On May 6 in 1937, New Jersey became home to one of the most widely known disasters in history – the Hindenburg disaster. The German passenger airship exploded with 36 fatalities and the most widely accepted hypothesis for the cause of the explosion was that the hydrogen used for buoyancy had been ignited by a static spark. A radio broadcast of the event was made famous by Herbert Morrison exclaiming on air “Oh, the humanity”. Aside from the significant human tragedy of the day, it was also a disaster for the reputation of hydrogen.
The world today however faces a new challenge; the serious negative effects of burning fossil fuels, and the need to use more environmentally friendly, clean energy. Among these technologies, Hydrogen Energy Storage and Fuel Cells seem to have the most promising future.
Recent technological developments are promising a better economic viability to the hydrogen production process, its non-pollutant fuel condition and its facility to storage and transporting are making green hydrogen highly attractive as an alternative to fossil fuels. Everything suggests that we are witnessing the start of a hydrogen-use boom. The aim of this article is to help provide a good introduction about hydrogen utilization as a reserve energy, as well as a non-polluting fuel. We will also look to briefly explain the key developments and limitations of the technology.
What is hydrogen?
Hydrogen is the most abundant chemical element in the universe. In its pure state, it is a non-toxic, odourless and colourless gas. Even though there are no hydrogen deposits in its pure state in the earth's crust, its combination of two hydrogen atoms with one oxygen atom produces the most abundant substance on the planet: water. It is highly flammable and has a high specific energy.
What is Hydrogen Energy Storage?
There are multiple methods of energy storage, which depend on the type of energy to be stored, which can be: Chemical, Biological, Electrochemical, Electrical, Mechanical, or Thermal energy. Hydrogen Energy Storage is a chemical energy storage method that consists of obtaining Hydrogen from water, through the electrolysis process, and storing it in special containers or tanks, for future use as a fuel source. The stored hydrogen can then be used to produce electricity, either in large thermoelectric plants or in fuel cells for cars and other transports.
Why it works as energy storage?
Hydrogen works as an energy store because several reasons:
It has a very high specific energy or energy value per unit mass (between 120 and 142 MJ/kg or 33.3 kWh/kg), almost 3 times the value of gasoline (44 MJ/kg or 12 kWh/kg) and other fuels.
Its combustion with oxygen only produces heat and water as waste, so it is non-polluting. According to a study conducted by McKinsey, for the Hydrogen Council, hydrogen could reduce CO2 emissions by around 6 metric Gt, based on 2017 values.
The main process used for its production, water electrolysis, is a relatively simple and technologically mature process. At present, technological advances have been developed that make this process more efficient and economical.
Storage and transportation can be done safely. It can be stored in a gaseous state in high-pressure metal tanks, or in a liquid state (for which cryogenic equipment is used).
What makes hydrogen “green hydrogen”?
Although hydrogen is a colourless gas, the term “green hydrogen” is applied to the hydrogen produced using non-polluting energy sources (such as solar or wind) to generate the electrical energy required in the Electrolysis process.
Hydrogen as a fuel
Hydrogen can be used as fuel, either burned on a large scale (as in thermoelectric plants), or on a smaller scale in fuel cells for electric cars and other transportation.
As mentioned earlier, hydrogen has one of the highest specific energy values of all known fuels (between 120 and 142 MJ/kg). This factor, together with the absence of polluting emissions and the high efficiency of the fuel cells used in cars, make it very attractive as a fuel source.
According to the Alternative Fuels Data Center (AFDC) of the U. S. Department of Energy (DOE), a hydrogen fuel cell coupled to an electric motor is between two to three times more efficient than an internal combustion machine running on gasoline. There are several types of fuel cells that work with hydrogen, the Polymer Electrolyte Membrane (PEM) fuel cell type being the most used in automobiles.
