Millions of people across the globe still depend on liquefied petroleum gas, or LPG, for cooking, heating, and power generation. This bottled gas—primarily propane and butane—has become essential infrastructure in developing nations and rural communities worldwide. Yet LPG comes almost entirely from fossil fuel extraction, either as a byproduct of crude oil refining or from natural gas processing. As the world confronts climate change and energy security concerns, researchers and engineers face a critical question: can we produce LPG from renewable sources instead?
The answer increasingly points toward bioethanol, the alcohol produced from crops like sugarcane, corn, and cellulosic plant materials. With over 80 million tonnes of ethanol manufactured globally each year, this renewable fuel represents an enormous potential feedstock. But there is a fundamental technological gap. While bioethanol is already used to blend with gasoline for vehicles, converting it into LPG range hydrocarbons—propane and butane—has remained stubbornly difficult. Most existing routes produce unacceptably low yields of these valuable gases, making commercial deployment impractical.
A new research initiative called Project KatJa! is attempting to overcome this barrier through novel catalyst chemistry and process design. The work offers insights into how renewable fuels infrastructure could be diversified beyond current pathways, with particular implications for nations like India that have substantial ethanol production capacity but depend heavily on imported fossil fuels.
Why Renewable LPG Matters for Energy Transition
LPG occupies a unique position in global energy systems. Unlike gasoline or diesel, which are primarily used in vehicles, LPG serves essential functions in cooking, space heating, agriculture, and manufacturing. In many countries, especially across South Asia, Africa, and Latin America, LPG is the primary cooking fuel for hundreds of millions of households. The appeal is straightforward: it is clean relative to biomass or coal, portable, storable, and works with existing stove and burner technology.
The problem is sourcing. Most LPG comes from oil and gas fields, creating supply vulnerabilities and carbon emissions. Fossil LPG production also comes with environmental costs during extraction and processing. Industrial markets are tightening in response to climate commitments, making alternatives increasingly attractive from both energy security and emissions perspectives.
Currently, only one commercial pathway exists for producing bioLPG at scale: hydrotreating vegetable oils and animal fats, a process that yields biopropane as a byproduct. This approach, already deployed in Europe and North America, generates roughly one million tonnes of bioLPG annually. But it competes with food production for feedstock and relies on limited supplies of waste fats. A more abundant, dedicated pathway using renewable ethanol could expand production substantially and diversify supply chains.
The Technical Roadblock: Why Ethanol Conversion Is Difficult
The fundamental challenge lies in molecular engineering. Ethanol is a simple two-carbon molecule. Propane and butane contain three and four carbon atoms respectively. Converting ethanol into these molecules requires breaking apart and recombining the carbon skeleton through a catalytic process—a seemingly straightforward chemical transformation that turns out to be extraordinarily difficult in practice.
Chemists have known for decades that a process called methanol-to-gasoline, or MTG, can be adapted for ethanol inputs. The MTG process, developed and commercialized for coal-derived methanol, uses zeolite catalysts—porous crystalline materials that act as molecular sieves—to convert methanol into gasoline-range hydrocarbons. As a side reaction, it produces small amounts of LPG, typically around 20 percent of the product slate. But when researchers tried substituting ethanol for methanol, the results were disappointing. Yields of propane and butane fell dramatically. The catalysts degraded rapidly as carbon-rich deposits called coke accumulated on their surfaces. The most commonly used catalyst, a zeolite called H-ZSM-5, preferred to convert ethanol into ethylene, a two-carbon gas used in plastics production, rather than into the desired three and four-carbon products.
Previous attempts to solve this problem had employed water or additional regeneration cycles, but these approaches enlarged reactor vessels and increased operational complexity and cost. For a process to be commercially viable, it needs to operate continuously or with minimal downtime. Frequent shutdowns for catalyst cleaning translate into capital expenditure and lost production time—a barrier that had discouraged investment in ethanol-based routes.
Project KatJa!: A New Catalyst Platform
In 2022, a research collaboration led by a major LPG distribution company initiated a comprehensive screening program to identify proprietary catalyst formulations that could overcome these limitations. The team conducted systematic testing of dozens of catalyst candidates, evaluating not just the total yield of LPG components but their stability over time.
