Illinois study explores feasibility of creating sustainable jet fuel from food waste

University of Illinois College of Agricultural, Consumer and Environmental Sciences

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Sabrina Summers and Yuanhui Zhang, University of Illinois Urbana-Champaign, hold vials of the sustainable aviation fuel developed in their lab.

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Credit: Marianne Stein/College of ACES

URBANA, Ill. – The aviation industry accounts for a large portion of global greenhouse gas emissions. Biobased, sustainable aviation fuel (SAF) can mitigate climate impacts, but transitioning to SAF faces critical supply chain constraints. A research team at the University of Illinois Urbana-Champaign has developed a method to produce jet-grade fuel from food waste, contributing to a circular bioeconomy. In a new paper, published in Nature Sustainability, they focus on technical and economic considerations.

In a previous study, the researchers outlined the process of developing SAF that meets aviation standards. This study follows the same general approach, converting food waste to crude oil through hydrothermal liquefaction (HTL), a process that mimics natural formation of crude oil in a fraction of the time, and refining it with a catalyst.

“However, here we use a simpler approach with less catalytic intensity and greater focus on distillation, which is commonly used for industrial purposes. This is a more economical and environmentally friendly method. But the quality of the fuel is not as good, and it needs to be mixed with regular jet fuel,” said corresponding author Yuanhui Zhang, Founder Professor in the Department of Agricultural and Biological Engineering (ABE), part of the College of Agricultural, Consumer and Environmental Sciences and The Grainger College of Engineering at the U. of I.

Zhang compared this to the use of ethanol for cars; it must be blended with fossil fuel to work in car engines.

“It would be very difficult to produce enough SAF to meet industry needs, so it makes sense to take a biodiesel approach with a percentage blend,” he explained. “Our tests are based on a 50-50 blend, so it will certainly be feasible to use a 10% or 20% blend of SAF with regular fuel.”

The researchers conducted tests on key parameters to ensure their SAF product meets jet fuel standards set by the American Society for Testing and Materials (ASTM) and the Federal Aviation Administration.

“We are still doing this work on a very small scale. But my lab is now set up to produce several liters of upgraded fuel, which is enough for diesel engine tests. After that, the next step will be jet engine tests,” Zhang said. 

The biggest bottleneck in SAF production is getting the waste from disposal to reclamation and recovery, Zhang noted. Most food waste ends up either in a landfill or a wastewater treatment plant, where it is separated and converted into sludge. Collecting and reusing food waste presents logistical challenges, but the HTL process enables use of treated wastewater as feedstock.

While HTL offers a promising approach to create SAF from wet waste, it leaves a toxic, nutrient-rich byproduct called HTL aqueous phase, or HTL-AP. Zhang and his team explored ways to recover acid and nutrients from HTL-AP through electrochemical (EC) treatment. 

The researchers also conducted techno-economic and lifecycle analysis for the integrated process of upgrading the biocrude oil and treating the HTL-AP byproduct. They developed three scenarios for the analysis: A baseline where HTL-AP was sent to a centralized wastewater treatment plant; treatment with EC technology to recover and valorize HTL-AP; and a future scenario based on improved EC technology. 

Compared to the baseline scenario, using EC technology nearly tripled the cost per gallon due to higher capital and operating costs. However, technological advances are expected to lower the EC costs, so they become equivalent to baseline in the future. 

The team also evaluated global warming potential (GWP), which indicates how much global warming is affected by CO2 emissions. They estimated that both the baseline and the improved EC treatment would be able to achieve negative carbon emissions, leading to lower GWP.

The study outlines a technically feasible and environmentally beneficial pathway for turning urban organic waste into SAF and promoting a circular bioeconomy, the researchers concluded.

The paper, “A circular hydrothermal refinery for sustainable aviation fuel from food waste,” is published in Nature Sustainability [DOI: 10.1038/s41893-026-01848-1].

Research in the College of ACES is made possible in part by Hatch funding from USDA’s National Institute of Food and Agriculture. This study was also supported by the National Science Foundation (award no. 1804453), the Department of Energy (project no. DE-EE0009269), and the 2115 Talent Development Program of China Agricultural University.

