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NASA’s Zero-Boil-Off Tank Experiments To Enable Long-Duration Space Exploration

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Thursday, March 14, 2024

Figure 1. The Gateway space station—humanity’s first space station around the Moon—will be capable of being refueled in space. Credit: NASA, Alberto Bertolin, Bradley ReynoldsNASA’s Zero-Boil-Off Tank experiments address the challenge of managing cryogenic propellants in space, crucial for future Moon and Mars missions, with potential Earth-bound benefits in hydrogen energy applications.Do we have enough fuel to get to our destination? This is probably one of the first questions that comes to mind whenever your family gets ready to embark on a road trip. If the trip is long, you will need to visit gas stations along your route to refuel during your travel.NASA is grappling with similar issues as it gets ready to embark on a sustainable mission back to the Moon and plans future missions to Mars. But while your car’s fuel is gasoline, which can be safely and indefinitely stored as a liquid in the car’s gas tank, spacecraft fuels are volatile cryogenic liquid propellants that must be maintained at extremely low temperatures and guarded from environmental heat leaks into the spacecraft’s propellant tank. And while there is already an established network of commercial gas stations in place to make refueling your car a cinch, there are no cryogenic refueling stations or depots at the Moon or on the way to Mars. Furthermore, storing volatile propellant for a long time and transferring it from an in-space depot tank to a spacecraft’s fuel tank under microgravity conditions will not be easy since the underlying microgravity fluid physics affecting such operations is not well understood. Even with today’s technology, preserving cryogenic fuels in space beyond several days is not possible and tank-to-tank fuel transfer has never been previously performed or tested in space.Propellant Management in Space: Overcoming Boil-OffHeat conducted through support structures or from the radiative space environment can penetrate even the formidable Multi-Layer Insulation (MLI) systems of in-space propellant tanks, leading to boil-off or vaporization of the propellant and causing tank self-pressurization. The current practice is to guard against over-pressurizing the tank and endangering its structural integrity by venting the boil-off vapor into space.Onboard propellants are also used to cool down the hot transfer lines and the walls of an empty spacecraft tank before a fuel transfer and filling operation can take place. Thus, precious fuel is continuously wasted during both storage and transfer operations, rendering long-duration expeditions—especially a human Mars mission—infeasible using current passive propellant tank pressure control methods.Introducing ZBO: A New Horizon in Fuel EfficiencyZero-Boil-Off (ZBO) or Reduced Boil-Off (RBO) technologies provide an innovative and effective means to replace the current passive tank pressure control design. This method relies on a complex combination of active, gravity-dependent mixing and energy removal processes that allow maintenance of safe tank pressure with zero or significantly reduced fuel loss.Zero Boil-off Storage and Transfer: A Transformative Space TechnologyAt the heart of the ZBO pressure control system are two proposed active mixing and cooling mechanisms to counter tank self-pressurization. The first is based on intermittent, forced, subcooled jet mixing of the propellant and involves complex, dynamic, gravity-dependent interaction between the jet and the ullage (vapor volume) to control the condensation and evaporation phase change at the liquid-vapor interface.The second mechanism uses subcooled droplet injection via a spraybar in the ullage to control tank pressure and temperature. While the latter option is promising and gaining prominence, it is more complex and has never been tested in microgravity where the phase change and transport behavior of droplet populations can be very different and nonintuitive compared to those on Earth.Although the dynamic ZBO approach is technologically complex, it promises an impressive advantage over the currently used passive methods. An assessment of one nuclear propulsion concept for Mars transport estimated that the passive boil-off losses for a large liquid hydrogen tank carrying 38 tons of fuel for a three-year mission to Mars would be approximately 16 tons/year. The proposed ZBO system would provide a 42% saving of propellant mass per year.These numbers also imply that with a passive system, all the fuel carried for a three-year Mars mission would be lost to boil-off, rendering such a mission infeasible without resorting to the transformative ZBO technology.The ZBO approach provides a promising method, but before such a complex technological and operational transformation can be fully developed, implemented, and demonstrated in space, important and decisive scientific questions that impact its engineering implementation and microgravity performance must be clarified and resolved.The Zero-Boil-Off Tank (ZBOT) Microgravity Science ExperimentsThe Zero Boil-off Tank (ZBOT) Experiments are being undertaken to form a scientific foundation for the development of the transformative ZBO propellant preservation method. Following the recommendation of a ZBOT science review panel comprised of members from aerospace industries, academia, and NASA, it was decided to perform the proposed investigation as a series of three small-scale science experiments to be conducted onboard the International Space Station. The three experiments outlined below build upon each other to address key science questions related to ZBO cryogenic fluid management of propellants in space.Figure 2. Astronaut Joseph M. Acaba installing ZBOT Hardware in the Microgravity Science Glovebox aboard the International Space Station. Credit: NASAThe ZBOT-1 Experiment: Self-Pressurization & Jet MixingThe first experiment in the series was carried out on the station in the 2017-2018 timeframe. Figure 2 shows the ZBOT-1 hardware in the Microgravity Science Glovebox (MSG) unit of the station. The main focus of this experiment was to investigate the self-pressurization and boiling that occurs in a sealed tank due to local and global heating, and the feasibility of tank pressure control via subcooled axial jet mixing. In this experiment, the complicated interaction of the jet flow with the ullage (vapor volume) in microgravity was carefully studied.Microgravity jet mixing data was also collected across a wide range of scaled flow and heat transfer parameters to characterize the time constants for tank pressure reduction, and the thresholds for geyser (liquid fountain) formation, including its stability, and penetration depth through the ullage volume. Along with very accurate pressure and local temperature sensor measurements, Particle Image Velocimetry (PIV) was performed to obtain whole-field flow velocity