Hydrogen in Gas Turbines:
The use of hydrogens as gas turbine fuels has been demonstrated commercially, but there are differences between natural gas & hydrogen that must be taken into account in order to properly and safely use hydrogen in gas turbines.
#1. Burning Hydrogen
In addition to the difference in the combustion properties of hydrogen and natural gas, it is important to consider the impact on all gas turbine systems as well as the overall balance of the plant. In power plants with one or more hydrogen-fueled turbines, changes to the fuel components, down-cycle components, and plant protection systems may be required.
GE’s extensive field experience enables our engineers to understand the implications of using hydrogen as a gas turbine fuel. Since gas turbines are inherently fuels-flexible, they can be configured to operate on green hydrogen or similar fuels as a new unit or even after extended service on conventional fuels, i.e., natural gas. It can be upgraded.
The scope of modifications required to configure gas turbines to operate on hydrogen depends on the initials configuration of the gas turbines and the overall balance of the plant, as well as the desired hydrogens concentrations in the fuels.
#2. Story of Hydrogen
Commercial use of hydrogen as a gas turbines fuels has been shown, but there are differences between hydrogen & natural gas that must be considered in order to properly and safely use hydrogen in gas turbines. In addition to variations in combustion properties, the effect on all gas turbines systems as well as the totals balance of plants must be considered.
Power plants with one or more hydrogen-fueled turbines require the replacement of fuel components, down-cycle parts, and plant protection systems. Since the gas turbine is inherently fuel-flexible, it can be designed to run on greens hydrogen or similar fuels as new units or after years of operation on conventional fuels such as natural gas.
The extent of modifications required to convert a gas turbine to run on hydrogen is determined by the initial configuration of the gas turbine and the overall balance of the plant, as well as the hydrogen concentration required in the fuel.
How Hydrogen Turbines Work:
The animations below briefly explain how hydrogens turbines work. It is clear that integration has far-reaching benefits. The hydrogens turbine is based on a new integration of existing & proven components. This first hydrogen turbine will start the production of hydrogen for the Duval project: a broad consortium initiative in the region of North Holland overseen by HYGRO.
The consortium aims to create a green hydrogen production chain, achieve distribution to at least five hydrogen filling stations & be able to supply hydrogens to 100 trucks. And all this must be achieved together. The ENERCON wind turbines with a capacity of 4MW will be fitted to integrate electrolysis technology.
Due to the integrations of turbines and electrolysis, many components could be omitted, and hydrogen production would become less expensive, more efficient, & reliable. The hydrogen turbines, the first of their kind, will be demonstrated at ECN’s Wind Turbine Test Area in Wieringermeer.
First, the hydrogens are brought under high pressure & transported by road to filling stations. For the foreseeable future, we see hydrogen turbines connected directly to the hydrogen gas grid. The gas infrastructure would then act as a buffer to coordinate demand and supply.
As shown in the following figures, hydrogens can be generated from various feedstocks and chemical processes. Photosynthesis with algae, natural gas steam methane reformation (SMR), partial oxidation of crude oil, coal gasification, and water electrolysis are just a few examples. The following sections will go over steam’s methane reformation and electrolysis as potential hydrogen-production routes for energy production.
#1. Steam Methane Reforming
Most of the hydrogen steam generated today comes from methane reformation. A large portion of this hydrogen is used in the manufacture of ammonia for fertilizers or petrochemicals. In this process, natural gas methane is reacted with water and heat to form H2 and CO2 through two reactions:
- CH_4+H_2O\rightarrow CO+3H_2CH4+H2O→CO+3H2
- CO+H_2O\rightarrow CO_2+H_2CO+H2O→CO2+H2
Accords to these equations, one mole of CO2 & four moles of H2 is formed for every mole of methane use. Using the molecular weight of each part, 0.5 kilograms of H2 & 2.75 kilograms of CO2 are produced for every kilogram of methanes consumed. Every kilogram of H2 products creates 5.5 kilograms of CO2.
Accords to the GE reports, in terms of the volumes needed for power generation, a single 6B.03 gas turbine operates for 8,000 hours per year will consume about 33 million kg of H2 (per year). SMR would produce 178,000 metrics tons of CO2 per year if hydrogens were produced this way.
For certain gas turbines platforms, the following table presents the rates of CO2 output when scaled to hydrogens productions.
