Blue hydrogen is hydrogen produced from fossil fuel sources, with some of the GHG emissions captured and stored to prevent their release. This hydrogen, considered a low-carbon fuel or feedstock, is an alternative to hydrogen produced from fossil fuels without carbon capture (grey hydrogen). Blue hydrogen production uses available technologies, has limited risks, and is less expensive than some other low-carbon hydrogen fuels, such as green hydrogen produced from renewable-powered electrolysis. However, concerns exist about its low adoption, variable effectiveness, and competition with technologies that offer greater climate benefits. At its peak potential, blue hydrogen is less effective at reducing emissions than green hydrogen and more expensive than grey hydrogen, making investment in this possibly transitional technology risky. Blue hydrogen is theoretically an effective climate solution, but there are open questions around whether realistic deployment can meet its potential. We consider the deployment of blue hydrogen to be “Worth Watching.”
Based on our analysis, blue hydrogen is ready to deploy and feasible, but there is mixed consensus and limited data on its effectiveness in reducing emissions. Its climate impact has the potential to be high, but only if the technology is adopted aggressively and there are technological improvements around methane leaks, hydrogen leaks, and CCS. Therefore, this potential climate solution is “Worth Watching.”
| Plausible | Could it work? | Yes |
|---|---|---|
| Ready | Is it ready? | Yes |
| Evidence | Are there data to evaluate it? | Limited |
| Effective | Does it consistently work? | No |
| Impact | Is it big enough to matter? | No |
| Risk | Is it risky or harmful? | No |
| Cost | Is it cheap? | Yes |
Hydrogen is a fuel that can be used in place of fossil fuels in industrial, transportation, and energy systems. To deploy hydrogen (H₂) as an energy source or feedstock, it first needs to be extracted from other compounds. Each “color” is an informal term specifying hydrogen produced through a unique H2 production path, each with a different associated supply chain, process, and energy GHG emissions. Grey hydrogen, which uses natural gas as the source of hydrogen atoms and electricity, is the most produced and has high production emissions, estimated at 10–12 t CO₂-eq/t H2 on a 100-yr basis. One way to reduce emissions is by switching to blue hydrogen, which still uses fossil fuels but also uses carbon capture and storage (CCS) technologies to prevent the release of some of the CO₂ generated during production. Blue hydrogen has the potential to be a lower-emission source of energy relative to grey hydrogen or direct fossil fuel combustion.
Blue hydrogen is a plausible way to reduce emissions from grey hydrogen production. However, expert opinions are mixed on the magnitude of emissions that can be abated by producing blue hydrogen in place of grey hydrogen. The effectiveness of emissions reduction hinges on two main factors: upstream methane leakage rates and carbon capture rates, both of which are challenging to predict on a global scale. There is uncertainty around these performance metrics and the ability to effectively store and transport CO₂ at scale. Due to low current adoption, there is little real-world data to answer these questions. As of 2023, blue hydrogen comprised <1% of worldwide hydrogen production. While adding carbon capture to grey hydrogen production should help prevent emissions, there is limited evidence for both effectiveness and the ability to scale of this technology.
Compared to other types of low-carbon hydrogen, including green hydrogen produced from electrolysis powered by renewable energy, blue hydrogen is a technologically developed and lower-cost option. This makes it a near-term option to facilitate the transition to a global hydrogen economy. Expert estimates of cost per emissions avoided range widely, but the IEA estimates US$60–85/t CO₂ for lower carbon capture rates (55–70%) and US$85–110/t CO₂ for higher carbon capture rates (>90%). However, these costs are uncertain: with lower estimates of effectiveness, the cost could increase to ~US$260/t CO₂, including the cost to transport and store CO₂. If implemented with low GHG fugitive emissions and high CCS efficiencies, blue hydrogen can reduce emissions by more than 60% relative to current grey hydrogen production on a 100-yr CO₂‑eq basis. In this case, the climate impact of scaling blue hydrogen could be high. Estimates and targets for blue hydrogen production by 2050 range from ~30–85 Mt H₂. At that scale, even modest emissions savings relative to grey hydrogen (3 t CO₂‑eq/t H₂, 20-yr basis) would have a climate impact above 0.09 Gt CO₂-eq/yr by 2050. However, these adoption and effectiveness values are uncertain and depend on the quality of the infrastructure and rate of technology scaling, both of which are unproven.
