Volume 11 (2013)
  Number II

Supportd by Central Baltic Interreg IV A Programme project ECOHOUSING


Homepage: www.ecohousing-project.eu

Contents


Pages

267-274 A. Aboltins and J. Palabinskis
New types of air heating solar collectors and their use in drying agricultural products
Abstract |
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New types of air heating solar collectors and their use in drying agricultural products

A. Aboltins* and J. Palabinskis

Institute of Agricultural Machinery, Latvia University of Agriculture, Cakstesblvd. ⁵, Jelgava, LV – ³00¹, Latvia;
*Correspondence: aivars.aboltins@inbox.lv

Abstract:

The  aim  of  this  research  was  to  make  new  types  of  air  heating  solar  collection  foragricultural production drying and check their operation. In ²0¹¹ and ²0¹² were obtained twoLatvian Republic Patents for air heating solar collectors. One for an autonomous, compact air-heating solar collector, the other one for a cylindrical crop production drying device with solarcollector  that  can  be  used  for  drying  products.  So  there  are  two  different  types  of  dryingfacilities with solar collectors using sun-warmed air: cylindrical crop production drying device,and  autonomous,  compact  crop  production  drying  facility.  Cylindrical  facility  is  tested  fordrying  ¹⁹.⁵%  wet  wheat.  Autonomous,  compact  crop  production  drying  facility  is  tested  forfresh  carrots  and  apples  ⁵–¹0 mm  slices  drying,  using  ambient  air,  heated  with  the  solarcollector.  For  experimental  results  on  carrot  and  apple  slices  the  layers  of  humidity  andtemperature  changes  in  the  drying  process  are  given.  Grain  temperature  distribution  in  wetwheat layers during drying with heated ambient air depending from sun radiation is given.

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275-282 A. Barisa, G. Cimdina, F. Romagnoli and D. Blumberga
Potential for bioenergy development in Latvia: future trend analysis
Abstract |
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Potential for bioenergy development in Latvia: future trend analysis

A. Barisa*, G. Cimdina, F. Romagnoli and D. Blumberga

Institute of Energy Systems and Environment, Riga Technical University,Kronvalda Boulevard 1, LV – 1010, Riga, Latvia;
*Correspondence: Aiga.Barisa@rtu.lv

Abstract:

The paper discusses development trends of bioenergy production and use in Latvia.A methodology for the assessment of biomass potential was developed and applied to a Latviancase  study.  Four  scenarios  were  built  to  analyse  the  potential  of  biomass  supply  for  energyneeds  and  energy  costs.  The  biomass  resources  considered  are  forestry  residues  and  by-products, energy crops, and agricultural residues.The  evaluation  is  performed  on  the  basis  of  historical  data  analysis  and  literature  reviewapplying  indicators  with  sufficient  levels  of  information  aggregation  and  adequacy.  Futurebioenergy development patterns are assessed from technological, ecological and environmentalpoints of view. The analysis focuses on currently initiated cogeneration plant and boiler houseprojects  (planned  to  be  finished  in  two  years’  time)  and  maximum  available  bioenergyresources in country.The  analysis  indicates  the  biomass  potential  available  for  energy  needs  in  the  range  of  25–30 TWh per year in 2020, of which circa 15 TWh were used in 2011.  Key words: bioenergy, biomass potential, wood fuel.

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283-294 A. Beloborodko, K. Klavina, F. Romagnoli, K. Kenga, M. Rosa andD. Blumberga
Study on availability of herbaceous resources for production of solid biomass fuels in Latvia
Abstract |
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Study on availability of herbaceous resources for production of solid biomass fuels in Latvia

A. Beloborodko*, K. Klavina, F. Romagnoli, K. Kenga, M. Rosa andD. Blumberga

Riga Technical University, Institute of Energy Systems and Environment,Kronvalda blvd. 1, LV-1010 Riga, Latvia;
*Correspondence: anna.beloborodko@rtu.lv

Abstract:

Latvia  has  set  a  target  to  increase  the  gross  final  consumption  of  energy  fromrenewable energy sources up to 40% by 2020. To reach this ambitious objective an increase ofthe amount of energy produced from locally available biomass is a priority. In Latvia, as in theEuropean Union, consumption of wood and wood waste has increased during the last decade.At the same time, the export of pellets and briquettes produced in Latvia is a growing trend,therefore  production  amounts  depend  greatly  upon  export  market  demand.  In  the  light  of  aforeseeable increase in the global market for solid biofuels the same trend would be reproducedin Latvia. Consequently and in the light of an increase in energy consumption this would resultin shortages of the substrate biomass for the production of compressed biomass. To cover thegrowing biomass demand for both domestic consumption and export, potential biomass sourcesfrom agricultural and industrial sectors have to be investigated.The main objective of this paper is to determine the availability of potential herbaceous biomasssources  for  production  of  compressed  biofuels  in  Latvia.  In  order  to  reach  this  target  theavailable  amounts  of  herbaceous  agricultural  and  industrial  by-products  in  Latvia  have  beenevaluated and their energy potential has been calculated. In addition, the current use of thesematerials  is  described  and  sustainability  aspects  of  various  applications  of  such  materials  arediscussed.This study intends to provide the necessary background information to select the most suitableand  convenient  sources  (in  terms  of  availability  and  energy  value)  for  the  production  ofcompressed mixed biomass fuels at laboratory conditions and the consecutive determination ofquality and physical, mechanical, thermo-chemical and combustion properties of such fuels.Key words: biomass resources, renewable energy, by-product use, industrial synergies, mixedbiomass.

