Hydrogen fuel cells

Technological development and changes in the global industry force a constant need to look for new sources of energy. When it comes to batteries, the emphasis is now not only on high efficiency, capacity and efficiency, but also on ecology and the ability to work in various conditions. Hence, the whole problem comes down to the reconciliation of many factors, and the solutions proposed by the manufacturers focus on delivering specialized devices to the market. The electrolyte or the use of substances that, with their properties and parameters, will affect the efficiency of energy sources is also important. The breakthrough in this field turned out to be fuel cells, which, as electrochemical devices, allow to obtain electricity and heat from the reactions taking place in them. In short: cells convert the chemical energy of fuels such as hydrogen, methane, butane, methanol or gasoline into electricity.

DACPOL, addressing these needs and responding to market expectations, introduced hydrogen-based solutions to its offer, which in the future will be expanded with other energy sources. We currently offer PEM fuel cells of various power and installations that are complete power systems including a ventilation system, converter and housing.

Hydrogen - the simplest and lightest element

It is the simplest (one proton and one electron) and the lightest (14 times lighter than air) chemical element that begins the periodic table, accounting for about three-quarters of the mass of the universe. Hydrogen is contained in water that covers about 70% of the Earth's surface, and is also present in all organic matter. Hydrogen under normal conditions is a colorless gas, tasteless and odorless, slightly soluble in water (0.021 vol. H2 in 1 vol. H2O at 0°C). The low critical temperature of hydrogen (-239.9°C) makes its condensation more difficult than that of air and most other gases. The liquefied hydrogen is a colorless liquid with a specific weight of 0.07 g / cm3. Due to its low molecular weight (2.0158), hydrogen gas has the lowest specific weight among all gases - 0.08988 g / l at 0°C and 1 atm. Compared to gases, it also has a high diffusion rate and is the best heat conductor among them. It is a combustible gas, it burns with a clean, carbon-free and soot-free flame. In comparison with other popular fuels such as gasoline, methane and propane, hydrogen has a significantly higher calorific value, heat of combustion, ignition energy and flame speed.

Hydrogen storage

High RES shares in the power system may require long-term and seasonal storage, for example to supply electricity for several days with very little wind and sunlight.

Hydrogen and hydrogen fuels such as methane, Liquid Organic Hydrogen Carriers (LOHCs), and ammonia produced from electricity by electrolysis are potential options for long-term and large-scale energy storage. Salt caverns are the best choice for underground pure hydrogen storage due to their tightness and low risk of contamination. Alternative underground hydrogen storage options are also being explored, such as caves, aquifers, and oil and gas recovery sites.

Converting electricity into methane using energy produced from natural gas is another long-term hydrogen storage option.

Pure hydrogen is, in most cases, stored in pressurized tanks. Few of the materials of construction used in the manufacture of tanks suitable for hydrogen storage are available as it increases their brittleness considerably. Currently, the best solution is ultralight composite materials that can withstand pressures above 20 bar. They are used in prototypes of cars and buses. These include:

• Metal tanks made of steel, with a pressure of 200 bar, or of aluminum, with a maximum pressure of 175 bar.
• Aluminum tanks reinforced with glass, aramid or carbon fibers, withstanding maximum pressures above 250 bar.
• Cylinders made of fiberglass / aramid or carbon fiber composites with metal insert, withstanding maximum pressures of 305 and 438 bar respectively.
• The cylinders are made of typical carbon fiber covered with a polymeric layer that can withstand pressures above 661 bar.

Carbon nanofibers may become the material of the future for the construction of hydrogen tanks, including carbon nanotubes - structures with unique electrical and mechanical properties, resembling a mat woven of carbon ropes under an electron microscope. They conduct heat well and exhibit high strength, which makes them one of the strongest and stiffest materials discovered today.

Some tanks are used for long-term hydrogen storage and others for continuous filling and emptying.

Hydrogen is also stored in liquid form. Liquid hydrogen tanks can be used in transport and portable devices. The technology of producing liquid hydrogen, however, requires a large amount of energy, because as it is compressed, it must be cooled to a very low temperature (-252.87°C).

The most important advantage of storing hydrogen in liquid form instead of gaseous form is that it takes up a much smaller volume.

Liquefied hydrogen has been used as rocket fuel in internal combustion engines and fuel cells. When hydrogen is burned in a rocket engine, large amounts of energy are produced, releasing water and traces of ozone and hydrogen peroxide.