Despite the fact that generating hydrogens through SMR produces carbon dioxide, several projects are considering combining it with carbon capture & sequestration (CCS) to generate hydrogens.
The H21 Leeds City Gate and the Magnums Vattenfalls Project are two examples that are looking at using SMR to generate hydrogen.
The City of Leeds projects is expected to generate 2.4 billion m3 of hydrogens each year, and enough to provides heat & electricity to about 660,000 people.
A 90 percent carbon captures device is being considered part of these systems, which will capture about 1.5 million tonnes of CO2 annually. In the Netherlands, the Magnum Vattenfalls project proposes to converts existing gas turbines to run entirely on hydrogens.
The proposed plans are to produce hydrogen from natural gas, in which CO2 is collected and stored as a byproduct in underground bunkers. Transmitting hydrogen and storing it in power plants are also open issues.
The challenges of these projects are to generates carbon-free electricity using technology that requires large-scale CO2 separation. However, there are technologies that can produce H2 without releasing CO2.
#2. Water Electrolysis
The electrolysis of waters is a well-known process for the production of hydrogen. The chemical reactions that split waters are as follows:
H_2O\rightarrows H_2 + 1/2~O_2H2O→H2+1/2 O2
For every mole of water used in these reactions, one mole of hydrogen and half a mole of oxygen are produced. Using the molecular weight of each component, each gram of water would yield 0.11 grams of hydrogen & 0.89 grams of oxygen. Note how the total mass remains constant.
In other words, 9 grams (9 kg) of water are needed to produce 1 gram (1 kg) of hydrogen, with no losses in the electrolysis process. Using this knowledge, it is possible to determine the amount of water needed to support the power to hydrogen theory.
The tables below show how much water is needed to produce enough hydrogen to run the various GE gas turbines according to their report at 100 percent hydrogen.
For comparison, an Olympics-sized swimming pool requires 2500 m3 of water; electrolyzers producing hydrogens for typical gas turbines would use the same amount of water in about 250 hours just over ten days.
Running gas turbines on a hydrogen/natural gas mixture instead of 100% hydrogen not only reduces hydrogen flux but also reduces the amount of water needed to produce hydrogen.
Electrolysis often requires the use of electricity to separate water molecules. The high heat value (HHV) of hydrogen divided by the electrolyzer system efficiency determines the amount of power required:
“Electrolyzer Power” = HHV/\eta“ElectrolyzerPower”=HHV/η
The HHV of hydrogen is 12,756.2 kJ/Nm3 (141,829.6 kJ/kg), which translate to 3.54 kWh/Nm3 (39.39 kWh/kg). Water-to-hydrogen conversion requires 5.45 kWh/m3 (60.61 kWh/kg), assuming 65 percent efficiency is the electrolyzer system, a commercially available technology.
As well as increasing the performance of the electrolyzer, running a gas turbine on a mixture of hydrogen and natural gas will reduce some of the power requirements.
Hydrogen Combustion Evolution:
For many years, the heat from the burning of coal was used to boil water, overheat the steam, and then expand it through a turbine/alternator to generate electricity. The Rankine cycle is a form of conventional power generation.
Another method of generating electricity was by burning natural gas in compressed air, expanding the heated combustion products through an electric turbine, and using shaft power to drive both the compressor and generator, a process known as gas turbine arrangement known as the Breton Cycle.
Additional energy can be generated by using hot exhaust gases to lift steam into the turbine/alternator and produce additional electricity. A combined-cycle gas turbine is a name given to this combination (CCGT).
Two technical routes were built after environmental damage to trees and land was related to sulfur dioxide (SO2) emissions from coal flue gas of power plants. One option was to clear the SO2 from the flue gas, while the other was to gasify the coal to make the synthetic gas Syngas, a mixture of carbon monoxide & hydrogen.
Syngas is pumped into gas turbines, which burn in the same way as natural gas. Sulfur species will be removed from syngas using chemical processes designed for the petrochemical industry. This operation (IGCC) was named Integrated Gasification Combined Cycle. Since the characteristics of the fuels gas differed, differents combustion regimes were required for gas turbines.
Meanwhile, NOx development has raised health & environmental concerns. Low-NOx burners & selective catalytic reduction were used in coal-fired power plants. Gas turbine manufacturers have designed low-NOX burners for older models in diffusion-type burners that use so-called “wet” systems of water or steam injection, and then “dry” versions for modern machines that use staged or Lean premixes use combustion techniques. -Which is called “dry low emission” or DLE burner.