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Journal

Nature Sustainability

DOI

10.1038/s41893-026-01848-1 

Article Title

A circular hydrothermal refinery for sustainable aviation fuel from food waste

Article Publication Date

23-Jun-2026

 

Tracking melanoidins to improve food-waste biogas recovery

Maximum Academic Press

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By combining ultraviolet-visible spectroscopy, three-dimensional excitation-emission matrix fluorescence spectroscopy, parallel factor analysis, methane production tests, and microbial community analysis, the team found that higher hydrothermal temperatures continuously promoted melanoidin formation, especially above 140 °C. These compounds showed a clear dose-dependent inhibitory effect: low doses reduced digestion efficiency and methane quality, while high doses triggered near-complete system collapse.

Food waste is rich in organic matter and is widely considered a promising substrate for anaerobic digestion, a process that converts biodegradable materials into methane-rich biogas. Hydrothermal pretreatment is often used to accelerate the breakdown of complex food-waste components and overcome the slow hydrolysis stage of digestion. However, higher pretreatment temperatures can also promote Maillard reactions between sugars and amino compounds, generating melanoidins. Because melanoidins are structurally complex, difficult to isolate, and lack standard reference materials, their formation and biological effects have remained hard to quantify. These uncertainties have limited the optimization of hydrothermal pretreatment coupled with anaerobic digestion.

A study (DOI: 10.48130/een-0026-0008) published in Energy & Environment Nexus on 21 April 2026 by Guangsuo Yu’s & Lu Ding’s team, East China University of Science and Technology, reports that melanoidins increase with hydrothermal temperature and inhibit methane production by disrupting methanogenic microbial communities.

The researchers first prepared simulated food waste composed of cooked rice, pork, and cabbage, representing starch-rich, protein-rich, and cellulose-rich components. The waste was hydrothermally treated at 120, 140, 160, 180, and 200 °C for one hour, and the resulting hydrothermal liquid products were analyzed. Dissolved organic carbon increased up to 160 °C, indicating enhanced hydrolysis of macromolecules, but declined at higher temperatures as polymerization and condensation shifted carbon into less soluble products. Meanwhile, pH decreased from 5.62 to 3.59 as temperature increased, showing stronger acidification. The team then used UV-Vis spectroscopy to assess aromaticity and color-related absorption. SUVA254 and absorbance at 350 nm both rose markedly when temperatures exceeded 140 °C, indicating increased formation of aromatic, brown-colored melanoidin-like compounds. To strengthen semi-quantitative characterization, they applied three-dimensional fluorescence spectroscopy and parallel factor analysis. The model identified two fluorescent components, with Component 1 assigned mainly to melanoidins. Its maximum fluorescence intensity increased continuously from untreated samples to the 200 °C group, reaching 374.14 a.u., confirming that melanoidins accumulated progressively with hydrothermal severity. The researchers next prepared food-waste-derived melanoidins and added them to anaerobic digestion systems at four dosage levels: 2.08, 4.16, 6.24, and 8.32 mg·mL−1. Low-dose additions reduced methane content and impaired digestion performance without causing full acidification failure. In contrast, high-dose additions sharply suppressed methane production by 98.15% and 99.24%, with methane content dropping below 10% and final pH values falling well below the optimal range for methanogens. Microbial sequencing showed that melanoidins reshaped bacterial and archaeal communities. Bacterial groups related to acid fermentation remained active, but methanogenic archaea, including key methane-producing taxa, were strongly disrupted. This suggests that melanoidins mainly block the methane-production stage rather than the early acid-production stage.

Overall, the study reveals that hydrothermal pretreatment is a double-edged strategy for food-waste resource recovery. While it can enhance hydrolysis and accelerate substrate breakdown, excessive thermal severity promotes melanoidin accumulation, which weakens methane production and may collapse anaerobic digestion systems. By establishing a semi-quantitative approach for tracking melanoidins and linking dosage effects to microbial responses, the work offers practical guidance for selecting hydrothermal conditions that balance organic-matter solubilization with biological digestibility. Future applications may include pretreatment-temperature control, melanoidin monitoring, and microbial management strategies to improve stable biogas production from food waste.

