Hydrogen as a fuel for gas turbines
A pathway to lower CO2
www.ge.com/power/future-of-energy Executive Summary In order to combat man-made climate change, there is a global need for decarbonization,* and all sectors that produce carbon dioxide (CO2) must play a role.
The power sector’s journey to There are two ways to systematically have operated on fuels with at least 50% decarbonize, often referred approach the task of turning high efficiency (by volume) hydrogen. These units have gas generation into a zero or near zero- accumulated more than one million operating to as the Energy Transition, carbon resource: pre and post-combustion. hours, giving GE a unique perspective is characterized by rapid Pre-combustion refers to the systems and on the challenges of using hydrogen as deployment of renewable energy processes upstream of the gas turbine and a gas turbine fuel. resources and a rapid reduction in post-combustion refers to systems and processes downstream of the gas turbine. GE is continuing to advance the capability of coal, the most carbon-intensive The most common approach today to its gas turbine fleet to burn hydrogen through power generation source. Based tackle pre-combustion decarbonization is internally funded R&D programs and through on our extensive analysis and simple: to change the fuel, and the most US Department of Energy funded programs. experience across the breadth talked about fuel for decarbonization of the The goals of these efforts are to ensure power sector is hydrogen. that ever higher levels of hydrogen can be of the global power industry, GE burned safely and reliably in GE’s gas turbines believes that the accelerated GE is a world leader in gas turbine fuel for decades to come. and strategic deployment of flexibility, including more than 75 gas turbines that have (or continue to) operate *Decarbonization in this paper is intended to mean the reduction renewables and gas power of carbon emissions on a kilogram per megawatt hour basis. on fuels that contain hydrogen. This fleet can change the near-term has accumulated more than 6 million trajectory for climate change, operating hours and produced more enabling substantive reductions than 450 Terawatt-hours of electricity. It in emissions quickly, while in includes a group of 25 gas turbines that parallel continuing to advance GE believes that using the technologies for near zero- hydrogen as a fuel is carbon power generation. Part one of the potential of this deployment of gas power may involve the use of hydrogen ways to decarbonize as a fuel in order to reduce gas power generation
CO2 emissions.
As of 2020 there were ~1,600 GW of gas turbines installed globally, and gas power accounted for ~22 percent of global electricity generated. The vast majority of gas turbines burn natural gas, or methane
(CH4), to release energy which ultimately produces the electricity we use at home, schools, factories, in the community and for industry.
Hydrogen as a Fuel for Gas Turbines 2 Introduction Figure 1 depicts the two methods for PRE- POST- decarbonizing a gas turbine: pre and CO BUSTIO CO BUSTIO post-combustion. For pre-combustion decarbonization a fuel such as hydrogen containing no carbon or a carbon neutral fuel such as biogas is burned in the gas USE A ZERO OR CARBO RE O E CARBO FRO turbine. GE gas turbines have a long history EUTRA FUE THE P A T E HAUST of burning fuels ranging from hydrogen, Hydrogen blue green in arbon a ure li uid sol en s to natural gas and high molecular weight yn e i rene able e ane arbon a ure solid sorben s hydrocarbons, to diesel fuel, to crude iofuels y fuel y les onia H oil. Each fuel has unique challenges.