Key future developments in green-hydrogen economy:
Existence of hydrogen in a natural state is very scarce. Expensive industrial processes are necessary to obtain it. Currently, these processes aren´t that efficient and mostly employ polluting energy sources. Water electrolysis is one such processes. It consists in circulating an electric current through water in a tank that causes evaporated hydrogen and oxygen to split, these are then collected and packed in pressurized vessels.
The main disadvantage of electrolysis is its high production cost. Electrolysis is energy-intensive. It also requires the use of highly expensive and scarce metal catalysts, such as platinum and iridium. These catalysts aren’t able to withstand for a long time the high temperatures or the highly acidic environment present in the process.
Technological advances in increasing efficiency and reducing the electricity cost production through photovoltaic cells and wind energy have improved the use of electrolysis. Many facilities are already using non-polluting solar and wind energies to generate the necessary electricity in this process.
One of the most ambitious proposals in this regard is that of the joint team between Tractebel Engineering and Tractebel Overdick. These engineering firms claim they have developed a technology to produce hydrogen through electrolysis, using reconditioned offshore platforms powered by wind farms near these platforms.
Recently, researchers from the School of Chemistry at Monash University, in Australia, led by Dr. Alexandr Simonov, have gone public with the discovery of more economical and resistant catalysts than platinum and iridium. The researchers engineered a self-recovering system, in which it is possible to reuse the dissolved electrode-material. In traditional electrolysers, this material can’t be reused.
A similar project involving a team of researchers from the University of Arkansas, United States, led by professors Jingyi Chen and Lauren Greenlee, recently published in the journal Nanoscale their discovery that the use of nickel and iron-based nanocatalysts help to weaken the links between oxygen and hydrogen, allowing their separation to be faster. This discovery and its subsequent scalability for industrial use would make the electrolysis process more efficient and less expensive.
Commercial interest for green-hydrogen powered vehicles
In the transportation sector there is an increasing interest in the reduction of carbon dioxide (CO2) emissions by different players in the sector. This interest has been mainly motivated by the urgent need to meet the goals established in the 2015 United Nations Climate Change Conference, COP 21 (Paris Agreement). According to the United Nations Climate Change website: “The Paris Agreement central aim is to strengthen the global response to the threat of climate change by keeping a global temperature rise this century well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius.”
One of the main leads in this regard has been the creation, in January 2017, of the Hydrogen Council, “the largest industry-led effort to develop the hydrogen economy”. This Council has been constituted by the principal companies across the entire value chain associated with transportation, industrialization, energy sources, and hydrogen production and distribution.
By November 2017, this Council published a remarkably interesting report “Hydrogen Scaling-UP Study” that includes all the short, medium and long-term projections and actions necessary to meet the goals of the Paris Agreement. Among these projections, the following stand out in the transportation sector:
Medium and large-sized hydrogen-powered vehicles will be available for sale in the next 5 years from 2017. Then, when costs go down, smaller vehicles will be marketed.
The Fuel Cell Electric Vehicles (FCEVs) will be the most commercialized, since they are the ones that best meet the performance requirements.
An equivalent percentage to 8,33% (1 in 12 ) of all cars sold in California, Germany, Japan, and South Korea could be powered by hydrogen by 2030. Likewise, the Council estimates that “more than 350,000 hydrogen trucks could be transporting goods, and thousands of trains and passenger ships could be transporting people without carbon and local emissions”.
By 2050, hydrogen would cover 18% of global energy demand; The CO2 emission will reduce by 6 Gt; Hydrogen and equipment sales would reach about US $ 2.5 trillion and up to 30 million jobs would create in the sector.
Germany’s BMVI (Federal Ministry of Transport and Digital Infrastructure) has taken action that demonstrates the commitment to green-hydrogen development as a replacement for fossil fuels in the European transportation.