While it has some advantages, blue hydrogen is still a less effective solution than green hydrogen, while costing more than grey hydrogen. Though it could be useful for near-term energy decarbonization, this risks taking resources away from renewable energy and green hydrogen development. The infrastructure required to scale hydrogen-based energy is expensive and will require technical advances and policy incentives to be competitive with fossil fuels. There are mixed expert opinions about the realistic level of avoided emissions that blue hydrogen may reach. The theoretical worst-performing blue hydrogen plants (low capture rates, high methane leaks, high-emission electricity sources) have been predicted to lead to more emissions on a near-term basis than direct natural gas combustion. Additionally, there is uncertainty around whether CCS can meet its technical potential at a reasonable cost. While experts predict >95% carbon capture rates are possible, facilities currently in operation capture less than this target, some less than 60% of all emitted carbon. For blue hydrogen to be feasible and scalable, CO₂ transport and storage need to be low-emitting, stable, and available. Only ~8% of CO₂ currently captured from blue hydrogen production is injected in dedicated storage, with the rest used in industry, enhanced oil recovery, and other applications. Finally, an understudied risk is hydrogen leaks. Hydrogen transport and storage require larger volumes than fossil fuels, increasing the risk of leaks. Hydrogen has an indirect planet-warming effect by increasing the levels of other atmospheric GHGs. At scale, the IEA estimates that high H₂ leakage rates could contribute 0.1 Gt CO₂-eq/yr in additional emissions, potentially canceling out any positive climate impacts.
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Greenhouse gas quantity expressed relative to CO₂ with the same warming impact over 100 years, calculated by multiplying emissions by the 100-yr GWP for the emitted gases.
Greenhouse gas quantity expressed relative to CO₂ with the same warming impact over 20 years, calculated by multiplying emissions by the 20-yr GWP for the emitted gases.
Reducing greenhouse gas concentrations in the atmosphere by preventing or reducing emissions.
The process of increasing the acidity of water or soil due to increased levels of certain air pollutants.
Benefits of climate solutions that extend beyond their ability to reduce emissions or store carbon (e.g., benefits to public health, water quality, biodiversity, advancing human rights).
The extent to which emissions reduction or carbon removal is above and beyond what would have occurred without implementing a particular action or solution.
An upper limit on solution adoption based on physical or technical constraints, not including economic or policy barriers. This level is unlikely to be reached and will not be exceeded.
The quantity and metric to measure implementation for a particular solution that is used as the reference unit for calculations within that solution.
Farming practices that work to create socially and ecologically sustainable food production.
Addition of trees and shrubs to crop or animal farming systems.
Spread out the cost of an asset over its useful lifetime.
A crop that live one year or less from planting to harvest; also called annual.
black carbon
Made from material of biological origin, such as plants, animals, or other organisms.
A renewable energy source generated from organic matter from plants and/or algae.
An energy source composed primarily of methane and CO₂ that is produced by microorganisms when organic matter decomposes in the absence of oxygen.
Carbon stored in biological matter, including soil, plants, fungi, and plant products (e.g., wood, paper, biofuels). This carbon is sequestered from the atmosphere but can be released through decomposition or burning.
Living or dead renewable matter from plants or animals, not including organic material transformed into fossil fuels. Peat, in early decay stages, is partially renewable biomass.
A type of carbon sequestration that captures carbon from CO₂ via photosynthesis and stores it in soils, sediments, and biomass, distinct from sequestration through chemical or industrial pathways.
A climate pollutant, also called soot, produced from incomplete combustion of organic matter, either naturally (wildfires) or from human activities (biomass or fossil fuel burning).
High-latitude (>50°N or >50°S) climate regions characterized by short growing seasons and cold temperatures.
The components of a building that physically separate the indoors from the outdoor environment.
Businesses involved in the sale and/or distribution of solution-related equipment and technology, and businesses that want to support adoption of the solution.
A chemical reaction involving heating a solid to a high temperature: to make cement clinker, limestone is calcined into lime in a process that requires high heat and produces CO₂.
A four-wheeled passenger vehicle.