###

References

DOI

10.48130/een-0026-0008

Original Source URL

https://doi.org/10.48130/een-0026-0008

Funding Information

This work was supported by the project of the National Key Research and Development Program of China (Grant No. 2022YFC3902404), and the National Natural Science Foundation of China (Grant No. 22278142).

About Energy & Environment Nexus

Energy & Environment Nexus is a multidisciplinary journal for communicating advances in the science, technology and engineering of energy, environment and their Nexus.

---

DOI

10.48130/een-0026-0008 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Semi-quantitative characterization of melanoidins during hydrothermal treatment of food waste and their impact on anaerobic digestion

 

Brazil Launches World-First Ethanol-Powered Grid Engine

By Haley Zaremba - Jun 04, 2026

 

• Brazil has launched the world's first ethanol-powered engine designed specifically to generate grid electricity, at the Suape II power plant in Pernambuco, developed with Finnish firm Wärtsilä.
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• The pilot comes as the U.S. proposed a 25% tariff on Brazilian ethanol on June 1, citing unfair trade practices — adding geopolitical weight to Brazil's push for domestic ethanol applications.
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• Brazil's ethanol sector is worth roughly $20 billion and already supplies mandatory blends of up to 100% for flex-fuel vehicles; if the grid engine proves viable, it could reshape how countries use biofuels to back up intermittent renewables.
• 
  

Brazil is undertaking a major biofuels experiment that could be majorly disruptive for the global energy landscape if it proves effective. The South American country is filthy rich in biomass, and is seeking to use ethanol in novel applications – in this case, to power the energy grid. A new ethanol-powered engine designed specifically to provide electricity to the grid was just launched at the Suape II power plant in Pernambuco, in a world first.

Brazilian energy company Suape Energia has partnered with Finnish technology firm Wärtsilä to develop the engine, a pilot model which will test whether or not the technology is viable in real-world conditions. The testing will be extensive, providing thousands of hours of data over the coming years that will tell the researchers a lot about the approach's performance, sustainability, and economic viability.

The engine will run on ethanol sourced primarily from sugarcane grown in Brazil. Brazil is the top producer as well as the top consumer of sugarcane-derived ethanol in the world, and finding a way to convert it into usable and affordable electricity would be a major win for the nation's energy autonomy and security. Typically, this ethanol is used to power vehicles. Using it in grid applications is a novel and potentially majorly disruptive approach.

“Brazil is a world leader in ethanol production, but its potential use in electricity generation has up to now been overlooked,” said José Faustino Cândido, the technical director of Suape Energia.

This innovation comes at a time of broad experimentation with ethanol in Brazilian markets. “A new wave of biofuel innovation is sweeping the nation,” Reuters reported this week.

Brazil's ethanol sector is huge, representing around USD $20 billion. It's the second largest ethanol industry in the world, behind the United States. The country has been a longtime champion of “flex-fuel” cars able to run on a mandatory blend of at least 30 percent ethanol, and up to 100 percent ethanol. This policy has helped to shield Brazilian consumers from the current oil and gas prices that are causing so much pain at petrol pumps around the world.

While Brazil is “uniquely positioned” to test out this technology thanks to its robust ethanol supply chains and infrastructure, the ramifications of this test extend far beyond the Brazilian context. According to a recent report from Interesting Engineering, “the project's developers hope to show that ethanol can provide a source of dispatchable power, electricity that can be generated on demand, at a time when many countries are seeking ways to complement intermittent renewable energy sources such as wind and solar.”

This new domestic use for ethanol also comes at a politically fortuitous time for Brazil, as the United States proposed a 25 percent tariff on Brazilian ethanol just this week. On June 1, the Office of the U.S. Trade Representative released a report finding that “Brazil's acts, policies and practices with respect to ethanol market access are unreasonable and burden or restrict U.S. commerce.” In other words, the federal government conducted an investigation into Brazil's ethanol trade policies and determined that they have unfairly disadvantaged the United States and other trading partners by unduly restricting the market.