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295-306 L. Bisenieks,, D. Vinnikov and I. Galkin
PMSG based residential wind turbines: possibilities and challenges
Abstract |
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PMSG based residential wind turbines: possibilities and challenges

L. Bisenieks¹,*, D. Vinnikov² and I. Galkin¹

¹Institute of Industrial Electronics and Electrical Engineering, Riga TechnicalUniversity, Kronvalda Blvd. 1, LV-1010 Riga, Latvia;
*Correspondence: lauris.bisenieks@rtu.lv
²Department of Electrical Drives and Power Electronics, Tallinn University ofTechnology, Ehitajate tee 5, EE19086 Tallinn, Estonia

Abstract:

This paper presents an overview of technologies for wind energy conversion intoelectrical energy with the help of residential wind turbines. The theory of wind energyconversion into mechanical energy is shown. Wind velocity distribution and normalised energyyield examples are given to improve understanding of wind energy availability and converteroperation modes. Additionally the wind velocity dependency of the height above ground isexplained. The pros and cons of wind turbine generators are analysed. Converter topologiesgalvanically isolated for interfacing a permanent magnet synchronous generator based variablespeed wind turbine with a residential power network is analysed. Main emphasis is on thecombination of a rectifier and an isolated quasi-Z-source (qZS) based DC/DC convertertopology proposed by the authors. The topology (rectifier coupled with a qZS basedgalvanically isolated step-up DC/DC converter) is essential to generate regulated DC voltage(400 V DC typical for 230 V AC output) despite wide variations in the output voltage of a windgenerator. The operation principle of the proposed topology is described. Experimental andsimulation results are presented and analysed.

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307-318 A. Jasinskas,, R. Simonavičiūtė, E. Šarauskis, A. Sakalauskasand S. Čekanauskas
Assessment of unconventional bioenergy plant chopping, milling and pelleting quality indicators and physical-mechanical properties
Abstract |
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Assessment of unconventional bioenergy plant chopping, milling and pelleting quality indicators and physical-mechanical properties

A. Jasinskas¹,*, R. Simonavičiūtė¹, E. Šarauskis¹, A. Sakalauskas¹and S. Čekanauskas²

¹Aleksandras Stulginskis University, Faculty of Agricultural Engineering,Institute of Agricultural Engineering and Safety, Kaunas-Akademija,Studentu str. 15A, LT-53361 Kauno r., Lithuania;
*Correspondence: algirdas.jasinskas@asu.lt
²Aleksandras Stulginskis University, Experimental Station, Kaunas-Akademija,LT-53361 Kauno r., Lithuania

Abstract:

This paper provides the research results of techniques for solid biofuel preparation,while usage of chopping (chipping), milling and pressing (pelleting) of the unconventionalbioenergy plants – elephant grass (Miscanthus x giganteus), fibrous hemp (Futura 75) andfibrous nettle. These energy plants were grown in the experimental fields of the Institute ofAgriculture, Aleksandras Stulginskis University and Lithuanian Research Centre forAgriculture and Forestry. It was approved as the methodology for solid biofuel preparation ofunconventional bioenergy plants, and was selected as the technique for plant chopping, milling,pressing, and the technique for determination of plant chaff, mill and pellet quality. There arepresented results of the experimental research. There were determined the unconventionalbioenergy plant stems, chaff and mill chopping quality, in justification of the use of the drumchopping and hummer milling equipment for prepared chaff and mill fractional composition.The quality of stem chaff and mill fineness was defined according to the most widely usedmethodology approved by the EU countries. There were determined physical-mechanicalproperties of these unconventional bioenergy plant chaff, mill and pellets – plant moisturecontent, bulk density, natural slope and failure angles. Key words: elephant grass, hemp, nettle, stems, chaff, mill, pellets, moisture content, bulkdensity, fractional composition.INTRODUCTION

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319-328 S. Kalinauskaitė,, A. Sakalauskas, E. Šarauskis, A. Jasinskasand M. Ahlhaus
Relation of energy content variations of straw to the fraction size, humidity, composition and environmental impact
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Relation of energy content variations of straw to the fraction size, humidity, composition and environmental impact

S. Kalinauskaitė¹,*, A. Sakalauskas¹, E. Šarauskis¹, A. Jasinskas¹and M. Ahlhaus²

¹Aleksandras Stulginskis University, Studentų g. 11, Akademija, Kauno r.LT-53361, Lithuania; *Correspondence: solveiga.kalinauskaite@gmail.com
²Fachhochschule Stralsund, Institut für Regenerative Energie Systeme (IRES),Zur Schwedenschanze 15, 18435 Stralsund, Germany

Abstract:

Biomass is the major source of renewable energy, the use of which is very importantin energy, environment and economical aspects. Biomass enables the replacement of fossilfuels, the importance of biomass usage is related to global warming questions. Biomassmoisture content is one of the main factors affecting straw preparation for the usage cost.In this research the main focus is on straw and different biomass composition and how itinfluences the solid biofuels preparation for usage, paying attention to straw fraction, humidity,composition and finally how it influences the energy and environmental aspects. Testedsamples consist of different composition- raw straw, 100% yellow straw pellets, 100% greystraw pellets, 98% straw pellets with 2% additives, 50% straw and 50% hay pellets, 49% strawand 49% hay pellets with 2% additives, 100% hay pellets, 98% hay pellets with 2% additivesand additionally two samples of straw briquettes with different chop size – (20 mm) and(30 mm and 10 mm). This research pays attention to the main material characteristics –moisture value, ash content, HHV (higher heating value), pyrolysis coke. Research results willhelp to find the best biomass pellet and briquette composition for solid biofuel usage. Duringthe research it was found that the lowest moisture value was 98% hay pellets with 2% CaOadditive – 5.79%. Highest amount of ash value was found in 50% straw and 50% haycomposition pellets – 0.021 g. Highest amount of HHV were tested pellets which consisted of98% hay with 2% CaO additives. Highest amount of pyrolysis coke in organic and dry matterwere in 100% yellow straw tested samples.Achieved results will help to estimate material fraction, humidity and composition on biomasspreparation for conversion steps, following biomass usage energy and environmentrequirements. These research results will help to realise further tasks of agricultural biomassusage in practice.