measurements to validate a Computational Fluid Dynamics (CFD) model.Figure 3. Validation of ZBOT CFD Model Predictions for fluid flow and deformation of a spherical ullage in microgravity by a subcooled liquid jet mixing against ZBOT experimental results: (a) Model prediction of ullage position and deformation and flow vortex structures during subcooled jet mixing; (b) PIV image capture of flow vortex structures during jet mixing; (c) Ullage deformation captured by white light imaging; and (d) CFD model depiction of temperature contours during subcooled jet mixing. (ZBOT-1 Experiment, 2018) Credit: Dr. Mohammad Kassemi, Case Western Reserve UniversitySome of the interesting findings of the ZBOT-1experiment are as follows:Provided the first tank self-pressurization rate data in microgravity under controlled conditions that can be used for estimating the tank insulation requirements. Results also showed that classical self-pressurization is quite fragile in microgravity and nucleate boiling can occur at hotspots on the tank wall even at moderate heat fluxes that do not induce boiling on Earth.Proved that ZBO pressure control is feasible and effective in microgravity using subcooled jet mixing, but also demonstrated that microgravity ullage-jet interaction does not follow the expected classical regime patterns (see Figure 3).Enabled observation of unexpected cavitation during subcooled jet mixing, leading to massive phase change at both sides of the screened Liquid Acquisition Device (LAD) (see Figure 4). If this type of phase change occurs in a propellant tank, it can lead to vapor ingestion through the LAD and disruption of liquid flow in the transfer line, potentially leading to engine failure.Developed a state-of-the-art two-phase CFD model validated by over 30 microgravity case studies (an example of which is shown in Figure 3). ZBOT CFD models are currently used as an effective tool for propellant tank scaleup design by several aerospace companies participating in the NASA tipping point opportunity and the NASA Human Landing System (HLS) program.Figure 4. White light image captures of the intact single hemispherical ullage in ZBOT tank before depressurization by the subcooled jet (left) and after subcooled jet mixing pressure collapse that led to massive phase change bubble generation due to cavitation at the LAD (right). (ZBOT-1 Experiment, 2018). Credit: Dr. Mohammad Kassemi, Case Western Reserve UniversityThe ZBOT-NC Experiment: Non-Condensable Gas EffectsNon-condensable gases (NCGs) are used as pressurants to extract liquid for engine operations and tank-to-tank transfer. The second experiment, ZBOT-NC will investigate the effect of NCGs on the sealed tank self-pressurization and on pressure control by axial jet mixing. Two inert gases with quite different molecular sizes, Xenon, and Neon, will be used as the non-condensable pressurants. To achieve pressure control or reduction, vapor molecules must reach the liquid-vapor interface that is being cooled by the mixing jet and then cross the interface to the liquid side to condense.This study will focus on how in microgravity the non-condensable gases can slow down or resist the transport of vapor molecules to the liquid-vapor interface (transport resistance) and will clarify to what extent they may form a barrier at the interface and impede the passage of the vapor molecules across the interface to the liquid side (kinetic resistance). By affecting the interface conditions, the NCGs can also change the flow and thermal structures in the liquid.ZBOT-NC will use both local temperature sensor data and uniquely developed Quantum Dot Thermometry (QDT) diagnostics to collect nonintrusive whole-field temperature measurements to assess the effect of the non-condensable gases during both self-pressurization heating and jet mixing/cooling of the tank under weightlessness conditions. This experiment is scheduled to fly to the International Space Station in early 2025, and more than 300 different microgravity tests are planned. Results from these tests will also enable the ZBOT CFD model to be further developed and validated to include the non-condensable gas effects with physical and numerical fidelity.The ZBOT-DP Experiment: Droplet Phase Change EffectsZBO active pressure control can also be accomplished via injection of subcooled liquid droplets through an axial spray-bar directly into the ullage or vapor volume. This mechanism is very promising, but its performance has not yet been tested in microgravity. Evaporation of droplets consumes heat that is supplied by the hot vapor surrounding the droplets and produces vapor that is at a much lower saturation temperature. As a result, both the temperature and the pressure of the ullage vapor volume are reduced. Droplet injection can also be used to cool down the hot walls of an empty propellant tank before a tank-to-tank transfer or filling operation. Furthermore, droplets can be created during the propellant sloshing caused by acceleration of the spacecraft, and these droplets then undergo phase change and heat transfer. This heat transfer can cause a pressure collapse that may lead to cavitation or a massive liquid-to-vapor phase change. The behavior of droplet populations in microgravity will be drastically different compared to that on Earth.The ZBOT-DP experiment will investigate the disintegration, coalescence (droplets merging together), phase change, and transport and trajectory characteristics of droplet populations and their effects on the tank pressure in microgravity. Particular attention will also be devoted to the interaction of the droplets with a heated tank wall, which can lead to flash evaporation subject to complications caused by the Liedenfrost effect (when liquid droplets propel away from a heated surface and thus cannot cool the tank wall). These complicated phenomena have not been scientifically examined in microgravity and must be resolved to assess the feasibility and performance of droplet injection as a pressure and temperature control mechanism in microgravity.Back to Planet EarthThis NASA-sponsored fundamental research is now helping commercial providers of future landing systems for human explorers. Blue Origin and Lockheed Martin, participants in NASA’s Human Landing Systems program, are using data from the ZBOT experiments to inform future spacecraft designs.Cryogenic fluid management and use of hydrogen as a fuel are not limited to space applications. Clean green energy provided by hydrogen may one day fuel airplanes, ships, and trucks on Earth, yielding enormous climate and economic benefits. By forming the scientific foundation of ZBO cryogenic fluid management for space exploration, the ZBOT science experiments and CFD model development will also help to reap the benefits of hydrogen as a fuel here on Earth.Project LeadDr. Mohammad Kassemi (Dept Mechanical & Aerospace Engineering, Case Western Reserve University)Sponsoring OrganizationBiological and Physical Sciences (BPS) Division, NASA Science Mission Directorate (SMD)

