A lot of different EU directives and regulations set the targets to decrease greenhouse gas emissions, to increase the share of renewable energy, and to improve energy efficiency. Biofuel usage is directly linked to all of these problems. Since the first generation food-based biofuels should not receive public support after 2020, investigations of next generation biofuels are topical. Hydrotreated vegetable oil (HVO) is one of the most promising next generation biofuels in the near future. This article deals with the results of mathematical modelling to determine the main diesel engine operating parameters (power, torque and fuel consumption) running them on HVO and its blends with fossil diesel fuel. The modelling results of the car Opel Insignia 2.0 CDTi show that every 5% of HVO in fuel blend reduces maximum power and torque of around 0.38% while raising specific fuel consumption by volume of around 0.10%. Analyzing the most realistic scenario in the near future – 7% HVO and 93% fossil diesel blend, the predicted fuel consumption increase (0.14%) and power and torque decrease (0.54%) is inconsiderable for vehicle exploitation, and HVO seems to be a promising biofuel to replace biodiesel in fuel blends and to promote reaching the EU targets.

This experimental study assesses the influence of ignition timing on emissions from a production four cylinder port injection spark ignition engine. The aim of this research was to evaluate the necessity of ignition timing correction when the regular gasoline vehicle is being adapted for the use of E85 fuel. Tests were conducted in the Alternative Fuels Research Laboratory of Latvia University of Agriculture in December 2013. The engine was fuelled with the ethanol-gasoline blend E85 or the commercial gasoline A95. The engine was tested within a vehicle in a chassis dynamometer in steady state conditions, which resemble driving at 50 km hE-1 and 90 km hE-1. The original engine control unit was replaced with a programmable one. Engine-out and tailpipe exhaust gas samples were taken and analysed with a FTIR-type analyser AVL SESAM. Carbon monoxide (CO), unburned hydrocarbons (HC), nitrogen oxides (NOx), acetaldehyde and unburned ethanol emission volumetric share is presented. CO, HC and acetaldehyde emissions were not affected by variation of the ignition timing within the tested range. NOx and ethanol emissions were reduced with the ignition timing retard. The emissions of CO, HC and NOx were reduced, when the engine was fuelled with the E85 fuel, comparing with the gasoline use. Ignition timing, optimized for the gasoline, was found suitable for the E85 fuel from the emission analyses point.

The paper discusses heat transfer and the step response of a low-power induction motor to no-load mode under fan cooled and naturally cooled conditions. In Latvia University of Agriculture (LUA) in the electric drive laboratory the experimental tests were performed on a 1.1 kW totally enclosed fan cooled three phase induction motor with a fan mounted on a shaft for fan cooled conditions and with a fan taken off for naturally cooled conditions. The transient temperatures are measured in nine points of the stator end windings and in two points of the stator frame using thermocouples. Temperature is measured by using K type thermocouples and Pico-Log TC – 08 data logger. The current and voltage are measured by using Simple Logger II L562 two channel data logger. Measurement data are processed and archived using data loggers Pico-Log Recorder, Simple Logger II and Data View software. The experimental test results show that ventilation plays an essential role in the heating process of small power induction motors. Mathematical and virtual models of induction motor windings heating are represented to simulate the heating process of induction motor under no-load mode and different cooling conditions.

Europe’s future wood demand for energy is expected to increase by 10 million to 200 million m3 in the period 2010- 2030. This will be supplied by both domestic sources (forests, industrial residues post-consumer wood waste), but also from sources outside Europe. The EU-28 predicts a near future (2020) gap between solid biomass supply and demand for renewable energy: 21.4 million tonnes of oil equivalents (MTOE). This is estimated via preliminary renewable energy action plans (NREAP’s) per country. The EU-28 expects wood pellet import will merely complete this gap of 21.4 MTOE, with more than 50 million tonnes of pellets. This implies a feedstock need of 125 million m3 of wood from forests and other sources outside the EU-28. A practical approach to include bioenergy in wood sector models should start with the input of wood pellets. Ideally, three types of bioenergy markets should be considered, in which pellets and the other major woody feedstock are included: 1. Large scale power production (the UK, Belgium, the Netherlands, all importing pellets from outside the EU-28); 2. Medium scale combined heat and power (CHP’s) including those in the forest sector (Nordic countries use pellets and chips for energy, merely imported from the EU-28); 3. Small scale residential heating (Germany, Austria and Italy, using wood pellets and logs from regional sources). We suggest starting with inclusion of medium scale CHP’s, followed by large scale power production. Small scale heating is relatively stable and should not have large impacts on future markets.

The paper covers spatial analysis of the Measure “Afforestation of agricultural and other than agricultural lands” implemented in Poland within the framework of the Rural Development Programme 2007 – 2013 (RDP 2007 – 2013). Beneficiaries obtained payments for afforestation based on the commitments made during the programming perspective of 2004 – 2006 or they joined the programme during the perspective of 2007 – 2013. Data obtained from the Department for Direct Payments of the Ministry of Agriculture and Rural Development as of 31 December 2012 formed the base of the analysis. Payments made in the country to the beneficiaries considering their activity and absorption of funds within the framework of the measure are presented. Next, given the disbursements made in voivodships and counties of Poland, the activity of beneficiaries was indicated and average disbursements per beneficiary were determined. The analysis aims at investigating the consistency of the afforestation policy implemented in Poland as of 2004 and showing the role of afforestation projects implemented within the RDP framework. The aim of the article is to show spatial changes in the intensity and dynamics of agricultural land afforestation projects implemented within the framework of the RDP 2007 – 2013 considering natural conditions. The afforestation rate and the ownership structure of the forestland in Poland is diverse. Afforestation allows and rationally manages agricultural land, which is of little use for agricultural production. The utilization of EU funds supporting afforestation of agricultural land in Poland is characterized by spatial variability.