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329-334 P. KicCzech University of Life Sciences Prague, Faculty of Engineering, Kamycka
Hot-air heating of family houses with accumulation of energy in the floor
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Hot-air heating of family houses with accumulation of energy in the floor

P. KicCzech University of Life Sciences Prague, Faculty of Engineering, Kamycka

129, 16521, Prague 6, Czech Republic; e-mail: kic@tf.czu.cz

Abstract:

Abstract: This article shows the results of measurements of a hot-air floor system utilisingaccumulation of energy, which is based on the use of excessive heat from the fireplace. Theenergy from the fireplace first directly heats the house and then is stored in a special system inthe concrete floor. During the heating in the fireplace the room is not overheated which is verysuitable for low-energy houses. The main principle is based on specially designed accumulativefloors, consisting of a set of special chambers, which enables hot air from the fireplace to flowthrough. The layer of concrete floor is installed on the surface of these chambers.Special measuring methods were used to monitor the course of heating and cooling of the floorsand the resulting room temperature. The results of measurements in the experimental roomshowed that the accumulation of heat in the floor compensates temperature differences. Heatcan be intensively distributed around the house over time. A large proportion of the radiantcomponent of heat transfer very favourably influences the thermal comfort of the indoorenvironment. Key word: energy, heat radiation, concrete, thermal comfort.

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335-346 I. Laicāne, A. Blumberga, M. Rosa and D. Blumberga
Assessment of changes in households’ electricity consumption
Abstract |
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Assessment of changes in households’ electricity consumption

I. Laicāne*, A. Blumberga, M. Rosa and D. Blumberga

Faculty of Power and Electrical Engineering, Institute of Energy Systems andEnvironment, Riga Technical University, Kronvalda bulvaris 1, LV-1010, Riga, Latvia;
*Correspondence: ilze.laicane@rtu.lv

Abstract:

The purpose of this research is based on a literature review analysis mainly based onthe evaluation of the effectiveness from the smart metering implementation as a behaviouralfeedback on the consumer daily lives and their motivations on reducing energy consumption. Afeasibility analysis of the improved household monitoring system with integrated smart metersand assessment of changes in residential electricity consumption were performed. In this study,an initial assessment of the pilot project for smart meters installation were conducted; thepreparation of the questionnaire survey for involvement of households in the pilot project weredescribed; a literature review on the factors effecting users’ behaviour were conducted; andbased on this literature review an assessment of household electricity consumption and CO2emission savings were provided. This research serves as a basis for further research to explorefactors influencing the user behaviour and to make analysis on electricity consumptionreduction in households, as well as the further development of smart metering in Latvia.

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347-356 D. Lazdiņa, K. Liepiņš, A. Bārdule, J. Liepiņš and A. Bārdulis
Wood ash and wastewater sludge recycling success in fast- growing deciduous tree – birch and alder plantations
Abstract |
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Wood ash and wastewater sludge recycling success in fast- growing deciduous tree – birch and alder plantations

D. Lazdiņa*, K. Liepiņš, A. Bārdule, J. Liepiņš and A. Bārdulis

¹Latvia State Forest Research Institute Silava, Riga Street 111 2169, Salaspils,Latvia; *Correspondence: dagnija.lazdina@silava.lv

Abstract:

Due to the increasing of wood as energy renewable resource in power and heat plantsthe amount of wood ash as waste will increase. Wood ash contains plant macronutrientelements P, K and different elements as micronutrients, only organic and nitrogen are missing.Wastewater sludge from small municipalities is usually clean, first-class material and contains alot of nitrogen and phosphorus. Wood ash can be a good fertiliser and a liming material not onlyfor acid organic soils, but also for mineral soils, but with a less significant effect on the treegrowth in first seasons than a nitrogen rich fertiliser wastewater sludge.The effects that wood ash and wastewater sludge have on the increment and survival of treeswere tested during the years 2011 and 2012 on loam and loamy soils at plantations of blackalder, birch and grey alder, and they were compared with the results collected in the previousresearch started in 2005. It was observed that wood ash in the first two seasons did notsignificantly increase the growth of silver birch, as wastewater sludge did, but it had a positiveeffect on the annual increment of grey alder. Fertilisation of the whole field decreased thesurvival of trees because of weed competition and different injuries.The aim of the study was to evaluate the growth of fast-growing deciduous trees seedlings asshort rotation crop under fertilisation of wood ash, and wastewater sludge on former agriculturalland.

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357-366 V. Osadcuks, A. Pecka and R. Selegovskis
Energetic balance of autonomous hybrid renewable energy based EV charging station in winter conditions
Abstract |
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Energetic balance of autonomous hybrid renewable energy based EV charging station in winter conditions

V. Osadcuks*, A. Pecka and R. Selegovskis

Faculty of Engineering, Latvia University of Agriculture, J. Cakstes blvd. 5.,LV-3001 Jelgava, Latvia; *Correspondence: vtl@tvnet.lv

Abstract:

The paper presents an experimental research on energetic balance of an autonomoushybrid renewable energy based electric vehicle (EV) charging station. The experimental chargestation is located in the central part of Latvia in Jelgava city. The station is built using standardsmall-scale hybrid power system equipment: 24 V 300 Ah lead-acid battery, 2 kW photovoltaicarray, 300 W wind generator, hybrid charge controller and 1.6 kW inverter. The station iscapable to perform mode 1 EV charging (220 V, 50 Hz, up to 1.6 kW). The aim of the researchis to evaluate the operational possibilities, technical self-consumption and overall energybalance of the renewable resources based station during a winter period. Analysis on availablepower for EV charging, self-consumption and affecting environmental factors during a 6-dayperiod is performed. The time period was chosen to include days with temperatures below andabove zero and various levels of solar irradiation. Conclusions about possibilities andusefulness of winter-period exploitation are given.

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367-372 M. Repele, M. Dudko, J. Rusanova, K. Valters and G. Bazbauers
Environmental aspects of substituting bio-synthetic natural gas for natural gas in the brick industry
Abstract |
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Environmental aspects of substituting bio-synthetic natural gas for natural gas in the brick industry

M. Repele*, M. Dudko, J. Rusanova, K. Valters and G. Bazbauers

Institute of Energy Systems and Environment, Riga Technical University,Kronvalda Boulevard ¹, Riga, LV¹0¹0, Latvia;*Correspondence: mara.repele@rtu.lv

Abstract:

Firing of bricks is an essential manufacturing process during which the bricks obtainall  the  necessary  properties.  Life  cycle  assessment  studies  show  that  this  process  is  also  themost  energy  intensive  in  the  brick  manufacturing  process  and  results  in  the  largestenvironmental impact. Usually kilns are fired with natural gas, therefore substitution of fossilfuel  with  a  renewable  energy  source  is  considered  one  of  the  most  effective  approaches  forreduction  of  environmental  impact.  Bio-synthetic  natural  gas  (bio-SNG)  is  one  of  the  mostfeasible  substitutes  for  natural  gas  and  therefore  the  aim  of  the  study  was  to  compare  theenvironmental impacts of those energy sources.Comparison  of  the  life  cycle  of  the  environmental  impact  of  natural  gas  and  bio-SNG  wascarried out using the GEMIS (Global Emission Model for Integrated Systems) database. Bothenergy  sources  were  compared  on  the  basis  of  the  life  cycle  of  CO²  emissions,  cumulatedenergy and material requirement, land use and employment effects.Results show that by replacing natural gas with bio-SNG, greenhouse gases could be reducedand employment increased. However, cumulated energy, material and land requirement is largerwhen bio-SNG is used instead of natural gas.

