Sugar milling: Sweet taste of energy production

By Amanda Burdon 16 June 2009
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Long considered an environmental bad boy, the sugar industry has got in touch with its greener side, and found a future in the process.

Not so long ago, the sugarcane industry was at risk of becoming a pariah. It was blamed for environmental degradation – annual waste burn-offs sent giant plumes of smoke into the atmosphere, and nutrient-rich run-offs threatened the health of waterways – and mills and growers faced an uncertain future.

Today the outlook is much brighter, thanks to a clever harnessing of the innate properties of sugarcane, one of nature’s most efficient factories. Absorbing sunlight, moisture and carbon dioxide, it makes two forms of energy – sugar and fibre.

Australian mills still produce sugar in much the same way they have for more than a century. It’s what happens to the waste that has been revolutionised. Instead of being set ablaze in open fields, it’s burned to generate power in Australia’s first baseload co-generation power plants – plants with a continuous output of electricity driven by an amalgam of heat and power.

Sugar-cane to supply electricity to households

Through their co-operatively run, century-old mills at Condong and Broadwater, sugarcane growers in northern NSW’s Tweed and Richmond valleys are not only producing sugar and steam for their crops’ processing plants, they’re helping supply electricity to 60,000 households.

“It’s a revolutionary change that adds considerable value to the crop and will help our industry to remain economically and environmentally viable,” said Greg Messiter, the former chief executive officer of the NSW Sugar Milling Co-operative, who managed the transformation of Condong and Broadwater before retiring last year.

“Other sugar mills operate co-generation plants for the duration of their crushing season, but we are the first to operate for 12 months of the year, providing some 400 gigawatt-hours of electricity annually,” he said.

Almost the entire process is clean and green. Producing energy by using cane stalks and leaf matter (trash), as well as the fibrous leftovers from processing (bagasse) is ending one of the industry’s least savoury practices.

In the second half of each year, fires were lit in the fields to burn waste that neither the mechanical harvesters nor the mill could handle, generating a black fallout, known locally as “Ballina snow”, and a pall of smoke that lingered for weeks. Last season’s burning was significantly reduced; the mill is aiming for less than 10 per cent.

While NSW Sugar Milling is a small player in the national sugar industry, crushing just 5 per cent of the national crop, its joint venture with State-owned power company Delta Electricity heralds a big shift, and it doesn’t come cheap. Without burning, sugarcane growers have to contend with much denser cane fields and have had to upgrade their planting and harvesting equipment as a result. The two sugar mills have been modified (at a cost of $210 million) to function as small power stations.

NSW Cane Growers Association president Vince Castle said the changeover is one of the biggest and most expensive industry reforms since mechanical harvesting was introduced in 1975.

Despite this, there is an environmental benefit. “The cost of producing this electricity with large-scale biomass is twice that of traditional electricity generation, but by reducing the load on existing coal-fired generators it prevents some 400,000 tonnes of greenhouse gases from entering the atmosphere each year,” said Delta Electricity’s Greg Everett.

Much of the impetus for the project came from the Federal Government’s Mandatory Renewable Energy Target scheme, which allows Delta to create and sell certificates to electricity retailers – who, under the scheme, must buy a percentage of electricity from renewable sources to meet their own targets – for the renewable energy it creates.

Canegrowers, many of whom have spent thousands of dollars converting their operations, look forward to the day when they start receiving payments not just for their sugar, but also for the amount of fuel fibre they deliver to the mills.

“I think there will be very good results down the track because of the developing demand for and value of green electricity,” said Vince, 70, a third-generation cane farmer. “Burning cane was a necessary evil and something the growers were very good at, but I’m not sorry to see it go.”

Sweet success, indeed.

Source: Australian Geographic Jan – Mar 2009