Technologies that collect CO₂ before it enters the atmosphere, preventing emissions at their source. Collected CO₂ can be used onsite or in new products, or stored long term to prevent release.
A greenhouse gas that is naturally found in the atmosphere. Its atmospheric concentration has been increasing due to human activities, leading to warming and climate impacts.
Total GHG emissions resulting from a particular action, material, technology, or sector.
Amount of GHG emissions released per activity or unit of production.
A marketplace where carbon credits are purchased and sold. One carbon credit represents activities that avoid, reduce, or remove one metric ton of GHG emissions.
A colorless, odorless gas released during the incomplete combustion of fuels containing carbon. Carbon monoxide can harm health and be fatal at high concentrations.
Activities or technologies that pull CO₂ out of the atmosphere, including enhancing natural carbon sinks and deploying engineered sinks.
Long-term storage of carbon in soils, sediment, biomass, oceans, and geologic formations after removal of CO₂ from the atmosphere or CO₂ capture from industrial and power generation processes.
carbon capture and storage
carbon capture, utilization, and storage
A binding ingredient in concrete responsible for most of concrete’s life-cycle emissions. Cement is made primarily of clinker mixed with other mineral components.
methane
Gases or particles that have a planet-warming effect when released to the atmosphere. Some climate pollutants also cause other forms of environmental damage.
A binding ingredient in cement responsible for most of the life-cycle emissions from cement and concrete production.
carbon monoxide
Neighbors, volunteer organizations, hobbyists and interest groups, online communities, early adopters, individuals sharing a home, and private citizens seeking to support the solution.
A solution that potentially lowers the benefit of another solution through reduced effectiveness, higher costs, reduced or delayed adoption, or diminished global climate impact.
A farming system that combines reduced tillage, cover crops, and crop rotations.
carbon dioxide
A measure standardizing the warming effects of greenhouse gases relative to CO₂. CO₂-eq is calculated as quantity (metric tons) of a particular gas multiplied by its GWP.
carbon dioxide equivalent
The process of cutting greenhouse gas emissions (primarily CO₂) from a particular sector or activity.
A solution that works slower than gradual solutions and is expected to take longer to reach its full potential.
Microbial conversion of nitrate into inert nitrogen gas under low-oxygen conditions, which produces the greenhouse gas nitrous oxide as an intermediate compound.
Greenhouse gas emissions produced as a direct result of the use of a technology or practice.
Ability of a solution to reduce emissions or remove carbon, expressed in CO₂-eq per installed adoption unit. Effectiveness is quantified per year when the adoption unit is cumulative over time.
Greenhouse gas emissions accrued over the lifetime of a material or product, including as it is produced, transported, used, and disposed of.
Solutions that work faster than gradual solutions, front-loading their impact in the near term.
Methane produced by microbes in the digestive tracts of ruminant livestock, such as cattle, sheep and goats.
environmental, social, and governance
exchange-traded fund
A process triggered by an overabundance of nutrients in water, particularly nitrogen and phosphorus, that stimulates excessive plant and algae growth and can harm aquatic organisms.
The scientific literature that supports our assessment of a solution's effectiveness.
A group of human-made molecules that contain fluorine atoms. They are potent greenhouse gases with GWPs that can be hundreds to thousands times higher than CO₂.
food loss and waste
Food discarded during pre-consumer supply chain stages, including production, harvest, and processing.
Food discarded at the retail and consumer stages of the supply chain.
Combustible materials found in Earth's crust that can be burned for energy, including oil, natural gas, and coal. They are formed from decayed organisms through prehistoric geological processes.
greenhouse gas
gigajoule or billion joules
The glass layers or panes in a window.
A measure of how effectively a gas traps heat in the atmosphere relative to CO₂. GWP converts greenhouse gases into CO₂-eq emissions based on their 20- or 100-year impacts.
A solution that has a steady impact so that the cumulative effect over time builds as a straight line. Most climate solutions fall into this category.
A gas that traps heat in the atmosphere, contributing to climate change.
metric gigatons or billion metric tons
global warming potential
hectare
household air pollution
Number of years a person is expected to live without disability or other limitations that restrict basic functioning and activity.
