In Tasmania, one grower is turning to Gasification Technology to power his farm’s greenhouses and reduce costs. By CHRISTINE BROWN-PAUL
Biomass is a fuel that is developed from organic materials, a renewable and sustainable source of energy used to create electricity or other forms of power. Some examples of materials that make up biomass fuels include scrap lumber, forestry waste, wood chips, sawdust, rice and coconut husks, and crop and animal wastes. Increasingly, biomass is another alternative fuel source that is being used by growers to reduce energy bills and improve yields.
In north-west Tasmania, tomato grower Marcus Brandsema has plans to install a biomass gasifier to power his farm’s greenhouses with an aim to reduce power bills and improve yields.
Another grower in Tasmania—Hills Transplants—is a salad and herb growing business based in Devonport, which has installed a 2.5MW biomass heating system to heat its two glasshouses (nearly 1 square hectare). The system is powered by a waste stream of wet wood chips sourced from local timber processors.
Marcus Brandsema’s family business, J & A Brandsema Pty Ltd, has been growing greenhouse tomatoes in Tasmania for over 50 years. After their grandfather started up the business in 1958, the brothers Marcus and Anthony Brandsema took over the business in 2007. Today, the business is an innovative greenhouse company that successfully markets specialty tomatoes to the local market.
A hydroponic and glasshouse tomato grower with 1.1ha under cover, Marcus also sits on the board of Protected Cropping Australia (PCA), the peak industry body representing commercial hydroponic and greenhouse growers Australia wide. His commitment to the Australian protected cropping industry is evident in his years on the PCA Board of Directors, representing the fruit and vegetable sector.
In 2010, the Tasmanian tomato grower from Turners Beach won a national award for innovative approach to greenhouse production. Marcus Brandsema was awarded the 2010 TQA Australia Global Insights Award, which recognises excellence in environmental assurance, quality assurance and food safety. He used the $10,000 award to travel overseas to research alternate energy sources to heat greenhouses and reduce their carbon footprint, particularly the use of biomass gasification to replace LPG natural gas to power greenhouses.
Marcus’ family business—Brandsema Hydroponic Tomatoes—supplies Coles and Woolworths and independent supermarkets. With Dutch heritage, two generations of the Brandsema family have been growing on the same site since Marcus attended the local primary school.
When he was looking for ways to reduce his power bills and improve yields, Marcus turned to an Indian-made gasification system, which transforms agricultural or forest waste into energy and as a by-product, creates CO2.
“What happens is the organic material goes into a gasifier,” said Mr Brandsema, who recently returned from India where he met with manufacturers and engineers to watch the biomass plants in action.
“It’s operating at a reasonably high temperature, around 800 degrees Celsius or thereabouts, in a reduced oxygen atmosphere.
“The organic material doesn’t actually burn, but it oxidises and gives off a gas, which is useful to use downstream.
“Once the gas is produced we can then use it to fire a boiler to create hot water, which is what we need, especially in Tassie, to grow tomatoes,” he said.
“They clean it and use it in an engine, which can drive a generator, or a pump, or alternatively, the gas can be used as a fuel source.
“But the by-product of that is CO2 that would normally go up the flue as an emission, which we could extract from the flue and introduce into the greenhouse.”
According to Marcus, more research is required to establish the concentration of CO2 per unit of biomass.
He also hopes to subsidise the installation cost of the plant.
“After all, we are displacing a fossil fuel LPG with biomass, which is a renewable, be it wood waste or pyrethrum or any other biomass waste stream,” he said.
“That’s got to be a good thing from an environmental perspective, so there might be some initiative in that regard as well.”
In recent years, Brandsema Hydroponic Tomatoes has increased the area of cherry tomatoes where they now comprise 50% of total production. Brandsema is the largest grower of indoor cherry tomatoes in the country and is renowned for superior quality. Cherry tomatoes are graded automatically by camera with four colour and four sizes to maximise client appeal.
Truss tomatoes and the normal tomatoes are grown with emphasis being placed on vine ripening to maximise eating qualities. They are pruned at an early stage to promote even ripening and are packed as soon as picked and sent direct to the retailer. The medium used is coco peat and rockwool slabs with individual regulated drippers to each plant.
Plants are fed automatically 20-40 times per day, depending on conditions. Hydroponic water is reused with nutrient levels automatically adjusted, resulting in the most efficient use of water possible.
Approximately 40% of irrigation water comes from the roof area and is piped into a holding dam, the balance being from an on-property spring. The only water leaving the property is that contained in the fruit.
