The president of the Spanish Hydrogen Association clarifies the main doubts that exist about this chemical element and its use as an alternative fuel Hydrogen is called to be one of the fuels of the future, a possible substitute for gasoline or diesel, and an alternative to electric plug-in cars. Although only one model, the Hyundai Nexo, can currently enroll in Spain, and although the number of possible refueling points can be counted on the fingers of one hand, in Europe and Asia this technology is taking more and more weight . In addition, you cannot deny the doubts that this fuel generates, both for its profitability and its safety in everyday use. That is why Javier Brey, president of the Spanish Hydrogen Association , resolves many of the myths that surround this chemical element as fuel for cars of the immediate future. In the first place, the profitability of hydrogen due to its “possible” high production costs is often questioned, questioning if it is feasible to assume it at present . According to Javier Brey, the cost of hydrogen production depends on the method used. “Traditionally, it has been produced through the steam reforming of natural gas. In this case, the cost depends directly on the cost of natural gas, to which the amortization of investment costs must be added in the reformer himself ». For more details about car accessories click on porsche panamera outdoor car cover.
However, in the case that hydrogen is obtained by electrolysis of water, Brey says that “the cost will be directly proportional to the electricity used in the process. With renewable electricity at 2.5 cents per kWh (prices that already exist in Asia or MENA, and which are already being reached in Europe or America) hydrogen produced by electrolysis is competitive with that produced by steam reforming of natural gasand, of course, it becomes a viable alternative fuel, “he says. In the case of using surplus renewable electricity, the production costs of this hydrogen would be minimal, since “it is an energy that would be lost if it were not stored in the form of hydrogen. On the other hand, the investment costs in the electrolysers have been reduced so drastically in recent years that they are already competitive with those of the natural gas reformers, and, in many cases, they are even much smaller ».
How hydrogen is obtained
Regarding the production of hydrogen for use as an alternative fuel, there are currently multiple methods, among which Brey explains which are the most developed: A first method is called “Refurbished with natural gas steam”. This process “combines methane (the main component of natural gas) with water vapor to produce carbon dioxide (CO2) and hydrogen through an endothermic chemical reaction (it requires adding heat to the process). It has been the traditional method, and the one that has been used the most to produce the hydrogen that the industry was demanding “. A second method is through the electrolysis of water . Thus, using electricity dissociates the water molecule in its components (hydrogen and oxygen) . Known for decades “now resurges strongly by the improvement of electrolysis and by the reduction in price of renewable electricity that we have had in recent years,” as recognized by the president of the Spanish Hydrogen Association.
The burning of natural gas (combining it with oxygen in combustion proportions) would not produce hydrogen, but carbon dioxide and water (and heat energy, or heat, obviously), which are the only products of the complete combustion of any hydrocarbon.
Where energy is obtained for electrolysis
Once the methods of obtaining hydrogen are known, the next question that arises is where the energy necessary for the production of electrolysis comes from, so that the entire process is as efficient as possible. According to Brey, the goal is to produce hydrogen by electrolysis using electricity from renewable sources . In this way hydrogen would be free of emissions not only during its use, but also during its production. The efficiency of the electrolysis process exceeds 80%. This means that for every kWh of electricity used we will obtain at least 0.8 kWh in the form of hydrogen (higher calorific value).
Each kWh is equivalent to 3.6 MJ and the higher calorific value of hydrogen is 141.86 MJ / kg. “By making some simple calculations we see that with 1 MWh it would be possible to produce more than 20 kg of hydrogen (equivalent to about 2500 km of autonomy in a fuel cell vehicle).” For those who doubt whether the production of hydrogen is polluting, the answer is that it will depend on the method used for production . Thus, Javier Brey explains that “currently, hydrogen is obtained mainly by reforming natural gas with water vapor, a process that emits CO2 (if in this process biogas was used, the net emissions of carbon dioxide would be zero). But this production has been the traditional one, oriented to the industrial sector that consumed hydrogen “. As Renewable Energies are implanted, the availability of renewable and cheap electric power increases. And so, “if hydrogen is obtained by electrolysis of water and the electricity used in this process is 100% renewable, hydrogen will be free of polluting emissions, not only in its use but also in its generation”. On the other hand, fuel cells are electrochemical devices, not thermal machines, and, therefore, their performance is not limited by the Carnot limit .
A fuel cell is an electrochemical device that directly transforms the chemical energy of a fuel into electricity efficiently, silently and reliably; it also produces heat and water. The fuel cell does not work by combustion, but by electrochemical means, so it reaches higher efficiencies than internal combustion engines. They do not have moving parts so they do not generate noise or vibrations and their maintenance is simpler. In addition, they do not generate polluting emissions, nor greenhouse gases; just water.
Danger, explosive gas!
Another of the great doubts that arise from the use of hydrogen as a fuel is its possibility to explode and burn. The Hindenburg airship , destroyed by a fire when it landed in New Jersey on May 6, 1937, is mentioned as an example on numerous occasions . Well, like any other fuel, for an explosion or combustion to occur, an oxidizer (oxygen) and a source of energy for ignition is required . The tanks that store the hydrogen in the car have great security measures and inside contain 99.99% hydrogen purity.