NASA’s Zero-Boil-Off Tank experiments address the challenge of managing cryogenic propellants in space, crucial for future Moon and Mars missions, with potential Earth-bound benefits in...

Gateway Space Station Full Configuration

Figure 1. The Gateway space station—humanity’s first space station around the Moon—will be capable of being refueled in space. Credit: NASA, Alberto Bertolin, Bradley Reynolds

NASA’s Zero-Boil-Off Tank experiments address the challenge of managing cryogenic propellants in space, crucial for future Moon and Mars missions, with potential Earth-bound benefits in hydrogen energy applications.

Do we have enough fuel to get to our destination? This is probably one of the first questions that comes to mind whenever your family gets ready to embark on a road trip. If the trip is long, you will need to visit gas stations along your route to refuel during your travel.

NASA is grappling with similar issues as it gets ready to embark on a sustainable mission back to the Moon and plans future missions to Mars. But while your car’s fuel is gasoline, which can be safely and indefinitely stored as a liquid in the car’s gas tank, spacecraft fuels are volatile cryogenic liquid propellants that must be maintained at extremely low temperatures and guarded from environmental heat leaks into the spacecraft’s propellant tank. And while there is already an established network of commercial gas stations in place to make refueling your car a cinch, there are no cryogenic refueling stations or depots at the Moon or on the way to Mars.

Furthermore, storing volatile propellant for a long time and transferring it from an in-space depot tank to a spacecraft’s fuel tank under microgravity conditions will not be easy since the underlying microgravity fluid physics affecting such operations is not well understood. Even with today’s technology, preserving cryogenic fuels in space beyond several days is not possible and tank-to-tank fuel transfer has never been previously performed or tested in space.

Propellant Management in Space: Overcoming Boil-Off

Heat conducted through support structures or from the radiative space environment can penetrate even the formidable Multi-Layer Insulation (MLI) systems of in-space propellant tanks, leading to boil-off or vaporization of the propellant and causing tank self-pressurization. The current practice is to guard against over-pressurizing the tank and endangering its structural integrity by venting the boil-off vapor into space.

Onboard propellants are also used to cool down the hot transfer lines and the walls of an empty spacecraft tank before a fuel transfer and filling operation can take place. Thus, precious fuel is continuously wasted during both storage and transfer operations, rendering long-duration expeditions—especially a human Mars mission—infeasible using current passive propellant tank pressure control methods.

Introducing ZBO: A New Horizon in Fuel Efficiency

Zero-Boil-Off (ZBO) or Reduced Boil-Off (RBO) technologies provide an innovative and effective means to replace the current passive tank pressure control design. This method relies on a complex combination of active, gravity-dependent mixing and energy removal processes that allow maintenance of safe tank pressure with zero or significantly reduced fuel loss.

Zero Boil-off Storage and Transfer: A Transformative Space Technology

At the heart of the ZBO pressure control system are two proposed active mixing and cooling mechanisms to counter tank self-pressurization. The first is based on intermittent, forced, subcooled jet mixing of the propellant and involves complex, dynamic, gravity-dependent interaction between the jet and the ullage (vapor volume) to control the condensation and evaporation phase change at the liquid-vapor interface.

The second mechanism uses subcooled droplet injection via a spraybar in the ullage to control tank pressure and temperature. While the latter option is promising and gaining prominence, it is more complex and has never been tested in microgravity where the phase change and transport behavior of droplet populations can be very different and nonintuitive compared to those on Earth.

Although the dynamic ZBO approach is technologically complex, it promises an impressive advantage over the currently used passive methods. An assessment of one nuclear propulsion concept for Mars transport estimated that the passive boil-off losses for a large liquid hydrogen tank carrying 38 tons of fuel for a three-year mission to Mars would be approximately 16 tons/year. The proposed ZBO system would provide a 42% saving of propellant mass per year.

These numbers also imply that with a passive system, all the fuel carried for a three-year Mars mission would be lost to boil-off, rendering such a mission infeasible without resorting to the transformative ZBO technology.

The ZBO approach provides a promising method, but before such a complex technological and operational transformation can be fully developed, implemented, and demonstrated in space, important and decisive scientific questions that impact its engineering implementation and microgravity performance must be clarified and resolved.

The Zero-Boil-Off Tank (ZBOT) Microgravity Science Experiments

The Zero Boil-off Tank (ZBOT) Experiments are being undertaken to form a scientific foundation for the development of the transformative ZBO propellant preservation method. Following the recommendation of a ZBOT science review panel comprised of members from aerospace industries, academia, and NASA, it was decided to perform the proposed investigation as a series of three small-scale science experiments to be conducted onboard the International Space Station. The three experiments outlined below build upon each other to address key science questions related to ZBO cryogenic fluid management of propellants in space.

Astronaut Joseph Acaba Installing ZBOT Hardware

Figure 2. Astronaut Joseph M. Acaba installing ZBOT Hardware in the Microgravity Science Glovebox aboard the International Space Station. Credit: NASA

The ZBOT-1 Experiment: Self-Pressurization & Jet Mixing

The first experiment in the series was carried out on the station in the 2017-2018 timeframe. Figure 2 shows the ZBOT-1 hardware in the Microgravity Science Glovebox (MSG) unit of the station. The main focus of this experiment was to investigate the self-pressurization and boiling that occurs in a sealed tank due to local and global heating, and the feasibility of tank pressure control via subcooled axial jet mixing. In this experiment, the complicated interaction of the jet flow with the ullage (vapor volume) in microgravity was carefully studied.

Microgravity jet mixing data was also collected across a wide range of scaled flow and heat transfer parameters to characterize the time constants for tank pressure reduction, and the thresholds for geyser (liquid fountain) formation, including its stability, and penetration depth through the ullage volume. Along with very accurate pressure and local temperature sensor measurements, Particle Image Velocimetry (PIV) was performed to obtain whole-field flow velocity measurements to validate a Computational Fluid Dynamics (CFD) model.

