After a 16-m high dam was constructed and a 297-ha pond was arranged in the River Šušvė nearby Angiriai in 1980, the previous natural flow regime of the river has changed: 15500000 m3 of water accumulated above the dam is not discharged via a natural bed, but through two 1.5x1.5 m bottom orifices, and flood discharges (up to Q1% = 296 m3 sE-1) are directed into the lower reach through a 16-m high shaft spillway of floods. Such arrangement of the Angiriai dam ensured it to become an essential obstacle for migrating fish. In 2000, after the arrangement and operation of Angiriai hydro-electric power station, the water regime downstream the dam has been changed and new hydrological pulses as well as ecosystem biodiversity are to be adapted. Thus, the operation of Angiriai HPS on the River Šušvė generating hydroelectric power can have adverse effect on the river habitats and hydro ecological connectivity. To evaluate the effect, the eco-hydraulic water regime measurements in 2005 in a lower stretch with and without turbines operating were made. The study results showed that artificial water levels fluctuation (≈ 4 m hrE-1) induced by Angiriai hydro-electric power station as well as the discharge flowing through the bottom orifices due to high velocities (13–14 m sE-1) and temperature differences could create stressful situations for young fish in the lower bank. According to the data of soil texture of the Šušvė River, the bed armoring process is going on below the Angiriai HPS is quasistable and no impact of HPS operation is found.

Primary energy resource consumption in the world is surveyed in the work and oil yield, production and consumption evaluated on the world level, also showing its density in the view of several states. Oil reserves are evaluated and the states with biggest oil reserves stated. The research proves consumption of primary energy oil in the world is increasing continuously. There are primary energy resources to be acquired in Latvia evaluated and primary energy resources in means of final consumption divided between types of energy estimated.

One can reasonably argue that issues related to the increased use of renewable energy resources in the energy production processes in Latvia, are at the forefront and will remain there in the future. This relates to the aspect that Latvia is not rich in non-renewable energy resources (around 70% of total primary energy consumption in Latvia is ensured by import, which can lead to undesired effects in many areas), but at the same time, there are available renewable energy resources in Latvia, with an untapped potential to be recognized. In particular this applies to fuel wood, which is already (year 2012) the most important domestic fuel in Latvia. In this context it is important to emphasize that, according to the particular study results, if unexpected socio-economic developments do not take place, raw wood material resources required for different types of fuel wood production in Latvia should be available in the same amount as it is now if not more. As for increasing the amount of fuel wood use in Latvia, an enormous ‘potential’ can be seen in general use boiler houses, where there are currently no technological limitations to utilize this ‘potential’. General use cogeneration plants can be recognized as an even greater ‘potential’ for greater use of fuel wood in Latvia, but given the circumstances of energy supply in Latvia, the ‘potential’ is currently available on a very limited basis. At the same time it is important to note that both of these ‘potentials’ could be significantly reduced in the next few years.

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.

Aim of the paper is to identify low productivity lands distribution in Vidzeme region, identify enterprises that could use wood chips from willow plantations established on these lands as the main resource in electricity and heat production and calculate produced wood ash amount from these enterprises that could be used as fertilizer and could be recycled in SRC plantations. For better soil fertility evaluation and economic turn predictions all agricultural lands are evaluated in quality units, where one quality unit in money is equal to 5.38 EUR or 70 kg of rye. According to studies, traditional farming in lands, which are below 38 quality units, could be unproductive. In Vidzeme region are 501,880 ha of agriculture lands from which 206,574 ha (52%) are lands with quality assessment under 38 units. According to local farmers’ opinion, the real quality unit, below which economically profitable farming is impossible, are 25 quality units. There are 87,900 ha of agricultural lands under 25 quality units, which represent 18% from all agricultural lands in region. These lands could be used by growing SRC plantations in 2013; the region has 48 enterprises that used wood chips, with total amount of 170,500 oven-dried tonnes per year. Wood chips from SRC plantation could be used in these enterprises. To fulfil the wood chip demand in the region, about 17,000 – 34,000 ha of agricultural land should be planted with SRC plantations. To increase the yields from these lands, fertilization is recommended. In this region are more than 300 enterprises, which use wood as the main resource for electricity or heat production leading to 14,000 oven-dried tons of wood ash production every year.

The paper aims at analyzing agricultural production for energy generation purposes, including the production of agricultural biogas, as an opportunity for functional diversification of agriculture and for multifunctional rural development in Poland. There have been many changes observed in Polish agriculture. New directions of crop production and of the use of agricultural products have emerged. One of the changes is the increasing significance of the production of agricultural biogas and energy from biogas. There have been built both small-scale and large-scale biogas plants. Most of the agricultural biogas plants are located in northern, western and south-western Poland, i.e. in the areas where there are relatively large farms which can provide a supply of substrates necessary for the production of agricultural biogas. The formation of biogas plants and the use of agricultural production for generating energy are an eagerly anticipated trend contributing to the dissemination of renewable energy sources, the functional diversification of agriculture, the development of additional economic activities in rural areas, and the increase in the energy security of particular regions and the entire country.