clean H2 from water occurs by a system known as water splitting. Its simplest form uses an electrical current passing through 2 electrodes to complete the endergonic hydrolysis of water into hydrogen and oxygen. Nonetheless, it is essential to highlight that the Water splitting process can only be considered a good and eco-friendly alternative for green H2 production if the input energy in the electrolyser is being supplied from renewable energy sources; otherwise, this system would not produce a 100% green and clean hydrogen.
Wind energy is highly essential in energy sources since it is clean, renewable, and inexpensive. Furthermore, it has the potential to provide significant benefits to locations and nations with favourable wind conditions. However, one of the significant challenges for wind power utilisation is wind power plants are usually installed in places far from regions with high electricity consumption, resulting in long-distance transmission and high-power losses. Thus, the exploration of local use of wind power has been considered, and the utilisation of local green hydrogen production using electrolysers would be a great opportunity.
The greatest challenge for wind power utilisation for water electrolysis is that sometimes the wind-to-power conversion is inefficient; thus, the power would not supply the electrolyser’s requirements. Therefore, wind-power farms are usually installed close to the ocean or in other regions with constant and high wind velocities to overcome this challenge.
Solar energy is inexhaustible, clean, and the most abundant energy resource on Earth, providing more energy than global annual energy consumption in one hour (4.3 × 1020 J). Among the strategies to produce green hydrogen from water electrolysis using sunlight, two approaches have received significant attention and will be discussed. The first one is the direct conversion of solar energy to hydrogen in a photoelectrochemical cell. An electrolyser is powered by a photovoltaic cell in the latter, and the systems can operate independently.
The efficiency of the PEC cell depends on the light-harvesting capability of the semiconductor; e.g., the large bandgap of TiO2 (3.2 eV in anatase phase) restrains its application to absorption of UV-light, which corresponds to only 4% of the solar spectrum. In this sense, the modification of the electronic band structure of the semiconductors by doping has been proposed to extend the light absorption to the visible light region. Furthermore, semiconductors with a narrow bandgap, such as WO3, BiVO4, Fe2O3, and CdS, can be used as alternatives to TiO2. Researchers worldwide have worked hard in the past decades to improve efficiency and the costs of the hydrogen produced from a PEC, but this strategy is out of commercial applications.
The PV-electrolysis system can be more competitive than the above devices. In a PV system, the electrolyser’s energy input is supplied by PV devices connected. In a PV-electrolysis system, the solar panels capture solar light and transport the energy, usually via wires, to a separate electrolyser.
The greatest challenge faced by the development of these coupled devices is the achievement of high solar-to-hydrogen (STH) efficiencies due to a limitation to solar energy conversion. The improvement of STH efficiencies can be a significant driving force for reducing the H2 generation cost. Thus, some changes and modifications need to be made to the system to make it suitable. Using a multi-junction solar cell with two electrolysers in series, researchers found an effective way to minimise the excessive voltage generated by a multi-junction solar cell, allowing greater utilisation of the high-efficiency PV for water splitting STH efficiency of over 30% . Nonetheless, these prototypes still need to be improved and adapted to reduce the cost of H2 and make the use of electrolysers commercially suitable.
2.2 Distribution and storage
There are many innovative ways to distribute and store hydrogen. For example, Canada’s extensive natural gas pipeline network, in conjunction with additional storage and distribution infrastructure, may be used to transport the hydrogen from production to end-use locations. However, to ensure we are ready to take full profit of the many benefits of hydrogen, processes must be put in place to facilitate uptake of new technologies, hasten pipeline blending, and increase the number of refuelling stations all over the map.
Many gas companies are looking into using natural gas infrastructure to store and transport green hydrogen; some companies are also considered blending green hydrogen into the natural gas system to avoid supply constraints and clean up the system.
We can mention the example of Enbridge Gas, a firm that is supporting Ontario’s energy transition by investing in clean opportunities across multiple markets. This includes H2 and renewable natural gas produced from organic waste, which can green the supply by curtailing traditional or geological natural gas and reducing greenhouse gas emissions. These projects have the additional benefit of being local clean-energy solutions that use existing pipeline infrastructure.
Such a low carbon hydrogen-blending project is the first of its kind in North America. It is an essential step in greening the gas supply that millions of Ontario homeowners and businesses depend on to heat their homes and energise industry. In addition, the successful implementation will support Enbridge Gas in pursuing additional and larger scale H2 blending activities in other parts of its distribution system.