Validation of ZBOT CFD Model Predictions

Figure 3. Validation of ZBOT CFD Model Predictions for fluid flow and deformation of a spherical ullage in microgravity by a subcooled liquid jet mixing against ZBOT experimental results: (a) Model prediction of ullage position and deformation and flow vortex structures during subcooled jet mixing; (b) PIV image capture of flow vortex structures during jet mixing; (c) Ullage deformation captured by white light imaging; and (d) CFD model depiction of temperature contours during subcooled jet mixing. (ZBOT-1 Experiment, 2018) Credit: Dr. Mohammad Kassemi, Case Western Reserve University

Some of the interesting findings of the ZBOT-1experiment are as follows:

  1. Provided the first tank self-pressurization rate data in microgravity under controlled conditions that can be used for estimating the tank insulation requirements. Results also showed that classical self-pressurization is quite fragile in microgravity and nucleate boiling can occur at hotspots on the tank wall even at moderate heat fluxes that do not induce boiling on Earth.
  2. Proved that ZBO pressure control is feasible and effective in microgravity using subcooled jet mixing, but also demonstrated that microgravity ullage-jet interaction does not follow the expected classical regime patterns (see Figure 3).
  3. Enabled observation of unexpected cavitation during subcooled jet mixing, leading to massive phase change at both sides of the screened Liquid Acquisition Device (LAD) (see Figure 4). If this type of phase change occurs in a propellant tank, it can lead to vapor ingestion through the LAD and disruption of liquid flow in the transfer line, potentially leading to engine failure.
  4. Developed a state-of-the-art two-phase CFD model validated by over 30 microgravity case studies (an example of which is shown in Figure 3). ZBOT CFD models are currently used as an effective tool for propellant tank scaleup design by several aerospace companies participating in the NASA tipping point opportunity and the NASA Human Landing System (HLS) program.
Intact Single Hemispherical Ullage in ZBOT Tank

Figure 4. White light image captures of the intact single hemispherical ullage in ZBOT tank before depressurization by the subcooled jet (left) and after subcooled jet mixing pressure collapse that led to massive phase change bubble generation due to cavitation at the LAD (right). (ZBOT-1 Experiment, 2018). Credit: Dr. Mohammad Kassemi, Case Western Reserve University

The ZBOT-NC Experiment: Non-Condensable Gas Effects

Non-condensable gases (NCGs) are used as pressurants to extract liquid for engine operations and tank-to-tank transfer. The second experiment, ZBOT-NC will investigate the effect of NCGs on the sealed tank self-pressurization and on pressure control by axial jet mixing. Two inert gases with quite different molecular sizes, Xenon, and Neon, will be used as the non-condensable pressurants. To achieve pressure control or reduction, vapor molecules must reach the liquid-vapor interface that is being cooled by the mixing jet and then cross the interface to the liquid side to condense.

This study will focus on how in microgravity the non-condensable gases can slow down or resist the transport of vapor molecules to the liquid-vapor interface (transport resistance) and will clarify to what extent they may form a barrier at the interface and impede the passage of the vapor molecules across the interface to the liquid side (kinetic resistance). By affecting the interface conditions, the NCGs can also change the flow and thermal structures in the liquid.

ZBOT-NC will use both local temperature sensor data and uniquely developed Quantum Dot Thermometry (QDT) diagnostics to collect nonintrusive whole-field temperature measurements to assess the effect of the non-condensable gases during both self-pressurization heating and jet mixing/cooling of the tank under weightlessness conditions. This experiment is scheduled to fly to the International Space Station in early 2025, and more than 300 different microgravity tests are planned. Results from these tests will also enable the ZBOT CFD model to be further developed and validated to include the non-condensable gas effects with physical and numerical fidelity.

The ZBOT-DP Experiment: Droplet Phase Change Effects

ZBO active pressure control can also be accomplished via injection of subcooled liquid droplets through an axial spray-bar directly into the ullage or vapor volume. This mechanism is very promising, but its performance has not yet been tested in microgravity. Evaporation of droplets consumes heat that is supplied by the hot vapor surrounding the droplets and produces vapor that is at a much lower saturation temperature. As a result, both the temperature and the pressure of the ullage vapor volume are reduced. Droplet injection can also be used to cool down the hot walls of an empty propellant tank before a tank-to-tank transfer or filling operation. Furthermore, droplets can be created during the propellant sloshing caused by acceleration of the spacecraft, and these droplets then undergo phase change and heat transfer. This heat transfer can cause a pressure collapse that may lead to cavitation or a massive liquid-to-vapor phase change. The behavior of droplet populations in microgravity will be drastically different compared to that on Earth.

The ZBOT-DP experiment will investigate the disintegration, coalescence (droplets merging together), phase change, and transport and trajectory characteristics of droplet populations and their effects on the tank pressure in microgravity. Particular attention will also be devoted to the interaction of the droplets with a heated tank wall, which can lead to flash evaporation subject to complications caused by the Liedenfrost effect (when liquid droplets propel away from a heated surface and thus cannot cool the tank wall). These complicated phenomena have not been scientifically examined in microgravity and must be resolved to assess the feasibility and performance of droplet injection as a pressure and temperature control mechanism in microgravity.

Back to Planet Earth

This NASA-sponsored fundamental research is now helping commercial providers of future landing systems for human explorers. Blue Origin and Lockheed Martin, participants in NASA’s Human Landing Systems program, are using data from the ZBOT experiments to inform future spacecraft designs.

Cryogenic fluid management and use of hydrogen as a fuel are not limited to space applications. Clean green energy provided by hydrogen may one day fuel airplanes, ships, and trucks on Earth, yielding enormous climate and economic benefits. By forming the scientific foundation of ZBO cryogenic fluid management for space exploration, the ZBOT science experiments and CFD model development will also help to reap the benefits of hydrogen as a fuel here on Earth.