The BMVI recently approved €23.5 million to finance several hydrogen mobility projects such as a hydrogen-powered bus, a fuel-cell-powered street sweeper, forklift trucks and a fleet of 50 fuel cell vehicles to tap into a popular urban mobility concept: ride pooling, a comfortable and secure shared-trip service designed to decongest traffic in highly inhabited cities. Andreas Scheuer, Minister of BMVI, stated that clean energy sources such as hydrogen and fuel cells would be fundamental elements in achieving the goal of a transportation system free from the use of polluting fuels.
SImilarly, the Korean multinational Hyundai has taken a great step forward in the race towards the green-hydrogen economy, by publicly announcing at its FCEV Vision 2030” Conference that they expect to manufacture up to 500,000 fuel-cell vehicles by 2030, as well as another 200,000 vehicles for industrial use. According to their estimates, by 2030, “the global market for hydrogen-powered road vehicles will be two million vehicles”.
Chung Eui-sun, executive vice-chairman of the Hyundai Motor Group states that Hyundai will help hydrogen becomes an economically viable energy source and expands its use beyond the transportation sector, to achieve a global society based on clean energy.
There have been other smaller-scale actions, which confirm that, step by step, the green-hydrogen economy is occupying relevant spaces in the most important cities of the globalized world. One of them is that of the British corporate-taxi company Green Tomato Cars, which has just acquired another 25 FCVE Toyota taxis, to join them to its existent fleet of 27 taxis acquired in 2015.
Jonny Goldstone, founder and CEO of Green Tomato Cars, states that both passengers and drivers enjoy the trip and, above all, the pleasant feeling of acting responsibly with the environment.
A short cut to hitting climate targets
The election of the new European Commission’s president, German minister of defence Ursula von der Leyen, in July 2019, opens up great opportunities to speed up the development of green hydrogen production technologies. Von der Leyen made it clear that climate and environment issues will have priority on her agenda. In the speech previously to her election, the minister promised to increase the short-term objective of reducing greenhouse gases by 2030 from a current 40% to at least 50%, respect to 1990 levels. Von der Leyen also announced the proposal of a “Green Deal for Europe”, during her first 100 days. This Deal would include new legislation for Europe to be carbon-neutral in 2050 and the first continent in the world to be climate-neutral.
Experts suggest that, once she takes office in November 2019, one of von der Leyen's first actions would be the revision of gas legislation (gas package) to focus on the so-called “gas decarbonisation package” (GDP). In this new legislation, decarbonisation potential of gas would be prioritized. Replacing coal by gas in coal-fired power plants, as well as increasing the production of green gases, such as biogas and hydrogen produced with renewable energy (solar or wind) would be the GDP’s pillars. Due to current high production cost of green-hydrogen, experts believe that the transition from fossil fuels to green hydrogen will be a gradual process.
Economics indicate there will be a transition stage, where blue hydrogen would be the main actor, since its production cost is cheaper than green hydrogen. Though there would be a greater emphasis on carbon capture technology for any blue hydrogen. However, recent and future technological advances to improve the efficiency of both electrolysers and renewable energies will significantly reduce the production cost of green hydrogen; in August 2019 Bloomberg New Energy Finance (BNEF) announced that the cost of producing green hydrogen could drop dramatically by 2030, reaching levels that would make it competitive with the price of natural gas.
Limitations of Hydrogen as a Technology
The high production cost is the main obstacle that hydrogen has to overcome to replace fossil fuels.
As mentioned earlier, the electricity-intensive use and very expensive metal electrodes makes the hydrogen production process expensive. As already discussed, this limitation could be overcome thanks to current and future technological advances to improve the efficiency of electrolysers and wind and solar conversion equipment.
Another limitation is that the current hydrogen production process still produces CO2 emissions at a level that is not compatible with future targets for reducing pollutant emissions by 2030, and zero-emissions by 2050. Though most experts remain optimistic that this limitation can be gradually overcome by applying CO2 reduction technologies, such as carbon capture and storage.
It is likely that hydrogen is going to play an increasingly large role in our lives going forward and we should all get ready for the hydrogen boom.