In October 2020, the Ontario Energy Board approved an application by the company to enhance the Markham Power-to-Gas facility to pilot the blending of renewable H2 gas into the existing natural gas network, reducing carbon emissions. This pilot project will initially provide a maximum hydrogen blended content of up to two per cent of the natural gas supplied to approximately 3,600 customers in Q3-2021, abating up to 117 tons of CO2 equivalent from the atmosphere. The project has alledged not to impact customer bills.
The transportation sector contributes a staggering 20 per cent of carbon emissions globally. Increased spendings on infrastructure will incentivise the adoption of zero-emission vehicles, including coordinated hydrogen refuelling infrastructure efforts focused on regional hubs. High profile, medium- and heavy-duty fuel cell EV pilot projects will help raise awareness and best practices for prototype deployments for goods and people moving in all sectors: on-road, rail, marine, and aviation.
Hydrogen is accelerating e-mobility into the future. Most fuel cell engine suites are designed as flexible power building blocks for transportation and stationary power products. Light duty applications are zero-emissions solutions for warehouse equipment manufacturers producing products like AGVs, small robotics, and aerospace UAVs, mid-range vehicles consist of delivery vans or light/medium duty cargo trucks used for on-road middle-mile delivery, heavy-duty applications comprise on-road trucking fleets for high utilisation last-mile delivery or long-haul trucking.
For example, ground support equipment is used in port fleets around the world – this includes deck loaders, airport baggage tractor tuggers, and belt loaders. Fuel cell-powered electric ground support equipment is today’s zero-emission answer to several issues with traditional diesel power. Case in point to longer-range, zero-emission fleets are a reality today. Fuel cell-powered fleet vehicles can achieve greater payload, higher range, and faster refuelling, all for a lower cost of ownership when compared to their battery counterparts. Also, drivers cite a smoother ride and quieter, cleaner experience over traditional vehicles.
2.4 Feedstocks for industry
Hydrogen can be used as feedstock in many industrial processes. For example, it can be used for decarbonising steel manufacturing and is an essential component for oil sands upgrading. Governments need to develop policies that will ensure long-term certainty to encourage private sector investments and innovation.
Steel is responsible for eight per cent of global carbon dioxide emissions annually, making it one of the biggest carbon emitters, and accounts for approximately 30 % of the global industrial CO2 emissions. In Europe, the steel industry aims at a CO2 reduction of 80–95% by 2050 , and so in February 2021, a new European H2 Green Steel industrial initiative was launched. It will produce 5M tons of high-quality CO2-free steel, mobilise 2.5B€ investments and create 10,000 jobs. The initiative has the scale, ambition, and innovative business model to become a flagship of the continent’s position at the forefront of the transformation of energy-intensive industries. This case is critical to delivering on Europe’s climate neutrality pledges.
Direct reduction processes and an electric arc furnace provide the basis for CO2 reduction in the steel industry. In using natural gas as a reducing agent, approximately one-third of the CO2 emissions can be saved compared to the conventional blast furnace/basic oxygen furnace route. But an alternative pathway to achieve a further reduction of CO2 emissions is the utilisation of renewable hydrogen as the energy source and reducing agent for the production of direct reduced iron.
As the reforming gases in the direct reduction process already comprise 55 % hydrogen, natural gas can be partly replaced by hydrogen and achieve a further reduction in carbon dioxide emissions. Ripke and Kopfle  stated that no changes are required for the existing processing plants up to a substitution rate of about one-third of the required natural gas. Using H2 as a reducing agent enables achieving higher reduction degrees from iron ore. Nevertheless, the reduction process is thermally unfavourable due to the endothermic nature of the reaction between hydrogen and iron oxide.
3 HYDROGEN OPPORTUNITIES
Developing an at-scale renewable hydrogen economy is a strategic priority for Canada, Germany, the U.S., and Chile. This is needed to diversify their future energy mix, generate economic benefits and achieve net-zero greenhouse gas emissions by 2050 (or before). This will require a radical transformation of the current energy system.
The world has all the ingredients necessary to develop a competitive and sustainable hydrogen economy. The research and consultations that led to advanced economies’ “hydrogen strategies” highlight how we can get there. In most research and consultations, the following cross-cutting themes emerged .
Attentiveness in the global energy transformation is proliferating, with projections indicating at least a tenfold increase in hydrogen demand in the coming decades. Since 2010, global demand for this fuel has grown by a moderate 28%. However, studies indicate that hydrogen, backed by the right incentives, investments, and policies, could provide between 18-24% of global energy demand by 2050, with some regions and countries being much higher.