This brief review of the recent birch studies is focused on different aspects, such as species distribution, growing conditions, species identification, changes due to environmental factors. All mentioned investigations were carried out in Lithuania. This analytical study summarises the results and increases knowledge dissemination to the international audience. When reviewed and summarized considerable part of relevant literature sources, we realised new problems and challenges; for example, aiming to clarify the peculiarities of the growth and crown condition of the dominant birch species (Betula pendula Roth. and B. pubescens Ehrh.) under the changing climate and anthropogenic pollution.

Climate in Latvia has been changing in last decades, and it is predicted to continue changing; therefore, it is important for forestry sector to understand how these climatic changes might affect tree growth and survival. In order to assess climate suitability effect on Scots pine (Pinus sylvestris L.) provenances in Latvia, height and survival data from a Scots pine provenance trial located in three geographically distant places in Latvia were analysed together with several climatic indices. Provenances in the corresponding trial originated from Latvia, Poland, Germany, Belarus, Russia and Ukraine. Thirty year average climate data values from 1961 – 1990 for the 64 origins of provenances were acquired from the WorldClim project. Correlation analysis between provenance average values for height and survival and climate index values for the origins of the provenances confirm that there is a relation between these amounts, and the relation differs between the three site locations, indicating that suitability of climate is an important factor affecting the results of provenance trials. Cluster analysis confirmed that provenances from distant origins might have a very similar growth and survival rates; therefore, geographical location of the provenance origins cannot be considered as the only influential factor on these rates and the results from provenance trials have to be analysed together with climate data in order to make conclusions about the suitability of the provenances.

Pine, spruce and birch stem’s quality is different in regions of Latvia, but the differences are not included in the tables and models of assortment outcome. Therefore, it is not possible to predict accurately the outcome of round wood assortments. The aim of the research was to evaluate the regional differences of final felling sawlog outcome for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and birch (Betula spp.) in Latvia and to set the regions with a different sawlog outcome. Data from 1645 final felling areas was used for pine, 1202 for spruce and 1531 for birch from the years 2010 – 2012. Firstly, the sawlog outcome of 97 territorial units was set by using the data of the final felling areas sawlog outcome of pine, spruce and birch. Secondly, territorial units with a similar sawlog outcome were consolidated in regions. The smallest regional difference of sawlog outcome was found for spruce (9.4%), slightly larger for pine (10.5%) and the largest difference for birch (16.2%). Three regions with the different sawlog outcome were found for Scot pine, six for Norway spruce and seven for birch. Several spruces and birch regions have similar sawlog outcome but those do not have borders. They are between regions with higher or lower sawlog outcome. Sawlog outcome of neighbouring regions differ for at least 4 – 5%.

The aim of the study is to ascertain how different compositions of stand species affect the work of the harvester in commercial thinning under Latvia’s conditions. The data of the harvester – time-tracking files (*.drf) have been used as a basis for the study, where productivity is expressed as the prepared amount of round timber in cubic meters in a unit of time – an hour (m**3 hE-1). The data were collected from 100 commercial thinning areas which were divided into three types depending on the composition of the species: pure pine stands, pure spruce stands and deciduous tree mixed stands (mixed with coniferous trees). All the data for the study were collected in the forests managed by JSC ‘Latvia`s State Forests’. By summarizing the data, it has been established that in pure pine stands the average volume of the stem to be removed is 0.092 m**3, in mixed stands – 0.085 m**3 and in pure spruce stands - 0.068 m**3. The research demonstrates that the harvester showed its highest productivity while working in pure pine stands – 3.96 m**3 hE-1, the second best result was achieved in the mixed stands – 3.67 m**3 hE-1, but the lowest rate was demonstrated in pure spruce stands – 3.09 m**3 hE-1. Significant differences were observed in the productivity of the harvester between pure pine and pure spruce stands. Comparing the calculations of standard deviations in the harvester productivity, it can be seen that they are the biggest in mixed stands, while the lowest rate is demonstrated in pure spruce stands.

Thermal wood modification has been intensively studied in the recent decades because of the possibility to produce wood with improved biodurability and dimensional stability without use of harmful chemicals. Beside altered physical characteristics, wood colour is changed to lighter or darker brown as a result of thermal treatment. Growth of interest in thermal wood treatment has stimulated numerous researches concerned with discoloration of thermally modified wood which is subjected to light exposure. The objective of this study was to evaluate the colour stability of thermally modified hardwood during storage in the dark where wood discolouration is not photoinduced but rather a result of oxidative ageing. Three thermally modified hardwood species – aspen (Populus tremula L.), alder (Alnus incana Moench), birch (Betula pendula Roth.), where investigated. Wood discoloration was monitored by spectrophotometrical measurements of reflectance spectra and chromaticity parameter calculations using CIELAB colour system where L* is the lightness, and a* and b* are the chromatic coordinates. The colour stability of thermally modified wood as well as of untreated wood of the same species was examined by means of assessment of the colour parameter changes (ΔL*, Δa*, Δb*, ΔEab). All wood specimens under study discoloured during the experiment, but the colour change did not exceed two units that are common and accepted for wood products. Untreated and thermally modified wood showed different trends of discoloration during storage in the dark. The final colour changes that were fixed at the end of the experiment were greater for the thermally treated wood.