Typical applications

• Argon-hydrogen mixtures are used as shielding gases in plasma and TIG welding. These mixtures are used primarily in the welding of austenitic stainless steel and some nickel alloys.
• Hydrogen in combination with argon can also be used to produce plasma cutting compounds (mainly for stainless steel and aluminum). In the glass industry, hydrogen is used to polish the edges.
• Hydrogen is also used in the production of carbon steels, special metals and semiconductors.
• In electronics, it is commonly used as a reducing agent and carrier gas.
• Other hydrogen-based processes include hydrotreating of petroleum products, flue gas desulphurization, metal heat treatment and leak testing. Hydrogen is also used in various petrochemical and chemical processes.
• Hydrogen is used to supply the flame in industrial and laboratory burners.

PEM Fuel Cells

PEM technology (Proton Exchange Membrane or Polymer Electrolyte Membrane) consists in supplying fuel cells with pure hydrogen or reformate. In such a situation, the membrane is a polymeric material, e.g. Nafion. A characteristic feature of PEM cells is high efficiency in the production of electricity - up to 65% - and a small amount of heat released. The great advantage is also the good tracking of the cell in systems subjected to changing loads, as well as the short start-up time. These properties result from the low temperature of the reaction taking place in the cell: 60 - 100°C.

The electrolyte allows the flow of cations, but prevents the flow of electrons. The chemical reaction that takes place in the cell consists in breaking down the hydrogen into a proton and an electron at the anode, and then joining the reactants at the cathode. Electrochemical processes are accompanied by the flow of an electron from the anode to the cathode, bypassing the impermeable membrane. The electrochemical reaction of hydrogen and oxygen produces electricity, water and heat. Fuel - hydrogen pure or mixed with other gases - is fed continuously to the anode, and the oxidant - pure oxygen or a mixture (air) - is fed continuously to the cathode.

The fuel cell is not theoretically discharged. In fact, degradation or failure of components limits its service life. The main application of PEM cells is in vehicle drives and construction of stationary or portable energy generators.

Fuel cells advantages

High reliability - no moving parts, high quality of supplied energy. The energy supplied by the fuel cells is very resistant to disturbances. Fuel cells are an ideal source of power for medical devices, measuring devices, computers, etc. Fuel cells are characterized by high efficiency and energy density. A fuel cell is always smaller and lighter than other energy sources of comparable power. The efficiency of fuel cells in generating electricity reaches up to 50%. In the process of cogeneration, electricity and heat production, fuel cells achieve efficiency of up to 85%. We can use various types of fuel in fuel cells. Fuel cells can run on any hydrogen-rich fuel. Obtaining hydrogen from fuel can take place inside the fuel cell, the so-called internal reforming or outside the link in an external device called fuel reformer. Due to the phenomenon of electrolysis, hydrogen for a fuel cell can be produced using alternative energy sources. Pollution resulting from the production of energy using "conventional" methods is the cause of environmental degradation and the emergence of new civilization diseases. The fuel cell produces 25 times less pollution compared to combustion generators. In the case of fuel cell supply with hydrogen, the amount of pollutants produced is traceable. Individual fuel cells can be linked together to achieve the desired level of generated power (scalability). Fuel cell assemblies of various shapes are used both to power a single light bulb and to power industrial machinery. The use of PEM cells also includes vehicle drives and the construction of stationary or portable energy generators.

The principle of operation of a fuel cell is well known, and progress is currently made in the development of materials for the construction of electrodes, membranes, seals and catalysts. The aim of the research is to extend the life and efficiency of the cell while reducing its production costs. In addition, new technologies for the production of cell components are being developed by replacing machining with precise spraying technologies. The results of the research are already visible to end users: the life cycle of fuel cells is lengthening and the price of energy produced is decreasing at the same time.

DACPOL's offer includes not only the supply of fuel cells themselves, but also ready-made systems and support in the field of work with hydrogen technology. The simplest model of cooperation is to design and build a hydrogen cell tailored to the individual needs of the user. The requirements may concern not only electrical parameters, but also environmental requirements and working conditions, application or special execution. The production stage is in fact the last stage of the entire process, which begins with the exact identification of the customer's needs and the determination of the next design steps.

The characteristic features of the cells supplied by DACPOL are:

• High energy density, which is related to the properly designed microstructure of the elements that make up the stack,
• Simplified structure making the stack more compact, lighter and more effective than similar solutions,
• Scalability to build larger (more powerful) solutions.

In addition to supplying only hydrogen cells as energy sources, DACPOL also offers the possibility of building a complete hydrogen-based power supply system for the customer. Such a solution includes a cell, a heat exchanger, a converter and a casing providing mechanical protection with assembly. We will also help you select the appropriate components when the user already has some of the above-mentioned elements. system.