Project Lead

Dr. Mohammad Kassemi (Dept Mechanical & Aerospace Engineering, Case Western Reserve University)

Sponsoring Organization

Biological and Physical Sciences (BPS) Division, NASA Science Mission Directorate (SMD)

Read the full story here.
Photos courtesy of

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Wetlands viewed as an impediment to progress “It is going to be even harder to protect those wetlands that are left because the best tool we had to protect those wetlands, the federal Clean Water Act, is really being gutted,” said Mark Sabath, an attorney with the nonprofit Southern Environmental Law Center.The wetlands around Charleston support oyster beds that filter water and cling to long, wooden piers that stretch over shallow water and into the Ashley River. Kingfishers and egrets fly between the cordgrass. It's a humid, sticky place during blazing summers in the South. A vein of the river becomes Halsey Creek, shooting into the Wagner Terrace neighborhood, a suburban area north of Charleston's historic downtown. Waves of communities called it home after World War II: it was predominantly Jewish along with Greek and Italian immigrants in the decades following the war, shifting to African American in the 1960s and 1970s. 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While the Indian government said ethanol usage reduces pollution, some users said it is affecting their mileage and damaging older engines. Most fuel pumps in India now sell the 20% ethanol blend or unblended gasoline that’s nearly twice as expensive. Lower ethanol blends are being phased out. Environment experts also said grain production for ethanol can displace food crops and sometimes generates more planet-warming gases than it saves. Indian car owners say ethanol reduces mileage Ethanol, typically made from corn, sugarcane or rice, is considered cleaner than petroleum-based gasoline. The Indian government said its blending program has already cut carbon emissions by 74 billion kilograms (163 billion pounds)— equivalent to planting 300 million trees — and saved over $12 billion in oil imports in the last decade.“I think it’s good for the environment,” said Vijay Ramakrishnan, a businessman in Chennai. “But I’ve noticed a drop in mileage in my vehicle in recent months. Given how expensive fuel already is this further drop is only adding to my costs.”Ramakrishnan, who commutes over 100 kilometers (62 miles) daily, wants the government to offer more fuel choices.Amit Khare, who runs a popular YouTube channel on automobiles, said many followers complain about a significant drop in mileage from E20. Some owners of older cars have told him that they are having engine trouble.“E5 is the best fuel, E10 is manageable, but E20 has given a lot of trouble,” he said. Ramya Natarajan of the Bengaluru-based Center for Study of Science, Technology and Policy said ethanol can be good for some engines if they are compatible, but agreed that it can reduce mileage. Indian farmers want clarity on crops needed for ethanol Farmers said they need clarity on government procurement plans for ethanol production. Ramandeep Mann, a farmer in India's northern Punjab state, said farmers significantly increased corn acreage last year in hopes of selling it for fuel, but the price dropped after the government allocated large amounts of rice to ethanol makers. The amount of ethanol blended with gasoline in India grew from 8% to 20% in the last five years. Most of the ethanol now comes from grains, as opposed to the sugarcane, its traditional source. Mann said prices for sugarcane have also dropped this year. He said it’s good that the government is tackling climate change, but it should put farmers and their prices ahead of ethanol mandates. Previously, surplus crops not needed for food were the primary source of India's ethanol, but that's beginning to change, according to Natarajan of CSTEP. “With the push for E20 blends or even more, a lot more area has to be cultivated which in turn means it’ll be replacing other crops,” she said. Climate experts said biofuel production can have minimal environmental impact when it’s made from waste or inedible vegetation and processed in facilities that run on clean energy. But when crops are grown explicitly for biofuels, it has a higher carbon footprint because of the fertilizer and fuel involved.India’s ethanol strategy is part of a broader effort to reduce emissions, cut oil imports and boost agriculture, said Purva Jain, an energy specialist at the Institute for Energy Economics and Financial Analysis.But she said a faster transition to infrastructure for electric vehicles might be better. A 2022 study by her organization found that installing solar power for EV charging can be a much more efficient land use than growing crops for biofuel. However, ethanol producers have invested significant sums in manufacturing and need a steady, growing market for their product now, said CK Jain, president of the Grain Ethanol Manufacturers Association. He said India should increase the percentage of ethanol mixed with gas and encourage the sale of compatible vehicles. “We need to have higher blending as soon as possible, otherwise the industry will go into deep financial trouble,” Jain said. Other experts advocated for a middle ground. A 10% blend of ethanol with gasoline, can be a “win-win” solution said Natarajan of CSTEP. She said that would allow for use of existing crops without putting too much pressure on increased cultivation. Khare, the YouTube influencer, said keeping lower blends available would help older vehicles. “The government can bring E20 or even up to E85 programs on top of that, that’s completely fine. But consumers need to be given the option,” he said. The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropies, a list of supporters and funded coverage areas at AP.org.Copyright 2025 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.Photos You Should See – Oct. 2025

Climate
Government
Business

If Trump’s EPA abandons climate policy, could California take over on greenhouse gases?

Legal experts, including a former federal official and UCLA professor, say California could go it alone if the federal government stops regulating greenhouse gases. One reason to try is to protect the state’s clean-car economy.