But while Brazil is leaning more heavily than ever into biofuels, the United States is in turmoil over how to regulate ethanol on its own soil. The Republican party is sharply divided over biofuels quotas of the kind that have benefitted Brazil during this latest oil price shock. Last month the House narrowly passed a bill to codify year-round sales of E15 ethanol fuel with a 15 percent ethanol blend in a major win for the corn lobby and for agricultural states. The bill will now have to go through the Senate, where its future is uncertain.

By Haley Zaremba for Oilprice.com

 

India Launches 85% Ethanol Fuel to Cut Oil Import Dependence

By Charles Kennedy - Jun 05, 2026

India is launching on Friday a new fuel blend with an 85% ethanol component as part of the fuel flex mobility program of the world's third-largest crude importer to reduce dependence on imported oil.

The E85 fuel was officially launched at a ceremony in New Delhi in the presence of India's Minister of Petroleum and Natural Gas, Hardeep Singh Puri.

On Thursday, Puri launched India's first flex-fuel passenger vehicle by Maruti Suzuki in New Delhi. Flex-fuel vehicles can operate on a range of ethanol–petrol blends, from E20 up to E100.

India now has the capability to produce ethanol from multiple feedstock sources such as broken grains, agricultural waste, bamboo, and sea weed, the oil minister said.

NITI Aayog, the government's think tank, officially classifies ethanol-based Flex-Fuel Vehicles (FFVs), including vehicles running on high ethanol blends such as E85, as Zero-Emission Vehicles.

E85 fuel also produces near-zero particulate matter (PM) emissions, making flex-fuel vehicles a promising solution for addressing the country's growing air pollution challenge, the government said on Thursday.

“Flex Fuel Vehicles offer India a practical solution to reduce crude oil imports, strengthen the rural economy through ethanol demand, and advance low-carbon mobility,” Puri said during the Launch of Hero MotoCorp’s First Flex-Fuel Motorcycle in New Delhi this week.

India, which depends on Middle East’s oil supply for nearly 50% of its crude imports, has scrambled to diversify its purchases in recent months, including by boosting Russian imports to record highs amid U.S. waivers for Russian oil loaded on tankers.

The world’s most populous country has been suffering from the crisis, which has crippled not only its crude supplies, but also those of the main cooking fuel, liquefied petroleum gas (LPG). Oil marketing companies in India have raised fuel prices for the fourth time in less than a month, after holding off on price hikes for two months after the war began.

India’s economic pains are intensifying every day that the Strait of Hormuz remains closed. One of the highest-performing emerging markets in recent years is scrambling to contain the oil shock that is spreading to consumer prices, foreign exchange reserves, current accounts, and economic growth.

By Charles Kennedy for Oilprice.com

 

Uncertainty and Diverse Approach Slow Orders for Alternative Fuel Vessels

CMA CGM took delivery of the largest LNG-powered containership, CMA CGM Notre (24,212 TEU) Dame, as the first of 10 in a new class (CMA CGM)

Published Jun 4, 2026 6:19 PM by The Maritime Executive

 

The pace of orders for alternative fuel vessels has slowed in 2026, reports DNV in its latest analysis of the orderbook from the DNV Alternative Fuels Insights platform. It reports that by the end of May 2026, the share of alternative-fueled vessels in total tonnage was “notably lower” than over the same period in 2025. 

“While the pace of alternative-fueled contracting has varied compared to 2025,” says Jason Stefanatos, Global Decarbonization Director at DNV Maritime, “what is also becoming clear is that fuel choice is no longer approached as a single bet. Owners are increasingly treating it as a portfolio decision, managing fuel optionality, timing of investment, and exposure to future regulation as they navigate long-life asset decisions.”

Owners have to weigh the balance between the investment in new technologies and the dangers of creating stranded assets that could become obsolete before their planned economic lives. Weighing on the industry is the continued uncertainty and diversity in the regulatory environment. Last October, the United States and others succeeded in scuttling the International Maritime Organization’s push for the Net Zero Framework, which was further compounded by the failure to show a clear path in the April 2026 meeting. Many have said this creates the possibility of divergent, regional regulatory regimes.

