Student engineers sweetening the deal on clean energy

Chemical engineering students from the University of Queensland (UQ) have helped investigate how sugarcane could be used as a clean energy source to create hydrogen.

Professor Damien Batstone of UQ’s Faculty of Engineering, Architecture and Information 

Technology, said bagasse, or sugarcane pulp, and other agricultural residues were an abundant resource that could generate ‘green’ or carbon-negative hydrogen at scale.

Biomass from crushed sugarcane stalks and leaves could also potentially produce hydrogen for under $3 per kilogram, one third of the cost of current options, he added.

Last year, 150 students in 36 teams were tasked with designing a process to produce hydrogen gas from bagasse with either thermal gasification or hydrothermal gasification as their process.

Generating pure hydrogen

Caitlin Welsh, a chemical and materials engineer who has a Bachelor of Engineering (Hons) from UQ, and her team, were responsible for designing a thermal gasification process for an input of 2000 t/day of bagasse. 

“I was allocated the pre-treatment node where I was required to design units to heat and dry the bagasse in preparation for gasification,” she said.  

“Part of my role was to ensure the bagasse was pre-treated to ensure highest possible efficiency. I needed to do this while ensuring the pre-treatment node did not counter the energy savings in the gasifier. 

“So, I applied energy integration in my design by utilising steam produced downstream in my pre-treatment for heating of bagasse.”

Welsh, who is currently working at Visy Board as a graduate engineer, said that, with thermal gasification, there will always be by-products such as ash, tar, carbon dioxide and carbon monoxide gas.

“The hydrogen can, however, be extracted and the by-products captured in the downstream process,” she said.

Eva I Iong Lam, who also has a Bachelor of Engineering (Hons) from UQ, and her team were involved in the cutting-edge hydrothermal gasification process.

“It is similar to that of thermal gasification, except it involves wet biomass,” she said.

“Not only does it save energy in the drying of bagasse, but it also allows for lower operating temperatures with the possibilities to utilise a variety of biomasses as feedstocks.”

Chemical engineering students from the University of Queensland (UQ) have helped investigate how sugarcane could be used as a clean energy source to create hydrogen.
Eva I Iong Lam and Caitlin Welsh helped investigate the use of sugarcane to produce hydrogen.

A graduate chemical engineer who now works at Engeny Water Management, I Iong Lam said the slurry was fed into the reactor, then produced a supercritical fluid where its heat energy was integrated with other processing units through a series of heat exchangers.

“Hydrogen is produced more readily under supercritical water conditions in this process,” she said. 

“The gases were then separated by chemisorption using Methyldiethanolamine (MDEA) solvent.” 

The models she created were also able to recover the majority of water present in the gas streams using flash tanks, so it could be repurposed within the plant.

“A key challenge was the limited availability of materials that could withstand high temperatures and pressures,” I Iong Lam said.

“I chose stainless steel 316 as the construction material for a flash tank receiving supercritical fluids as it has excellent resistance to corrosion, thermal and pressure stress.”

A future biomass technology

While gasification has been widely applied to coal processing, it has not been applied to hydrogen production from biomass at large scale, Batstone said.

“This offers an alternative pathway with potential for higher profits for canegrowers, and for sugarcane to be used in ethanol and plastic production, while fully utilising the biomass residues,” he said.

Welsh hopes that her career will include further involvement in sustainable engineering solutions, while I Iong Lam wants to continue to focus on water consulting.

“You get clean water by just turning on a tap, we never really spend a moment to appreciate the processes and people behind it,” she said. “Now, I am hoping to make a positive difference to the community I live in.”.

To develop the work done by the students, a future project by UQ will involve growers, sugar companies and likely end-users and include governments investing in a hydrogen economy.

Energycane produces more biodiesel than soybean at a lower cost

Bioenergy from crops is a sustainable alternative to fossil fuels. New crops such as energycane can produce several times more fuel per acre than soybeans. Yet, challenges remain in processing the crops to extract fuel efficiently.

Four new studies from the University of Illinois explore chemical-free pretreatment methods, development of high-throughput phenotyping methods, and commercial-scale techno-economic feasibility of producing fuel from energycane in various scenarios.

The studies are part of the ROGUE (Renewable Oil Generated with Ultra-productive Energycane) project at U of I. ROGUE focuses on bioengineering accumulation of triacylglycerides (TAGs) in the leaves and stems of energycane, enabling the production of much more industrial vegetable oil per acre than previously possible.