The DLE path is attractive because it prevents the use of water or steam:
- Water purity standards are extremely stringent to prevent impurities from accumulating on expansion turbine blades and to reduce cooling, which results in hot spots.
- The water is released as steam along with the exhaust gases, costing the plant money.
- Waters are recognized as a limited resource, and commercial use of fresh water must be reduced to conserve it.
- Certain climatic conditions may cause a characteristic plume which should be avoided if possible.
- The lifetime of turbine blades is also shortened by water injection and steam injection.
- The amount of water required is important, and it is often impossible to achieve the same rate of pollution reduction as with “dry” techniques.
On the bright side, the mass flow through the expansion turbine increased, and as the water blinks, some power increased. Wet combustors are currently the only option for some fuels, especially if very low NOx emissions are required.
When global warming was related to increasing levels of CO2 in the atmosphere, one of the main reasons was pollution from power plant coal flue gas. Two technical paths were once again established.
One was the capture of post-combustion CO, which involved clearing the CO from the flue gas emitted by conventional power plants. The second is pre-combustion capture, which involves separating hydrogen from syngas from IGCC plants and feeding it into a gas turbine to burn like natural gas. CO2 and SO2 can be washed together.
Because of the very different characteristics of hydrogens as a fuels gas compared to naturals gas, further modifications to the combustions systems as well as modifications to the auxiliaries systems would be required.
Once again, two paths were taken for gas turbines. The first was to improve the water- or steam-injected diffusion burner to use hydrogen, while the second was to redesign the DLE burner to burn hydrogen.
The manufacturer is working on both approaches, with DLE being the ultimate goal as it avoids all the drawbacks listed above. Even though advanced designs are becoming popular, examples of each stage of combustion process improvement are still in use today.
Large Gas Turbines:
Larger equipment has different capacities for the natural gas/hydrogen mixture depending on the type of combustion installed. Siemens has tested its F-Class machines with hydrogens levels in the fuel gas ranging from 30% to 73%. The results of the tests show that pollutions and activity targets could be met.
#1. Light Industrial Gas Turbine
Siemens has put a lot of works into designing some of its small industrial gas turbines to run on natural gas/hydrogen mixtures for both diffusion and DLE combers. Work is still ongoing in this area, particularly with DLE burners, and increased hydrogen capabilities are being noted.
Introducing up to 30 volts of hydrogen into the natural gas system would not appear to be a technical problem for most of these small gas turbines with DLE compressors, but above that, some changes to the system designed for natural gas would be required.
However, it has been demonstrating that the DLE combustion design used on turbines in the 25 MW–57 MW range simples cycles; natural gas fuel can burn up to 60% hydrogen 40 percents natural gas. Low NOx production at 100 percent hydrogen is currently being developed, with completion expected in mid-2020.
#2. Aeroderivative Gas Turbine
With water injection and diffusion combustor for NOx control, the SGT-A35 (27.2–32.1MWe) can handle 15-volt percent hydrogen in aero-derivative natural gas fuel with DLE combustor, but with diffusion combustor and water for NOx control.
With an injection, the SGT-A35 and SGT-A65 (53.1-66MW) can handle 100 volts percent hydrogen. With natural gas fuels in ISO conditions, all gas turbine performance figures are in a simple cycle and are based on configuration and model.
High-Volume Hydrogen Gas Turbines:
In preparation for the massive power sector transition toward decarbonization, several major power equipment manufacturers are designing gas turbines that run on high-hydrogen-volume fuels. According to several experts, efforts to build 100 percent hydrogen-fueled gas turbines by companies such as Mitsubishis Hitachi Power Systems (MHPS), GE Powers, Siemens Energy, & Ansaldo Energy have recently been shifted into high gear.
Due to the new carbon reduction. Policies around the world have accelerated renewable energy potential. Firms, which all make big gas turbines but are fighting for a shrinking market share, are also competing to gain a foothold in potential markets, including those that could prosper in the hydrogens economy.
Experts point out that hydrogens are odorless & non-toxic and have the highest energy contents of common fuels by weight, allowing them to be used as energy carriers in a variety of applications from transportation & industry to power generation.
