Farmers spin straw into energy gold… just not in Australia

On our property in south-west Victoria we are about to prepare for burning about 1000 hectares of stubbles, usually with 2-3 tonnes of straw per hectare. All around us other farmers are doing the same – totalling tens of thousands of hectares locally, and many millions of hectares across the higher production cropping parts of Australia.

Usually stubble burning is restricted to those higher rainfall areas where the large amounts of straw can make it difficult to sow and where burning also removes the problem pests of slugs and mites that would afflict the next year’s germinating crop.

So we are still talking many millions of tonnes of straw about to go up in smoke, where each tonne has the energy value of nearly double that of brown coal, and similar to that of dry wood.

While the canola stalk is quite hard to get a clean burn over the paddock, and burning wheat stubble can be also be patchy and unsatisfying unless it is dry and warm with the wind just right, the barley and oat stubbles are an arsonist’s delight.

After getting the downwind side burning back maybe 50 metres from the break around the edge you then fire the whole paddock, and the roar of burning and the colour of the smoke and flames is deeply satisfying.

But we know that this practice may not be allowed here much longer. It has been illegal for many years in the EU, where anyone torching straw like this would be heavily fined or jailed.

Instead in the EU, and increasingly in the USA, Ukraine and elsewhere, this straw and stalk would be being used for production of energy in its various forms – including conversion to ethanol (up to 270 litres of ethanol per tonne of straw), fuelling of small to midsize regional power plants (of 5-30 MW-e), for industrial heat production, or even chopped and mixed in with high-nitrogen content materials (like chicken manure or slaughter wastes) for production of biogas.

In some countries they pelletise it for use as bedding for racehorses, for absorbent litter for fuel or chemical spills and even for household heating. And here and elsewhere people are proving that straw can be turned into a renewable diesel fuel.

The capital costs of straw-fuelled combined heat and power plants are often less than the cost per MW of electricity produced by wind farms, and far more effective in displacing fossil fuel use, as this source of renewable electricity is available to suit demand, just as electricity is from gas or coal-fired plants.

The full utilisation of the heat produced by these plants means they have an energy conversion efficiency of about 85 per cent and significantly improves their economics. It also means there is no need for cooling towers with their high use of potable water.

Countries and regions where these plants are located appreciate the permanent jobs created (significantly more jobs per MW of energy produced than with any other renewable energy source), and as the straw comes from local farmers, they are getting more income.

In Denmark, the furnace ash with its balance of nutrients is returned to the farm fields that provided the straw. And because the heat and electricity, and sometimes transport fuel or upgraded biogas, comes from within the community this money stays cycling within the economy of the region instead of being ‘exported’.

All of these factors together have meant that Danes, Poles, Swedes, Chinese, Italians, Brazilians and others have invested in developing this biomass resource.

Denmark was a leader through the 1980s in developing modern equipment for using straw for farm heating. Legislation there in 1993, enacted as part of phasing out coal use, stipulated use of at least one million tonnes a year of straw for energy production, and part of this is in straw-fuelled combined heat and power plants.

Denmark was also where production of ethanol from straw was perfected (with a pilot plant supplying the ethanol for VIP cars for the 2009 COP 15 summit in Copenhagen).

The first commercial-scale European cellulosic ethanol plant is at Crescentino in Italy, and produces about 50 million litres a year from over 200,000 tonnes a year of crop residues.

Danish designs for straw-fuelled furnaces have been exported widely, including to the UK, Spain and China, and China is now the world leader in implementing ‘modern’ straw-to-energy technologies. More than 10 million tonnes a year there fuel up to 40 regional power stations, and yet more straw is used there in gasification systems and in anaerobic digestion, as well as in pilot plants making cellulosic ethanol. With up to 300 million tonnes of straw annually available China is only just beginning to make use of this resource.

But here on our farm, as with cereal and oil seed growers in higher rainfall regions across Australia, we are likely to be burning our stubbles for quite a few years yet, as no one in positions of power and influence (or in state and federal policy development) seems to know about all these other options, or appears to care.

Andrew Lang is a farmer and farm forester in SW Victoria, and is a vice president and board member of the World Bioenergy Association