In addition, it must be borne in mind that hydrogen is a very volatile gas, which, in the case of a small leak , would dissipate rapidly and would not reach the concentrations necessary for explosive conditions. In closed spaces, such as garages, basic ventilation would be sufficient to guarantee safety. In addition, hydrogen is not toxic, so breathing a certain amount mixed in the air poses no health risks, and its impact on the environment is low. Javier Brey further explains that for more than a hundred years “hydrogen has been produced, transported and used for commercial and industrial purposes with an exemplary safety record”.
Applications of hydrogen as an energy vector already have standards and standards, as well as for other fuels, which have been developed and implemented to ensure safe transport and use. In this regard, it should be noted that the aerospace industry uses hydrogen as fuel without major incidents, and that hydrogen cars, which are already available in the market, have specific safety systems, have passed all the required tests and are as safe as any other vehicle in the market. In this regard, it is worth noting that the Hyundai Nexo(fuel cell electric vehicle) has obtained the maximum score of five stars in the Euro NCAP safety tests, thus becoming the safest SUV in the market. In short, hydrogen is a fuel that, like any other, managed with the proper rules and safety measures , is completely safe. But what could happen in the event of an accident? Being a flammable gas, it is more or less dangerous than if a gasoline car is set on fire? Bray explains that “as early as 2001 this was one of the biggest concerns for users. Therefore, Dr. Michael R. Swain, from the University of Miami , conducted an experiment in which subjected to two cars of identical characteristics, one with compressed hydrogen tanks and one with fuel tank, to the same eventuality : suffer a fuel leak that catches fire ».
In the following images, you can check what happened (car with hydrogen tanks on the left and with fuel tank on the right):
Hydrogen, being a very volatile gas escapes quickly upwards, and when it is ignited we can see a vertical flame that does not manage to damage any part of the vehicle . As time passes, the hydrogen in the tank is running out and the flame loses strength until it ends up extinguishing, leaving slight damage to the vehicle. On the contrary, gasoline, through the leakage caused in the tank, forms an aerosol that distributes small drops of fuel throughout the cabin, especially towards the lower areas. By igniting the fuel, the flames spread rapidly throughout the vehicle. At the end of the experiment the gasoline car ends up completely calcined, in total sinister conditions.
Can hydrogen be generated with the surplus of wind or solar plants?
Currently, the electrical system works in such a way that only the electricity that is going to be consumed is produced , the electricity demanded at that moment. This implies that there are no surpluses as such, what happens is that the facilities do not work at full capacity or even some are stopped or disconnected. That is to say “energy is being wasted that could be produced only because at that moment there is no demand”, according to the president of the Spanish Hydrogen Association. This problem becomes even greater as the percentage of renewable energy in the electric mix increases. «Non-manageable renewable energies (such as solar or wind energy) are intermittent and with a strong seasonal character. This implies that there will be moments of great renewable production in which a large part of the installed power is wasted and, at the same time, there can be weeks with low renewable production in which an extra contribution is required, to satisfy the demand “.
Therefore Javier Brey considers a large-scale energy storage system necessary and for long periods of time (including from season to year of the year); This is another of the great roles of hydrogen. In those moments in which the capacity of renewable electricity production exceeds the demand, instead of stopping those facilities, the electricity would be derived to electrolyser parks. “There, hydrogen would be produced to store it and transform it back into electricity, through the use of fuel cells, at a time when renewable production does not meet demand. Obviously, that hydrogen could be used for other uses, such as transport or industry. The International Agency for Renewable Energy, IRENA , highlights the role of hydrogen as a necessary complement to electricity in the energy transition. Hydrogen will allow coupling and decarbonizing four large sectors of the economy: industry, buildings, energy and transport, while increasing the flexibility of the electrical system and facilitating greater penetration of renewable technologies. The following diagram shows the role of hydrogen as an integrating element of the different renewable energy sources and end uses:
Integration of renewables to end-use applications using hydrogen
Integration of renewables to end-use applications using hydrogen – Hydrogen from Renewable Power: Technology Outlook for the Energy Transition “, IRENA, 2018
a.Energy: the capacity of hydrogen to store energy on a large scale and for long periods of time is especially useful to achieve a greater penetration of renewable energies in the electric mix (it allows to reach 100% of renewable energy in the generation mix electrical).
b.Industria: in Spain there are many industries that consume hydrogen as a raw material (refineries, biorefineries, ammonia factories, fertilizers …). The possibility of using hydrogen obtained from renewable energy sources both as a raw material and to obtain process heat would greatly contribute to the decarbonisation of this sector.
c.Residencial: the injection of hydrogen into the natural gas network would reduce the consumption of this fossil fuel, so used in the heating of buildings.
d.Transportation: the fuel cell electric vehicles will complement those of the battery. They expand the market of electric mobility to applications where batteries are currently limited (trucks, trains, buses, boats, trucks …), or providing the same autonomy and recharge capabilities as current vehicles
The “Hydrogen Council”, launched in January 2017 at the World Economic Forum , whose members include leading companies that invest along the hydrogen value chain, including transportation, industry and exploration, production and energy distribution, is currently the largest effort led by the industry to develop the hydrogen economy.
According to the vision that the Hydrogen Council has for the hydrogen economy in 2050, hydrogen is a central pillar of the energy transformation that is required to limit global warming to two degrees centigrade. To reach the two-degree scenario, the world will need to make dramatic changes year after year and reduce CO2 emissions related to energy by 60% by 2050.