A unit of land area comprising 10,000 square meters, roughly equal to 2.5 acres.
hydrofluorocarbon
hydrofluoroolefin
Particles and gases released from use of polluting fuels and technologies such as biomass cookstoves that cause poor air quality in and around the home.
Organic compounds that contain hydrogen and carbon.
Human-made F-gases that contain hydrogen, fluorine, and carbon. They typically have short atmospheric lifetimes and GWPs hundreds or thousands times higher than CO₂.
Human-made F-gases that contain hydrogen, fluorine, and carbon, with at least one double bond. They have low GWPs and can be climate-friendly alternatives to HFC refrigerants.
internal combustion engine
Greenhouse gas emissions produced as a result of a technology or practice but not directly from its use.
Device used to power vehicles by the intake, compression, combustion, and exhaust of fuel that drives moving parts.
The annual discount rate that balances net cash flows for a project over time. Also called IRR, internal rate of return is used to estimate profitability of potential investments.
Individuals or institutions willing to lend money in search of a return on their investment.
internal rate of return
A measure of energy
International agreement adopted in 2016 to phase down the use of high-GWP HFC F-gases over the time frame 2019–2047.
A measure of energy equivalent to the energy delivered by 1,000 watts of power over one hour.
kiloton or one thousand metric tons
kilowatt-hour
A land-holding system, e.g. ownership, leasing, or renting. Secure land tenure means farmers or other land users will maintain access to and use of the land in future years.
Gases, mainly methane and CO₂, created by the decomposition of organic matter in the absence of oxygen.
leak detection and repair
Regular monitoring for fugitive methane leaks throughout oil and gas, coal, and landfill sector infrastructure and the modification or replacement of leaking equipment.
Relocation of emissions-causing activities outside of a mitigation project area rather than a true reduction in emissions.
The rate at which solution costs decrease as adoption increases, based on production efficiencies, technological improvements, or other factors.
Percent decrease in costs per doubling of adoption.
landfill gas
Greenhouse gas emissions from the sourcing, production, use, and disposal of a technology or practice.
low- and middle-income countries
liquefied petroleum gas
A measure of the amount of light produced by a light source per energy input.
square meter kelvins per watt (a measure of thermal resistance, also called R-value)
marginal abatement cost curve
Livestock grazing practices that strategically manage livestock density, grazing intensity, and timing. Also called improved grazing, these practices have environmental, soil health, and climate benefits, including enhanced soil carbon sequestration.
A tool to measure and compare the financial cost and abatement benefit of individual actions based on the initial and operating costs, revenue, and emission reduction potential.
A greenhouse gas with a short lifetime and high GWP that can be produced through a variety of mechanisms including the breakdown of organic matter.
A measure of mass equivalent to 1,000 kilograms (~2,200 lbs).
million hectares
Soils mostly composed of inorganic materials formed through the breakdown of rocks. Most soils are mineral soils, and they generally have less than 20% organic matter by weight.
A localized electricity system that independently generates and distributes power. Typically serving limited geographic areas, mini-grids can operate in isolation or interconnected with the main grid.
Reducing the concentration of greenhouse gases in the atmosphere by cutting emissions or removing CO₂.
Percent of trips made by different passenger and freight transportation modes.
megaton or million metric tons
A commitment from a country to reduce national emissions and/or sequester carbon in alignment with global climate goals under the Paris Agreement, including plans for adapting to climate impacts.
A gaseous form of hydrocarbons consisting mainly of methane.
Chemicals found in nature that are used for cooling and heating, such as CO₂, ammonia, and some hydrocarbons. They have low GWPs and are ozone friendly, making them climate-friendly refrigerants.
Microbial conversion of ammonia or ammonium to nitrite and then to nitrate under aerobic conditions.
A group of air pollutant molecules composed of nitrogen and oxygen, including NO and NO₂.
A greenhouse gas produced during fossil fuel combustion and agricultural and industrial processes. N₂O is hundreds of times more potent than CO₂ at trapping atmospheric heat, and it depletes stratospheric ozone.
Social welfare organizations, civic leagues, social clubs, labor organizations, business associations, and other not-for-profit organizations.
