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.

Sugarcane and the Creation of Carbon-Negative Hydrogen

Professor Damien Batstone speaks to AZoCleantech about his game-changing research on how sugarcane can be used as a clean energy source to produce hydrogen.

What drove your research into sugarcane as a clean energy source to create hydrogen?

We had previously researched the conversion of sugarcane into alternative products (such as biopolymers) and found this to be highly favorable economically. Whereas sugar production utilizes bagasse as thermal energy, this is a residue when making biopolymers, liquid sugar, or ethanol. This residue can then be used for electricity generation or alternative energy products such as hydrogen.

What makes sugarcane a suitable resource that could revolutionize hydrogen production?

We are using the bagasse fraction, as the juice fraction can be utilized elsewhere (e.g., for ethanol or biopolymer production). Very few other crops result in such a huge and relatively reliable amount of biomass, making it ideal for large-scale hydrogen production.

Can you explain the processes your team has used in its research?

We investigated two technologies. Thermal gasification is a dry process and is carried out at a high temperature. The bagasse is dried, and then incomplete combustion results in a mixture of gases, which further react to hydrogen and carbon dioxide. The carbon dioxide is extracted (and may be captured for storage), leaving the hydrogen as a product. We also investigated hydrothermal gasification, which is a similar reaction, but at high pressure and in wet conditions. This avoids needing to dry the bagasse before processing.

Would the use of sugarcane to make hydrogen be a costly process? Could this technology be adopted on a much larger scale?

Based on our economic analysis, the process can make hydrogen at $1.5-$3/kg, which is a lower cost than any other form of non-fossil hydrogen. It can be made at an even lower cost if we do not produce the hydrogen at high pressure. This technology is only applicable at a larger scale (500+ t bagasse per day), and we have evaluated up to 2500 t bagasse per day. For reference, the lower scale is a moderate-sized sugar mill, while 2500 t/d is the largest-sized sugar mill.

What happens to the carbon dioxide produced during production?

It is currently separated from hydrogen as a sour gas stream (which also includes sulfides). This can either be geo-stored or used industrially.

This research offers the potential for positive environmental benefits if adopted on a larger scale. Please can you explain this in more detail?

It represents a sustainable source of low-cost hydrogen while offering the ability to fix the carbon-dioxide for industrial use or long-term storage.

How would cane growers benefit from this alternative pathway for the industry?

Cane growers and mills are highly exposed to world commodity sugar pricing, with the cost of production often exceeding sugar prices. Producing alternative products from juice (such as biopolymers or fuel) while processing the bagasse into hydrogen provides improved profitability. A hydrogen production hub also provides improved regional benefits, including an industrial base and employment.

Why is this research important for the wider hydrogen production industry?

As an important future energy carrier and major industrial input, continuity and diversity of non-fossil hydrogen production is essential. The only other major source of non-fossil hydrogen is renewable electricity, which is subject to spot pricing fluctuations and variation in supply. We also produce it at a far lower cost and potentially at a larger scale than electrolytic hydrogen.

Why is hydrogen important for the future of converting unusable energy? How does this research project fit into this?

Hydrogen converts electricity and otherwise unusable energy to a highly versatile, clean, chemical energy source. It is the best way to decarbonize the industrial chemical ecology, including clean metallurgy, vehicle fuels (conventional and emerging, including hydrogen directly), fertilizer, plastics, and commodity chemicals. It can even be used to make food. While it can be transported, as a highly compressed gas or liquid, or as liquid ammonia, one of the best ways to use it is to connect a hydrogen producer directly to the end-user.

What challenges have you faced during your research and how were these overcome?

The technology is relatively conventional, given it has been used in coal gasification for over a century, and some challenges (e.g., the formation of toxic byproducts) are mitigated by the clean nature of bagasse. Key challenges relating to the high-pressure process included the limited availability of materials capable of withstanding high temperatures and pressures. This increased the cost of the hydrothermal process substantially. We also found that the need to compress hydrogen for sale was an economically limiting factor.

How can farmers and sugar companies go about applying the research findings to their businesses in the future?

A future project will be large in scale and will involve the direct involvement of growers, sugar companies, and likely end-users. It will also include governments investing in a hydrogen economy, incentivizing the industry, and improving the sugar industry’s economic sustainability.  Sugar companies are already assessing the technology, and farmers should assess future technologies and product streams.

What are the next steps for the project?

A position paper is being produced in Q1 2021, which will present the study’s aggregate outcomes and be made publicly available. Outcomes from the work are currently being provided to sugar companies.

About Damien Batstone

Professor Damien Batstone leads environmental biotechnology and resource recovery research programs at The Advanced Water Management Centre, The University of Queensland, Australia. Research work has focused on renewable energy from biomass, the production of commodity chemicals from renewable sources, and the water-energy-food nexus, including the production of novel feeds for aquaculture from gases such as hydrogen. He coordinated the final year undergraduate chemical engineering design course at UQ from 2017-2020, in which 150-200 students design a novel process from concept to final design. The 2020 design challenge was hydrogen from bagasse.

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.