Brandsema’s tomatoes are marketed throughout Tasmania and through one mainland outlet. Brandsema’s tomatoes have a unique selling point on the Tasmanian market in that they are grown locally. And he is one of only two greenhouse tomato growers on the island.
“There is not that much competition. The other tomato suppliers to Tasmania are larger growers from Victoria and NSW. But they only ship TOV’s (tomatoes on the vine) to Tasmania. We can’t compete with them in terms of price, so it makes no sense to try. That is why we grow other varieties that are hard to import. Besides this, all of the imports need to be fumigated, a time-consuming process that is not contributing to the quality,” Marcus said.
All of the tomatoes at Brandsema are picked loose and packed into 200 and 250 gram clamshells. The Brandsemas focus on the local market—their entire product is sold directly to supermarket chains and independent retailers in Tasmania. Other outlets include corner-shops, veggie sheds or other businesses that want tomatoes to come directly to them.
“If customers appreciate locally grown produce, they are willing to pay a bit more for this,” Marcus said.
“So far it has been a pretty good season, we are picking ahead of budget, which is good. It looks like we will have a good year,” Anthony Brandsema said.
“The cropping season at Brandsema in Tasmania usually starts in July. First planting in the glasshouse is early, usually 21st of June 2014, the shortest day. This crop continues till the first week of June 2015. The plastic house is planted later, mid-July.
The Brandsemas built the original plastic house, a Richel structure, themselves while the glasshouse was built by Faber Greenhouses from New Zealand.
“We are growing Rijk Zwaan’s ‘Cheramy’ variety for the fifth consecutive year. We are very happy with the variety; it might not provide the highest yields, but it tastes very good,” he said.
Aside from the Cheramy crop, the Brandsemas also grow Syngenta’s ‘Angelle’ on contract for Tomato Exchange in NSW. Some of these tomatoes are shipped back to Melbourne. This is about 10-15 half pallets a week.
Anthony Brandsema says that growing on just one hectare is not always that efficient. In order to increase the efficiency of the business, innovation is key, he says.
“In 2006, I won the Nuffield Scholarship, which allowed me to travel a lot in order to gather inspiring ideas. I went to Canada and learned how growers increased their energy efficiency with biomass boilers,” Anthony Brandsema said.
“In 2007, we installed a biomass boiler ourselves that burns woodwaste, woodchips and forest waste. Next to this we have LPG on site and we run a buffer tank. We use the LPG on nice and bright conditions for the CO2. And in the winter we also have the biomass boiler for supplementary heating. The gas prices are really high, it is too expensive, and so we need to have innovative alternatives available for this.”
Unlike many growers who look to expand their acreage in order to increase the efficiency of their businesses, the Brandsemas are not able to do this, facing physical constraints.
“We have run out of land where we are at the moment”, said Marcus.
“We have a very small block and we are in the middle of town. What we want to do is make sure that we get the best return from our operation as it stands now.
“This can be achieved by selling more produce directly to customers rather than to supermarkets. We need to get better value for the product first,” he said.
“Once we have explored these possibilities, we can then determine if the market is good and valuable enough for us to expand. We are not quite there yet.”
The current on-farm boiler set-up
The current biomass boiler at Brandsema Hydroponic Tomatoes burns woodchips, sawdust and sawmill residue to heat up water to keep the greenhouse warm. This boiler provides a ‘base load’ of heat. The emission from this cannot be used as a form of CO2 to be introduced into the greenhouse, because other gas levels, such as nitrogen oxide, are too high.
The farm also uses LPG, which is used for the production of CO2 for the crop during sunshine hours. The heat by-product of this is stored in a buffer tank, to be used as needed. The use of the biomass boiler means Brandsema Hydroponic Tomatoes need less LPG, as they burn LPG for the purposes of CO2 only, and the heat load comes more from the biomass boiler.
The use of gasification changes things a bit. A gasifier exposes biomass to heat in an oxygen restricted chamber. This causes the biomass to give off volatile gasses (producer or syn gas). If oxygen were present, then the biomass would simply burn.
The Syn gas is then conditioned and cleaned, to be used in a burner in much the same way as LPG or natural gas is used. The emission from this is clean enough to use as CO2 enrichment in the greenhouse, with no further treatment.
The use of a gasifier means a biomass fuel source can be used for both heating and CO2 enrichment. This would eliminate the need for LPG (in the case of Brandsema Hydroponic Tomatoes) or natural gas, a fossil fuel, for CO2 enrichment.
About the author
Christine Brown-Paul is a Sydney-based journalist and a regular contributor to PH&G, with a special interest in the environment and sustainable technology. Email: firstname.lastname@example.org Ω
PH&G November 2015 / Issue 161