A material or energy source that relies on resources that are finite or not naturally replenished at the rate of consumption, including fossil fuels like coal, oil, and natural gas.
nitrogen oxides
nitrous oxide
The process of increasing the acidity of seawater, primarily caused by absorption of CO₂ from the atmosphere.
An agreement between a seller who will produce future goods and a purchaser who commits to buying them, often used as project financing for producers prior to manufacturing.
Productive use of wet or rewetted peatlands that does not disturb the peat layer, such as for hunting, gathering, and growing wetland-adapted crops for food, fiber, and energy.
A measure of transporting one passenger over a distance of one kilometer.
The longevity of any greenhouse gas emission reductions or removals. Solution impacts are considered permanent if the risk of reversing the positive climate impacts is low within 100 years.
A mixture of hydrocarbons, small amounts of other organic compounds, and trace amounts of metals used to produce products such as fuels or plastics.
Private, national, or multilateral organizations dedicated to providing aid through in-kind or financial donations.
An atmospheric reaction among sunlight, VOCs, and nitrogen oxide that leads to ground-level ozone formation. Ground-level ozone, a component of smog, harms human health and the environment.
passenger kilometer
particulate matter
Particulate matter 2.5 micrometers or less in diameter that can harm human health when inhaled.
Elected officials and their staff, bureaucrats, civil servants, regulators, attorneys, and government affairs professionals.
System in a vehicle that generates power and delivers it to the wheels. It typically includes an engine and/or motor, transmission, driveshaft, and differential.
People who most directly interface with a solution and/or determine whether the solution is used and/or available.
The process of converting inorganic matter, including carbon dioxide, into organic matter (biomass), primarily by photosynthetic organisms such as plants and algae.
Defined by the International Union for the Conservation of Nature as: "A clearly defined geographical space, recognised, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values". References to PAs here also include other effective area-based conservation measures defined by the IUCN.
Very large or small numbers are formatted in scientific notation. A positive exponent multiplies the number by powers of ten; a negative exponent divides the number by powers of ten.
Small-scale family farmers and other food producers, often with limited resources, usually in the tropics. The average size of a smallholder farm is two hectares (about five acres).
soil organic carbon
Carbon stored in soils, including both organic (from decomposing plants and microbes) and inorganic (from carbonate-containing minerals).
Carbon stored in soils in organic forms (from decomposing plants and microbes). Soil organic carbon makes up roughly half of soil organic matter by weight.
Biologically derived matter in soils, including living, dead, and decayed plant and microbial tissues. Soil organic matter is roughly half carbon on a dry-weight basis.
soil organic matter
sulfur oxides
sulfur dioxide
The rate at which a climate solution physically affects the atmosphere after being deployed. At Project Drawdown, we use three categories: emergency brake (fastest impact), gradual, or delayed (slowest impact).
Climate regions between latitudes 23.4° to 35° above and below the equator characterized by warm summers and mild winters.
A polluting gas produced primarily from burning fossil fuels and industrial processes that directly harms the environment and human health.
A group of gases containing sulfur and oxygen that predominantly come from burning fossil fuels. They contribute to air pollution, acid rain, and respiratory health issues.
Processes, people, and resources involved in producing and delivering a product from supplier to end customer, including material acquisition.
metric tons
Technology developers, including founders, designers, inventors, R&D staff, and creators seeking to overcome technical or practical challenges.
Climate regions between 35° to 50° above and below the equator characterized by moderate mean annual temperatures and distinct seasons, with warm summers and cold winters.
A measure of how well a material prevents heat flow, often called R-value or RSI-value for insulation. A higher R-value means better thermal performance.
Individuals with an established audience for their work, including public figures, experts, journalists, and educators.
Low-latitude (23.4°S to 23.4°N) climate regions near the Equator characterized by year-round high temperatures and distinct wet and dry seasons.
United Nations
Self-propelled machine for transporting passengers or freight on roads.
A measure of one vehicle traveling a distance of one kilometer.
vehicle kilometer
volatile organic compound
Gases made of organic, carbon-based molecules that are readily released into the air from other solid or liquid materials. Some VOCs are greenhouse gases or can harm human health.
watt
A measure of power equal to one joule per second.
A subset of forest ecosystems that may have sparser canopy cover, smaller-stature trees, and/or trees characterized by basal branching rather than a single main stem.
year