Governments around the world are releasing and executing hydrogen strategies that are building global momentum. In 2020, the Netherlands, Norway, France, Germany, Spain, and the European Union as a unit seized this momentum by developing hydrogen strategies that eye up to a 200-fold increase in electrolyser capacity by 2030 . In 2019, Canada launched a new Hydrogen Initiative under the Clean Energy Ministerial, designed to be the cornerstone for global hydrogen deployment. In addition, Chile launched its national strategy in November 2020 , pursuing the world’s cheapest green hydrogen in 10 years. Its strategy sets a mark of 25 GW by 2030 with an outstanding hydrogen production cost of less than $1.50/kg.
Back in 2017, Japan became one of the first countries to implement a basic hydrogen strategy, and it has since set out detailed plans to become a “hydrogen society” . The strategy notably seeks to attain cost parity with competing fuels for power generation, such as liquefied natural gas. It has also outlined concrete cost and efficiency targets per application, targeting electrolyser costs of $475/kW, an efficiency of 70%, and a production cost of $3.30/kg by 2030. It also has multiple deals underway for international trade in H2. The Hydrogen Energy Supply Chain, for example, is entrusted to delivering hydrogen converted from coal gasification from Australia. The first liquid hydrogen ship was delivered by the end of 2019, and the first blue ammonia shipment arrived in Q3 2020.
The attraction to hydrogen is growing throughout the world. However, states need to act now to ensure we are not left behind. The time to act is now: the need to counteract climate change is driving a major restructuring of the world’s energy infrastructure. The development of an at-scale, renewable hydrogen economy is a strategic priority for many countries because they need to diversify their future energy mix, generate economic benefits and achieve net-zero emissions by 2050.
3.2 Signature projects
The South American nation is identified amongst the key strategical countries for H2 production  thanks to low-cost solar electricity. The Atacama Desert of Chile presents one of the highest global horizontal irradiation values globally, equal to more than 2 kWh/m2 with capacity factors beyond 30% for PV, which has experienced dramatic growth in its installed capacity the last years. The Atacama desert is also extremely promising for CSP plants, which can reach capacity factors beyond with estimated Levelised Cost of Electricity “LCOE” of 55 US$/MWh at utility-scale. Such extremely low-cost electricity can be competitively implemented for solar-driven electrolysis as an opportunity to increase the penetration of the abundant, economic and sustainable solar energy in the national energy matrix through solar fuels e particularly solar-hydrogen e both as domestic energy vector and for bulk exportation to other countries.
In the Chilean National Green Hydrogen Strategy, which was launched in 2020, solar energy is acknowledged as innovative technology. Business opportunities have been identified for the Atacama and Antofagasta regions in the North of Chile. But there is also important action in the windy south; Enel Green Power Chile, part of the Italian multinational energy giant, is leading a project to install a pilot renewable hydrogen production plant using an electrolyser powered by wind energy Punta Arenas, in the southernmost Magallanes Region.
Islands are ideal polygons and showcases for the demonstration of individual hydrogen technologies and the entire mini hydrogen, that is, “hydricity” economies. There are already several ongoing or proposed demonstrations of the integrated hydrogen systems on islands worldwide . They vary in size from kW to MW and in scope from a refuelling station to a complete autonomous island energy supply.
The PURE (Promoting Unst Renewable Energy) project is situated on the island of Unst in the Shetland Islands in the most northern part of Scotland. The area has some of the best wind and wave energy sources in Europe. The system consists of two 6 kW wind turbines that provide electric power to heat five business units directly. Excess electricity from the wind turbines is used to produce hydrogen, which can then be stored and is also used to fuel a fuel cell/battery hybrid vehicle and for a backup power unit consisting of a 5 kW fuel cell and an inverter.
The world’s largest green-hydrogen plant became operational near Linz in November 2019. The cutting-edge facility has a 6 MW capacity and generates hydrogen through electrolysis powered by renewable power. Located at a site owned by steel manufacturer Voestalpine, the carbon-neutral plant is a testing ground for scaling up hydrogen operations to an industrial level, potentially decarbonising “hard-to-abate” industries like steel, cement and chemicals production .
Globally, steel accounts for between 7-9% of all direct emissions from fossil fuels. Mitsubishi Heavy Industries is working with Voestalpine to develop a steel production process using hydrogen, potentially replacing the fossil fuels that currently power steelmaking.
Wind power installed in Spain at the end of 2020 reached 27,370 MW, making it the first power generation technology, with an electricity demand coverage of around 28% .
