Decarbonization of power systems Is now a major topic of discussion for the energy industry. The first focus of the decarbonization initiative is the power generation sector, where, in recent years, the cost of solar and wind production has plunged drastically. Current scenarios suggest it can effectively compete with fossil fuel with no government support.
Carbon-dioxide (CO2) is the main culprit fueling the climate crisis a.k.a global warming. In attempts to bring world carbon footprint all the way down to zero, major countries, including France, Germany, China, Japan, the U.K., and the U.S. all are doing playing their role. Countries are taking initiatives, such as single-use plastic ban, increasing the use of renewable energy, tax subsidies for companies developing electric cars, requiring car companies to curb emissions, and many others. However, there is another effective way to reduce global CO2 reliance – Power to Gas (P2G) technique.
For several years, the energy sector utilized power generated from natural gas to yield significant CO2 savings. Soon the industry incumbent learned that continuing to burn fossil-derived natural gas will not be suitable for a long term objective of net-zero carbon footprint by 2050.
Today, sections of the gas industry are considering several other options to decarbonize the gas grid–
• Conversion of the gas network to hydrogen.
• More use of biogas/bio-methane
• Production of hydrogen or carbon-neutral methane through power to gas (P2G)
Power to Gas (P2G)
Human-made hydrogen and methane derived mainly from burning fossil fuels and biomass. The conversion of power to gas (P2G) means the use of renewable power supply to acquire these fuels through electrolysis and methanation. P2G relies on electrolysis – using electricity to separate water into its component elements of hydrogen (H2) and oxygen (O). Although the pilot P2G plants have been around since the late 1990s and early 2000s, commercial deployment started around five years ago. P2G is still in its nascent stage. The separated hydrogen can either be used directly – added to the present gas mix – or put through a second level that reacts to the H2 with CO2 to produce methane (CH4).
Methane is a vital element of natural gas; can be utilized directly in any regular gas application. The CO2 used in the methanation process is seized derived from the air, or biomass, to ensure a closed carbon cycle.
Methods of Power to Gas
There are two standard methods to convert power to gas – electrolysis, and methanation.
1. Electrolysis: The star for P2G is to use excess electricity to produce hydrogen with oxygen as a by-product. After several initial purifications, the electrolysis process is applied to water. There are three sub-methods of electrolysis-
A. Alkaline Electrolysis (AEL) is the most established technology, using an aqueous alkaline solution as the electrolyte. The technique is available for more than $1000/kw and takes around 30 to 50 minutes to restart the system after a shutdown. Since it consumes more time, it is less suitable for dealing with an intermittent power supply with continuous start and stops.
B. Polymer Electrolyte Membrane (PEM) is a newer technology than AEL; it is also available commercially. It costs over $2000/Kw and has shorter equipment lifespan than AEL.
C. Solid Oxide Electrolysis (SOEC) system has been coined more recently; is still at the laboratory level. Though the technique is not yet commercialized, makers say it will cost more than PEM and will be more efficient than the previous technologies.
2. Methanation: In the electrolysis process, nearly 10 U.S. gallons (38kgs) of water is required to produce to derive one kilogram of hydrogen. Hydrogen derived through electrolysis can be used in a further processing step, where it replaces a carbon source to produce methane. Methanation is an advanced process that is widely applied in industries. To be suitable for P2G applications, methanation requires to be adapted for intermittent operations. Currently following two types of methanation techniques are being tested in P2G experimental plants –
A. Catalytic methanation is a thermo-chemical process – occurring in the range of 200 to 750˚C – using a nickel catalyst. Though the industry is mainly dependent on this process, it is less suitable for intermittent operations.
B. Biological methanation converts H2 and CO2 to methane using methanogenic microorganisms. These microorganisms function under anaerobic conditions in an aqueous solution at a temperature ranging 20˚C to 70˚C. This process is more suitable for intermittent operations.
Application of Hydrogen derived through P2G
Although the P2G process first experimented between the late 1990S and early 2000s, it has got more attention in the last five years. Scientists have proposed several application of hydrogen derived via the process. There is a wide array of alternatives regarding how hydrogen can be used to decarbonize the energy grid.
1. The hydrogen can be used as a transport fuel. This is one of the highest value applications, mainly by replacing oil products for long-distance transportation, such as railways.
2. The hydrogen could also be used to produce heat, mainly suitable for industrial applications.
3. The excess hydrogen could also be stored and used later to generate electric energy through combustion or a fuel cell. In this, the P2G is performing a similar role to batteries, but with the storage potential.
4. The hydrogen can be utilized in the existing natural gas grid. There is a rising concord that a higher hydrogen content – as much as 1% and in some cases as high as 5%, could be put without having an impact on the gas grid. Some tests are being conducted to evaluate the impact of higher concentrations of hydrogen.
5. To directly decarbonize the natural gas network, the hydrogen can be utilized in the methanation process in which it is reacted with carbon source to produce biomethane suitable for deploying into the natural gas grid.
Is P2G Cost-effective?
Today, the P2G technology is not followed by every major country. While Europe is leading the race, Germany has only 30 experimental facilities in function; they are still far from making profits. The primary reason being the high cost of the process. The price is not anticipated to compete with fossil gas without government subsidies and regulations. P2G plants are capital-intensive. Even if facilities already exist in adequate numbers, there is no enough excess electricity is generated for the P2G process to be profitable.
Leading P2G Producers
• Hydrogenics (Canada)
• ITM Power (UK)
• McPhy Energy (France)
• Siemens (Germany)
• MAN Energy Solutions (Germany)
• Nel Hydrogen (Norway)
• Thyssenkrupp (Germany)
• Electrochaea (Germany)
• Exytron (Germany)
• GreenHydrogen (Denmark)
European countries are making huge investments in the P2G process. Countries like France and Germany have the largest share amongst others. In recent years, Germany has seen a growing demand for P2G technology, along with the growing requirement for hydrogen from chemical and fuel cell transportation in the country. In the western continent, Canada’s Hydrogenics is making significant progress in the industry.
Our think tanks predict that the P2G market will touch $42 million by 2024 from the current market worth of $26 million, at a compound rate of 10.1% every year.
1.What is Power to gas process?
In an eco-friendly power system; however, hydrogen could play a different role: as an important storage means and a medium of balancing power distribution grids: excess wind and solar energy can be utilized to produce hydrogen via water electrolysis. This process is known as power-to-gas.
2. Why is Methanatioin Important?
Methanation is a very crucial process. Especially in current natural setting where we seek to allievate CO2 emissions further and producing SNG from biomass through the methanation process does this rather than using natural gas. Methane is used in the gas that supplies our homes with energy and heating.
3. How can gas be converted into electricity?
Open cycle – natural gas is burned to produce pressurised gas which rotates the blades of a turbine linked to a generator. Inside the generator, magnets rotate, causing the electrons in wires to move, creating an electrical current – thus generating electricity.
4. How is electricity generated using hydrogen?
Currently, most hydrogen is made from natural gas. A fuel cell combines hydrogen and oxygen to produce electricity, water, and heat. Fuel cells are compared to batteries. Both convert the energy generated by a chemical reaction into usable electricity.