The key innovation was discovering catalyst materials that maintained reasonable selectivity toward propane and butane over extended operation periods. While standard H-ZSM-5 catalysts showed rapid deterioration in selectivity within three to four days of operation, certain proprietary catalyst formulations displayed markedly different behavior. The researchers found that when the catalyst did accumulate coke deposits and selectivity declined, periodic regeneration using air—literally burning off the carbon at elevated temperature—returned the catalyst to near-original performance. This cycle could be repeated over multiple weeks of operation.
The critical reaction conditions were identified through extensive experimentation. Operating at approximately 400 degrees Celsius in a fixed-bed reactor configuration, the proprietary catalysts converted ethanol into a mixture of hydrocarbons. The process produced the desired propane and butane fractions along with other products including aromatic compounds such as benzene and toluene, and some ethylene.
Testing demonstrated stable performance over a two-week operational window. Selectivity toward propane and butane remained above 35 to 40 percent on a molar basis when optimized for the three-carbon product. When reaction conditions were pushed to favor the three-carbon propane fraction over the four-carbon butane, selectivity increased, but this accelerated both ethylene formation and catalyst deactivation rates. The regeneration cycle, which involves passing air through the reactor at elevated temperature, could be performed without degrading the underlying catalyst, allowing multiple regeneration cycles without loss of activity.
From a process perspective, the need for periodic regeneration remains a trade-off. Multiple reactors operating in rotation can maintain continuous production while individual units cycle through regeneration. This approach is more complex than single-pass operation, increasing both capital costs and operational oversight requirements. However, it is far simpler than the alternatives that had been proposed previously.
The Global Ethanol Landscape: Abundant Feedstock, Untapped Potential
Ethanol production is already a mature, geographically dispersed industry. In 2021, global ethanol output reached approximately 80.7 million tonnes. The United States dominates production at 44.4 million tonnes, primarily from corn fermentation. Brazil contributes 22 million tonnes, mostly from sugarcane. The European Union produces 4 million tonnes, while India, China, and Canada each contribute between 1 and 2.5 million tonnes.
This is first-generation bioethanol, produced from food crops and molasses. But the feedstock landscape is expanding. Second-generation or advanced ethanol can be manufactured from agricultural residues like corn stover and wheat straw, forestry waste, and wood mill residues. In Europe alone, the potential for advanced ethanol from these sources by 2030 is estimated at 1,432 petajoules, equivalent to roughly 20 million tonnes of additional bioLPG production capacity.
A third pathway involves capturing gases from steel production facilities—industrial synthesis gases that can be converted to ethanol. This route has the potential to generate up to 64 million tonnes of renewable LPG globally without requiring any agricultural land or competing with food production.
Taken together, the global potential for bioLPG production from ethanol conversion reaches 32 million tonnes annually using first-generation feedstocks. This expands to approximately 48 million tonnes if second-generation advanced ethanol is included. By comparison, current global renewable LPG production stands at roughly one million tonnes, suggesting that on-purpose bioLPG from ethanol could increase sustainable LPG supply by a factor of 30 to 50.
Implications for India: Domestic Energy Diversification and Clean Cooking
India's energy landscape makes this research particularly significant. The country produces 2.5 million tonnes of ethanol annually, representing three percent of global output. This ethanol comes from sugarcane molasses, the residue remaining after sugar crystallization, and increasingly from other approved feedstocks including agricultural residues and industrial byproducts. India also imports substantial quantities of LPG for cooking, heating, and industrial uses, creating energy security and balance of payments pressures.
The potential applications of bioLPG technology within India's energy framework are substantial. The country has invested heavily in clean cooking fuel adoption through programs like Pradhan Mantri Ujjwala Yojana, which aims to provide LPG access to rural and underserved households. Currently, this relies on imported or domestically produced fossil LPG. Bioethanol-derived LPG could theoretically supply a portion of this demand while supporting the agricultural sector through value-added processing of sugarcane and crop residues.
India's existing ethanol production infrastructure and sugarcane cultivation base could be expanded to support bioLPG manufacturing. Conversion facilities would create rural employment in engineering, operations, and maintenance. The feedstock—agricultural residues and molasses—represents economic activity that currently goes underutilized. Scaling advanced ethanol production from crop residues could generate additional income for farmers while reducing agricultural waste burning, which contributes significantly to air quality degradation in northern India during harvest seasons.