“The productivity of these non-food crops is very high per unit of land. Soybean is the traditional crop used for biodiesel, but we can get higher yield, more oil, and subsequently more biofuel from lipid-producing energycane,” says Vijay Singh, Founder professor in the Department of Agricultural and Biological Engineering (ABE) at U of I and co-author on all four papers.

Biofuel production from crops involves breaking down the cellulosic material and extracting the oil in a series of steps, explains study co-author Deepak Kumar, assistant professor in the Chemical Engineering Department at State University of New York College of Environmental Science and Forestry (SUNY-ESF) and adjunct research scientist at the Carl R. Woese Institute for Genomic Biology at U of I.

“The first step is to extract the juice. That leaves bagasse, a lignocellulosic material you can process to produce sugars and subsequently ferment to bioethanol,” Kumar says.

“One of the critical things in processing any lignocellulosic biomass is a pretreatment step. You need to break the recalcitrant structure of the material, so enzymes can access the cellulose,” he adds. “Because energycane is a relatively new crop, there are very few studies on the pretreatment and breakdown of this bagasse to produce sugars, and to convert those sugars into biofuels.”

The pretreatment process also yields some unwanted compounds, which inhibit enzymes that convert the sugar into biofuels. The U of I researchers investigated the best pretreatment methods to maximize the breakdown while minimizing the production of inhibitors. Typically, the pretreatment process uses chemicals such as sulfuric acid to break down the biomass at high temperature and pressure.

“We use a chemical-free method, which makes it more environmentally friendly,” Kumar explains. “Furthermore, harsh chemicals may alter the oil structure or quality in the biomass.”

The researchers tested their method using nine different combinations of temperature and time intervals. They were able to achieve more than 90% cellulose conversion at the optimal conditions, which is equivalent to results from chemical pretreatment methods.

The second study built on those results to further investigate the relationship between temperature, inhibitor production, and sugar recovery.

“We pretreated the lignocellulosic biomass over a range of different temperatures to optimize the condition for minimal inhibitor generation without affecting the sugar recovery. Then we added cryogenic grinding to the process,” says Shraddha Maitra, postdoctoral research associate in ABE and lead author on the study.

“In cryogenic grinding, you treat the bagasse with liquid nitrogen, which makes it very brittle, so upon grinding the biomass fractures easily to release the sugars. This further increased sugar recovery, mainly xylose, by about 10% compared to other refining processes,” Maitra explains.

Other industries use similar methods, for example for spices and essential oils, where it is important to preserve the qualities of the product. But applying them to biofuel production is new.

In a third study, Maitra and her co-authors investigated time-domain nuclear magnetic resonance (NMR) technology to determine the stability and recovery of lipids by monitoring changes in total, bound, and free lipids after various physical and chemical feedstock preprocessing procedures.

The research team’s fourth study investigated the commercial-scale techno-economic feasibility of engineered energycane-based biorefinery. They used computer modeling to simulate the production process under two different scenarios to determine capital investment, production costs, and output compared with soybean-based biodiesel.

“Although the capital investment is higher compared to soybean biodiesel, production costs are lower (66 to 90 cents per liter) than for soybean (91 cents per liter). For the first scenario, processing energycane had overall slightly lower profitability than soybean biodiesel, but yields five times as much biodiesel per unit of land,” says Kumar, the lead author on the study.

“Energycane is attractive in its ability to grow across a much wider geography of the U.S. south east than sugarcane. This is a region with much underutilized land, yet capable of rain-fed agriculture,” says ROGUE Director Steve Long, Ikenberry Endowed Chair of Plant Biology and Crop Sciences at the University of Illinois.

“As a perennial, energycane is suitable for land that might be damaged by annual crop cultivation. Our research shows the potential to produce a remarkable 7.5 barrels of diesel per acre of land annually. Together with co-products, this would be considerably more profitable than most current land use, while having the potential to contribute greatly to the national U.S. goal of achieving net zero greenhouse gas emissions by 2050. This proves how valuable it is to build on the successes already achieved in bioengineering energycane to accumulate oils that are easily converted into biodiesel and biojet,” Long states.


Story Source:

Materials provided by University of Illinois College of Agricultural, Consumer and Environmental Sciences. Original written by Marianne Stein. Note: Content may be edited for style and length.

Sugarcane to hydrogen investigated

Final-year chemical engineering students at The University of Queensland are investigating how sugarcane can be used as a clean energy source to create hydrogen.