DNV calculates that so far in 2026, there have been a total of 119 orders for alternative-fuel vessels, but the orders are focused on the more established fuels. The majority are for LNG (50 percent), with LPG/ethane carriers running a close second (42 percent). The orders for methanol/ethanol lagged at just four in the first five months, reports DNV, the same as ammonia, and just one order for hydrogen.

This varies from the recent past, when methanol seemed to be gaining ground on LNG. At one point, they were nearly equal for new orders. With LNG showing new momentum, DNV calculates that there are now more than twice as many LNG orders (663) as methanol (313), which, however, remains in second place overall in the orderbook. LPG remains a niche with just 197 orders.

The pace of the orders also varies by sector. Containerships accounted for 42 of the 60 orders for LNG vessels, followed by 12 orders for car carriers. 

“As in previous years, ordering of alternative-fueled vessels has been led by the container segment, but dynamics are shifting,” explains Stefanatos. “While activity remains strong, the focus has moved towards smaller vessels, with fewer very large containerships, which are historically more likely to adopt alternative fuels, being ordered. At the same time, we are seeing increased activity in tanker and bulker segments.”

After packing the orderbook for ultra-large container vessels, and pushing the level to records, the focus shifted among many of the carriers to feeders that can be used to support their hub strategies. DNV highlights that most of the feeders and even mid-size container vessels still use conventional fuel, in part due to supply issues and smaller ports. This is being reflected in the orders.

Some segments, however, are focusing on LNG. For example, The Maritime Executive calculates that among large ocean-going cruise ships, half the orderbook is for LNG dual-fuel vessels (49 percent by number of vessels). By tonnage, it is even more dramatic, with 64 percent of the cruise ship orders incorporating LNG dual-fuel propulsion. Currently, about a third of the cruise ships in service are LNG, while the first methanol-ready cruise ships have also been delivered.

DNV’s data shows that conventional fuel continues to dominate the broader commercial shipping industry, where 95 percent of ships in operation (by tonnage) and 99 percent (by number of ships) operate on conventional fuel. Large ships are leading the take-up for alternative fuels, with 35 percent of the orderbook (by gross tonnage) incorporating alternative fuel capabilities, while overall just 15 percent of the orders are for alternative-fueled vessels.

The trends were continuing in May 2026. DNV reports a total of 36 orders for alternative-fueled vessels. However, 26 were for LPG/ethane carriers, just eight for LNG-fueled vessels, and two ethanol-fueled bulk carriers. Notably, there were no methanol-fueled orders while ammonia and hydrogen continue to wait for further developments in the technology and infrastructure.

While the pace has slowed for the adoption of alternative fuels, DNV believes owners are still advancing fuel and technology decisions against a backdrop of evolving regulatory and market conditions.

BHP Tests Out Tallow-Based Biofuel Blend With GCMD's Assistance

Berge Lyngor (VesselFinder / Graeme Waller)

Published Jun 3, 2026 2:36 PM by The Maritime Executive

In a development that could increase availability of biofuels, Australian mining giant BHP and Singapore's Global Centre for Maritime Decarbonisation (GCMD) said they are piloting the use of an unusual kind of blended bio-based bunker fuel made partially from waste animal fat.

The impact of blending cooking oil and waste animal fat could be significant, considering that until now, biofuels for global shipping have relied heavily on used cooking oil, a feedstock whose availability is approaching its projected limits. For this reason, the production of biofuels from waste animal fats is seen as a promising option to expand the supply.

The BHP-chartered Newcastlemax bulk carrier Berge Lyngor (206,330 dwt), owned and operated by Berge Bulk and used to transport iron ore from Western Australia to China, is being used in the bio-blend pilot project. In early May, the 300-meter bulk carrier — which sails under the UK flag and was built in 2009 — bunkered in Singapore with a B100 bio-blend of 50 percent tallow-derived biodiesel and 50 percent used cooking oil.

The biodiesel was sourced and supplied by HAMR Energy, while the cooking oil was supplied by Mitsui & Co. Energy Trading Singapore. Mitsui also blended the fuel, while Dan-Bunkering coordinated and executed the bunkering operation.