In Spain, two categories of mini-grid systems could be developed. One is related to the peninsula area, where very few electrically isolated areas exist. Still, where they do, energy supplies are usually provided by diesel generators or very small hybrid renewable installations (wind/photovoltaic) with batteries for storage. Islands are the other application for which hydrogen mini-grids are appropriate; an example is the RES2H2 project situated in the Canary Islands. The RES2H2 project implemented a wind–hydrogen prototype system, financed by the Fifth Framework Programme of the European Commission; the system was put into operation in 2007.
The prototype installed in Spain was designed to satisfy a theoretically isolated village’s electricity and water needs (mini-grid type). When the electricity supply exceeded the theoretical demand, a 100 kW alkaline electrolyser used excess electricity to produce 0.99 kg of hydrogen per hour at 25 bar (5500 Nm3 of storage), and a reverse osmosis plant (40 kWe of nominal power) also used this excess electricity to produce a maximum of 110 m3 per day of desalinated water. When power from the wind turbine did not cover the demand, the stored hydrogen was used in six 5 kW PEM fuel cells to produce electricity.
Wind + solar + storage
A small pilot-scale system was developed and installed at Matiu/Somes Island in Wellington Harbor to evaluate the real-world potential for hydrogen energy storage. This “remote” island is powered by a hybrid renewable energy system, including wind and solar PV generation, backed up by a diesel genset. In addition, an electrolyser based hydrogen storage system has been installed to evaluate the technology readiness level and commercial potential for this type of technology. The hydrogen gas is currently used to substitute for LPG in cooking applications and will also be used in the future for instant water heating.
The UNIDO-ICHETs Bozcaada Wind-Solar Hydrogen project, on a Turkish Bozca Island, aims to study how hydrogen and renewable energies can be integrated into stand-alone applications for the powering of island communities. This experimental power plant supplied by AccaGen produces electricity thanks to a 20 kW solar photovoltaic array and a 30 kW set of wind turbines and stores an equivalent amount of energy as hydrogen via a 50 kW electrolyser. Then, at times of grid failure or peak demand, the stored hydrogen can be converted back into electricity using a 35 kW hydrogen engine and a 20 kW fuel cell, allowing uninterrupted electricity supply to the equivalent of twenty households for up to 24 h.
4 PROMISING TECHNOLOGIES
4.1 General applications
Nowadays, one of the most important applications of hydrogen is in the petrochemical industry, including hydrocracking (hydrogenation to produce refined fuels with smaller molecules and higher H/C ratios) and hydroprocessing (hydrogenation of sulfur and nitrogen compounds to further remove them as H2S and NH3) for the purification of petroleum and fuels.
Besides, hydrogen is essential in the base industry primarily through the synthesis of ammonia from the direct reaction with N2 at high temperatures and pressure in the well-known Haber-Bosch Process. It is worth mentioning that ammonia is fundamental for fertilisers production and the improvement of agricultural performance. Hydrogenation can also be applied to decrease unsaturation in fats and oils and some fine chemical synthesis.
Hydrogen has been used in the electronics industry as a protective and carrier gas, in deposition processes, for cleaning, and in etching and reduction processes. Another example is its use in the metallurgic industry in the reduction stages and in the direct reduction of iron ore, which involves separating oxygen from the iron ore using hydrogen and synthesis gas (syngas).
A strategic application of the H2 is to consider it as a fuel, being applicable for direct combustion, by itself or in some blends with natural gas. Also, Fuel Cells (FCs), where it can provide reliable and efficient energy power, can be used in stationary power stations and as a good candidate for vehicles.
Although presenting great potential for several applications, according to a sense from 2018 , 51.70% of total H2 worldwide is used for refining, 42.62% is used for ammonia production, and only 5.68% is used for other applications, including its use as a clean and renewable fuel.
4.2 Leveraging low-cost renewables and other low-carbon tech
There exist different low-carbon hydrogen production methods. However, low-carbon and low-cost hydrogen developments are still limited. Low-carbon H2 includes hydrogen from renewable electricity, blue hydrogen and aqua hydrogen (hydrogen from fossil fuels via the new technology). Green H2 is an expensive strategy compared to fossil-based hydrogen. Blue hydrogen has some attractive features, but the carbon capture use and storage (CCUS) technology is high cost, and blue H2 is not inherently carbon-free. As a result, engineering experts have focused on creating additional low-cost, low-carbon hydrogen technologies.
