Wind energy development policy and prospects in Lithuania

According to the EU Directive 2001/77/EC 7% of all electricity production is to be generated from renewable energy sources (RES) in Lithuania in 2010. Electricity production from RES is determined by hydro, biomass and wind energy resources in Lithuania. Further development of hydro power plants is limited by environmental restrictions, therefore priority is given to wind energy development. The aim of this paper is to show estimation of the maximum wind power penetration in the Lithuanian electricity system using such criteria as wind potential, possibilities of the existing electricity network, possible environmental impact, and social and economical aspects. Generalization of data from the meteorological stations and special measurements shows that the highest average wind speed in Lithuanian territory is in the coastal region and at 50 m above ground level reaches 6.4 m/s. In regard to wind resource distribution in this region, arrangement of electricity grid and environment protection requirements, six zones have been determined for wind power plant construction. Calculations have shown that the largest total installed capacity of wind farms, which could cause no significant increase in power transmission expenses, is 170 MW. The threshold, which cannot be passed without capital reconstruction of electricity network, is 500 MW of total capacity of wind farms.     

The method of hardening soil rippers by surfacing and technical-economic assessment

The wear resistance and feasibility of applying soil rippers have been studied after surfacing for use in the clayey soil. The study illustrates laboratory and production research of standard and novel (with large grain tungsten carbide) material for manual electric arc surfacing. Hardness and wear resistance in the clayey soil have been determined. Rippers (and the components of soil cultivating machinery yield the least wear by using wear-resistant materials and the comprehensive surfacing of tailing and lateral surfaces. It is shown that hard-alloy tips of rippers are better suited for clayey soil, which is the toughest to cultivate. The best wear resistance in clayey soil is found in hard-alloyed layers of Fe-C-Cr-Si-Mo-Nb-W and Fe-C-Mn-B alloys. The wear rate depends on the depth of cultivation and varies exponentially.     

Trends and sustainability criteria of the production and use of liquid biofuels

Environmental impacts associated with the use of fossil fuels, rising prices, potential limitations in supply and concerns about regional and national security are driving the development and use of biomass for bioenergy, biofuels and bioproducts. However, the use of biomass does not automatically imply that its production, conversion and use are sustainable. Conflicts between various ecosystem services (economic production of food, fodder and fuels, biodiversity, social and cultural values, etc.) that are provided by fertile land are increasing as well. Hence, a developed thinking on how to balance between these services is desirable.There is a significant amount of information available on biofuels and their sustainability. In this paper, different initiatives and sustainability criteria for biofuels are presented and assessed.35 criteria were found in emerging sustainability assessment frameworks. The majority of 12 criteria were focused on environmental issues, 4 were social and only 1 was economic. Energy balance and greenhouse gas balance were perceived as especially critical, social criteria ranked generally low. Although being perceived as important, food security ranked very low.     

Long-term prediction of creep strains of mineral wool slabs under constant compressive stress

The results obtained in determining the creep strain of mineral wool slabs under compressive stress, used for insulating flat roofs and facades, cast-in-place floors, curtain and external basement walls, as well as for sound insulation of floors, are presented. The creep strain tests were conducted under a compressive stress of σ _c =0.35σ _10%. Interval forecasting of creep strain was made by extrapolating the creep behaviour and approximated in accordance with EN 1606 by a power equation and reduced to a linear form using logarithms. This was performed for a lead time of 10 years. The extension of the range of the confidence interval due to discount of the prediction data, i.e. a decrease in their informativity was allowed for by an additional coefficient. Analysis of the experimental data obtained from the tests having 65 and 122 days duration showed that the prediction of creep strains for 10 years can be made based on data obtained in experiments with durations shorter than the 122 days as specified by EN 13162. Interval prediction of creep strains (with a confidence probability of 90%) was based on using the mean square deviation of the actual direct observations of creep strains in logarithmic form to have the linear trend in a retrospective area.     

Relationship between the time of day of trauma infliction and the dynamics of endothelial mitotic activity

Endothelial mitotic activity of the rabbit jugular veins depending on the daytime of trauma infliction was studied. In the first series of experiments (I), the operations were performed from 8 to 10 a. m., and in the second (II)-- from 8 to 10 P. M. After the operation one animal was killed every 3 hour, for 5 days. Mitotic activity (MK %) was studied continuously 8 mm from the wound edge in flat film preparations. The data obtained were statistically treated using approximation of the process course by the method of weighed sliding averages. Independently of the time of trauma infliction, the first mitoses in the endothelium appear after 21 h. Further, mitotic proliferation has a wavy character of different intensity in different tissue areas. Lack of similarity in the organism circadiam phase at the time of operation, produces distinct differences in the course of the process which are seen in asynchronity of the daytimes when the rise and recession of mitotic activity occur and in different length of these waves. In I series the length of these waves equals to 36, and in II series-- to 48 h. After the evening operation, 24-hour rhythm superimposed on its aliquat 48-hour activity is slearly seen. After the morning operation, daily rhythm is not observed. After the evening operation the process is more intense and has a greater length along the endothelial layer.     