By running on the bio-blend, Berge Lyngor had the potential to reduce greenhouse gas emissions by about 79 percent per voyage compared to sailing on VLSFO, according to the partners.

BHP and GCMD say the pilot project is needed to assess how biofuels from multiple feedstocks can be blended, handled, and used under real-world operating conditions. Challenges include fuel quality, handling, traceability, and onboard vessel performance.

Understanding onboard performance is key, since biofuels derived from different feedstocks have different properties that may impact operations. On the downside, these can include potential corrosion from oxidation and fuel system clogging caused by wax formation.

The outcomes are expected to shed light on the practical steps needed to integrate biofuel blends from different feedstocks into existing supply chains — a development that is expected to provide shipowners and operators with greater flexibility for fuel buying.

"As the world's largest bulk charterer, we want to continue to test and trial alternative fuels that will help increase supply and send industry demand signals for further investment," said Emma Roberts, BHP Vice President, Maritime & Supply Chain Excellence. "At a time when fuel security is vitally important to global trade, building opportunities for future biofuels is critical."

Top image: Berge Lyngor (VesselFinder / Graeme Waller)

 

First Ethanol-Methanol Bunkering Operation Completed in Rotterdam

The first bunkering with a pre-blended mix of ethanol-methanol took place in Rotterdam (X-Press Feeders/METHANAVE)

Published May 29, 2026 6:15 PM by The Maritime Executive

 

In a closely watched development that is being called a groundbreaking bunkering, the Port of Rotterdam recently hosted the first ethanol-methanol operation. It comes as there is growing interest in the maritime sector of ethanol as a possible easy addition to alternative fuels.

Singapore-based shipping company X-Press Feeders partnered with consultancy firm METHANAVE to trial the bunkering of the blended fuel on the container ship Eco Levant. The bunkering was conducted at the Port of Rotterdam, marking the first time that a bunker vessel supplied ethanol to a seagoing vessel. Maersk has also reported that it was trying ethanol on its pioneering methanol dual-fuel feeder ship Laura Maersk, and engine manufacturers WinGD and Everllence reported progress adapting engines to ethanol.

Operated by X-Press Feeders, the 148-meter (485-foot) Eco Levant was built in 2024 and sails under the flag of France. The dual-fuel vessel was designed to operate on green methanol, thus enabling her to reduce greenhouse gas (GHG) emissions by up to 65 percent. The vessel was ideal for the trial that involved delivering and bunkering a marine fuel blend consisting of 10 percent ethanol and 90 percent methanol under controlled operating conditions.

While methanol bunkering is established in the commercial shipping industry, ethanol and methanol have, in the past, been bunkered separately on the seagoing vessel. In the trial bunkering of the blended fuel on Eco Levant, both fuels were delivered separately by a single inland bunker vessel, with the batches mixed (blended) on board the receiving vessel.

The successful bunkering of the blended fuel is a critical milestone for X-Press Feeders, which is pursuing ambitious decarbonization goals targeting net-zero by 2050. Part of this strategy has been exploring and evaluating practical low-emission fuel solutions that can support greater fuel flexibility and long-term decarbonization. The fact that ethanol has the ability to reduce GHG emissions by as much as 90 percent compared with heavy fuel oil has seen the alternative fuel start to gain attention in the shipping industry.

“Maritime fuel pathways are continuing to evolve. At X-Press Feeders, we believe it’s essential to continue evaluating and advancing viable solutions that can support the long term decarbonization of our fleet,” said Shivendu Gadkar, Head of Fleet Efficiency and Performance at X-Press Feeders.

Rotterdam, Europe’s largest port, has strategically positioned itself as a hub for alternative fuels. Today, the port ranks as the world’s second-largest bunker facility, with approximately 10 million tonnes of fuel bunkered annually. Its commitment to various alternative fuels has been evident following the successful ammonia bunkering pilot that was conducted last year.

“This milestone demonstrates that Rotterdam is ready for a wide range of alternative fuels. Together with all parties in the port, we aim to enable the bunkering of all alternative, low-carbon fuels in the future, promoting greater sustainability for international shipping,” said Matthijs van Doorn, Port of Rotterdam Authority commercial director.