In summary Legal experts, including a former federal official and UCLA professor, say California could go it alone if the federal government stops regulating greenhouse gases. One reason to try is to protect the state’s clean-car economy. California has long cast itself as the nation’s climate conscience — and its policy lab. Now, as the Environmental Protection Agency moves to revoke the backbone of federal climate rules — the scientific finding that greenhouse gases threaten human health — one of the state’s top climate officials is weighing a provocative idea put forward by environmental law experts: If Washington retreats, California could lead on carbon-controlling regulation.   Absent what’s known as the endangerment finding, the EPA may soon consider abandoning the legal authority under the Clean Air Act to regulate greenhouse gases from vehicles, power plants and other sources, furthering the Trump Administration’s stated aim to dismantle U.S. climate policy.  While decrying the prospect of such a move, climate advocates say a repeal would yield a silver lining: California and other states could in theory set their own greenhouse gas rules for cars and trucks, regulations previously superseded by federal authority. Cars and trucks represent more than a third of California’s greenhouse gas emissions. A long shot regulatory gambit could clean some of the nation’s dirtiest air – and keep the state’s clean-car transition alive. “All options are currently on the table,” Lauren Sanchez, chair of the California Air Resources Board, told CalMatters in an interview. Authority states have never had before A former federal official and expert on the Clean Air Act – who is also a law professor at UCLA – first floated this idea.  Ann Carlson wrote in the law journal Environmental Forum that an aggressive federal action against climate policy “could, ironically, provide states with authority they’ve never had before.” The Trump administration now argues that greenhouse gases do not endanger health and that regulation is more harmful — a claim widely rejected by scientists, businesses and environmental groups, as well as states, including California. The Phillips 66 refinery in Wilmington, on Sept. 30, 2025. Photo by Stella Kalinina for CalMatters “If greenhouse gases aren’t covered by the Clean Air Act,” Carlson told CalMatters, “then California could presumably regulate them — and so could every other state.” Carlson, who ran the National Highway Traffic Safety Administration until last year and has written extensively about the landmark law, argues that the act only preempts state rules for pollutants it actually covers. States “have a pretty strong legal argument” to regulate greenhouse gases, she said. The EPA, for its part, argues that states would still be barred from setting their own standards, arguing that its broad authority over air pollution covers even emissions the agency chooses not to regulate. That’s a view shared by the Alliance for Automotive Innovation, a trade association and lobbying group, which supported overturning California’s phaseout of new, gas-powered cars, as well as the American Trucking Associations, which has opposed some of California’s rules on trucks. Carlson said that argument doesn’t hold up. In her Environmental Forum article, she wrote: “If Congress didn’t intend the act to cover greenhouse gases, as the administration argues, then it’s hard to believe Congress intended to preempt states and localities from regulating them.” In other words, she says, preemption has its limits.  Other experts agreed the idea is worth considering.  Ethan Elkind, who directs the climate program at UC Berkeley’s Center for Law, Energy and the Environment, said that states are free to “do whatever they want,” as long as the federal government hasn’t preempted them.  Not a slam dunk for California to step in For the better part of a century, California has worked to curb air pollution at the state and local level. The state’s vanguard status positions it well to test Trump’s move to curb federal climate regulation, say experts.  “I personally would be advocating that they move ahead,” said Mary Nichols, a former air board chair. “And if I were there, I would be looking to gain support for doing it.” California holds a unique status under federal law. It can set tougher tailpipe-emission standards than the rest of the country — a recognition of its early leadership in fighting smog. Since 1968, the state has obtained more than 100 federal waivers for its vehicle rules, and other states can adopt California’s standards under certain conditions. UC Berkeley law professor Daniel Farber said the state could even take a dual-track approach. “We don’t really think we need a waiver,” he would argue after EPA abandons the field, “but just in case we do: yes, give us one.” California’s latest clash with Washington stems from a decades-long dance over who sets the nation’s toughest clean-car rules. The state’s strict vehicle rules have helped spur innovations from catalytic converters to cleaner fuel to electric cars. The regulatory push began in Los Angeles after skies grew so smog-choked they stung peoples’ eyes. In 1966, California adopted the nation’s first tailpipe standards. When Congress passed the 1970 Clean Air Act, it gave the state rare authority to set tougher rules — making California both a laboratory and a trailblazer, so long as it secured a federal waiver. In 2002, California passed the nation’s first law regulating greenhouse gas emissions from vehicles. The Supreme Court’s 2007 Massachusetts v. EPA ruling confirmed those gases are pollutants under federal law, leading to the Obama administration’s 2009 “endangerment finding” that they harm public health. Such a move would fit California’s pattern of pushing first and asking permission later. In 2005, the state adopted its greenhouse-gas standards for vehicles and sought a waiver before it was even clear whether carbon qualified as pollution under federal law. The EPA initially denied that request in 2008 but reversed course a year later, granting the waiver in 2009. “So this wouldn’t necessarily be a slam dunk approach for the state to take, but I think the legal avenue is now there,” said Elkin, of UC Berkeley. Targeting cars with new regulation If California tried to regulate greenhouse gases on its own, it would have both experience and infrastructure to rely on. The process would look a lot like how the state has written past clean-car rules — except this time, the target would be carbon itself. California’s clean-car rules have operated within the permission-seeking framework set up by the Clean Air Act — until this year, when Trump and Congress moved to block the state’s plans to phase out gas cars and tighten diesel-truck standards. Trump’s EPA then went further by proposing to repeal the 2009 endangerment finding, framing it as a win for “consumer choice.” Most of the state’s climate programs already run under authority of California’s own groundbreaking state laws: clean-energy mandates for utilities, a carbon-trading program for businesses, even standards to cut the carbon in fuels. Cars are different. They’re sold into a national market, and tailpipe emissions have long been federally preempted — one reason California has needed Washington’s permission to go its own way. If the state decides to test those limits, regulators would need to draft new rules and open them to public review — a process that could take years. California has already started down the path of new rules for clean cars and trucks. Last month, the Air Resources Board began the process of crafting clean car rules in response to the Trump administration’s rollback of the state’s new gas-car ban — a revocation the state is also fighting in court. In December, the board plans to begin the process of writing new emissions rules for trucks. The automobile association declined to comment on the new rulemaking effort.  Patrick Kelly, vice president of energy and environmental affairs for American Trucking Associations, said the group would work with its state affiliate to “respond to specific proposals. “ “More broadly, (our group) supports achievable national standards and opposes a patchwork of state and local standards that Congress sought to avoid,” Kelly wrote in an email. Gov. Gavin Newsom swears in incoming California Air Resources Board Chair Lauren Sanchez on Oct. 1, 2025. Photo courtesy of Office of the Governor Asked by CalMatters whether the new rulemakings could become the vehicle for California to go its own way under Trump, Sanchez, the air board chair, said it’s an option staff is studying. “It’s something that staff is looking into, and I look forward to digging into myself,” Sanchez said. No downside to trying, and some upsides Even if legal experts like the idea in theory, UC Berkeley’s Dan Farber says California going forward alone is a longshot in practice.  “There’s a chance you would win,” Farber said, of the argument that the state could directly regulate greenhouse gas emissions from cars. “You’re buying a lawsuit, but other than litigation expenses, I don’t think there’s much downside in trying to do it.” Farber and others point out that the Trump administration and car and truck manufacturers would almost certainly sue to block state-level efforts to regulate greenhouse gases.  The Alliance for Automotive Innovation warned, in comments to the EPA, that if states were not preempted, any unregulated emission “would then become fair game,” creating conflicting standards across the country. Automakers have long argued that letting states write their own climate rules would create a costly patchwork of standards, raising prices for consumers and complicating production for a national market. California is in somewhat of a legal quandary. The Clean Air Act requires California to meet national pollution standards, and the state still has some of the most air-polluted regions in the country. The state’s solutions rely heavily on clean-car and truck rules to meet those requirements. If California falls short, it could lose federal highway funding, a situation that Sanchez called a “no-win, Catch 22.”  After decades of regulation and incentives, California has built a reputation as a leader in electric cars, and experts said if the state pushes further on policy, that could help keep California’s clean-car transition alive and its electric-vehicle goals within reach.  Nick Nigro, founder of Atlas Public Policy, said California could also risk getting ahead of consumers if it goes it alone. Electric cars proved less popular than policymakers expected when it originally passed its goal to do away with sales of new gas-powered cars.  “What is clear is that the program was not overwhelmingly popular amongst the public, even in California, right?” Nigro said. “That’s usually a flag for policymakers.” Craig Segall, an independent consultant and former state air board deputy, said there’s another factor to consider: by preserving demand and infrastructure for EVs, the state could maintain a beachhead for innovation that a future president might build on. With no coherent federal policy to compete in the global EV market, California could again use its regulatory and investment muscle — just as it once did in helping spawn electric car maker Tesla — to push the market forward. “What the feds are basically signaling here is that the field is open for anyone who’s serious about being a competitive car or truck company in five years,” Segall said. “One of those paths is: the world’s fourth largest economy figures out ways to take its manufacturing economic capacity and just plow ahead.”

