Project to transform sewage sludge into clean water and energy awarded a share of £4.5 million by Ofwat Involves extracting energy from the waste produced during sewage and water treatment Gases obtained can be used to power engines or heat people’s homes. An Aston University project that could transform sewage sludge into clean water and energy has been awarded a share of £4.5 million by Ofwat.
The University project with engineering consultancy ICMEA-UK involves extracting energy from the waste produced during sewage and water treatment and transforming it into hydrogen and/or methane. The gases can then be used to power engines or heat people’s homes.
The aim is to create a sustainable and cost-efficiently run wastewater processes, plus extra energy.
The initiative was one of ten winners of Ofwat’s Water Discovery Challenge, of which the Aston University scientists and two industrial partners have been awarded £427,000.
Dr Jude Onwudili based at Aston University’s Energy and Bioproducts Research Institute (EBRI) is leading the team of scientists who will work with the partners to develop a trial rig to transform solid residues from wastewater treatment plants to hydrogen and/or methane.
The two-stage process will involve the initial transformation of organic components in the sludge into liquid intermediates, which will then be converted to the fuel gases in a second stage.
The project is called REvAR (Renewable Energy via Aqueous-phase Reforming), and Dr Onwudili will be working with lead partner and engineering consultancy company ICMEA-UK Limited and sustainable infrastructure company Costain.
REVAR combines the use of hot-pressurised water or hydrothermal conditions with catalysts to achieve high conversion efficiency. The technique can treat sewage sludge in just minutes, and it is hoped that it will replace existing processes. In 2013, a Chartered Institution of Water and Environmental Management report stated that the sector is the fourth most energy intensive industry in the UK.
Dr Onwudili said: “This project is important because millions of tonnes of sewage sludge are generated in the UK each year and the water industry is struggling with how to effectively manage them as waste.
“Instead, they can be converted into valuable feedstocks which are used for producing renewable fuel gases, thereby increasing the availability of feedstocks to meet UK decarbonisation targets through bioenergy.
“We will be taking a waste product and recovering two important products from it: clean water and renewable energy. Overall, the novel technology will contribute towards meeting UK Net Zero obligations by 2050 and ties in with the University’s purpose to make our world a better place through education, research and innovation.”
The Water Discovery Challenge aims to accelerate the development and adoption of promising new innovations for the water sector. Over the next six months, winners will also receive non-financial support and will be able to pitch their projects to potential water company partners and/or investors.
The 10 winning teams are from outside the water industry and were chosen because of their projects’ potential to help solve the biggest challenges facing the sector.
The competition is part of the Ofwat Innovation Fund, run by the water regulator Ofwat, with Challenge Works, Arup and Isle Utilities and is the first in the water sector to invite ideas from innovators across industries.
Helen Campbell, senior director for sector performance at Ofwat, said: “This competition was about reaching new innovators from outside the sector with different approaches and new ideas, and that’s exactly what the winners are doing.
“The products and ideas recognised in this cross-sector challenge will equip water companies to better face challenges of the future – including achieving sustainability goals and meeting net zero targets – all while providing the highest-quality product for consumers.”
ENDS
A Blueprint For Carbon Emissions Reduction in the UK Water Industry The Chartered Institution of Water and Environmental Management https://www.ciwem.org/assets/pdf/Policy/Reports/A-Blueprint-for-carbon-emissions-reductions-in-the-water-industry.pdf
Ofwat Innovation Fund
Ofwat, the Water Services Regulation Authority for England and Wales, has established a £200 million Innovation Fund to grow the water sector’s capacity to innovate, enabling it to better meet the evolving needs of customers, society and the environment.
The Innovation Fund, delivered in partnership with Challenge Works (formerly known as Nesta Challenges) and supported by Arup and Isle Utilities, is designed to complement Ofwat’s existing approach to innovation and to help deliver against Ofwat’s strategy which highlights the role of innovation in meeting many of the challenges the sector faces.
About ICMEA-UK
Based in Sheffield, in the North of England, ICMEA-UK is the UK arm of an established Italian innovative engineering company ICMEA SRL. They are an innovative Engineering consultancy company, and work in partnership with a range of other organisations to provide innovative, bespoke solutions to problems where an Engineering solution is required.