The hydrogen industry is well established in areas using it as a feedstock, despite the fact that it is not freely discovered in nature and is extracted through a different energy source, e.g., light, electricity. Created, or “improved” should be made or heat.
However, as core technologies for the production of hydrogen using renewable electricity, such as proton exchange membrane electrolyzers and fuel cells, achieve technological maturity and economies of scale, hydrogen is increasingly seen as the missing link in the energy transitions.
Gearing Up for a Hydrogen Society:
MHPS, joints ventures between Mitsubishis Heavy Industries and Hitachi, has been particularly vocal about its efforts to adhere to Japan’s plan to become the “Hydrogen Society,” announced in 2011 as a result of the Fukushima Daiichi nuclear plant meltdown.
It was done. The government-industry partnership will be split into three phases: first, it will expand its existing fuel cell initiatives to help reduce hydrogen and fuel cell prices; Second, it plans to introduce large-scale hydrogen power generation & hydrogen supply infrastructure; And finally, it will provide a zero-carbon supply system in the production process.
MHPS presented a business case for increasing hydrogen use in the power sectors at IHS Markit’s CERAWeek in Houstons in March 2019, stating that it would make hydrogen-powered gas turbines a “world CO2-free world using renewable energy”.
Wants to make hydrogen a major component of society. 2050.” Although naturals gas will continue to play a key role in addressing the variability from renewables, the next phases of development will “involve energy storage using hydrogen,” according to Paul Browning, president, and CEO of MHPS.
He explained that hydrogen production from renewable energy through electrolysis – which uses additional renewable energy to break down a water molecule – was used to store “renewable hydrogen” and later used in a combined cycle gas turbine (CCGT). Since 1970, MHPS has tested 29 gas turbines units with hydrogen contents ranging from 30 percent to 90 percent, totaling more than 3.5 million operating hours.
One of the company’s biggest problems was reducing the high NOx emissions associated with hydrogen combustion without sacrificing performance. Since hydrogen has faster flames than naturals gas, MHPS wanted to reduce the risk of combustion oscillations and “flashbacks” (backfires) in high hydrogens mixtures.
One approached was to create a “diffusion combustor” that injects fuels into the air using the company’s dry low-NOx (DLN) technologies. The combustor reduces NOx emissions by injecting steam or water, but it maintains a wider range of stable combustion even though the properties of the fuel differ by up to 90%.
According to the company, it can manage outputs equivalents to 700 MW in combined cycle form with a turbine’s inlet temperatures of 1,600C and reduce carbon emissions by about 10% compared to a conventional CCGT when fired with 30% hydrogen can reduce. By 2023, MHPS plans to converts one of three units to renewable hydrogen at Vattenfall’s 1.3-GW Magnums combined cycle plants in the Netherlands.
The Groningen project, which involves replacing the 440-MW M701F gas turbine, said Browning, will adapt the combustion technology to “live inside the NOx envelope similar to a natural gas power plant, but have it burn 100 percents hydrogen, Browning said.
He predicted 100 percent would be achieved within the next decades. Nonetheless, the project is criticals to MHPS’s goals of providing customers with a gas turbine that can be modified to run entirely on hydrogens, he said.
He acknowledged that the hydrogen-powered gas turbine would require onsite electrolysis and storage for renewable hydrogen supply, which would require “very low electricity costs. What we are looking for is sufficient renewable penetration on the electrical grid to make onsite electrolysis economically viable,” he said.
California is going there right now, but other states have a long way to go. We think lithium-ion batteries will be the best option if you want to store electricity for short periods of time,” Browning said, explaining how the technologies will survive against advances in battery storage. He acknowledges that the economics of hydrogens “does; no matter how long you store it.”
Future of Hydrogen Gas Turbines:
The difficulties with hydrogens gas turbines are that they must operate without sacrificing performance, startup time, or NOx emissions. This is accomplished by creating combustors designs that use a high ratio of hydrogen to natural gas.
As the hydrogens economy develops over the next decades, gas turbines will be able to meet market needs without compromising today’s high-performance standards in terms of emissions, reactivity, and productivity.
Transition to Hydrogen Turbines:
Mitsubishi Power, a member of the Mitsubishi Heavy Industries Group, began its gas-turbines business in the 1960s. In the 1990s, the grown need for energy securities to reduces Japan’s reliance on imported fossil fuels ignited research efforts into hydrogen.