Governmental policy and prospect in electricity production from renewables in Lithuania

In Lithuania, the generation of electricity is based on the nuclear energy and on the fossil fuels. After the decommissioning of Ignalina nuclear power plant in 2009, the Lithuanian Power Plant and other thermal plants will become the major sources of electricity. Consequently, the Lithuanian power sector must focus on the implementation of renewable energy projects, penetration of new technologies and on consideration of the future opportunities for renewables, and Government policy for promoting this kind of energy. Production of electricity from renewable energy is based on hydro, biomass and wind energy resources in Lithuania. Due to the typical climatic condition in Lithuania the solar photovoltaics and geothermal energy are not used for power sector. Moreover, the further development of hydropower plants is limited by environmental restrictions, therefore priority is given to wind energy development and installation of new biomass power plants. According to the requirements set out in the Directive 2001/77/EC of the European Parliament and of the Council of 27 September 2001 on the promotion of electricity produced from renewable energy sources in the internal electricity market [Official Journal L283, 33–40, 27 October 2001], 7% of gross consumption of electricity will be generated from renewable energy by 2010 in Lithuania. The aim of this paper is to show the estimation of the maximum renewable power penetration in the Lithuanian electricity sector and possible environmental impact.     

Promotional policy and perspectives of usage renewable energy in Lithuania

The article outlines renewable energy (RE) sources according to the energy efficiency policy in Lithuania as well as practical experience of implementation of RE projects within the framework of the government policy to promote RES use due to the requirement of the European Union. The main goal of the country is to reduce the import of fossil fuel, to improve environment conditions and to reduce the climate change impact. Analysis of implemented RE projects and forecasts for the future projects are also presented. Most of the efforts in Lithuania were aimed at drafting the biomass (wood chips, wood waste, straw, biogas) and small hydro projects and their subsequent implementation. At present the total capacity of wood-chip-fuelled boilers reached above 251 MW. No serious obstacles can be seen for the extension of wood fuel use. At present, new demonstrational projects have been started covering geothermal energy, solar energy, biogas, biofuels for transport and other. In this time, the RE sources comprise 7.69% of national energy balance. Taking into account feasible resources of RE (it is more than 19.85 TWh/year) and the ongoing implementation of projects it is clear that the share of RE sources will constitute 12–13% of national energy balance in 2010 year. The main factor limiting further growth is high investment costs. The electricity production from local and RE sources in Lithuania is mainly based on hydro energy. At this time the wind energy is not used for this purpose. The electricity production from local and renewable energy sources is about 3.22% of the total consumption.     

An analysis of the biological rhythms of pain sensitivity in mice during thermal stimulation

Circadian oscillations of the 8-hr rhythmic components in nociceptive sensitivity were found in mice. A 12-hr rhythm was close to a sinusoidal one. Circadian waves of the pain threshold were asymmetric and the highest in the middle of the light phase, about 16 hrs. The group rhythms of nociceptive sensitivity appeared to be a result of synchronised separate rhythms.     

Current status and prospects of biomass resources for energy production in Lithuania

Basic biomass sources in Lithuania are comprised of wood, straw, biofuel and biogas. The current status and the problems from using biomass for energy production in Lithuania are analyzed. The possibility of utilizing wood waste, firewood, straw and biogas for energy is evaluated. Forest comprises about 2.05 Mha or 31.3% of Lithuanian land area. About 4.3 million m³ solid volume of wood per year can be used for fuel (843 ktoe). Wood as fuel is used directly or in processed form (briquettes, pellets and chips).Agriculture produces approximately 1.5–2.0 million tons of straw each year for animal feed, litter and olericulture. Around 30–40% (130 ktoe) could be used as fuel for energy production. Boiler houses for combusting the straw have increased and now comprise about 7 MW. Straw is also used for heating private houses.Sources for biogas production include sludge from water cleaning equipment, animal manure and organic waste in food processing companies. Total volume of operating bioreactors comprises about 24 000 m³, and annual production of biogas is 6.3 million m³ per year (3.4 ktoe). By year 2010 the total volume of bioreactors will increase to 35 000 m³ and about 50 000 m³ by 2040.In Lithuania biodiesel and bioethanol are mainly used in blending with conventional fuel. Following the requirements of the European Union (EU), 2% of total consumed fuel per year is to be produced in 2005. By 2010 biofuel should comprise not less than 5.75% of all fuel existing in the market.     

Efficiency analysis of combined biomass and solar energy in Lithuania

In this paper were performed analyses of the renewable energy impact on reduction of the greenhouse gas (GHG) emissions. The pilot integrated biomass and solar water heating system at public institutions of Lithuania were analyzed. Purpose of this analysis was to evaluate systems′ efficiency of performance. It has been executed for measurements of produced energy, consumed water, and burned biofuel in summer and winter time. Analysis showed that heat load for domestic hot water is too low for biomass boiler for summer season. That problem could be improved with optimizing solar heating system. Modernization of this system could significantly reduce energy costs and emissions of carbon dioxide and demonstrate an integrated solution with bio and solar energies utilization in this system. Investigation shows that Lithuania can reduce GHG emission to 8 % in the period 2008–2012 by increasing use of biomass, solar, and others renewables and achieve the requirement of the Kyoto protocol.