Climate
Government
Energy

How thousands of fossil fuel lobbyists got access to UN climate talks – and then kept drilling

Exclusive: Research shows oil, gas and coal firms’ unprecedented access to Cop26-29, blocking urgent climate actionMore than 5,000 fossil fuel lobbyists were given access to the UN climate summits over the past four years, a period marked by a rise in catastrophic extreme weather, inadequate climate action and record oil and gas expansion, new research reveals.Lobbyists representing the interests of the oil, gas and coal industries – which are mostly responsible for climate breakdown – have been allowed to participate in the annual climate negotiations where states are meant to come in good faith and commit to ambitious policies to reduce greenhouse gas emissions. Continue reading...

More than 5,000 fossil fuel lobbyists were given access to the UN climate summits over the past four years, a period marked by a rise in catastrophic extreme weather, inadequate climate action and record oil and gas expansion, new research reveals.Lobbyists representing the interests of the oil, gas and coal industries – which are mostly responsible for climate breakdown – have been allowed to participate in the annual climate negotiations where states are meant to come in good faith and commit to ambitious policies to reduce greenhouse gas emissions.The roughly 5,350 lobbyists mingling with world leaders and climate negotiators in recent years worked for at least 859 fossil fuel organizations including trade groups, foundations and 180 oil, gas and coal companies involved in every part of the supply chain from exploration and production to distribution and equipment, research shared exclusively with the Guardian has found.Just 90 of the fossil fuel corporations that sent lobbyists to climate talks between 2021 and 2024 accounted for more than half (57%) of all the oil and gas produced last year, according to the analysis by Kick Big Polluters Out (KBPO), a coalition of 450 organizations campaigning to stop the fossil fuel industry blocking and delaying global climate action.These corporations, which include many of the world’s most profitable private and publicly owned oil and gas majors, accounted for the production of 33,699m barrels of oil equivalent in 2024 – enough to cover more than the entire area of Spain with a 1cm blanket of oil.The same 90 firms also account for almost two-thirds (63%) of all short-term upstream fossil fuel expansion projects which are gearing up for exploration and production, according to the newly released Global Oil and Gas Exit List – a dataset which includes more than 1,700 companies covering more than 90% of global oil and gas activity.If executed, these expansion projects will produce enough oil – 2.623m km² at 1cm thickness – to coat the entire landmass of seven European countries (France, Spain, Germany, Denmark, Sweden, Finland and Norway) combined.The findings have renewed calls for fossil fuel companies and other big polluters to be banned from the annual climate negotiations amid mounting scientific evidence that the world has failed to limit the rise in global temperatures to 1.5C above preindustrial levels,.“This information clearly exposes corporate capture of the global climate process … the space that should be about science and the people has been transformed into a large carbon business hall,” said Adilson Vieira, spokesperson for the Amazonian Work Group. “While forest communities fight for survival, the same companies that cause climate collapse buy credentials and political influence to continue expanding their fossil empires.”“Not only are Indigenous peoples on the frontlines of their extractive sites suffering human rights violations, but we also face the brunt of climate chaos on our lands with worsening floods, wildfires, and extreme heat waves. We need to take down the ‘for sale’ sign on Mother Earth and bar entry to Cop for oil and gas lobbyists,” said Brenna Yellowthunder, lead coordinator for the Indigenous Environmental Network, a member of KBPO.The 30th UN climate summit (Cop30) opens on Monday in Belem, a city in the Brazilian Amazon – the world’s largest rainforest, which is being destroyed by ever-expanding fossil fuel exploitation, industrial agriculture, and mining, among other extractive industries.The annual meetings are where every country in the world negotiates on how best to tackle the climate crisis. The decisions should be driven by the legally binding United Nations Framework Convention on Climate Change (UNFCCC) treaty, and the 2015 Paris agreement to curtail global heating to under 1.5C.The research analyses the fossil fuel lobbyists known to have attended the negotiations in Glasgow (Cop26), Sharm el-Sheikh (Cop27), Dubai (Cop28) and Baku (Cop29). Until then, information about lobbyists was not collated by the UNFCCC.Growing anger at the lack of meaningful action by the world’s wealthiest, most polluting countries has been compounded by revelations that the fossil fuel industry appears to be granted greater access to the climate talks than most countries.Last year, 1,773 registered fossil fuel lobbyists attended the summit in Azerbaijan – 70% more than the total number of delegates from the 10 most climate-vulnerable nations combined (1,033).But the true reach of fossil fuel tentacles is undoubtedly deeper as the lobbyists data excludes executives and other company representatives on official country delegations participating directly in the confidential negotiations, and those attending as guests of governments, known as overflow delegates.The largest number of known lobbyists in recent years were representing state-owned companies from the United Arab Emirates, Russia and Azerbaijan.Many of the world’s most profitable fossil fuel corporations have also been present at recent Cop summits, at a time when governments faced huge public pressure – but failed – to agree to phase out fossil fuels despite deadly climate impacts affecting every corner of the planet.Between 2021 and 2024, Shell sent a combined total of 37 lobbyists, BP sent 36, ExxonMobil 32 and Chevron 20.In the past five years, the four oil majors made more than $420bn in combined profits.On Friday the Exxon CEO Darren Woods will headline a Cop30 launch event in Brasilia hosted by the US chamber of commerce called Pragmatic Business Solutions for Carbon Accounting and Emission Reductions. The US, which like every state is legally obliged under international law to tackle the climate crisis, has withdrawn from the Paris agreement and is not sending a country delegation to the summit.Petrobas, the majority state owned Brazilian multinational which sent at least 28 lobbyists to the past four climate summits, was recently grant ed a licence to conduct exploratory oil drilling in the sea off the Amazon, which is home to multiple Indigenous communities and about 10% of the planet’s known species.A spokesperson said: “Petrobras will be present at COP30, as it has been at previous talks, because it recognizes the opportunity to discuss sustainable models… The company’s participation in COP30 reinforces its commitment to follow and contribute to international debates on climate and energy.”Shell, BP, ExxonMobil and Chevron did not respond to requests for comment.After years of campaigning by civil society groups, Cop delegates this year are being asked to publicly disclose who is funding their participation – and confirm that their objectives are in alignment with the UNFCCC. But the new transparency requirement excludes anyone in official government delegations or overflows, and calls for stricter conflict of interest protections to cut industry influence have not been adequately heeded, advocates say.“The new rules are a welcome start, but they come decades too late … and transparency without exclusion is performative. You cannot claim to fix a process already captured by the very corporations burning the planet and fueling wars,” said Mohammed Usrof, executive director of the Palestinian Institute for Climate Strategy. “The UNFCCC must move from disclosure to disqualification… without reform this process will not save the world, and instead, will just help bury it.”UNFCCC has been contacted for comment.

