Timber technology - Skog og landskap

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Sprucing up wood protection Pioneering electro-osmotic pulsing technology, developed by researchers based at the Norwegian Forest and Landscape Institute looks to challenge existing chemical methods of preservation with the innovative PLEOT technique PURSUING MORE SUSTAINABLE consumption of ecosystem services requires not only innovation in the production of new materials, but also a need to maintain existing materials by increasing their longevity and durability. When this can be achieved it lessens the need for new materials, reducing our impact on the environment. In more recent decades, wood has been held in particularly high regard as a building material which impacts the environment considerably less than its steel and concrete equivalents. In Nordic countries, wood is now being seen as an alternative for larger constructions as demonstrated in such building projects as opera houses, airports, bridges and more commonly as cladding in smaller homes. Yet most European timber products show little resistance to the decay caused from environmental circumstances in comparison to the more durable wood species from tropical forests of South America. MICROSCOPIC MARAUDERS Much of the damage to wood used in buildings is actually caused by wood-decay fungi, bacteria, insects or marine borers which thrive even in the bitter conditions of northern Europe. Protecting the wood against the unavoidable wear produced by invasive fungal marauders is therefore paramount to the durability of the product. Chemical wood preservatives have proven PLEOT successful in the past, but the environmental pressure of producing and using these can contribute to ecological problems. Hence an alternative solution is desired. This has led to an innovative approach by the Norwegian Forest and Landscape Institute in cooperation with the industry partner Miljøteknologi AS – challenging traditional methods of chemical wood protection by using electro-osmotic pulsing technology known as PLEOT (from the Norwegian abbreviation of Pulserende Likestrøms Elektro-Osmose Teknologi). This means that the motion of polar liquid, through a membrane or a porous material, is used to dehydrate the desired area to minimise the potential for fungal growth. The process involves placing electrodes across the material and applying a direct current, this enables water and ions to be transferred through the electric fi eld. This transference is a direct consequence of diffuse double-layer cations in the pores of the materials which specifi cally function to target negatively charged electrodes or cathodes. When these cations are dissolved in water, the water molecules that are present form chemical bonds with the cation. When these travel to the cathode the water molecules are dragged along with it. Moreover, those water molecules, due to the polar nature of water, will also pull along more water molecules that are not bonded to the cation. WWW.RESEARCHMEDIA.EU 97
INTELLIGENCE PLEOT PATENTED WOOD PROTECTION BY MEANS OF ELECTRO OSMOTIC PULSING TECHNOLOGY OBJECTIVES To develop and test a new wood protection system using electro-osmotic pulsing. Carbon storage can be extended by increasing the lifespan of wood products. The working group is conducting laboratory and fi eld trials in order to evaluate electro-osmotic pulsing technology on different wood species and against various fungi species. The primary goal is to prevent deterioration of wood products caused by fungal attack in outside applications. PARTNERS Norwegian Forest and Landscape Institute, Norway Miljøteknologi AS, Porsgrunn, Norway FUNDING Norwegian Research Council Miljøteknologi AS Innovation Norway CONTACT Dr Andreas Treu Project Coordinator Norwegian Forest and Landscape Institute Norsk institutt for skog og landskap Pb 115 NO-1431 Ås Norway T +47 64 94 90 29 E andreas.treu@skogoglandskap.no DR ANDREAS TREU is a researcher at The Norwegian Forest and Landscape Institute. He studied Forest Sciences and Forest Ecology in Göttingen, Germany, where he received his doctoral degree in 2006. His research interests lie within the fi eld of wood technology, especially in biodegradation and protection of wood. 98 INTERNATIONAL INNOVATION THE POTENTIAL OF PLEOT The Norwegian Forest and Landscape Institute has shown successful applications for this technique as highlighted in recent tests. So far the testing has only been carried out by introducing fungi strains onto the wood species in petri dishes. Some have been attached to cables for the PLEOT technique to be administered and these have been compared to untreated wood samples. The results so far have been promising. There was little or no mass loss from the PLEOT protected wood specimens, though there was a little discolouration at the cathode end, whereas the unprotected wood lost a signifi cant amount of mass to the fungi. The discolouration in the protected wood is hypothesised to stem from the cable elements, such as nickel and copper, also travelling with the electric fi eld to the cathode end, but new electrode material has been developed to avoid this effect and is now under testing. Current fi ndings show that PLEOT fully protects Scots pine sapwood, Norwegian spruce and beech wood samples over 16 weeks when exposed to the fungi Coniophora puteana and Trametes versicolor in the laboratory trials. These tests demonstrate that fungal degradation of untreated wood samples due to the colonisation of microorganisms can be stopped or slowed down to a controlled pace if protected by PLEOT, demonstrating the potential which the research holds for further treatments and different scenarios. LONG TERM SUCCESSES Potential criticism of the method is negligible. For example, from the perspective of sustainability, the protection techniques of PLEOT do not provide a completely carbon-neutral means of wood protection as it relies on the application of an electrical pulse. Though far less damaging than its chemical counterpart, the electricity SMALL TEST HOUSES PROTECTED BY MEANS OF PLEOT used by PLEOT must be applied constantly. Yet the electricity consumed is normally only a few milliampere (mA), and is insignifi cant in relation to the benefi ts offered: “The combination of a pulsing pattern and a very low electric current does not lead to high energy consumption,” highlights Project Coordinator Dr Andreas Treu. Ultimately, the advantages of using PLEOT over the alternatives demonstrate superior functionality and environmental awareness compared to replacing wood structures over time or using chemical alternatives. Treu asserts that PLEOT is in line with his vision of future wood use: “A sustainable future for wood products should include renewable, sustainable and environmentallyfriendly technologies to protect wood”. THE FUTURE POTENTIAL The future potential of the wood protection systems offered by PLEOT is evident. The technology shows defi nite potential, and the restrictions of the process will become apparent during the developmental phase. A fi eld test is already underway in Telemark, Norway. The PLEOT technique is being applied to the wood on a post offi ce façade and the researchers expect less bacterial and fungal growth. Finally, researchers want to turn their attention to following the performance of the process in example projects such as houses and old buildings, depending on interest from architects and engineers. As wood preservation becomes an issue not only for owners but for the environment, the work carried out by the Norwegian Forest and Landscape Institute shows alternative methods that have great promise as an eco-friendly solution. Successful tests, a promising range of applications and a potential to become a widespread, conventional technique underlines the fact that the development of the technology demonstrates research with real merit.
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Timber technology - Skog og landskap

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