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373-380 K. Rugele,, L. Mezule, B. Dalecka, S. Larsson, J. Vanags and J. Rubulis
Application of fluorescent in situ hybridisation for monitoring methanogenic archaea in acid whey anaerobic digestion
Abstract |
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Application of fluorescent in situ hybridisation for monitoring methanogenic archaea in acid whey anaerobic digestion

K. Rugele¹,*, L. Mezule¹, B. Dalecka¹, S. Larsson¹, J. Vanags² and J. Rubulis¹

¹Department of Water Engineering and Technology, Faculty of CivilEngineering, Riga Technical University, Kalku 1, LV-1658 Riga, Latvia;
*Correspondence: kristine.rugele@rtu.lv
²Institute of General Chemical Engineering, Riga Technical University,Kalku 1, LV-1658 Riga, Latvia

Abstract:

Anaerobic digestion of cheese whey offers a two-fold benefit: reduction of pollutionpotential and biogas production. Usually effective anaerobic digestion of acid whey is hinderedby low pH (~ 4.5) and low buffer capacity of the substrate. The aim of this study was toevaluate the process of acid cheese whey anaerobic digestion with respect to changes inmicrobial population dynamics and effective biogas production. The results showed that it ispossible to obtain high methane yields (176–278 L kg-1 VS-1) in a system with high organicloading rates (till 4.9 VS m-3 day) and no apparent acid inhibition on methanogenic microbialpopulation. Moreover, Archaea population showed the ability to rapidly adapt and activelyconvert the substrate.

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381-390 A. Žandeckis, V. Kirsanovs, M. Dzikēvičs and D. Blumberga
Experimental study on the optimisation of staged air supply in the retort pellet burner
Abstract |
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Experimental study on the optimisation of staged air supply in the retort pellet burner

A. Žandeckis*, V. Kirsanovs, M. Dzikēvičs and D. Blumberga

Riga Technical University, Institute of Energy Systems and Environment, Kronvalda blvd. ¹, Riga, LV-¹0¹0, Latvia;
*Correspondence: aivars.zandeckis@rtu.lv

Abstract:

The use of biofuels for heating purposes is beneficial from a greenhouse gas emissionpoint of view. But combustion of solid biofuels typically is related with high emission rates of CO, NOx, PAHs, VOCs and particle matter. The most important factor that is affecting the formation of harmful emissions is the way thecombustion process is organised. The amount of air injected and approach for the air supplysystem, are the most important factors affecting combustion process. Air staging is one of themost effective technical solutions for achieving complete combustion and low emissions. Themain idea of air staging is to inject air into different zones of a combustion process. The maingoal of this study is to optimise pellet combustion process in a ⁵00 kW boiler with staged airsupply. The research is based on on-site experiments and application of scientific instrumentation. Fly-away unburned fuel particles were discovered during the on-site experiments. Reduction of theamount of fly-away particles was set as a target function for the optimisation. The amount ofemissions (CO, NOx and particle matter) and the amount of incombustibles in fly ashes wereidentified. Two different solutions with applied secondary air supply nozzles were analysed. The results of the study show that even small changes in the way the combustion air is injectedcan significantly affect the combustion process.

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391-404 J. Vilgerts, L. Timma, A. Blumberga, D. Blumberga and Dz. Slišāne
Application of system dynamic model for the composting of petroleum contaminated soil under various policies
Abstract |
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Application of system dynamic model for the composting of petroleum contaminated soil under various policies

J. Vilgerts, L. Timma*, A. Blumberga, D. Blumberga and Dz. Slišāne

Riga Technical University, Institute of Environment and Energy Systems,Kronvalda bulvāris ¹, LV-¹0¹0 Riga, Latvia;
*Correspondence: lelde.timma@rtu.lv

Abstract:

In this paper the dynamic model for the composting of contaminated soils withpetroleum products is presented. The main objectives of this study is to gain a deeperunderstanding about the dynamic relations between composting process and demand in themarket and to determine how different policies will influence the model and therefore the totalamount of recycled contaminated soil. The methodology applied consists of a system dynamicmodel, which describes the relationships between the cause and effect in complex and dynamicsystems that have delays, feedbacks and non-linearities. The developed model passed both thebehaviour validity and the tests of behavioural sensitivity. The validation indicated that themodel is capable of generating ‘the right behaviour for the right reasons’. This paper shows theresults of four various policies (including reference scenario) and sensitivity analysis. Theresults of the research indicate that the most sensitive parameter is the volume available forcomposting, which is the main factor that influences the amount of recycled material.