Climate
Agriculture
Crisis

Climate Risk Rarely Leads to ECB Collateral Downgrade, Blog Finds

FRANKFURT (Reuters) -The European Central Bank is already factoring climate-related risk into the assessment of collateral used to borrow money...

FRANKFURT (Reuters) -The European Central Bank is already factoring climate-related risk into the assessment of collateral used to borrow money from the bank but this rarely leads to credit rating changes, a blog post published by the ECB said on Friday.The ECB's 2021 climate action plan made the integration of climate risks into its collateral framework a key priority and the bank expects climate risk to be factored into credit ratings of assets posted by banks when they borrow from the central bank."While climate risks are widely recognised, they rarely lead to rating changes," the blog post, which does not necessarily represent the ECB's views, argued. "Several persistent challenges still limit the full and consistent integration of climate change risk into credit ratings."The ECB is using both its own in-house credit assessment systems and external rating agencies to determine climate risk but neither method has so far had a huge impact on collateral valuation.When using its in-house system, the share of credit ratings affected by climate risks is below 4% and the adjustments made are typically limited to one rating grade, the blog said.In the case of external agencies, environmental, social, and governance factors influence approximately 13% to 19% of all rating actions across the major agencies but climate change-specific downgrades account for only 2% to 7%, the blog post argued.While actual risk may be greater, assessment is difficult because banks can mask the vulnerabilities of some debtors, risk mitigation strategies can reduce their perceived exposure and because rating horizons are short- and medium-term, whereas climate risks tend to be long term, the blog said."Furthermore, reliable, granular climate change-related data remain scarce, particularly for smaller issuers, sovereigns and structured finance," it argued.(Reporting by Balazs KoranyiEditing by Tomasz Janowski)Copyright 2025 Thomson Reuters.Photos You Should See – Oct. 2025

Climate

Suggested Viewing

Rise and Fall

A film to provide an awareness of climate change and the individual measures we can take to combat it. The production process of Rise and Fall began as your stereotypical documentary meant to showcase various aspects of the Earth and Ocean Sciences Department at UNCW. Still, as the interview process was underway, it was quickly decided to move in another direction. It is an essay film about the science of climate change, what we can do in our day-to-day lives to combat it, and its impacts. Without using talking heads, the images of the natural world provide a sensual look at what will be affected by climate change.

Climate
Nature
Documentary

THE WATER WILL TAKE US

This film tells the story of the victims of the flood of 2019 in Iran, which happened in the three provinces of North, Central and South of the country and left a lot of damages. The main narrators are three women who reveal the causes of this incident and mismanagements and tell the story of the people who were left to fend for themselves during the flood and after.

Water
Social Justice
Climate

CO2? CO-Nee!

Joep van Dijk is a passionate climate scientist. He likes to search for extreme examples that show how life can be lived sustainably. This documentary follows Joep on his CO2-neutral journey from Amsterdam to the United States of America and shows how this choice inspires himself and others to live a climate conscious life.

Climate
CO2
Sustainable

Total Disaster

Armed with realistic bird puppets, trickster environmental activists pretend to be oil company Total—staging a satirical press conference to introduce "RéHabitat," a program to rescue animals from the East African Oil Pipeline by relocating them to “more sustainable” habitats. Using humor and mischief, they expose a deadly ecological disaster in a zany effort to help #StopEACOP.

Activism
Energy
Animals

Eating the Future

Bafta-winner Mia McKenna-Bruce voices an eco-investigator who is traumatised by her work accessing factory farms and documenting animal abuses undercover. Terrified of a future of climate apocalypse, she embarks on a journey into the food systems that shape our planet, to look for hope.

Activism
Climate
Food

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