Professor Damien Batstone said bagasse and other agricultural residues were an abundant resource that could generate “green” or carbon-negative hydrogen at scale.

“One hundred and fifty students in 36 teams are analysing both thermal gasification, and the more cutting-edge ‘supercritical hydrothermal gasification’ method,” Professor Batstone said.

“The new approach looks promising, with the cost as low as one third that of the current options.”

The process uses waste biomass – crushed sugarcane stalks and leaf – to produce hydrogen for under $3 per kilogram.

Professor Batstone (right) said any carbon dioxide produced was captured, making the process carbon negative.

“The technology can be used with any waste biomass, including green waste and municipal waste streams, and the students’ economic models and design processes show it can be put into practise immediately,” he said.

“Adopting this new hydrogen production approach could have a tremendous impact on the sugarcane industry as farmers seek alternative uses for their crops and mill infrastructure.

“This offers an alternative pathway with potential for higher profits for canegrowers who may have considered exiting the industry, as well as job opportunities for regional areas and clear environmental benefits.

“The process allows sugarcane to be used in ethanol and plastic production, while fully utilising the biomass residues.”

Professor Batstone said agricultural residues were heated to between 400 and 1000 degrees Celsius to create “syngas”, then a series of conversion and separation processes generated pure hydrogen.

“It can be done at atmospheric pressure or at very high pressure in the presence of water,” he said.

“Gasification has been widely applied to coal processing but has not been applied to hydrogen production from biomass at large scale.”

Professor Batstone said the project required students to engage intensively with renewable energy and energy transformation, to give them an understanding of the industry’s key challenges at the outset of their careers.

“The federal government’s 2019 National Hydrogen Strategy identified hydrogen as a critically important future source of energy,” he said.

“It flagged creating hydrogen using fossil fuels at $3 per kilogram with significant carbon emissions, and non-fossil-based renewable electricity at significantly higher prices between $6 and $11 per kilogram.

“Industry professionals and UQ researchers are guiding the students in this emerging and vital field, and their work could have a real benefit for industry and the environment.”

Chemical and environmental engineering student Mr Kailin Graham said the project offered insight into real-life engineering work.

“Previous courses taught chemical engineering principles; this project required us to apply these as we would as engineers in the workforce,” he said.

“We engaged with the sugar industry and technology specialists, and it’s exciting to know that our work will have direct relevance to Australian industry.”

Professor Batstone said a position paper compiled from the teams’ findings would be made available to farmers and sugar companies for potential application in their businesses.

Partnership paves way for new planting technology in Australian cane industry

New Energy Farms (NEF) and Sugar Research Australia (SRA) have entered into a license agreement to introduce the NEF CEEDS technology into the Australian sugarcane industry.

NEF is a crop technology company, established in 2010, to develop artificial seeds for crops that do not produce conventional seeds, such as sugarcane.

NEF developed and patented the CEEDS technology for the multiplication and planting of sugarcane crops worldwide.
CEEDS are small coated propagules directly drilled in the field like conventional seed. NEF have already licensed CEEDS for commercial sugarcane use in other key sugarcane markets including Brazil and Central America.

The collaboration will utilise NEF’s experience in propagation of perennial grasses, in sugarcane and other high biomass crops like miscanthus and energy cane.

Testing will commence this season to evaluate the response of current and emerging Australian varieties in the production of CEEDS artificial seed. Subsequent trials will examine germination, plant establishment and crop performance under a range of Australian production conditions.

Dr Jason Eglinton, SRA executive ,manager for variety development and processing, said: “Establishing the crop is a major cost in sugarcane production. The value of just the sugarcane used for planting is around $25 million (€15 million) every year. New approaches in planting systems to release this industry value have been research topics before, but recent technological advances suggest it could now become a reality.

“This work will produce an understanding of the benefits and costs of the technology to inform potential adoption pathways. CEEDS also offers indirect benefits including the ability for growers to more rapidly change their variety mix and control of issues such as Ratoon Stunting Disease.”

The agreement will allow NEF to provide SRA with patented CEEDS technology to produce artificial seeds for the current, and future, sugarcane varieties in the Australian market.

“We are extremely pleased to have entered this License Agreement with SRA and we are very aware of the high level of respect in Australia and the wider sugarcane industry for their research and technology transfer activities,” said Dr Paul Carver, CEO of New Energy Farms.