About Costain
Costain helps to improve people’s lives by creating connected, sustainable infrastructure that enables people and the planet thrive. They shape, create, and deliver pioneering solutions that transform the performance of the infrastructure ecosystem across the UK’s energy, water, transportation, and defence markets.
They are organised around their customers anticipating and solving challenges and helping to improve performance. By bringing together their unique mix of construction, consulting, and digital experts they engineer and deliver sustainable, efficient, and practical solutions.
About Aston University
For over a century, Aston University’s enduring purpose has been to make our world a better place through education, research and innovation, by enabling our students to succeed in work and life, and by supporting our communities to thrive economically, socially and culturally.
Aston University’s history has been intertwined with the history of Birmingham, a remarkable city that once was the heartland of the Industrial Revolution and the manufacturing powerhouse of the world.
Born out of the First Industrial Revolution, Aston University has a proud and distinct heritage dating back to our formation as the School of Metallurgy in 1875, the first UK College of Technology in 1951, gaining university status by Royal Charter in 1966, and becoming The Guardian University of the Year in 2020.
Building on our outstanding past, we are now defining our place and role in the Fourth Industrial Revolution (and beyond) within a rapidly changing world.
For media inquiries in relation to this release, contact Nicola Jones, Press and Communications Manager, on (+44) 7825 342091 or email: n.jones6@aston.ac.uk
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Project to convert unwanted rice straw into cheap energy on a commercial scale Most rice straw in Indonesia is burned causing pollution and health problems Project will almost double affordable energy captured from waste. Scientists at the Energy and Bioproducts Institute at Aston University are to start a project to convert Indonesia’s unwanted rice straw into low-cost energy on a commercial scale.
Each year the country produces 100 million tonnes of the rice waste, of which 60% is burned in open fields, causing air pollution and has even been linked to lung cancer.
The amount burned is equivalent to approximately 85 Terawatts of electricity, which is enough to power Indonesia’s households 10 times over.
A consortium which includes Aston University aims to develop processes to capture more affordable energy from rice straw than ever before and demonstrate that it can be done on a commercial scale.
Part of the process involves a biomass conversion technology called pyrolysis. This involves heating organic waste materials to high temperatures of around 500 °C to break them down, producing vapour and solid products. Some of the vapour may be condensed into a liquid product called pyrolysis oil or pyrolysis bio-oil. Both the pyrolysis vapour and liquid bio-oil can be converted to electricity.
Current methods convert just 35% of the thermal energy of rice straw to affordable electricity. However, a newly patented combustion engine designed by consortium member, UK-based Carnot Limited, could see that doubled to 70%.
Energy extracted this way could help low and middle-income countries create their own locally generated energy, contribute to net zero by 2050, create new jobs and improve the health of locals.
The project will help develop a business model which could support companies and local authorities to produce local, cheap energy in Indonesia, and other countries with biomass capacity.
Three academic experts from different disciplines at Aston University are involved in this initial project, which focuses on Indonesia’s Lombok Island.
Dr Jude Onwudili, Dr Muhammad Imran and Dr Mirjam Roeder are based at Aston University’s Energy and Bioproducts Research Institute (EBRI).
Dr Jude Onwudili who is leading the team said: “This project has huge potential commercialisation of this combined technology will have significant economic benefits for the people of Indonesia through direct and indirect job creation, including the feedstock supply chain and electricity distribution and sales.
“About one million Indonesian homes lack access to energy and Indonesia's 6,000 inhabited islands make sustainable infrastructure development challenging in areas such as Lombok Island.
“The new techniques being explored could reduce environmental pollution, contribute to net zero and most importantly, provide access to affordable energy from sustainable local agricultural waste.
“Aston University is a global leader in bioenergy and energy systems, and I am delighted we received funding to explore this area.”
Over a power plant’s life, the project team have calculated that biomass produces cheaper electricity (approx. $4.3$/kWh) compared to solar (approx. $6.6/kWh), geothermal (approx. $6.9/kWh), coal (approx.$7.1/kWh), wind (approx. $8/kWh) and subsidised gas (approx.$8.4ckWh).