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407-412 K. Jansen,, M. Luik, M. Reinvee, V. Viljasoo, J. Ereline,H. Gapeyeva and M. Pääsuke
Hand discomfort in production assembly workers
Abstract |
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Hand discomfort in production assembly workers

K. Jansen¹,*, M. Luik², M. Reinvee², V. Viljasoo², J. Ereline¹,H. Gapeyeva¹ and M. Pääsuke¹

¹Institute of Exercise Biology and Physiotherapy, University of Tartu, Jakobi 5,EE51014 Tartu, Estonia²Institute of Technology, Estonia University of Life Sciences, Kreutzwaldi 56,EE51014 Tartu, Estonia; *Correspondence: jansen@ut.ee

Abstract:

The purpose of this study was to evaluate subjective hand discomfort in femaleproduction assembly workers. Thirty-seven females, working as assembly workers, aged from22 to 54 years (with mean ± SE age of 36.4 ± 10.4 years) participated in this study. The mean(± SE) height, body mass and body mass index of the subjects were 166.8 ± 4.2 cm,61.04 ± 9.5 kg and 21.9 ± 3.7 kg (m2)-1, respectively and their general employment stage asmanufacturing worker was 7.35 ± 5.5 years. Thirty-five workers were right-handed. In thechosen factory was implemented the Lean manufacturing production together with a number ofergonomically designed work places. For the most part of the workday assembly workers sit ona chair or stand behind their working desk, driving screws into an aluminium plate with apneumatic screwdriver. Discomfort in six regions of the hand, both right and left, wassubjectively estimated by the Cornell Hand Discomfort Questionnaire. Total discomfort scorewas calculated. The results indicated that the female assembly workers felt work-relateddiscomfort the most in the right wrist (79.2%), left wrist (6.2%) and in the right thumb jointarea (3.6%). Discomfort was less pronounced in the left pinkie and ring fingers (0.01%), leftthumb (0.2%) and in the right thumb (0.7%). In conclusion, this study indicates significantfeeling of discomfort in the right wrist. In order to avoid the problems caused by overload it isadvisable to do special exercises during short brakes. According to the results further research isneeded on the relationship between hand discomfort and the effect of exercise.

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413-420 H. Kalkis, Z. Roja, V. Kalkis and I. Rezepina
Ergonomics approach in entrepreneurship
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Ergonomics approach in entrepreneurship

H. Kalkis¹*, Z. Roja², V. Kalkis² and I. Rezepina¹

¹Faculty of Economics and Management, University of Latvia, Aspazijas blvd.5, LV-1050, Riga, Latvia; *Correspondence: henrijs.kalkis@lu.lv
²Ergonomics Research Centre, University of Latvia, K. Valdemara 48,LV-1013, Riga, Latvia

Abstract:

The research focuses on determination of the workload and work strain in small andmedium-sized metalworking enterprises of Latvia. A number of studies in the world prove thatthe effectiveness of an organisation is closely related to a human, performer of the work, whoseskills and health affect the results of the organisation’s activity. This research, by applyingergonomics load evaluation methods, showed that extensive workload and work strain inmetalworking enterprises has a negative impact on workers’ wellbeing and health. Theeconomics effectiveness calculations confirmed that the investments in ergonomics inmetalworking manufacturing processes maintain human resources and are economicallyfavourable in ensuring enterprise effectiveness, but further studies are necessary to evaluateworkers’ contribution and willingness to participate in ergonomics interventions.

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421-434 T. Koppel,, T. Tasa and P. Tint
Electromagnetic fields in contemporary office workplaces
Abstract |
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Electromagnetic fields in contemporary office workplaces

T. Koppel¹,*, T. Tasa² and P. Tint¹

¹Tallinn University of Technology, Ehitajate tee 5, EE19086 Tallinn, Estonia;
*Correspondence: tarmo.koppel@ttu.ee
²Tallinn University Haapsalu College, Lihula mnt. 12, EE90507 Haapsalu,Estonia

Abstract:

Technological  progress  and  widespread  use  of  electronics  has  rapidly  increasedlevels of electromagnetic fields (EMFs) in workplaces during the last decade. Today’s workersare exposed to levels of EMFs unprecedented in history. This has caused concern amongst thegeneral  public.  Although  the  EMF  levels  of  such  modern  devices  fall  within  current  safetylimits, the recent studies have still raised questions regarding the biological effects well belowthe  safety  limits.  The  European  Union  and  the  World  Health  Organization  have  called  forscientists to conduct more studies in this field and to investigate all aspects of EMFs. The aimof  this  study  was  to  quantify  the  actual  levels  of  the  EMFs  in  contemporary  workplaces.  Asmost  of  studies  have  only  addressed  a  certain  frequency  range,  this  study  covers  all  thespectrum  of  low  (LF),  intermediate  (IF)  and  high  frequency  (HF)  EMFs.  Altogether  69workplaces were investigated. Great variations were detected across the workplaces, dependingmainly  on  the  computer  set-up  configuration.  Exposure  levels  proved  to  be  affected  by  thenearby electrical equipment, arrangement of wires or faulty appliances. At the end of the paperthe  authors  discuss  different  network  connection  technologies  and  provide  the  results  whichsuggest solutions  for lower HF EMF exposures that allow  for following of the precautionaryprinciple.Key words: electromagnetic fields, occupational exposure, office, reduction, mitigation.

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435-440 Ü. Kristjuhan
Possibilities of prolonging human life in the near future
Abstract |
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Possibilities of prolonging human life in the near future

Ü. Kristjuhan

Chair of Labour Environment and Safety, Tallinn University of Technology,Ehitajate tee 5, EE19086 Tallinn, Estonia; e-mail: ulo.kristjuhan@ttu.ee

Abstract:

People are interested in health and long life. As a result of their activities, health isimproving and average life expectancy is increasing in most countries by two to three monthsevery year. It is around 76 years in Estonia and nearly 80 years in the European Union (onaverage) at present. Life expectancy is projected to increase to 84.6 years for men and to 89.1years for women in Europe by 2060. However, these figures are likely to be overly pessimistic.There are many ways of accelerating progress. Many of these are health behaviours: avoidingstress, controlling blood pressure, exercising and healthy diets do not require much additionalexpense. A combination of such measures can have an impressive effect on health and lifeexpectancy. Our experimental studies in the industry have shown that it is possible to postponeage-related changes by up to 20 years at present. More rapid prolonging of human life ispossible by advancing biogerontological studies and intervention programmes that need moreresources than they currently have available to them.

