Tag Archives: science
Southern U.S. Logging Soars To Meet Foreign Biofuel Demand
By Tanya Dimitrova , special to mongabay.com June 06, 2013 In order to meet the European Union’s goal of 20% renewables by 2020, some European utility companies are moving away from coal and replacing it with wood pellet fuel. The idea is simple: trees will regrow and recapture the carbon released in the burning of wood pellets, making the process supposedly carbon-neutral. But just like other simple ideas, it misses out important details that can turn it on its head. The catch is that the process could be carbon neutral only after the trees regrow to the original size. In the case of cutting 100-year old forest, it would take a century. If the forest is clear-cut, it may never regrow, unless replanted. If the new forest plantation is composed by different or fewer tree species, it will most likely store less carbon than the original forest. Finally, if the forest ecosystem was rich and valuable, as for example a wetland forest, its wildlife may be lost forever. Cutting old-grown forests, wetland forests and clear-cutting is illegal or highly regulated in most of Europe. In the Southern U.S., however, it is perfectly legal. That is where the large wood pellet producers are staging their operations. A Maryland-based company Enviva is one of the top five largest pellet producers in the US. Its facilities in North Carolina and Mississippi currently produce and export to Europe more than half a million tons of wood pellets every year. The company plans to triple its output in the next few years to meet ever-increasing demand for wood biomass fuel, mainly from European utilities, but also from U.S. power plants. Enviva’s facility in Ahoskie, North Carolina. The photograph shows that the company is using large quantities of whole tree trunks for its pellets. Photo by: Southern Environmental Law Center. Enviva claims that it produces wood pellets only from low-grade wood resources such as chips, bark, sawdust by-products, treetops, branches, and other forestry debris remaining after the tree trunks from commercial forests have been shipped for construction material. These unprocessed residues would most likely otherwise go unused as a resource. Additional biomass sources currently include low-grade wood fiber and small logs. However, North Carolina private loggers and land-owners interviewed for a Wall Street Journal investigative report last week admitted that trees more than 100 years old, including some from wetlands, does wind up in pellet plants. “Enviva, now they need wood bad enough that they’re paying for some swamp logging,” one logger said to the WSJ reporter. The company did not respond to an information request by Mongabay this week. Scot Quaranda from Dogwood Alliance, and NGO working on protecting Southern forests, explains that there is little to no regulation impacting the management of forests in the Southern U.S.. Unfortunately, 90% of the forests are privately owned and lack legal protection. Most of the management guidelines that are on the books are completely voluntary and do not include limitations to large-scale clear-cutting, conversion of natural forests to plantations, logging of wetlands, use of toxic chemicals, or logging of endangered forests. That is why Dogwood Alliance and the Natural Resources Defense Council have launched a new campaign, dubbed Our Forests Aren’t Fuel . “We focus our work on the marketplace, because in the South, big corporations drive both the destruction and changes in forest practices,” says Quaranda. The irony is that European utility companies restrict the import of wood pellets to developed countries such as the U.S. exactly in order to avoid illegal logging. “The US forest sector is well set up and managed, meets our sustainability criteria and the supplies of sustainable biomass are plentiful,” says Melanie Wedgbury from Drax Power—the largest British electrical power generation company. Last year Drax announced plans to transform itself into a predominantly biomass-fuelled generator. The company is converting three of its six generating units to run on 100% biomass instead of coal. According to a BBC report , Drax will be burning seven million tons of plant material a year. Bayou forest in Lousiana. Photo by: Rhett A. Butler. REFERENCE: Searchinger, Timothy D., et al. “Fixing a critical climate accounting error.” Science 326.5952 (2009): 527. Read more at http://news.mongabay…kycyOfw7HjE2.99 Continue reading
Biomass: When Could Torrefaction Be Commercially Viable?