Since 2010, decarbonization has become a major driver, and the urgency of climate change has driven growth. “Like many people, my house is only two meters above sea level, and I fear it will be submerged because of global warming,” says Satoshi Tanimura, who leads engineers at Mitsubishi Powers. “The developments of hydrogen-powered technologies will accelerate the transitions to a truly carbon-free society.”
In 2018, Tanimura’s team, in collaboration with Japan’s New Energy and Industrial Technology Development Organization (NEDO), developed gas turbines that run on 30% hydrogens & 70% natural gas – a major step towards a carbon-free society.
Their mixed-fuel turbine produces about 10% less CO2 than one powered by natural gas alone. The team is working to develop one powered entirely by hydrogen by 2025.
Hydrogen-gas turbines have many environmental & economic benefits, and Mitsubishi Powers is committed to facilitating the transition. Their turbines can be fitted to existing power plants and run on less pure forms of hydrogen, which can be taken in any form, from liquid hydrogen to ammonia.
They can also operate in combined-cycle power plants, which are more efficient because they use surplus heat to generates that powers a second turbine. “We have already achieved 64% power generation efficiency at our natural-gas, combined-cycle plant,” says Tanimura. “We could theoretically improve on this by increasing the combustion temperature of the gases.”
Also, Read: Gas Turbine Parts and Functions | Introduction to Gas Turbine Power Plant | Major Parts of Gas Turbine Power Plant | Gas Turbine | The Compressor of Gas Turbine Power Plant | Thermodynamic Cycle of Gas Turbine Power Plant
Tackling All Aspects in One Place:
Mitsubishi Power’s million-square-meter facility in Takasago, near Kobe, Japan, brings together the research and development, design, manufacturing, and validation phases of gas turbines in one place.
The site has its own power plants, & when energy demand falls in the spring and summer, the gas turbines are taken to the laboratory to confirm that the latest improvements will be able to achieve higher temperatures, higher efficiency, and lower nitrogen oxide emissions.
have been successful or not. Mitsubishi Heavy Industries manufactures a range of products from chemical plants to jet engines & wind turbines, & all information & technologies are shared through their research & innovation center.
It includes a research turbine, combustion-testing facilities, and a three-dimensional printer for large gas turbine parts. “As we build, test, and repair our parts here, we can develop and verify products in a rapid response cycle, which reduces costs,” says Tanimura. “It’s also an important place for young engineers to learn about our processes.”
A major breakthrough has been in reducing flashbacks, where the rapid combustion speed of hydrogen means the flame can shoot back down an incoming fuel nozzle. “This leads to a catastrophic failure of the system,” explains Tanimura. “We shrank the nozzle and improved the air and fuel mixture, which keeps it from shining back.”
Going Global with Hydrogen:
Mitsubishi Power is already integral to a number of international projects accelerating the hydrogen economy. In the Netherlands, Vattenfall Power Plant has installed three Mitsubishi M701F natural-gas-fired turbine units, each of which can generate 440 megawatts of electricity – enough to power more than 60,000 homes.
It is part of the Hydrogen-to-Magnum Project, which aims to convert gas turbine units to run on 100% hydrogens by 2027. Hydrogen produced from naturals gas is stored in nearby underground salt caves, and emitted CO2 is injected north down.
The ultimate goal is to make hydrogen onsite using wind-generated electricity. Such projects would cut CO2 emissions by two megatons per year and prevent natural gas power stations from becoming obsolete.
Hydrogen Turbine Generator:
Hydrogen is currently enjoying extraordinary political and commercial momentum, with a growing number of policies, national plans, and projects. The federal government announced support for Hydrogen Hub and previously issued a National Hydrogen Strategy.
At the same time, the opposition has also released its own hydrogen plan. Hydrogen technology is being adopted around the world with the hope that it can be produced from renewable energy sources. With gas-powered generation expected to remain an important part of the generation mix, there is increasing interest in the use of hydrogens in gas turbines while reducing carbon emissions.
Several manufacturers have already developed turbines that can handle a mixture of hydrogen and natural gas and are pursuing the development of turbines that can run on 100 percent hydrogen.
Locally, Twiggy Forest has announced a proposal to develop an 850-1000MW hydrogen power station at Port Kembla through Squadron Energy. The ultimates ambitions are to move to 100 percent hydrogen with an initial 30 percent hydrogen mix.