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441-448 Ü. Kristjuhan, and E.Taidre
Workability of older academics
Abstract |
Full text PDF (227 kB)

Workability of older academics

Ü. Kristjuhan¹,* and E.Taidre²

¹Chair of Labour Environment and Safety, Tallinn University of Technology,Ehitajate tee 5, 19086 Tallinn, Estonia; *Correspondence: ulo.kristjuhan@ttu.ee
²Statistics Estonia, Endla 15, 15174 Tallinn, Estonia

Abstract:

The population is aging. The proportion of the older and experienced workforce isincreasing in intellectual work. There are those people who are dreaming of retirement activitiesbut not everybody. Many older specialists are interested in working longer, after the traditionalretirement age. In comparison with times past, ‘young-old’ people (aged 65–74), are healthierthan their predecessors. There is an accepted retirement age (65–70) in most Europeanuniversities and also in the universities of many other countries. However, studies show thatthere is not any need for a special retirement age as there is no biological basis for retirement ata fixed age. Older and experienced academics should be used, first and foremost, for students’instruction (at the MSc and PhD level) and on research. Their accumulated wide knowledgeshould also be used in big projects. The best solution is an age-diverse workforce at theuniversity.

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449-456 J. Paju
Research of parameters of light emitting diode lamps and their suitability for lighting of working areas
Abstract |
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Research of parameters of light emitting diode lamps and their suitability for lighting of working areas

J. Paju

Tallinn University of Technology, Ehitajate 5, EE19086 Tallinn, Estonia;e-mail: jana.paju@ttu.ee

Abstract:

The current paper describes the results obtained during several experiments inTallinn University and Tallinn University of Technology considering the parameters of lightemitting diode (LED) lamps. Four different LED lamps were investigated, all of them defined(by vendors and/or manufacturers) fitting to replace a 60 W incandescent lamp. The lampsinvestigated were the only ones fitting the definition and possible to purchase from vendors inTallinn, Estonia in the beginning of year 2012, when the experiments were carried out. Severalmethods were used to determine parameters such as: working temperature of luminaires,illuminance, working power, the spectrum of created light, the flicker produced. According tothe results of flickering, frequency and the modulation index of the flickering were calculated.The purpose of the research was to draw conclusions concerning the hypothesis, that byreplacing a 60 W incandescent lamp (IL) with a fitting LED lamp, the lamp that uses lesselectrical power is equivalent to the previously popular IL by the spectral properties as well asthe produced illuminance. Conclusions were also drawn considering the influence of such lighton people exposed to it. Key words: LED lamps, working temperature of luminaires, illuminance, working power ofluminaires, spectrum of light, flickering of light, occupational health, colour rendering index.

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457-462 M. Reinvee, M. Luik and P. Kliimak
Noise emission from grain dryers and potential noise pollution
Abstract |
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Noise emission from grain dryers and potential noise pollution

M. Reinvee*, M. Luik and P. Kliimak

Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56,EE51014 Tartu, Estonia; *Correspondence: mart.reinvee@emu.ee

Abstract:

Noise  is  known  as  an  irritant  both  in  industrial  and  living  space  settings.  Also  thenegative effect of noise on people’s health and wellbeing is widely recognised. Usually in  thework  environment  the  impact  of  noise  can  be  easily  reduced,  for  example,  by  providingpersonal  protective  equipment  or  using  the  appropriate  administrative  tools.  However,  inresidential  areas  near  by  to  industry,  the  problem  is  quite  different.  Although  the  populationdensity  in  Estonia  is  quite  low  compared  to  other  European  countries,  there  are  rural  areaswhere industrial noise sources are located nearby to people’s homes.Also the awareness of noise hazard is rising among people, and company owners are forced todiminish  the  noise  levels  of  production.  This  generates  a  need  for  knowledge  about  noisereduction.  Current  study  aims  to  compile  data  about  the  noise  emission  of  grain  dryers  withmain concern towards noise direction. Results of the study can be applied in developing layoutsof grain dryers or in noise barrier development.Noise levels around the perimeters of different type grain dryers were measured with  a TES-1358A  sound  analyser  in  1/3  octave  band  segregation.  Measurement  data  was  compiled  intonoise maps. Specifications of Estonian laws were taken into account.  Key words: grain dryer noise, noise emission, non-occupational noise.

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463-470 M. Reinvee, J. Uiga, T. Tärgla, P. Pikk and A. Annuk
Exploring the effect of carbon dioxide demand controlled ventilation system on air humidity
Abstract |
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Exploring the effect of carbon dioxide demand controlled ventilation system on air humidity

M. Reinvee*, J. Uiga, T. Tärgla, P. Pikk and A. Annuk

Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56,EE51014 Tartu, Estonia; *Correspondence: mart.reinvee@emu.ee

Abstract:

Earlier studies have indicated that elevated or inadequate levels of carbon dioxide(CO2) in indoor air impairs users in the performance of decision-making. For this reason andalso for potential energy consumption reduction carbon dioxide based regulated demandcontrolled ventilation (DCV) systems are used. Although DCV systems use less electricalenergy than conventional ventilation systems, there is a problem in colder climates with thelowered humidity of air. It has been discovered in earlier studies that even brief exposure torelatively dry air has an impact on voice control parameters. In the current article, the humiditygains from ordinary usage of a faculty building, where a DCV system and room basedtemperature control is utilised, are examined. For that, the changes in the specific indoorhumidity were compared to the changes in the specific ambient humidity.

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471-478 A. Traumann, K. Reinhold and P. Tint
The model for assessment of health risks of dust connected with wood manufacturing in Estonia
Abstract |
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The model for assessment of health risks of dust connected with wood manufacturing in Estonia

A. Traumann, K. Reinhold and P. Tint*

Tallinn University of Technology, Ehitajate 5, EE19086 Tallinn, Estonia;
*Correspondence: piia.tint@ttu.ee

Abstract:

The Estonian woodworkers’ exposure to wood dust is investigated. The measurementequipment HazDust EPAM-5000 was used and the particle size was determined with themicroscope Axiolam ICc 3. On the basis of these measurements and literature data on wooddust hazardousness the model for determination of wood dust risk levels is worked out. The risklevel of wood dust in the Estonian wood-processing industry is III to IV on the five levels scale.The maximum wood dust concentration in the workplace air was 4.27 mg (m3)-1 and registeredby the polishing of window details. The better work conditions in the industry have been gainedwith effective ventilation and consistent cleaning of the workrooms. On the basis of theinvestigation it has been concluded that the working conditions in the wood processing industryin Estonia in 2012 have been improved considerably over the years 1990–2000.