With the availability of ethanol and its proven ability to be an additive in fuels, stakeholders will be following the Eco Levant trial. It will further enable the industry to assess bunkering procedures, fuel handling processes, and onboard operational performance associated with blended alcohol fuels under commercial operating conditions.

What’s In Your Gasoline? Understanding U.S. Motor Gasoline Formulations – Analysis

April 16, 2026 

By EIA

Motor gasoline in the United States is a blend of hydrocarbons and chemicals, with specific formulas varying by region and season. To meet federal air quality standards, the U.S. Environmental Protection Agency (EPA) and state regulators require different formulations, depending on air quality and location, which affect performance, cost, and emissions. In addition, warmer summer months require a different gasoline formulation than cooler winter months. Key differences between formulations include octane rating, volatility—commonly measured as Reid vapor pressure (RVP)—and emissions. This year, the EPA will relax federal enforcement of summer RVP standards to help reduce gasoline prices.


What are the main types of gasoline formulations in the United States?

There are two main types of gasoline: Conventional gasoline is the standard gasoline blend used in areas of the United States that meet federal air-quality standards. Conventional blend gasoline meets basic federal limits on emissions and volatility. Most of the United States uses this formulation.
Reformulated gasoline (RFG) is required by the Clean Air Act in areas with high smog. RFG burns cleaner than conventional gasoline but is typically more expensive to produce. Approximately 25% of U.S. gasoline sales are RFG, according to the EPA.

Both types of gasoline are available in different octane ratings (regular, midgrade, premium) and are usually blended with ethanol. In addition to conventional and reformulated gasoline, refiners adjust gasoline blends for summer and winter.

Why do gasoline formulations change seasonally?

The EPA uses RVP to regulate gasoline volatility: the lower the RVP, the less volatile the gasoline and the less evaporative the emissions. To reduce smog-forming emissions, the EPA mandates that summer grade gasoline has a lower RVP (less volatility) to control evaporation, which would normally increase in warm weather. In cold weather, higher volatility helps engines start more easily.

How do RVP limits change across regions?

During the summer season, EPA limits gasoline in the continental United States to an RVP of no more than 9.0 pounds per square inch (psi). However, regulators apply stricter limits in areas with air quality issues, including:Gasoline with a RVP no higher than 7.8 psi in areas requiring federally mandated gasoline

RFG program gasoline with RVP no higher than 7.4 psi in federally designated areas
Gasoline made to specification for State Implementation Plans (SIP) that are more stringent than federal requirements

How does the RVP limit change through the year?

The summer season for retailers and wholesale purchasers runs from June 1 to September 15. For refiners and bulk terminals, it starts earlier, running from May 1 to September 15, to allow time for supplies of summer-grade gasoline to get from producers to retailers. Some areas require longer periods for summer-grade gasoline use to further control emissions. Although not mandated, switching back to winter-grade gasoline in the fall is common because of its lower production cost.

Why is gasoline with lower RVP more expensive?

Gasoline with lower RVP is more expensive to produce because it requires pricier components for blending. For example, butane, a low-cost octane booster, has high RVP that limits its use in summer or RFG blends. Instead, lower RVP gasoline uses more expensive components such as alkylate to maintain octane while reducing RVP, contributing to higher retail prices.

Do all states follow the same rules?

Not exactly. The EPA sets federal standards but allows states or regions to set stricter gasoline specifications. Arizona, for example, requires the use of Cleaner Burning Gasoline (CBG) in parts of the state. California has stricter requirements than the federal government.

Data source: California Air Resources Board

The California Air Resources Board (CARB) requires gasoline RVP has no more than 7.0 psi during the summer season. In addition, CARB requires longer periods for summer-grade gasoline. These requirements contribute to consistently higher gasoline prices in California.

Principal contributor: Alex de Keyserling

Source: This article was published by the EIA

The U.S. Energy Information Administration (EIA) collects, analyzes, and disseminates independent and impartial energy information to promote sound policymaking, efficient markets, and public understanding of energy and its interaction with the economy and the environment.