The project will start in April 2023 with a total of £1.5 million funding for the four partners from Innovate UK.
Alongside Carnot Limited, the Aston University scientists will be working with two other UK-based businesses to deliver the project, PyroGenesys and Straw Innovations.
PyroGenesys specialises in PyroChemy technology which will convert 70% of the rice straw into vapour or bio-oil for electricity production, with the remainder converted into nutrient-rich biochar, which can be sold back for use as fertiliser on the rice farms.
Straw Innovations will contribute their rice straw harvesting and collection expertise, with their many years of similar operations in Asia.
Media
Social
Biography
Jude Onwudili is a Professor in Chemical Engineering in the Department of Chemical Engineering & Biotechnologies. He was previously a Research Fellow at the renowned Energy Research Institute, School of Chemical & Process Engineering at the University of Leeds, under the supervision of Professor Paul T. Williams.
Onwudili is an experienced researcher, having worked on a number of EPSRC-funded and industrially-funded research projects on catalytic and non-catalytic thermochemical (hydrothermal processing, pyrolysis and gasification) processing of biomass, plastics, algae and municipal solid wastes for the production of fuels, chemicals and materials.
He is a Director of the Energy and Bioproducts Research Institute (EBRI), Aston University, where he leads the Sustainable Chemicals and Fuels Group. He is also a Co-Director of the Aston-led Centre for Doctoral Training on Negative Emissions Technologies for Net Zero (NET2ZERO) and leads Industrial Engagement for both EBRI and the NET2ZERO Centre.
Areas of Expertise
Thermochemical and Thermo-Catalytic Processing
Hydrothermal Processing
Pyrolysis
Gasification
Chemical Process Design
Catalysis and Applied Catalysis
Bioenergy and Biofuels
Fuel and Liquid Gases
Education
University of Ibadan
BSc
University of Leeds
PhD
2005
Affiliations
Fellow, Royal Society of Chemistry (FRSC)
Associate Member – Institution of Chemical Engineers (IChemE)
Sustainable aviation fuel-range intermediates from self-aldol condensation of cyclohexanone using low-cost niobium phosphate catalyst
Journal of Cleaner Production
2025
Biomass-derived chemical feedstocks are sustainable precursors for producing the range of compounds found in conventional hydrocarbon fuels. For instance, pyrolysis of lignin can produce high yields of phenolic compounds, which in turn can be quantitatively converted into cyclic ketones such as cyclohexanone, a model precursor for energy-dense aviation fuel hydrocarbons. Producing aviation fuel range hydrocarbons from short-chain oxygenated compounds such as cyclohexanone, requires both carbon chain elongation and oxygen removal via deoxygenation chemistries. In this study, a range of high-density fuel precursor molecules with fuel relevant carbon numbers (C12 – C18), have been produced via solvent-free carbon-carbon coupling of cyclohexanone as a model lignin-derived ketone. In the experiments, niobium phosphate (NbOPO4) was synthesised and used as a solid acid heterogeneous catalyst. Batch reactions were carried out at 160 °C with 1h–3 h reaction times, under nitrogen or hydrogen atmospheres. Cyclohexanone conversions of between 68.4 % and 95.4 % were achieved depending on reaction atmosphere. High selectivity towards dimeric ketones, the primary products of aldol condensation of cyclohexanone, was obtained under hydrogen gas. Initial hydrogen pressure of 5 bar gave the highest selectivity (nearly 90 %) mainly towards the dimeric 2-cyclohexylidenecyclohexanone and 2-(1-cyclohexen-l-yl) cyclohexanone. In contrast, mostly alkyl aromatic hydrocarbons with >C12 carbon atoms (e.g., cyclohexylbenzene) were formed under nitrogen, indicating that the inert atmosphere promoted the dehydration and dehydrogenation of primary aldol products. Correspondingly, the Brønsted acid and Lewis acid sites of the NbOPO4 were enhanced under nitrogen, with 3.7 wt% coke formation compared to 0.9 wt% under hydrogen. This work highlights the effectiveness of a low-cost catalyst to produce high yields of compounds that can be converted, via further deoxygenation and hydrogenation, to potentially energy-dense liquid hydrocarbons within the sustainable aviation fuel range.
