Tag Archives: renewable energy

1720-1729 T. Vaimann, A. Rassõlkin, A. Kallaste and M. Märss
Feasibility study of a local power supply system for sparsely populated areas in Estonia
Abstract |
Full text PDF (286 KB)

Feasibility study of a local power supply system for sparsely populated areas in Estonia

T. Vaimann¹²*, A. Rassõlkin¹, A. Kallaste¹² and M. Märss¹³

¹Tallinn University of Technology, Faculty of Power Engineering, Department of Electrical Engineering, Ehitajate tee 5, EE19086 Tallinn, Estonia
²Aalto University, School of Electrical Engineering, Department of Electrical Engineering and Automation, PO Box 13000, FI00076 Aalto, Finland
³Estonian University of Life Sciences, Institute of Technology, Department of Energy Engineering, Fr.R. Kreutzwaldi 56/1, EE51014 Tartu, Estonia
*Correspondence: toomas.vaimann@ttu.ee

Abstract:

The paper analyzes the reasonability of using an off-grid hybrid power supply system or in other words a local grid for sparsely populated areas as well as the necessary components selection and price development of such system. Typical consumers are selected and all estimations and calculations are based on them. Consumer profiles are set and analyzed as well as different elements of the local power supply grid and the possibility of connecting to the traditional grid. Estonian example is used in this paper as the country lies relatively north and has some remote areas, where local power supply grids can be implemented. All prices in the paper are derived from the Estonian example. Necessity of further study is proposed.

Key words:

, , ,




1191–1199 A. Mäkiranta, J.B. Martinkauppi and E. Hiltunen
Correlation between temperatures of air, heat carrier liquid and seabed sediment in renewable low energy network
Abstract |
Full text PDF (345 KB)

Correlation between temperatures of air, heat carrier liquid and seabed sediment in renewable low energy network

A. Mäkiranta*, J.B. Martinkauppi and E. Hiltunen

University of Vaasa, Faculty of Technology, Electrical Engineering and Energy Technology, P.O. Box 700, FI-65101 Vaasa, Finland
*Correspondence: anne.makiranta@uva.fi

Abstract:

The low energy network based on renewable seabed sediment heat has been monitored for several years in Vaasa, Finland. In this study the temperatures of air, heat carrier fluid and seabed sediment are compared to each other and correlations between them are investigated. In this study data from one year 2014, was used. Correlations between these subjects clearly exist. The sizing of installed network seems to be correct; no overuse was detected.

Key words:

, , , ,




650–660 A. Ayhan
Biogas potential from animal waste of Marmara Region-Turkey
Abstract |
Full text PDF (476 KB)

Biogas potential from animal waste of Marmara Region-Turkey

A. Ayhan

University of Uludag, Faculty of Agriculture, Department of Biosystems Engineering,
TR16059, Nilüfer, Bursa, Turkey; e-mail: aayhan@uludag.edu.tr

Abstract:

The purpose of this study was to determine the biogas production capacity from animal wastes in Marmara region of Turkey for the years 2005–2014. The wastes from the cattle and hen in the region were considered the resource for biogas production taking the number of animals and the collectability of the wastes into the account. Three scenarios were evaluated to estimate the biogas capacity by assuming that 100% (theoretical potential), 50%, and 25% of the total animal waste could be used for biogas production in the region. For theoretical biogas production from cattle wastes, the greatest potential in the year 2014 was calculated for Balıkesir province with 145.53 Mm3, followed by Çanakkale, Bursa, Sakarya, and other seven provinces. Balıkesir had the highest biogas potential in 2014 from the poultry waste, too, followed by Sakarya, Kocaeli, Bursa, and other seven provinces. Biogas potential (100%) of Marmara region increased by 15% from 2005 to 2014 with 1,242.17 Mm3 in 2014. The heat and electrical energy equivalents of the biogas were found to be 7,453.02 GWh and 2,608.56 GWhe, respectively. In the other two scenarios, depending on the utilization rate of theoretical biogas potential: biogas amount, heat and electric power values were determined proportionally.

Key words:

, , ,




327–336 A. Brunerová, J. Pecen, M. Brožek and T. Ivanova
Mechanical durability of briquettes from digestate in different storage conditions
Abstract |
Full text PDF (647 KB)

Mechanical durability of briquettes from digestate in different storage conditions

A. Brunerová¹*, J. Pecen², M. Brožek¹ and T. Ivanova²

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Material Science and Manufacturing Technology, Kamýcká 129, CZ 165 00 Prague,
Czech Republic
²Czech University of Life Sciences Prague, Faculty of Tropical AgriSciences,
Department of Sustainable Technologies, Kamýcká 129, CZ 165 00 Prague,
Czech Republic
*Correspondence: brunerova@tf.czu.cz

Abstract:

A present research was conducted to determine mechanical durability of digestate briquettes and potential influence of different storage condition. Experiments were performed on briquette samples produced from digestate feedstock with moisture content of 8.2%, ash content of 10.9% and gross calorific value of 17.15 MJ kg-1 by hydraulic piston press with working pressure of 18 MPa with external diameter 50 mm and length 40–60 mm. Briquette samples were divided into two groups and stored inside and outside building. Both groups were subjected to five experimental testing during specific time period from May until late November 2014. Mechanical durability of each briquette was measured after every testing, subsequently overall mechanical durability of specific groups was calculated. Results showed the lowest mechanical durability after first measurement: 98.85% for Group 1 and 98.95% for Group 2. The biggest change in mechanical durability was observed between first and second testing, values of following measurements were approximately equal. The highest mechanical durability was achieved after fifth testing: 99.65% for Group 1 and 99.63% for Group 2. It implied mechanical durability equal to 99.44% for Group 1 and 99.45% for Group 2 in average. Research proved very high mechanical durability which corresponds to the highest category of this quality indicator given by standard EN ISO 17225-1. Difference between mechanical durability of groups stored in different conditions was considered as minor. Thereby briquettes made from digestate are not only secondary product of proper waste management, effectively modified fertilizer but as was found by results of this research it is also suitable fuel with outstanding mechanical properties.