From an energy security perspective, domestic bioLPG production would reduce reliance on imported fossil fuels. India currently imports significant quantities of crude oil and natural gas. Developing a renewable LPG production capacity aligned with agricultural output could contribute to long-term energy independence while supporting domestic industries.
However, substantial barriers must be addressed before large-scale deployment becomes feasible. Industrial-scale conversion plants require significant capital investment in reactors, separation systems, and infrastructure. Technology transfer and localization of catalyst production would be necessary to reduce costs. Regulatory frameworks would need to classify and certify bioLPG as equivalent to conventional LPG for safety and quality purposes. Supply chains for feedstock collection, particularly for agricultural residues, would need to be established and optimized. Economic models must demonstrate that bioLPG can compete on price with fossil LPG in a carbon-constrained policy environment.
Current Status and Remaining Questions
Project KatJa! is currently being scaled up from laboratory demonstrations to pilot-scale operations. Research teams at multiple institutions are working to optimize reactor design, refine catalyst formulations, and gather data on operational stability over extended periods. The team has demonstrated that the basic chemistry works and that catalysts can be stabilized through careful design.
Significant questions remain before commercialization. The exact economics of producing bioLPG at various scales—50,000 to 100,000 tonnes per year facilities, as well as larger hub-scale operations—need to be established. Energy efficiency and carbon lifecycle assessments will determine whether the environmental benefits justify the capital investment. Market development and policy support will be crucial; without regulatory incentives or mandates, bioLPG will struggle to compete against entrenched fossil LPG in many regions.
There is also the broader context of the energy transition. Rapid electrification of vehicles and buildings is expected to reduce demand for conventional LPG in developed nations, with projections suggesting a 25 to 50 percent decline in the European LPG market by 2050. This could either be a threat or an opportunity. Declining demand for fossil LPG would reduce profitability for traditional suppliers, creating an incentive to develop sustainable alternatives to maintain market share. Alternatively, if demand truly collapses, investment in new bioLPG capacity may not be justified.
One intriguing additional possibility emerged from the research: the process produces significant quantities of aromatic compounds alongside the target LPG fractions. With appropriate purification, these aromatics could potentially be used as feedstocks for other chemicals or fuels. More speculatively, the catalyst system might be adapted to produce sustainable aviation fuel if the product mixture can be certified against ASTM standards. This would diversify the revenue streams from a single conversion facility and improve overall economics.
The Broader Significance: Creating Options in an Energy Transition
The significance of this research extends beyond the specific chemistry of ethanol conversion. It represents an attempt to develop technology that works with existing infrastructure and consumer behavior rather than demanding wholesale transformation of energy systems. Billions of people already use LPG burners, stoves, and heaters. These appliances do not need to be replaced if the gas they burn is renewable rather than fossil-derived.
Bioethanol-derived LPG also sits at an intersection of agricultural and industrial policy. It creates value from agricultural residues and molasses that are currently underutilized or constitute waste streams. In regions with limited electrification and where biomass cooking remains dominant, a transition to renewable LPG represents genuine progress toward clean energy without requiring new consumer appliances or behavior changes.
The work undertaken in Project KatJa! demonstrates that technological innovation can expand options for the energy transition. Not all developing regions will be able to rely primarily on wind and solar electricity. Not all developing economies can afford rapid vehicle electrification. Renewable LPG offers a pragmatic intermediate pathway that uses abundant biomass feedstocks and leverages existing consumer infrastructure.
Whether this technology reaches commercial scale and global deployment will depend on catalyst stability verification at pilot scale, demonstration of acceptable economics, development of supportive policy frameworks, and ultimate market demand. The fundamental science is sound, and the preliminary engineering results are encouraging. The coming years will reveal whether Project KatJa! and similar initiatives can transform renewable energy ambitions into practical household fuels for millions of people worldwide.
References
Project KatJa! – On-Purpose BioLPG production from Ethanol. Presented by Dr Keith Simons, Head of Research and Development, LiquidGas UK, Edinburgh, November 2022.
UK Renewable Liquid Gas Modelling: Supply and heating demand pathways for bioLPG and rDME. Prepared for Liquid Gas UK. NNFCC, 2021.
ePure and E4Tech: E20 Supply and Demand Study. 2019. Available at: https://www.epure.org/
RFA (Renewable Fuels Association): Global Ethanol Production and Trade Statistics, 2021.
IHS Markit: Global LPG Production Projections and Renewable LPG Market Analysis, 2021.