10 May 2013 Andrew Mourant The pros and cons of the roasting process – torrefaction – for biomass crops is now under scrutiny as never before by university research teams around the UK, as Andrew Mourant reports… WHAT DOES the next decade hold for exploiting biomass as a commercially viable energy crop? And is there a business future for pre-roasting crops such as willow and poplar so these can be used effectively alongside coal in power stations? The idea has been around for almost 40 years but has yet to take off commercially. Many unanswered questions still surround the science and economics, but the energy world is striving to close that knowledge gap. The roasting process – torrefaction – is now under scrutiny as never before by university research teams around the UK, and is a significant part of the Supergen Bioenergy hub project. This, a five-year programme, has just started gathering momentum having attracted a £3.5mn grant from the Energy and Physical Science Research Council (EPSRC) . Supergen, based at the University of Manchester, intends uniting the best brains of industry and academia. It’s looking far beyond the process of torrefaction, adopting a “whole systems” approach – from crop production to its use in power stations. It’s also examining social and economic impacts besides the science. The problems created by untreated biomass at power stations are well-documented. The material is burned alongside coal which is crushed to powder in huge mills before being blown into the burners. But while coal is easily ground, most biomass is springy and fibrous. This limits the amount that can be processed and used in co-firing. Some power stations have invested heavily in separate mills for cutting biomass so they can use more of it. Torrefaction, however, has the potential to make a huge difference to their operations. After biomass is roasted in an airless environment at about 280°C, moisture, along with some gases and volatile substances, is lost. What’s left is transformed into a harder fuel that’s easier to crush, move and store. It also has a longer shelf life. Shrouded in secrecy Much of the new research is a work in progress, one in which industry collaborators are reluctant to discuss their involvement. Drax , for example, working alongside the University of Leeds, was reluctant to answer detailed questions from Renewable Energy Focus, with a spokeswoman saying only: ‘a lot of what we do in this area is confidential’. Drax provides ‘some guidance on the direction which research takes… through sharing feedback on our findings… we provide a link to the real world of business and engineering,’ a spokeswoman said. But she declined to say if there had been significant discoveries about which crops work best for torrefaction; or if Drax has learned from commercially advanced operations such as Topell in Holland – the Netherlands leads the world in the business application of this type of torrefaction technology. Eon, another partner with Leeds University, was also unforthcoming about its role. What is known is that the university’s work is wide-ranging. It’s considering, for instance, whether or not torrefied biomass could be at risk of spontaneous combustion; also its potential explosiveness when roasted and ready for use. Environmental impact Meanwhile environmental impacts are being examined at Bath University by researcher Dr Paul Adams. “We’ve done a lot of work on the use of resources and energy,” he said. “You often find there’s a lot of ‘embodied’ energy in creating biomass, for instance using inorganic fertilisers on the crop feedstock. Producing these is quite energy-intensive. “There are hundreds of crops that can be used for torrefaction. But another approach is to use industrial bi-product from forestry sawmills or furniture manufacturers that would otherwise go into landfill, decompose aerobically and release methane. Its global warming potential is 25 times higher than that of CO2. “Our assessment looks at the whole system of where biomass feedstock is coming from – from cradle to grave. We’re not just interested in carbon, but for instance, water, which is used not only in crop cultivation but the industrial process. Another aspect to consider is the use of metal in creating a torrefaction plant.” Other scientists are examining what torrefaction means for CO2 emissions, among them Dr William Hall at Coventry University. “We’ve been looking at the burning temperature and time the process takes,” he says. “It’s been theoretical: we’ve used hardwood and softwood in applying the model. We found that the CO2 emissions are linked to the conditions – there’s quite a narrow window of temperature. If you stray outside that window, you can increase emissions rather than reducing them.” Dr Hall has published detailed findings in the Journal of the Energy Institute. His work took two approaches. The first was to look at use the latent heat of hot syngas for torrefaction (syngas is a mix of carbon monoxide, carbon dioxide and hydrogen produced from gasifying a carbon-containing fuel). “But that’s only possible when the gasification plant and torrefaction plant are on the same site,” says Dr Hall. “So we also considered what happens when you use the heat from volatile torrefaction products that have been combusted.” In terms of reducing CO2, Dr Hall concludes that the ideal torrefaction temperature is 280°C for hardwood and 300°C for softwood where syngas heat was used to heat pre-dried woodchips. When torrefaction volatiles provided the heat source, the optimum temperature dropped to 240°C and 260°C for hardwood and softwood respectively. “The downside to torrefaction is that mass is lost and therefore the energy yield is never 100%,” says Dr Hall. “There are many uncertainties remaining about the process.” So, although torrefied products have a greater energy density than other biomass and less energy is needed to grind it up in power stations, the power industry must decide whether that overall energy loss is worth the effort and expense. Explosive risks? The focus at Leeds is about building up a knowledge base of how fuels behave; the dusts; the explosive risks, says research team leader Professor Jenny Jones. “We’re looking to see if torrefied fuels can be stored outside – whether they’re at risk of self-heating spontaneous combustion,” she says. “At the moment power stations have to invest in underground storage for biomass. It’s a big capital investment. As torrefied biomass has been heat-treated, you’ve removed a lot of the material that moulds will attack and cause it to spontaneously ignite.” Dr Daniel Nowakowski, who’s based at Aston University and has studied torrefaction for over two years, agrees. “Removing moisture and some volatiles makes it less sensitive to degradation and also hydrophobic (water repellent),” he said. “It’s good for storage and handling – there are major cost-savings.” Dr Nowakowski and his team used a small experimental reactor to torrefy various