For post-combustion decarbonization, there FIGURE 1: Means of decarbonizing a gas turbine is a tool chest of different technologies that can remove CO2 from the flue gases with the most common being in a process referred coal as a feedstock, typically in a process the electricity used in the process and the to as carbon capture. The general concept called steam methane reforming (SMR). utilization rate, or capacity factor of the of carbon capture involves introducing a The SMR process produces CO2 as a by- electrolyzers. specialized chemical which has an affinity product and most of this CO2 is released to to carbon into the plant exhaust stack. the atmosphere. An alternative method of A higher capacity factor tends to result in
Once the CO2 and the chemical bond, the producing hydrogen is through electrolysis lower hydrogen costs, all other factors being compound is taken to a separate vessel and in which a water molecule is broken into equal. Gas turbines are capable of operating separated into its constituents. The resulting its hydrogen and oxygen constituents by on hydrogen from any of the previously pure CO2 is taken to a compression tank and passing electricity through the water. No described sources. is ready for transportation. This CO2 is then CO2 is produced directly by the electrolysis transported to either a geologic formation process, but depending on the fuel source Transporting and storing hydrogen requires deep underground for permanent storage, of the electricity, CO2 could be produced. special considerations due to its property of or re-used in industrial processes, thus attacking and embrittling certain materials completing the process of Carbon Capture A color-based convention is being used and the extreme pressures and temperatures and Utilization or Sequestration (CCUS). internationally to describe and differentiate needed to compress and liquefy it. Hydrogen hydrogen production methods: embrittlement occurs when hydrogen It’s important to note that pre and post- atoms diffuse into a base material and • Grey (or black): Gasification combustion decarbonization approaches disrupt the microscopic structure of the of coal or reforming of natural can be employed on existing installed gas material that provides its strength. Some gas without carbon capture turbines as a retrofit or included in the stainless steels offer increased hydrogen design of a new power plant, avoiding • Blue: Reforming of methane (SMR) embrittlement resistance, but at a higher with carbon capture and storage the potential “lock-in” of CO2 emissions cost than the carbon steels typically for the entire life of the power plant. • Green: Electrolysis of water used for transporting natural gas. using renewable power Hydrogen is typically compressed to between HYDROGEN • Pink (Red): Electrolysis of 35 to 150 bar (~500 to ~2,200 psi) for pipeline INFRASTRUCTURE – water using nuclear power transmission whereas the distribution system PRODUCTION, TRANSPORT, • Turquoise: Pyrolysis of methane AND STORAGE that provides gas to many end users typically which produces hydrogen and operates at pressures less than ~7 bar solid carbon as a by-product Hydrogen is the most abundant element in (~100 psi). For storage, hydrogen is typically the universe, but despite its plentiful nature • White: Gasification or other process compressed to more than 350 bar (~5,000 psi. it does not exist on earth as a standalone using 100% biomass as a feedstock Hydrogen storage and transmission systems molecule. In other words, hydrogen likes may require specialized high-pressure to bond with other molecules. In order to The cost of hydrogen produced by these equipment and will require a significant yield pure hydrogen, it must be separated different methods can vary widely, with amount of energy for compression. Liquefying from its paired molecules, usually found in grey (or black) typically being the least hydrogen is even more of a challenge because it condenses from a gas into a liquid at less the form of water (H2O), or hydrocarbons expensive. The price for hydrogen produced than -250º C (~-420º F), requiring a significant (e.g., CH4). More than 90% of the hydrogen using the electrolytic processes (i.e., green, produced globally today uses natural gas or pink, red) depends primarily on the cost of
Hydrogen as a Fuel for Gas Turbines 3 amount of energy for cooling the gas to this reduction (SCR) system for NOX removal. The flame speed of hydrogen is an order temperature, and special double-walled Control of NOX is important because in most of magnitude faster than natural gas. This cryogenic tanks for storage. The largest jurisdictions it is a regulated pollutant that if is an important consideration for the safe tank of this kind in the world is located at unabated contributes to smog, acid rain, and and reliable operation of the combustion NASA’s Kennedy Space Center and stores ozone depletion. system. A higher flame speed could result approximately 3.2 million litres (~850,000 in the flame in the combustor propagating gallons) of liquid hydrogen. This amount of Hydrogen has a heating value that is upstream too far, resulting in a condition fuel would be consumed in a GE 7HA.03 gas approximately one-third of natural gas. called flashback that can cause combustion turbine rated at 430 MW in about 8 hours. This means that for a given volume of flow, hardware damage. Combustor configuration hydrogen delivers less energy. It is also a changes and associated turbine control smaller molecule than natural gas, meaning system changes may be needed to operate CONSIDERATIONS FOR that it can leak through seals that would with high concentrations of hydrogen fuel. USING HYDROGEN AS A GAS TURBINE FUEL be leak-free in a natural gas system. If a hydrogen/natural gas fuel blend with a Hydrogen is more flammable than natural gas and special considerations are needed for the The basic configuration of a gas turbine relatively low concentration of hydrogen is safe operation of a gas turbine with a natural capable of burning natural gas would remain used, the existing fuel delivery system may gas/hydrogen fuel blend. The gas turbine unchanged for burning hydrogen. Specific be adequate, but at higher concentrations enclosure and ventilation system need to areas that need to be addressed within the of hydrogen, larger fuel delivery system be designed to ensure the concentration of gas turbine, its accessory systems, and the components with materials not susceptible hydrogen is maintained outside of its upper plant itself include: 1) fuel delivery piping to hydrogen embrittlement, and welded seals and lower explosive limits. Hazardous gas and components, 2) gas turbine combustion may be required. and flame detection systems configured system and controls, 3) gas turbine for typical hydrocarbon fuels may need to enclosure, and 4) the heat recovery steam be supplemented with systems capable of generator (HRSG) and selective catalytic detecting hydrogen.