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479-486 A. Traumann, P. Tint, O. Järvik and V. Oja
Management of health hazards during shale oil handling
Abstract |
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Management of health hazards during shale oil handling

A. Traumann, P. Tint*, O. Järvik and V. Oja

Tallinn University of Technology, Ehitajate 5, EE19086 Tallinn, Estonia;
*Correspondence: piia.tint@ttu.ee

Abstract:

The current paper describes the investigations in Tallinn University of Technology ofthe hazardous gaseous phase during handling of shale fuel oil. The combined-method gaschromatography-mass spectrometry (GC-MS) was used for determination of the gaseouscomponents evaporating from the shale fuel oil during handling. Parallel measurements weremade using Dräger tubes. The model for determination of risk levels to the workers’ health iscompiled. The occupational illness stages are developed using statistical data of diagnoses madeby the occupational health doctors. In the case of benzene, xylene, toluene and phenol, the mainhealth impairments are divided into two different groups – irritating and neurotoxic effects.According to the proposed model, the exposure to toluene and xylene poses a justified risk (risklevel II), benzene and phenol an unjustified risk (risk level III). Without any additional controlmeasures applied, the risk for occupational diseases caused by these chemicals is significant.

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487-494 V. Viljasoo,, J. Zadin, H. Jüris and T. Pomerants
Combined air conditioning for heating rooms and improving of indoor climate
Abstract |
Full text PDF (321 kB)

Combined air conditioning for heating rooms and improving of indoor climate

V. Viljasoo¹,*, J. Zadin¹, H. Jüris² and T. Pomerants¹

¹Institute of Technology, Estonian University of Life Sciences, Krutzwaldi 56,EE51014 Tartu, Estonia; *Correspondence: viljo.viljasoo@emu.ee
²Company AIRMAKER GTR, Riia 181A, EE51014 Tartu, Estonia

Abstract:

Geothermal equipment consists of intake air pipes, vacuum wards and undergroundconnecting pipes, placed near to a villa. The heat exchange ventilation equipment MENERGA191191 used in ventilation systems makes air inside the device circulate. This patentedequipment differs from the analogues of Germany, Japan, United States, etc. by the coolingexchange device. This device enables remarkable advantages in mounting and construction bydecreasing the length, installation depth and number of air pipes, simplifying and reducing themaintenance and increasing the equipment durability. The geothermal equipment is meant forcreating an environment with a constant temperature of 4 ºC and adjustable relative humidity inwarehouses and basements. It is for improving an indoor climate in villas’ basements,preheating, and air conditioning based on air heating as well. This equipment is indispensablewhen preheating greenhouses and cooling air in the hot season. The analysis of air climateparameters (temperature ϑk, relative humidity Ws, dew point ϑp, absolute humidity Wa,velocity v, oxygen content O2, carbon dioxide content CO2, positive light air ions n+, negativelight air ions n–) passing through the geothermal equipment is presented in the article. Heattechnical data (air specific heat capacity, characteristics of heat and cold exchange processes)are presented. This article summarises the research results of indoor climate qualities andpresents data about energetic-economical efficiency of the geothermal equipment (air specificheat and gross capacities, return air flow specific heat and gross capacities, the economic effectof pre-heating the villa and the post-heating expenses were analysed).

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497-504 H. Mõlder,, J. Järvik, K. Pilt, M. Märss and R. Reiska
Microwave treatment against the attack of wood boring in timber structures
Abstract |
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Microwave treatment against the attack of wood boring in timber structures

H. Mõlder¹,*, J. Järvik¹, K. Pilt², M. Märss¹ and R. Reiska³

¹Department of Electrical Engineering, Tallinn University of Technology,Ehitajate tee 5, 19086 Tallinn, Estonia, *Correspondence: heigo.molder@ttu.ee
²Estonian Mycology Research Centre, Heina 7, 50604 Tartu, Estonia
³Department of Polymer Materials, Tallinn University of Technology, Ehitajatetee 5, 19086 Tallinn, Estonia

Abstract:

Timber is a sustainable building material that can be damaged by several biologicalagents, like insect activity, fungal decay and more. This is one of the most common problems inhistorical buildings. This paper gives an overview of microwave (MW) technologies, whichhave been used in wood boring insect control. Electromagnetic waves penetrate throughout theentire volume of treated material, causing water in wood and wood boring insects infestingwood to heat up simultaneously. The rise of temperature is the main effect used in MW pestcontrol. A microwave wood boring insect neutralisation device herein is introduced. This paperlooks at the long-distance microwave irradiation and radiation energy distribution of theirradiated surface. Tests for evaluation of wood pest elimination by MW radiation are specifiedand discussed.

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505-512 J. Papez and P. Kic
Wood moisture of rural timber constructions
Abstract |
Full text PDF (191 kB)

Wood moisture of rural timber constructions

J. Papez and P. Kic*

Czech University of Life Sciences Prague, Faculty of Engineering,Kamycka 129, 16521, Prague 6, Czech Republic;
*Correspondence: kic@tf.czu.cz

Abstract:

The aim of this paper is to present the methodology of measurement of moisturecontent of wood and show some results of this measurement in application on constructions ofagricultural buildings. Wood moisture can affect the durability of buildings. Measurements arein two different animal houses, which varied in design and implementation of the constructionmaterial (steel-wood and steel with wooden rafters). Both these buildings are relatively new(built in 2001 and 2009). There was measured also an older shed attached to the barn, which hasa storage and protective function. All these buildings are from spruce wood. The measurementwas based on the use of resistive sensor and capacitive sensor. Also determined was thetemperature and humidity of the air.From the results of measurements of tested buildings it is obvious that the moisture of the woodis in direct proportion with the relative humidity of the air. There are different results measuredby capacitive and resistive sensors. The suitability of the sensors for determination of woodmoisture was verified by gravimetric method, that is direct method and the results are veryaccurate. In the case of coniferous wood (especially spruce wood), there can be used withsufficient accuracy a capacitive sensor, which was used in all examined buildings. Key word: animal houses, wood, measurement, moisture content.