crops including beech, willow and switch grass. Trials were conducted at temperatures ranging from 225–300°C, with torrefying times ranging from 30 minutes to two hours. Meantime, Professor Gordon Adams is leading the Leeds University study into explosiveness. One problem, he says, is finding sufficient torrefied material with which to experiment. “While Jenny Jones’s group is making small quantities, one test we do is in a metre cube explosion vessel and you need kilos for that,” he said. “We’d been working 18 months before we got one of the manufacturers to deliver 20kgs. Several companies are making it – it will be big business one day.” However, such is the commercial sensitivity, and with negotiations between suppliers and power companies underway, Professor Adams was unwilling to name the producer. The explosiveness test for torrefied biomass uses a pulverised material whisked up with air in an upright pyrex Hartmann tube. “In terms of how little you need to react with air, the indication is that biomass is very reactive compared with coal,” says Professor Adams. “There have been a number of biomass plant explosions. Burning torrefied biomass is do-able but it will release volatility sooner.” The dust clouds created by biomass tipped into storage silos presents a hazard against which the industry has always to be on guard. The dangers were underlined by a fire at a Npower biomass plant in Tilbury, Essex, in February that prevented it exporting power to the grid for four months. While Npower claimed the fire was caused by a “number of relatively minor events that, taken in isolation would not have escalated”, smouldering dust from wood pellets ignited by drafts of air were widely speculated to have been the cause. Npower says it has since improved safety measures at the site. Still some way to go Developing a biomass supply chain and infrastructure for industrial scale torrefaction ‘could probably take a decade to get into place’, says Professor Adams. It raises big logistical questions – transporting the bulky crop with its significant water content is cumbersome and costly. However pellet plants are now being built; and the pellets, which are dried during the process, are easier and cheaper to ship than raw biomass. In business terms, working out just where to build a torrefaction plant will be crucial. That’s a question Professor Adams, for one, still struggles to answer. “Do you place it at source (near the feedstock crop) or near the power station?” he wonders. “The size of a big-coal fired station is such that you would need a torrefaction plant of its own. No one knows what the economics will be.” Continue reading
More Plant Sugars, More Biofuels: Funding Continues For J.B.E.I. Work
Monday, 15 April 2013 JBEI’s Henrik Scheller (left) and Dominque Loque, shown here with Arabidopsis plants, are engineering plant cell walls to make the sugars within more accessible. (Photo by Roy Kaltschmidt, Berkeley Lab) The Joint BioEnergy Institute has received a five-year renewal of funding from the United States Department of Energy. Under the terms of the renewal, J.B.E.I. will be funded by up to $25 million annually through 2018. The J.B.E.I. is a Bioenergy Research Center created by the D.O.E. to conduct research on the development of advanced, next-generation biofuel. Originally established in 2008, it was backed by a $125 million grant for the first five-year period. The J.B.E.I. is led by the Lawrence Berkeley National Laboratory but also includes researchers from the Sandia National Laboratory, the University of California campuses of Berkeley and Davis, the Carnegie Institution for Science, the Pacific Northwest National Laboratory, and the Lawrence Livermore National Laboratory. J.B.E.I. research, for the past five years, has focused on developing advanced biofuels from lignocellulosic biomass, which uses grasses and other non-food crops and agricultural waste to create alternatives to fossil fuels. Using synthetic biology techniques, the J.B.E.I. researchers seek to engineer plants to enable easy extraction of plant sugars from biomass and to increase the sugar yields of energy crops. Softer walls, less sugar A recent example of the work done in J.B.E.I. would be a genetically engineered Arabidopsis plant that produces less xylan in its cell walls (see related story ) and another with less lignin then the natural plant with more extractable sugars for the biofuel process. “Through the tools of synthetic biology, we have engineered healthy plants whose lignocellulosic biomass can more easily be broken down into simple sugars for biofuels,” said Dominique Loque, who directs the cell wall engineering program for J.B.E.I.’s Feedstocks Division. Lignocellulosic biomass is one of the most abundant organic materials found on Earth. It has been used as animal feed and in the creation of paper. Now scientists are focused on using lignocelluloses as a source of sugars for advanced biofuels. Lignocellulose makes up the plants cell walls. In order to get to the fermentable sugars, the lignocelluloses need to be broken down, a process that can be difficult, expensive and time consuming. Researchers have been searching for a way to reduce lignin, a major polymer in plant cell walls, to enable easier sugar extraction. Most efforts have however resulted in sever biomass yield reduction or a loss of integrity in the plant’s vessels, a key tissue for water and nutrient distribution. What Mr. Loque and his colleagues did was rewire the regulation of lignin biosynthesis and create an artificial positive feedback loop to enhance secondary cell wall biosynthesis in specific tissue. “When we applied our APFL to Arabidopsis plants engineered so that lignin biosynthesis is disconnected from the fiber secondary cell wall regulatory network, we maintained the integrity of the vessels and were able to produce healthy plants with reduced lignin and enhanced polysaccharide deposition in the cell walls,” said Mr. Loque. The researchers believe that this technique can also be implemented to other plant species for biofuel crops with less lignin and more sugar. Enhancing national security, increasing green jobs Aside from the J.B.E.I., the Energy Department also funds two other Bioenergy Research Centers, the BioEnergy Research Center led by Oak Ridge National Laboratory and the Great Lakes Bioenergy Research Center led by the University of Wisconsin-Madison. According to Energy Secretary Steven Chu, the establishment and support of these centers by the administration is intended to help the biofuels industry move forward to decrease the country’s dependence on foreign oil, as well as generate new clean energy jobs. As with the J.B.E.I., both the B.E.S.C. and the G.L.B.R.C. will be funded worth $25 million for the next five years. Emphasis during these years will be on bringing the new methods and discoveries in the centers to maturity to enable their transition into the marketplace. – K.R. Jabuena Continue reading