Sustainable aviation fuel-range intermediates from self-aldol condensation of cyclohexanone using low-cost niobium phosphate catalyst
Journal of Cleaner Production
2025
Biomass-derived chemical feedstocks are sustainable precursors for producing the range of compounds found in conventional hydrocarbon fuels. For instance, pyrolysis of lignin can produce high yields of phenolic compounds, which in turn can be quantitatively converted into cyclic ketones such as cyclohexanone, a model precursor for energy-dense aviation fuel hydrocarbons. Producing aviation fuel range hydrocarbons from short-chain oxygenated compounds such as cyclohexanone, requires both carbon chain elongation and oxygen removal via deoxygenation chemistries. In this study, a range of high-density fuel precursor molecules with fuel relevant carbon numbers (C12 – C18), have been produced via solvent-free carbon-carbon coupling of cyclohexanone as a model lignin-derived ketone. In the experiments, niobium phosphate (NbOPO4) was synthesised and used as a solid acid heterogeneous catalyst. Batch reactions were carried out at 160 °C with 1h–3 h reaction times, under nitrogen or hydrogen atmospheres. Cyclohexanone conversions of between 68.4 % and 95.4 % were achieved depending on reaction atmosphere. High selectivity towards dimeric ketones, the primary products of aldol condensation of cyclohexanone, was obtained under hydrogen gas. Initial hydrogen pressure of 5 bar gave the highest selectivity (nearly 90 %) mainly towards the dimeric 2-cyclohexylidenecyclohexanone and 2-(1-cyclohexen-l-yl) cyclohexanone. In contrast, mostly alkyl aromatic hydrocarbons with >C12 carbon atoms (e.g., cyclohexylbenzene) were formed under nitrogen, indicating that the inert atmosphere promoted the dehydration and dehydrogenation of primary aldol products. Correspondingly, the Brønsted acid and Lewis acid sites of the NbOPO4 were enhanced under nitrogen, with 3.7 wt% coke formation compared to 0.9 wt% under hydrogen. This work highlights the effectiveness of a low-cost catalyst to produce high yields of compounds that can be converted, via further deoxygenation and hydrogenation, to potentially energy-dense liquid hydrocarbons within the sustainable aviation fuel range.
Advancing CO2 utilisation via suspension-based carboxylation of single and mixed biomass-derived phenolics to produce high-value hydroxybenzoic acids☆
Chemical Engineering Journal
2025
Production of organic chemicals from CO2 and biomass-derived feedstocks can combine the twin advantages of reducing carbon emissions and promote sustainable bioeconomy. This study explores a suspension-based Kolbe–Schmitt reaction for transforming CO2 into valuable hydroxybenzoic acids (HBAs). Using sodium salts of biomass-derived phenolic compounds (phenol, 2-cresol, guaiacol, syringol, and catechol) four carboxylation scenarios at 225 °C for 2 h under pCO2 = 30 bar were investigated. The reaction mixture and products were characterised in detail by high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR), revealing previously unreported species, which helped to elucidate the mechanisms of aromatic C-H activation for CO2 insertion. Mechanistic insights were validated by introducing precursor phenolic compounds, which dramatically enhanced the yields of salicylic acid (97.9 %), 2-cresotic acid (89.2 %), and guaiacol (89.9 %), while enhancing the purity of these main products. Notably, adding precursor phenolic compounds in carboxylation of catechol boosted the yield of 2,3-dihydroxybenzoic acid by up to 96 % and improved selectivity by 52.5 %, in 2 h of reaction. Furthermore, the study demonstrates that phenolic salts can act as carboxylating agents via sodium-proton substitution to facilitate new carboxylation possibilities. For example, reacting a mixture of the five phenolics favoured formation of dicarboxylation products, including industrially relevant 2,3-dihydroxyterephthalic acid and 2-hydroxyisophthalic acid. The results of this work underline the promise of integrating advanced reaction engineering with CO2 valorisation, as a sustainable circular economy pathway for carbon capture utilisation and storage (CCUS). Efficient production of different HBAs can drive their demand, ensuring rapid process development for enhanced CO2 utilisation.
