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 COBUSTIO COBUSTIO 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 REMOE CARBON FROM turbine. GE gas turbines have a long history NEUTRA FUEL THE PAT EXHAUST of burning fuels ranging from hydrogen, • Hydrogen blue, green, in) • arbon apture liuid solvents) to natural gas and high molecular weight • yneic renewable) ethane • arbon apture solid sorbents) hydrocarbons, to diesel fuel, to crude • iofuels • xyfuel yles • onia NH ) oil. Each fuel has unique challenges. 3 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.