Influence of Elevated Pressure on the Torrefaction of Wood

The use of pressurized reactors in industrial processes can improve efficiency and economics. Torrefaction is a partial pyrolysis of lignocellulosic biomass designed to result in a solid product with improved fuel properties for utilization in combustion and gasification. In this work, the influence of elevated pressure on the torrefaction of wood has been investigated. Wood samples were torrefied using a pressurized thermogravimetric reactor (PTGR) with pressures of 0.1 to 2.1 MPa. The results indicate that reactor pressure, particle size of feedstock, and wood species are all factors in torrefaction yield improvements. Torrefaction at 2.1 MPa pressure improved the higher heating value (ca…

Measurement methodology for greenhouse gas emissions from storage of forest chips–A review

Abstract Research on greenhouse gas emission related to solid biofuels has focused mainly on the emissions from end use and the production chain. GHG emissions from the storage of forest chips have not received much attention in recent literature. In order for EU emission reduction targets to be fully understood, emissions from solid biofuel storage needs to be better described. Usually emissions from chip piles have been modelled using studies from organic waste composting but these two materials can differ appreciably; for example the C/N-ratio and moisture content. Herein, previous studies on greenhouse gas emissions from forest chips piles during storage are reviewed. The objective is t…

Torrefied versus conventional pellet production – A comparative study on energy and emission balance based on pilot-plant data and EU sustainability criteria

Abstract Torrefaction is an emerging technology which enables greater co-firing rates of biomass with coal. To date however there has been a lack of real production data from pilot-scale torrefaction plants. Without such data any environmental benefits of torrefied pellet production are difficult to quantify. In this study data on consumable inputs from a semi-industrial torrefaction plant and the physical properties of produced pellets are used to analyse energy input and air emissions of torrefied pellet production and product transport. EU sustainability criteria are used to compare CO2-equivalent emissions from torrefied and conventional pellet production starting from harvesting of log…

A comparative economic analysis of torrefied pellet production based on state-of-the-art pellets

Abstract Torrefied pellets have fuel properties superior to those of conventional wood pellets and potentially allow greater rates of co-firing and thus larger reductions in net CO 2 emissions. Despite the growing amount of scientific output on torrefaction, the economic feasibility of torrefied pellet production is still a topic of considerable uncertainty. This is an obstacle for decision makers looking to implement sustainable energy policies. This paper compares the economics of torrefied pellets to conventional wood pellets. Working backwards from demonstrated pellet properties, this work attempts to answer the following question: Based on state-of-the-art torrefied pellets, what would…

Bio-coal, torrefied lignocellulosic resources – Key properties for its use in co-firing with fossil coal – Their status

Abstract Bio-coal has received generous amounts of media attention because it potentially allows greater biomass co-firing rates and net CO2 emission reductions in pulverised-coal power plants. However, little scientific research has been published on the feasibility of full-scale commercial production of bio-coal. Despite this, several companies and research organisations worldwide have been developing patented bio-coal technologies. Are the expectations of bio-coal realistic and are they based on accepted scientific data? This paper examines strictly peer-reviewed scientific publications in order to find an answer. The findings to date on three key properties of torrefied biomass are pres…

Standard testing of photovoltaic modules for use in renewable energy education

A photovoltaic laboratory exercise has been devised and used in the educational curriculum of the Renewable Energy Programme at the University of Jyväskylä. The purpose of the experimental tasks is to give students of renewable energy a good understanding of standard testing procedures used in industry for characterising photovoltaic modules and to provide practical skills in sizing simple photovoltaic installations. Herein the experimental set-up, basic theory and measurement procedure are described. The experimental apparatus is simple to assemble and uses both standard laboratory equipment and recycled components. From the experimental results, the tested PV cell had a maximum efficiency…

Torrefaction technology for solid fuel production

On the use of a laboratory-scale Pelton wheel water turbine in renewable energy education

Abstract A laboratory-scale Pelton turbine for hydroelectric generation has been constructed and used in the educational curriculum of The Renewable Energy Programme at the University of Jyvaskyla. The construction of the Pelton turbine, the experimental apparatus and the measurement procedure are described. The apparatus is simple to make and uses inexpensive components, most of which can be found in standard science laboratories. From the experimental results, the turbine was found to have a maximum mechanical efficiency of 0.47 ± 0.02 for a water flow rate of 0.17 l / s . The Pelton turbine and apparatus demonstrate the principles of hydropower and are well suited for education in renewa…

From wood pellets to wood chips, risks of degradation and emissions from the storage of woody biomass – A short review

Abstract The compounds in stored woody biomass degrade as a result of chemical and/or biological processes during storage. These processes produce gaseous emissions. Recent studies concerning gaseous emissions from wood pellet storages are reviewed herein. The applicability of the results from pellet research to wood chips is discussed. Thorough scientific understanding on the storage phenomena of wood chips is extremely important as the threat of climate change and the need to reduce greenhouse gas emissions have led to an increased need to large scale wood chip storage to ensure supply. Typically the gases produced from stored woody biomasses are carbon monoxide (CO), carbon dioxide (CO 2…