Hydrogen has different properties than methane. Operating a
FIGURE 2:Systems that may require gas turbine on a fuel with hydrogen may require changes to modification when using hydrogen fuel combustion, fuel, and plant safety systems.
Gas turbine combustion system SCR
Gas turbine enclosure modifications: ventilation, hazardous gas detection, HRSG fire protection
Fuel accessory system: skids, valves, piping, purge systems Gas turbine controls
Hydrogen as a Fuel for Gas Turbines 4 The flame temperature of hydrogen is higher One additional consideration when blending Hydrogen fuel than natural gas. This could result in an hydrogen with natural gas as a fuel for gas increase in NOX emissions depending on the turbines is that there is not a 1:1 relationship capability for a concentration of hydrogen in the fuel and between the volume of hydrogen in the fuel gas turbine can be the specific combustion system in the gas and the CO2 emissions reduction achieved. turbine. GE combustion studies indicate Figure 3 shows this non-linear relationship., planned into a new a 50/50 mixture by volume of hydrogen/ and as an example, attaining a 50 percent natural gas could increase the concentration reduction in CO2 emissions requires a blend power plant project of NOX in the gas turbine exhaust by 35 that is ~75 percent (by volume) hydrogen. percent. For a plant under development this or retrofit into may require a larger or more efficient SCR Before finalizing any plan to blend an existing plant system. For existing power plants, there may hydrogen into natural gas for a power be some ability to accept increases in NOX plant, a full audit of all plant systems emissions based on existing SCR capabilities should be performed with the goal of (if installed), and the plant’s air permit limits. ensuring safe and reliable operation. Another mitigant could be to derate the power plant to maintain operation within the existing air permit’s NOX emission limits.
Hydrogen olu e
edu ion e ane olu e
FIGURE 3: Relationship between CO2 emissions and hydrogen/methane fuel blends (volume %)
Hydrogen by ea on en
in edu ion e ane by ea on en
Hydrogen as a Fuel for Gas Turbines 5 GE’S EXPERIENCE WITH HYDROGEN IN GAS TURBINES
GE gas turbines have been operating with hydrogen fuel blends in a variety of industrial applications, including steel mills, GE has decades of experience burning hydrogen and similar refineries, and petrochemical plants. GE is a world leader in gas turbine fuel flexibility, fuels in its gas turbines. This experience provides a unique including more than 75 gas turbines that have operated (or continue to) on fuels that perspective on how to use hydrogen as a fuel while ensuring contain hydrogen. This fleet has accumulated more than 6 million operating hours safe and reliable operation. and over 450 Terawatt-hours of power generation. It includes a group of 25 gas turbines that have operated on fuels with at least 50 percent (by volume) hydrogen. These units have accumulated more than one million operating hours. Figure 4 below highlights some of the projects that have used fuels with varying concentrations of hydrogen over the last 30+ years.