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513-520 U. Sannik,, L. Lepasalu and V. Poikalainen
Interactions between size reduction and thermal processes during treatment of animal by-products
Abstract |
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Interactions between size reduction and thermal processes during treatment of animal by-products

U. Sannik¹,*, L. Lepasalu² and V. Poikalainen²

¹Competence Centre of Food and Fermentation Technologies Akadeemia tee15A, 12618 Tallinn, Estonia; *Correspondence: urmas@tftak.eu
²Institute of Veterinary Medicine and Animal Sciences Estonian University ofLife Science, Kreutzwaldi 64, EE51014 Tartu, Estonia

Abstract:

Animal  by-products  from  slaughterhouses  often  go  through  a  process  known  asrendering  to  economically  recover  protein  sources.  Common  raw  material  treatmenttechnologies are: pre-handling; reduction of the size of raw material particles; thermal treatmentwith  pressure  or  sub-pressure  impact;  natural  or  artificial  chemical  treatment;  fractionation(percolating,  straining,  centrifuging  with  or  without  thermal  treatment,  etc.)  and  handling  ofmaterial fractions (dehydrating; defatting; demineralisation, etc.).Thermal  treatment  is  a  long-term  process  that  lasts  up  to  90 minutes  –  and  is  the  primarydisadvantage  of  known  solutions  because  hot  processing  influences  the  natural  properties  ofproteins contained in the raw materials rendering them less valuable.Size-reduction  is  the  most  power-intensive  phase  rendering  technologies  when  reproduciblegrinding conditions, short grinding times, precise results, and loss-free operation are required.The size reduction ratio of the material influences the effectiveness of the following treatmentstages  (thermal  impact  and  others)  and  quantitatively  affects  the  extraction  intensity  ofcomponents from the pre-treated material.To maximise the efficiency of heat treatment and fractionation operations on by-products forfood,  feeding,  or  technical  purposes  it  is  necessary  to  optimally  design  the  technologicalequipment  to  fit  within  the  specific  requirements  of  the  particular  cooking  and  renderingapplication.The knowledge gained from this project will be used by designers and equipment producers ofcooking, frying, and other heat treatment systems for food, feed and technical purposes.This information will enable more accurate determination of heating times corresponding to theprocessed material properties and batch loads.  Key words:  animal  by-products,  meat-bone  raw  material,  rendering,  crushing  ratio  andfineness, heat treatment, heat transfer coefficients.

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523-527 J. Ahokas,, H. Mikkola, T. Jokiniemi, M. Rajaniemi, W. SchäferH. Rossner, V. Poikalainen, J. Praks, I. Veermäe, J. Frorip and E. Kokin
ENPOS – Energy positive farm
Abstract |
Full text PDF (264 kB)

ENPOS – Energy positive farm

J. Ahokas¹,*, H. Mikkola¹, T. Jokiniemi¹, M. Rajaniemi¹, W. Schäfer²H. Rossner³, V. Poikalainen⁴, J. Praks⁴, I. Veermäe⁴, J. Frorip⁵ and E. Kokin⁵

¹University of Helsinki Department of Agricultural Sciences, PL 28(Koetilantie 5), 00014 Helsingin Yliopisto, Finland;
*Correspondence: jukka.ahokas@helsinki.fi
²Agrifood Research Finland MTT, MTT, Kotieläintuotannon tutkimus,Jokioinen Vakolantie 55, 03400 Vihti, Finland
³Estonian University of Life Sciences, Institute of Agricultural andEnvironmental Sciences, Kreutzwaldi 1, Tartu EE51014, Estonia
⁴Estonian University of Life Sciences, Institute of Veterinary Medicine andAnimal Sciences, Kreutzwaldi 62, EE51014 Tartu, Estonia
⁵Estonian University of Life Sciences, Institute of Technology, Kreutzwaldi 56,EE51014 Tartu, Estonia

Abstract:

In ENPOS (Energy Positive Farm) project possibilities to save energy on Estoni anand Finnish farms was studied. Energy can be saved easily and without large financial costs10 –30%. The most important thing is to increase the energy knowledge of the farmers. Thismeans advisory work and energy education.Energy bookkeeping and energy analysis are important things in energy consumption follow-up. The farm energy consumption should be followed and with this acquired knowledge farmerscan notice where they consume more energy than on average and also where they are betterthan others.Energy consumption is not easy to follow because this would mean in most cases energy meterassemblies and this is costly. New agricultural machinery could be designed so that they includeenergy consumptions meters.

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529-532 A. Pasila
Changes, challenges and opportunities in the wood energy supply chain
Abstract |
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Changes, challenges and opportunities in the wood energy supply chain

A. Pasila

Seinäjoki University of Applied Sciences, School of Agriculture and Forestry,Ilmajoentie ⁵²⁵, ⁶0⁸00 Ilmajoki, Finland;
e-mail: antti.pasila@seamk.fi

Abstract:

One of the biggest challenges in using bioenergy has been the problem of logistics;that is how, in many cases, to process and transport these low density and bulky raw materials.Finnish  forestry  technology  is  advanced  and  the  same  machinery  which  is  used  in  timberharvesting is often used in energy wood harvesting.A  change  in  the  forest  industry  has  however  caused  some  new  expectations  concerning  thewood  energy  supply  chain.  One  of  the  basic  requirements  for  woodchips  is  low  moisturecontent. In the transportation of wood chips high moisture content, and therefore a high weight,may limit the carrying capacity of vehicles and roads. Also in syngas and charcoal productiondry raw material is needed to be able to control the combustion process.The reduction of moisture content under natural drying conditions means an extended storagetime. With Finnish climate conditions this normally means a storage period of at least one year.The  various  types  of  energy  wood:  stems,  whole  tree  harvested  stems,  logging  residues  orstumps are piled in storage sites and covered. The raw material is chipped or crushed at theseintermediate storage sites and after that transported to bio-refineries.In  the  measurement  of  the  energy  wood’s  quality  and  quantity  there  are  some  differencescompared  to  timber  measurements.  Normally  the  timber  measurements  are  based  on  solidvolume in cubic metres. The forest harvesters are equipped with on-line measurement systems.This  on-line  measurement  is  more  complicated  to  carry  out  in  the  case  of  energy  wood.Especially difficult are the volume measurements in whole tree and stump harvesting. A newmethod used in the measurement of energy wood is weight.

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