Key words:

, , , , ,




999-1006 M. Repele, A.Paturska, K. Valters and G. Bazbauers
Life cycle assessment of bio-methane supply system based on natural gas infrastructure
Abstract |
Full text PDF (285 KB)

Life cycle assessment of bio-methane supply system based on natural gas infrastructure

M. Repele*, A.Paturska, 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:

Many sites for biogas production in Latvia currently do not have sufficient heat load to provide power production in co-generation mode. The alternative to relatively inefficient power production could be production of bio-methane which is known as one of the most important renewable option for gas supplies. After removal of contaminants bio-methane is of quality of natural gas and can be delivered to power plants and industry using the natural gas supply infrastructure. For analysis of environmental benefit of using bio-methane the environmental impact of the proposed solution has to be assessed. The aim of the study is to make life cycle assessment of the system for bio-methane supply to industrial plant via the natural gas grid. The analysed system includes bio-methane production and transport to the natural gas pipeline including the infrastructure. Functional unit was 1 MWh of bio-methane energy injected into the natural gas transmission pipeline. Life-cycle model was created and analysed with software ‘SimaPro’. ReCiPe and Eco-Indicator’99 were used as characterization methods to analyse the life-cycle environmental impacts. Results show the influence and contribution level expressed in mid-point categories as well as in a single-score indicator. The largest impact is created by use of fossil energy sources in production of bio-methane. The results can be used to design renewable energy supply systems and for the comparison of alternatives.

Key words:

, , ,




511-518 K. Klavina, A. Cinis and A. Zandeckis
A study of pressure drop in an experimental low temperature wood chip dryer
Abstract |
Full text PDF (387 KB)

A study of pressure drop in an experimental low temperature wood chip dryer

K. Klavina*, A. Cinis and A. Zandeckis

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

Abstract:

The use of wood materials, and logging residues in the energy sector is growing rapidly, and will follow the same trend in the following years in the entire EU. This development is related to the target of 20% renewable energy share in the primary energy consumption. Thus it is very important to increase the value of fresh wood materials by application of drying technologies. Drying allows increasing the efficiency and flexibility of combustion, transportation, and storage processes. The goal of this research is to study wood chip drying process in low temperature conditions as a promising solution for the use of low exergy energy sources, such as solar energy, geothermal, and waste heat. Low temperature drying processes typically require high parasitic consumption of electrical energy that is required to provide the air change in the wood chip body, but allows reduction of heat loss. This study was developed to collect experimental information required for designing, optimization and operation of low temperature dryers. Experimental setup was used to study wood chip drying process in controlled laboratory conditions. Air pressure loss is settled as the dependent variable. Thickness of wood chip layer and airflow rate were changed between the experiments. A comprehensive analysis of the obtained monitoring data is carried out.

Key words:

, ,




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 |
Full text PDF (549 KB)

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.

Key words:

, , , ,




295-306 L. Bisenieks,, D. Vinnikov and I. Galkin
PMSG based residential wind turbines: possibilities and challenges
Abstract |
Full text PDF (466 KB)

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.

Key words:

, ,




341-348 M. Schlegel, N. Kanswohl, D. Rössel and A. Sakalauskas
Essential technical parameters for effective biogas production
Abstract |
Full text PDF (409 KB)

Essential technical parameters for effective biogas production

M. Schlegel¹, N. Kanswohl¹, D. Rössel² and A. Sakalauskas³

¹Professorship of Technology and Process Engineering of Sustainable Agriculture, Institute forFarm Animals Sciences and Technology, University of Rostock, Justus-von-Liebig Weg 8,18059 Rostock, Germany; e-mail: mathias.schlegel@uni-rostock.de
²Colegio de Postgraduados, Campus San Luis Potosí, Iturbide No. 73, Salinas de Hgo., S.L.P.,C.P. 78600. México. e-mail: edietmar@colpos.mx
³Department of Agricultural Machinery, Lithuanian University of Agriculture, Studentu 11,LT-53361 Kaunas, Lithuania; e-mail: zum.katedra@lzuu.lt

Abstract:

Rising agrarian raw material prices in 2006 had a negative impact on the biogas sector in Germany, leading to the search for potentials for optimisation of production. A problem is the workload of the block-type thermal power station (BTPS). This is caused by biogas process disturbances, construction errors, technical problems and management mistakes as well as by oversizing of the BTPS. Technical problems appear in particular with BTPS and aggregates, stirring devices and fermenter heatings, measuring and control technology as well as foil caps. The BTPS is an essential part of the economic efficiency of biogas production. A 2% increase in efficiency, to 40%, lowers the costs about 1 Cent kWh -1el . To achieve sufficientstirring power, the device type, heights and angle adjustment are vital. The substrate dosing engine must be adjusted to the particular substrates. The fermentation has to be controlled continuously. Parameters such as substrate amount, temperature, pH-factor, fermenter chamber load, gas amount and composition, ammonium concentration and short-chained fatty acids should be controlled regularly. Large temperature variations can lead to foam formation, resulting in a reduction of the gas yield. Disinfectants, antibiotics and a too tall fermenter chamber load can also have a negative influence. Low methane content often may often result from high sulphur and ammonia content in biogas composition, high aerial dosage accompanying desulphurisation as well as to coarse input material.

Key words:

, ,