Timeline of GE Experience with H² and Associated Fuels
1x6B 2x6F 2x6F Syngas 1xGE10 High 2x7F Syngas 1x7F 1x7F IGCC Refinery Refinery H2 Coal IGCC 2x9E Refinery IGCC (USA) IGCC (USA) (Europe) (USA) (Asia) (Europe) (USA) (India)
1990 2000 2010
1x7E 1x6B Refinery 1x6B Refinery 1xGT13E2 3x9E Refinery 2xGT11N2 2xLM2500 1x7F Syngas IGCC (USA) (Europe) (Korea) Refinery (Europe) Steel Mill Steel Mill IGCC (Korea) (Europe) (Brazil) (China)
FIGURE 4: Timeline of selected projects with hydrogen fuels
Hydrogen as a Fuel for Gas Turbines 6 All GE gas turbines have the ability to Development of GE’s DLN 2.6e combustor burn hydrogen fuel to some degree. The system began as part of the US Department specific amount that can be burned in any of Energy’s (DOE) Advanced IGCC/Hydrogen particular gas turbine model depends on Gas Turbine program. During this program, several factors, but most importantly on the multiple pre-mixing configurations were combustion system. tested at GE’s Global Research Center in a single nozzle test facility as well as at GE’s Combustion systems are usually classified Gas Turbine Technology Lab in Greenville, as either diffusion systems or lean premix South Carolina. The DLN 2.6e combustion systems. Diffusion systems usually have very system is capable of a 50/50 hydrogen/ high flame temperatures as well as high NOX natural gas blend by volume and it is emissions, and typically use a diluent such currently offered on GE’s 9HA and 7HA.03 as water, steam, or nitrogen injected into the gas turbines. The first gas turbine with combustor to reduce the NOX emissions level. the DLN 2.6e combustion system entered commercial service at the end of 2020. Lean premix combustion systems operate with a lower flame temperature compared to GE is continuing to develop a diffusion combustion system, resulting in increased hydrogen capability lower NO emissions. GE’s dry low emissions X for its gas turbines through (DLE) and dry low NOX (DLN) are lean premix combustion systems. Most DLE and DLN in-house R&D and testing as combustion systems are limited in the well as participating in US DOE amount of hydrogen they can utilize due hydrogen fuel programs. to risks of flashback and flame holding as discussed previously.
Hydrogen capability of GE gas turbines
Hydrogen olu e
eroderi a i e
lass
F lass
H lass
Today Fu ure a abili y
FIGURE 5: All GE gas turbines have hydrogen capability
Hydrogen as a Fuel for Gas Turbines 7 It is possible to operate new units and Addressing climate change is an Conclusion upgrade existing units for operation on these fuels with appropriate consideration urgent global priority and one Supporting the to the combustion system, fuel accessories, that we think we can do a better global need for deep emissions, and plant systems. For existing units, these upgrades can be scheduled with job of accelerating progress on— planned outages to minimize the time the decarbonization, plant is not generating power, and for new starting now—not decades from units these capabilities can be part of the there are multiple initial plant configuration or phased in over now. We believe there are critical time as hydrogen becomes available. Given pathways to achieve GE’s experience in the industry, with over and meaningful roles for both gas six million operating hours on hydrogen and power and renewable sources of low or near zero similar low heating value fuels, many of the technical questions on the viability of this energy to play, advancing global carbon emissions fuel for power generation applications have with gas turbines. been answered. progress faster today with coal- to-gas switching while continuing These are typically categorized as pre or post- Having both pre or post- combustion methods. One pre-combustion combustion technologies to develop multiple pathways option is the use of 100% hydrogen or a can prevent future lock-in for low-to-near zero carbon gas blend of hydrogen and natural gas. This of CO emissions, enabling gas could be blue hydrogen, green hydrogen, or 2 technologies in the future. hydrogen produced from an alternative low turbine power plants to be or zero carbon emission production process. a key element of any future SCOTT STRAZIK Regardless of the source of hydrogen, gas energy ecosystem focused on CEO, GE GAS POWER turbines operating on blends of hydrogen reducing carbon emissions. and natural gas, or on 100% hydrogen will see reductions in CO2 emissions.
AUTHORS CONTRIBUTORS gegaspower.com Dr. Jeffrey Goldmeer Jason Benway John Catillaz Deb Jaqueway Jim Donohue Parag Kulkarni
Hasan Karim © GE, 2021 William Lawson GEA34979 (03/21) 8