In Western Canada, a novel, cost-effective technique for extracting hydrogen from oil sands (natural bitumen) and oil fields has been developed and marketed. Aqua hydrogen is term specialists have coined for the production of hydrogen from this new technology. Aqua is a colour that is halfway between green and blue. It depicts a type of hydrogen production that does not generate CO2, like green hydrogen but is created using fossil fuel energy, like blue hydrogen. Unlike CCUS, which is compensatory concerning carbon emissions as it captures, uses and stores produced CO2, the advanced method is transformative in that it does not emit CO2 in the first place. To promote the development of the low-carbon hydrogen economy, the current challenges, future directions and policy recommendations of low-carbon hydrogen production methods, including green hydrogen, blue hydrogen, and aqua hydrogen, are investigated in the paper.
Plug Power is one of the world’s leading providers of clean hydrogen and zero-emission fuel cell solutions. Their first green hydrogen plant will be located in Pennsylvania, U.S — they are working with partners at Brookfield on that which will be their hydro plant. This will be their first 10 ton/day 100 per cent green hydrogen plant; it is expected to be up and running producing hydrogen fuel by the end of 2022.
The firm is also finalising the location of a power purchase agreement powered by wind assets. It consists of a large wind farm in Texas which is the source of electricity to produce 30 tons/day of green H2. But what’s exciting here apart from just also being the green hydrogen is that Plug Power has been able to source the correct cost of 24/7 renewable electricity, which allows them actually to produce this hydrogen at cost parity and sell it at a similar price to grey hydrogen while still maintaining the margin and getting the return on these assets as we are making those investments .
5 WHY GREEN HYDROGEN NOW?
Over the last years, clean energy enthusiasts have been engaging with stakeholder groups to develop a strategy that will set them on the path to meet their climate goals of becoming net-zero by 2050. This will position some states and companies as world-leading producers, users and exporters of renewable hydrogen and associated technologies.
Blending low-carbon intensity hydrogen into existing natural gas networks for use in both industry and the built environment — i.e. heat and power — provides the most significant demand opportunity for hydrogen. In addition, there is an opportunity in identifying synergies between hydrogen and other bio-based renewable fuels, along with creating a market for low-carbon products being used in domestic infrastructure. Amongst the plethora of possible international trading routes, those which link coastal strategic H2 producers such as Chile (Atacama Region), Argentina (Patagonia Region), Australia, North Africa (Morocco, Algeria), Middle East (Saudi Arabia, Iran) and coastal strategic H2 importers such as Japan, USA (California), Northern Europe and Korea stand out.
In addition to the political momentum behind green hydrogen, there is a financial incentive: according to an article in Forbes , there are more than U$S 90 billion of hydrogen projects under development today — although not all of them are green — and significant demand is already materialising. Moreover, renewable hydrogen can solve many problems as we work towards a 100% emission-free power system.
To begin with, there is an increasing amount of intermittent renewable energy assets that are added onto the grids, and we all know that wind doesn’t always flow, the sun doesn’t always shine, sometimes power is too low, sometimes it is too much, and the power demand is now being decoupled with the generation. H2, mainly when produced using renewable energy that would otherwise have been curtailed, are both capable of long-term storage and rapid ramping, meaning it can precisely match the dispatchable resources that the grid will need.
The renewable sector needs sustained support for innovation across the value chain to ensure (energetically) transitioning economies maintain their competitive edge. Activities can be coordinated across regional research centres that boost specific expertise and fundamental collaborations between public and private-sector researchers domestically and internationally.
 Dawood, F.; Anda, M.; Shafiullah, G. M. ; International Journal of Hydrogen Energy 2020, 45, 3847.
 Germscheidt, R. L., Moreira, D. E., Yoshimura, R. G., Gasbarro, N. P., Datti, E., dos Santos, P. L., & Bonacin, J. A. Hydrogen Environmental Benefits Depend on the Way of Production: An Overview of the Main Processes Production and Challenges by 2050. Advanced Energy and Sustainability Research, 2100093.
 Jia, J., Seitz, L. C., Benck, J. D., Huo, Y., Chen, Y., Ng, J. W. D., … & Jaramillo, T. F. (2016). Solar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30%. Nature communications, 7(1), 1-6.
 Gallardo, F. I., Monforti Ferrario, A., Lamagna, M., Bocci, E., Astiaso Garcia, D., & Baeza-Jeria, T. E. (2020). A Techno-Economic Analysis of solar hydrogen production by electrolysis in the north of Chile and the case of exportation from Atacama Desert to Japan. International Journal of Hydrogen Energy. doi:10.1016/j.ijhydene.2020.07.050
 Barbir, F. (2016). Hydrogen Islands–Utilisation of Renewable Energy for an Autonomous Power Supply. Hydrogen Science and Engineering: Materials, Processes, Systems and Technology, 1075-1096