Influence of surface acidity/basicity of selected metal oxide catalysts and reaction atmospheres on the ketonisation of propionic acid to produce 3-pentanone as a liquid biofuel precursor
Renewable Energy
2025
Defossilisation of the transportation sector can be achieved via the conversion of renewable biomass into drop-in liquid hydrocarbon-rich fuels. Bio-oils from the pyrolysis of lignocellulosic biomass contain significant proportion of carboxylic acids, which can be upgraded to liquid fuel range precursors via C-C coupling e.g., ketonisation. In this present study, ZrO2, SiO2, and SiO2–ZrO2 were synthesised and used for the ketonisation of propionic acid to 3-pentanone, in a stirred 100 mL batch reactor between 300 ᵒC and 400 ᵒC under 10 bar initial pressure of nitrogen or hydrogen. The order of ketonisation activity by the catalysts was: ZrO2 > SiO2–ZrO2 > SiO2 under both nitrogen and hydrogen atmospheres, based on their different surface acidity/basicity properties. Under nitrogen, ZrO2 catalyst showed high activity and selectivity towards 3-pentanone with the highest yield of 70.3 % at 350 ᵒC. Interestingly, the catalyst gave 12.2 % higher yield of 3-pentanone under hydrogen than nitrogen. This indicated positive influence of hydrogen towards the ketonisation reaction, possibly by preventing formation of intermediates and thus enhancing catalyst stability. Preliminary tests involving mixtures of propionic acid, and a bio-oil sample shows that ZrO2 was still selective toward ketonisation in the presence of other classes of compounds in bio-oils.
Kinetic and mechanistic studies of Pt/C-catalysed hydrothermal conversion of butyric acid for on-purpose production of renewable propane
Chemical Engineering Journal
2025
Catalytic hydrothermal decarboxylation of butyric acid represents a promising pathway to produce renewable propane as a major product. The decarboxylation reaction of butyric acid, which can be sourced from biomass at industrial scale, has demonstrated the potential to yield significant amounts of propane, making the process attractive for commercialisation. However, the development of industrial-scale process for the butyric acid-propane route requires the availability of accurate data on reaction kinetics, thermodynamics and equilibria. This present study examines the kinetics of butyric acid hydrothermal decarboxylation to produce propane using a 5 wt% Pt/C catalyst. Reactions were conducted between temperatures of 513 K and 533 K using a non-stirred batch reactor. To confirm that the results reflected true reaction kinetics, potential limitations due to both external and internal mass transport were thoroughly evaluated. A second-order rate expression with respect to butyric acid, with an activation energy value of 118 kJ
Kinetics of hydrothermal reactions of n-butanol over Pt/Al2O3 catalyst for biopropane fuel gas production
Chemical Engineering Journal
2024
Energy defossilisation using drop-in biofuels is an important step towards Net Zero. Producing low-carbon clean-burning propane fuel from biomass provides such additional sustainability benefits. In this work, kinetics of hydrothermal reactions of n-butanol, a biomass-derived feedstock, to produce propane over 5 wt% Pt/ catalyst have been studied from 523- 573 K. Experimental data revealed negligible internal and external mass transfer effects and, when fitted to an integral power-rate law equation, gave activation energy of 70 kJ mol−1 (n-butanol reaction order = 1). Furthermore, an appropriate Langmuir-Hinshelwood model was developed, which predicted similar activation energy 62 kJ mol−1. Low adsorption enthalpies for n-butanol (–33.51 kJ mol−1) and water (−18.16 kJ mol−1) indicated weak interactions on the catalyst surface. These agreed with the fast reaction rate of ≈1.0 x 10-5 mol gcat-1 s−1 obtained at ≥ 548 K. As a new research area, generation of such accurate kinetics data will contribute to process development for large-scale biopropane production.
