Written by Anna Strom
Thursday, 22 March 2012 18:42
Bio4Energy scientists have said that 45 per cent of fossil fuels used in Rikard Gebart said almost most half Sweden's transport fuel could come from biomass. Photo by Bio4Energy.
road transport in Sweden could be replaced by renewable alternatives produced by gasification of forest-sourced biomass or its waste streams. However, “smart” solutions such as pretreatment technologies to render the raw material more malleable had to be further developed for the biofuels, in turn, to be produced on large scale and become a cost competitive alternative to fuels based on fossil oil, they said.
The comments came at an Umeå Renewable Energy Meeting, this month at Umeå University in northern Sweden, where Anders Nordin of B4E serves as a professor.
“We have to build huge, extremely costly infrastructure. We need pretreatment technology and gasification technology… Switching from fossil fuels to biomass is not that straight forward. You have to do it smart, preferably using torrefaction”, Nordin told an audience of 60, mostly academics.
Forest-sourced biomass needs pretreatment to be cost efficent in large-scale biofuel production, according to Anders Nordin. Photo by Bio4Energy.Roasting biomass
He was referring to a pretreatment method which, he said, had similarities with roasting coffee beans, although in the case of the B4E research the material to be roasted, or torrefied, was forest-sourced biomass or grasses. Torrefaction would rid the biomass of excess moisture, protect it from contamination and render it more homogenous, giving it similar density properties to coal, Nordin said. All of which would make for easier transportation, storage and conversion of the biomass in the gasifier.
Indeed, in a recent report analysing the European biofuels market, German consultants ecoprog GmgH found the supply to refineries with feedstock, including its transportation, to be the most cost-intensive step in the value chain for biofuels.
Meanwhile, perfected torrefaction technology for rendering the biomass fit for becoming a biofuel would become affordable in five years’ time, according to Nordin. Process control and friction during compaction of the biomass were notable aspects that needed further development.
“Torrefaction will take another five years until it’s decently priced”, he said.
For his part, Rikard Gebart, acting head of the research and development institute Energy Technology Centre at Piteå in northern Sweden, claimed that this country had “unused” forest biomass to the tune of 70 terawatt hours worth of bioenergy, 40 TWh of which could be gasified for use as biofuels in cars and lorries.
An expert in gasification technology, professor Gebart said that “about 45 per cent of (the automotive transport fuel that) we are using today can be replaced in a best possible scenario”, assuming that 50-to-60 per cent of the biomass energy content could be retained in the resulting fuel.
While recognising that the Sweden-based production of biofuels for use in road transport was minimal, both Gebart and Nordin expressed optimism that biomass-based gasification coupled with torrefaction could make a considerable contribution to increasing the share of gaseous or liquefied biofuels in automotive transport in Sweden, if the technology needed was brought up to scale.
In fact, Nordin revealed, the pair was not only conducting trials to gasify torrefied biomass materials developed at pilot facilities at Umeå in industrial-scale reactors at the premises of B4E industrial partners at Piteå, but also working with industrial partners looking to expand their commercial operations.
Entrained flow gasification of ‘green’ coal
The scientists preferred technology included using a pretreated biomass-based material that mimicked the hydrophobic behavior and homogenous character of coal when converted in an entrained flow gasifier.
“We can mimic the coal behavior in the gasifier... by increasing temperatures. 90-95 per cent of the energetic content is retained in the torrefied material. The rest, contained in the gas, is recovered so it is not lost”, Nordin mused;
“This technology developed for coal… is sufficiently cheap.
“We simply produce a green coal that eventually will be (be used on a large scale in gasification to become) commercial”.