With a wholesale value of approximately $350 million, the Australian banana industry is one of the largest fruit growing industries in the country and an important contributor to the economies of rural communities in banana growing areas. However at full production, Queensland’s banana industry produces around 60,000 tonnes of waste.

Growcom’s Banana Waste 2 Energy (BW2E) project aims to capture the energy in banana waste for on-site power generation and transport fuel. The BW2E project is designed to process 2,500 tonnes of banana waste per year, producing at least 86,506 cubic metres of methane gas.

Growcom is Queensland’s peak horticultural organisation which delivers commercial services to members and the industry. The organisation’s BW2E project has been developed from a 2005 University of Queensland Chemical Engineering Department study, Digestion of Waste Bananas to Generate Energy in Australia, headed by Associate Professor William Clarke.

The study demonstrated the technical feasibility of digesting banana waste and producing methane gas at a commercial scale in Australia. It found that producing biogas from bananas requires simple infrastructure, with feedstock (bananas) that is simple to handle and produces a high yield of methane per unit weight of dry banana.

Biogas – a mixture primarily of methane and carbon dioxide – is generated through a process called anaerobic digestion, through which bacteria degrades biological, or organic material. Australia has an established bioenergy industry with mature extraction technology. The sugar industry has been using bioenergy to supply electricity and heat requirements for over 100 years and today, bioenergy supplies electricity equivalent to the needs of approximately 400,000 households.

However Growcom Director Keith Noble says that while the industry’s technology and science are mature, they require socialising and adaptation. Explaining this, Mr Noble says that while there are many people who could make methane from plant waste, Growcom could not find any information on how to do it practically and at reasonable cost either on-farm or in the backyard. Nor could the company determine the implications of public liability and what the social considerations would be for neighbours and workers.

“The Australian Standards are written for large-scale commercial plants worth millions, and we’re struggling to interpret these for our scale,” Mr Noble says.

Initially supported by the Australian Banana Growers Council and the University of Queensland, Growcom jumped on the idea to solve the problem of onsite waste and improve the industry’s carbon footprint. On-site power generation through biogas is an ideal solution for growers and pack houses. Bananas are geographically compact, grown in areas remote from population centres with high conservation value and are produced on mass with low margins. The project is being supported by a grant from the Queensland Sustainable Energy Innovation Fund.

One significant threat to the industry is cyclones. Cyclone Larry hit Queensland in early 2006, leaving a path of devastation in its wake. Many Australians felt the impact of the cyclone, if not directly, through the devastation to Australia’s banana industry. Over 310,000 tonnes of bananas are grown in Australia each year, of which 250,000 tonnes are grown in northern Queensland. However as Mr Noble says, perhaps cyclone Larry was a ‘wasted’ opportunity. Even facing such devastation, biogas from bananas offered a solution.

Growcom originally applied for funding from the Queensland Sustainable Energy Innovation Fund in late 2006, however very wet season conditions delayed the project, with on-ground works beginning mid 2007.

The BW2E project aims to prove the quality and yield of methane gas from bananas using a continuously fed digester. The resulting gas will be analysed for its methane content, scrubbed to remove the carbon dioxide – which has no energy value – then compressed for use in power generation and as a substitute for diesel and petrol in farm vehicles.

Growcom believes the Queensland banana industry alone is capable of sustaining at least ten digester units and that there is further potential at other pack houses throughout Australia as well as wholesale markets and food processing facilities.

The project is currently being trialled at a Queensland pack house.

“We have built an in-ground High Density PolyEthylene digester - 450,000 litre capacity - and the infrastructure to get the waste from the shed into the digester without disrupting existing shed practices. We have commenced loading and are now adjusting the chemistry to achieve conditions conducive to methane production,” says Mr Noble.

“Dr Bill Clarke visited recently and was confident our system will work with time,” he continues, “as it can take up to 90 days for digestion to commence. We have also purchased a gas compressor and storage, and have the design for gas cleanup. Currently, a diesel Hilux is being converted to run on biogas and will have a generator converted to power the shed.”

Growcom says the BW2E project will provide a beneficial and commercial outlet for bananas, thus benefiting individual farming businesses as well as their surrounding local economies. If the project is successful, other benefits include solving the problem of on-farm waste, powering 1,300 vehicle equivalents, electricity sales and improving the industry’s greenhouse balance. Another benefit of the project is that the digester will produce an environmentally acceptable high quality fertiliser as a by-product.

Of course there are some practical considerations the project has to tackle. As Mr Noble explains, there are not necessarily on-site brain surgeons to use and maintain the digesters, therefore the units must fit with routine farm operations, be independent of routine external technical input and must not smell or leak.

Mr Noble says that the application of the BW2E project will most likely be for on-farm use and ancillary to mainstream farming operations rather than as energy production in its own right.

After the initial set up with the banana industry, Growcom plans to investigate sourcing suitable substrate material from other fruit and vegetable processing facilities. The operation also has export capabilities for further expansion into remote areas such as Indonesia or the Philippines. Mr Noble says that the technology will potentially enable local communities with suitable substrate material available to generate their own energy.

Mr Noble says the company is happy with the project and its development so far.

“It has enabled us to explore a field we previously knew little about, and there is strong interest from growers in the project, he says. “We are confident biogas has a role in future farming operations, particularly horticulture because of the high volumes of waste that can be produced in some situations.”