Hydrogen is the simplest and most abundant element in the universe. It is a major component of water, oil, natural gas, and all living matter. Despite its simplicity and abundance, hydrogen rarely occurs naturally as a gas on Earth. It is almost always combined with other elements. It can be generated from oil, natural gas, and biomass or by splitting water using renewable solar or electrical energy.
Once hydrogen is produced as molecular hydrogen, the energy present within the molecule can be released, by reacting with oxygen to produce water. This can be achieved by either traditional internal combustion engines, or by devices called fuel cells. In a fuel cell, hydrogen energy is converted directly into electricity with high efficiency and low power losses.
Hydrogen, therefore, is an energy carrier, which is used to move, store, and deliver energy produced from other sources.
Hydrogen is a clean fuel that, when consumed in a fuel cell, produces only water. Hydrogen can be produced from a variety of domestic resources, such as natural gas, nuclear power, biomass, and renewable power like solar and wind. These qualities make it an attractive fuel option for transportation and electricity generation applications. It can be used in cars, in houses, for portable power, and in many more applications.
Hydrogen is an energy carrier that can be used to store, move, and deliver energy produced from other sources.
Today, hydrogen fuel can be produced through several methods. The most common methods today are natural gas reforming (a thermal process), and electrolysis. Other methods include solar-driven and biological processes.
Thermal processes for hydrogen production typically involve steam reforming, a high-temperature process in which steam reacts with a hydrocarbon fuel to produce hydrogen. Many hydrocarbon fuels can be reformed to produce hydrogen, including natural gas, diesel, renewable liquid fuels, gasified coal, or gasified biomass. Today, about 95% of all hydrogen is produced from steam reforming of natural gas.
Water can be separated into oxygen and hydrogen through a process called electrolysis. Electrolytic processes take place in an electrolyser, which functions much like a fuel cell in reverse—instead of using the energy of a hydrogen molecule, like a fuel cell does, an electrolyser creates hydrogen from water molecules.
Solar Driven Processes
Solar-driven processes use light as the agent for hydrogen production. There are a few solar-driven processes, including photobiological, photoelectrochemical, and solar thermochemical. Photobiological processes use the natural photosynthetic activity of bacteria and green algae to produce hydrogen. Photoelectrochemical processes use specialized semiconductors to separate water into hydrogen and oxygen. Solar thermochemical hydrogen production uses concentrated solar power to drive water splitting reactions often along with other species such as metal oxides.
Biological processes use microbes such as bacteria and microalgae and can produce hydrogen through biological reactions. In microbial biomass conversion, the microbes break down organic matter like biomass or wastewater to produce hydrogen, while in photobiological processes the microbes use sunlight as the energy source.
A fuel cell uses the chemical energy of hydrogen or another fuel to cleanly and efficiently produce electricity. If hydrogen is the fuel, electricity, water, and heat are the only products. Fuel cells are unique in terms of the variety of their potential applications; they can provide power for systems as large as a utility power station and as small as a laptop computer.
Fuel cells can be used in a wide range of applications, including transportation, material handling, stationary, portable, and emergency backup power applications. Fuel cells have several benefits over conventional combustion-based technologies currently used in many power plants and passenger vehicles. Fuel cells can operate at higher efficiencies than combustion engines and can convert the chemical energy in the fuel to electrical energy with efficiencies of up to 60%. Fuel cells have lower emissions than combustion engines. Hydrogen fuel cells emit only water, so there are no carbon dioxide emissions and no air pollutants that create smog and cause health problems at the point of operation. Also, fuel cells are quiet during operation as they have fewer moving parts.
How Fuel Cells Work
Fuel cells work like batteries, but they do not run down or need recharging. They produce electricity and heat as long as fuel is supplied. A fuel cell consists of two electrodes—a negative electrode (or anode) and a positive electrode (or cathode)—sandwiched around an electrolyte. A fuel, such as hydrogen, is fed to the anode, and air is fed to the cathode. In a hydrogen fuel cell, a catalyst at the anode separates hydrogen molecules into protons and electrons, which take different paths to the cathode. The electrons go through an external circuit, creating a flow of electricity. The protons migrate through the electrolyte to the cathode, where they unite with oxygen and the electrons to produce water and heat.
Hydrogen – Power Plant
Hydrogen Plants could become a big player in the energy industry, with the potential of being a direct replacement for conventional fossil fuel plants. As an intermediate step, they could help to reduce emissions of current power plants. These approaches are dependent on the method of hydrogen production and there are two ways hydrogen plants can used:
1. The Renewable Way
One of the issues with current renewable energy technologies is the energy cannot be stored and must be used. When energy demand is low, this causes other energy sources to reduce output or be shut down temporarily in some cases. Hydrogen technology has the potential to fill this void.
Renewable energy is used to power electrolysers which will split water into hydrogen and oxygen. It is this hydrogen that can be stored and then converted back into electricity to meet the energy demands. This process is carried out using hydrogen fuel cells *link to fuel cell page/blurb*. This method utilises ‘green hydrogen’.
2. The Non-Renewable Way
Hydrogen plants can also be used to ‘recycle’ waste hydrogen form conventional power plants. The hydrogen from conventional plants is a by-product and is normally burned off. Although this still utilises fossil fuels, using a hydrogen plant in conjunction can create energy using this by-product meaning no air pollution. This is known as ‘blue hydrogen’.
Hydrogen plants can be zero-carbon or can help reduce emissions. Here is a list of hydrogen plant advantages:
- Energy security – can cope with variations in energy demand
- Zero carbon – dependant on hydrogen production method
- Quiet Operation