Comparative techno-economic modelling of large-scale thermochemical biohydrogen production technologies to fuel public buses: A case study of West Midlands region of England
Renewable Energy
2022
This work presents techno-economic modelling of four thermochemical technologies that could produce over 22,000 tonnes/year of hydrogen from biomass for >2000 public transport buses in West Midlands region, UK. These included fluidised bed (FB) gasification, fast pyrolysis-FB gasification, fast pyrolysis-steam reforming, and steam reforming of biogas from anaerobic digestion (AD). Each plant was modelled on ASPEN plus with and without carbon capture and storage (CCS), and their process flow diagrams, mass and energy balances used for economic modelling. Payback periods ranged from 5.10 to 7.18 years. For operations with CCS, in which the captured CO2 was sold, FB gasification gave the lowest minimum hydrogen selling price of $3.40/kg. This was followed by AD-biogas reforming ($4.20/kg), while pyrolysis-gasification and pyrolysis-reforming gave $4.83/kg and $7.30/kg, respectively. Hydrogen selling prices were sensitive to raw material costs and internal rates of return, while revenue from selling CO2 was very important to make biohydrogen production cost competitive. FB gasification and AD-biogas reforming with CCS could deliver hydrogen at less than or around $4/kg when CO2 was sold at above $75/tonne. This study showed that thermochemical technologies could produce biohydrogen at competitive prices to extend the current use of electrolytic hydrogen-fuelled buses in Birmingham to the wider West Midlands region.
Process modelling and economic evaluation of biopropane production from aqueous butyric acid feedstock
Renewable Energy
2022
Catalytic hydrothermal decarboxylation of biomass-derived butyric acid can produce renewable biopropane as a direct drop-in replacement fuel for liquefied petroleum gases. In this present study, experimental results from a batch reactor have been used to develop a hypothetical continuous process to deliver 20,000 tonnes/year of biopropane, as base-case capacity, from 10 wt% aqueous butyric acid. A combination of process synthesis and ASPEN Hysys simulation have been used to formulate a process flowsheet, after equipment selection. The flowsheet has been used to carry out economic analyses, which show that the minimum selling price of biopropane is $2.51/kg without selling the CO2 co-product. However, with the incorporation of existing UK renewable energy incentives, the minimum selling price can reduce to $0.98/kg, which is cheaper than the current $1.25/kg selling price for fossil liquefied petroleum gases. Sensitivity analysis based on raw material costs and production capacities show profound influence on the minimum selling price, with strong potentials to making biopropane competitive without incentivisation, whereas the influence of selling CO2 is marginal. While this biopropane technology appears promising, it still requires more detailed technical and process data, life-cycle analysis and detail economic costings and testing at a pilot-scale prior to commercial exploitation.
Optimisation of Propane Production from Hydrothermal Decarboxylation of Butyric Acid Using Pt/C Catalyst: Influence of Gaseous Reaction Atmospheres
Energies
2021
The displacement and eventual replacement of fossil-derived fuel gases with biomass-derived alternatives can help the energy sector to achieve net zero by 2050. Decarboxylation of butyric acid, which can be obtained from biomass, can produce high yields of propane, a component of liquefied petroleum gases. The use of different gaseous reaction atmospheres of nitrogen, hydrogen, and compressed air during the catalytic hydrothermal conversion of butyric acid to propane have been investigated in a batch reactor within a temperature range of 200–350 °C. The experimental results were statistically evaluated to find the optimum conditions to produce propane via decarboxylation while minimizing other potential side reactions. The results revealed that nitrogen gas was the most appropriate atmosphere to control propane production under the test conditions between 250 °C and 300 °C, during which the highest hydrocarbon selectivity for propane of up to 97% was achieved. Below this temperature range, butyric acid conversion remained low under the three reaction atmospheres. Above 300 °C, competing reactions became more significant. Under compressed air atmosphere, oxidation to CO2 became dominant, and under nitrogen, thermal cracking of propane became significant, producing both ethane and methane as side products. Interestingly, under a hydrogen atmosphere, hydrogenolytic cracking propane became dominant, leading to multiple C–C bond cleavages to produce methane as the main side product at 350 °C.
