Sustenable energy sources utilisation.

Kralikova, Ruzena ; Wessely, Emil

Abstract: Sufficient, renewable, safe and environmentally acceptable assurance of fuels and energy may be classified as one of most global tasks of mankind to which the countries worldwide pay extraordinary attention. Necessity of energy and exploitation of the energetic sources is increased permanently and it subjects to the population increase with which the economic and environmental problems are also advanced.

Key words: Environment, energetic plants, energy sources

1. Introduction

Sufficient, renewable, safe and environmentally acceptable assurance of fuels and energy may be classified as one of most global tasks of mankind to which the countries worldwide pay extraordinary attention. Necessity of energy and exploitation of the energetic sources is increased permanently and it subjects to the population increase with which the economic and environmental problems are also advanced.

2. Energy consumption--problem of sustainability

The energy consumption is increased permanently. Energy used at the present is originated from prevailingly fossil fuels. Although the fossil fuels are created continuously, their present consumption exceeds their creation multiply and so they are considered to be non-renewable. Limitation of these energy sources and damage of environment as a consequence of fossil fuel combustion require solving these issues. The most important negative demonstration of the fossil fuel combustion may be seen on the global climatic changes, which are the result of the glasshouse gas emissions.

The production reduction of the glasshouse gas originated when combusting the fossil fuels may be reached by conversion to cleaner fuels and reduction by their consumption. These alternative is represented by renewable energy sources which are capable to assure the permanent society development because they are cleaner and more favourable for the environment that the fossil fuels. Production and consumption of the "green energy" may be the instrument to support the energy production from renewable energy sources even in the spite of increased costs to be incurred by the consumers to green energy products according to the principle "the contaminator shall pay".

3. Renewable energy sources

European policy strengthens its influence on the energy and environmental sectors towards bio-energy development and climate change mitigation. Various schemes have been implemented at EU, national and regional levels to make bio energy competitive. This problem lines to identify trends for bio-energy utilisation.

From the total balance consumption of the primary energetic sources such as crude oil, natural gas, coal, lignite, etc. with respect to the limited resources, the necessity of utilisation of the secondary energetic sources which originate as a consequence of usage of fuels and energy used in the energetic and production processes and of energetically usable technological wastes is resulted.

At the present, special attention shall be paid to renewable energetic sources such as water, wind, solar, geothermal energy as well as energy recovered from the bio-mass, figure 1. Their importance consists in relative inexhaustibility of them and the energy to be recovered from the biomass may be classified as the most perspective of them.

[FIGURE 1 OMITTED]

Energy may be recovered from the biomass using the wooden material wastes, agricultural wastes, and excrements of agricultural animals, plant, household and other biologic wastes. Renewable energy sources are forward energetic sources of domestic origin, mainly the energy from water, biomass and geothermal energy with the minimum environmental impacts. Technically usable potential of the renewable energetic sources is illustrated in the Table 1.

As resulting from the above-mentioned data, no renewable energy source is sufficiently utilised at the present. The primary energetic sources in 1997, the renewable sources covered 3,33% of the total energy consumption. Usable potential of renewable energy sources is generally conditioned by sufficiency of investment capital and achievement of the environmental requisitions.

The long-term target in the area of renewable energy source utilisation in the Slovak Republic is the achievement of the level to be comparable with the utilisation level in the most countries of the European Union. To achieve this target it is necessary to make true the prices of fuels and energy, to create the suitable legislation, economic and financial background and support the business activities systematically. Higher utilisation of renewable energy sources should be manifested in energetic industry impact reduction to the environment, employment rate increase when constructing and operating the renewable energy sources and approximately the same number of work position may be achieved in developing, projecting, consulting, trading, producing and sub-delivering the renewable energy sources.

4. Energy productions from the biomass

The term "biomass" means any plant derived organic matter available on a renewable basis, including dedicated energy crops and trees, agricultural food and feed crops, agricultural crop wastes and residues, wood wastes and residues, aquatic plants, animal wastes, municipal wastes, and other waste materials. Handling technologies, collection logistics and infrastructure are important aspects of the biomass resource supply chain.

The biomass is one of the most universal and most prevalent energy sources world-wide. Its advantage is that it offers not only a wide variety of the input raw materials but also its universal usage in the energetic industry. It is possible to use it not only to produce the electric energy and heat in modern incinerators. Liquid and gaseous forms of the biomass (Ethanol, Methanol, wooden gas, bio-gas) may be used to drive the motorcars. From the point of view of its perspective, the biomass is considered to be the key renewable energy source on the level of both small and big technological units. With respect to various biomass forms, the energy included in it is different. Energetic content of dry plants (moisture content: 15-20%) is approximately 14 MJ.kg-1. Chemical composition of the biomass, however, makes the biomass to be more ecological fuel than the coal significantly. It is connected with the lower Sulphur content of the biomass than that of the coal. The ash content after combusting also is lower than that of the coal and, moreover, the biomass ash may be used as dung because it does not consist of any toxic substances and other contaminants but it consists of nutritive only. From the point of view of energy production from the biomass, the following processes are enforced at the present in the practice:

* Direct incineration.

* Thermo chemical processing (such as pyrolyse or degassing).

* Biologic processes such as anaerobic decay or fermentation, which cause the production of gaseous and liquid bio-fuels.

The immediate product of these processes is heat used in the production site or in surroundings of it. Heat is used either directly to prepare the hot water or to produce the steam with the consecutive drive of the power generator and power production. Other products are e.g. charcoal or liquid bio-fuels to drive the motorcars. Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. It is derived from numerous sources, including the by-products from the timber industry, agricultural crops, raw material from the forest, major parts of household waste and wood. A major component of all biomass to power, fuels, and products research is characterizing the biomass feedstock, products, and intermediates.

Analytical chemists are developing unique methods, assays, measurement tools, and correlations to better understand the chemical composition of raw biomass feedstocks and the array of solid, liquid, and slurry samples produced during research and commercialization.

Biomass does not add carbon dioxide to the atmosphere as it absorbs the same amount of carbon in growing as it releases when consumed as a fuel. Its advantage is that it can be used to generate electricity with the same equipment or power plants that are now burning fossil fuels. Biomass is an important source of energy and the most important fuel worldwide after coal, oil and natural gas.

4.1 Combusting the wood, straw and rapid-growing wood plants

Using the wood for the energetic purposes may be considered to be local sources, which rate the minimum requirements; to transport only and so it is relative cheap when comparing it with classical fossil fuels. At the present the boilers for wood fuels were improved significantly and so the combustion efficiency is very high. The basic types of the wood fuels are wood briquettes, wood splits and wood pellets belong, Figure 2.

[FIGURE 2 OMITTED]

Wastes from the agricultural production are a very important energetic source when considering their energy contents. Straw or dung belongs to this group particularly. These sources are used very intensively in several countries. At the present, automated machines provided with straw charging having the minimum pollution emissions caused by the combustion process are prevailingly used. Some plant kinds characterized by rapid growth or by quality of oil to be produced may be raised for the purposes of their future energetic utilisation. So-called energetic plants are similarly used as wood or straw to produce heat, power etc. From the point of view if the energy production the total energetic balance of these plants is very good, i.e. ration of output and input energy is approximately 5:1.

A variety of fuels can be made from biomass resources, including the liquid fuels ethanol, methanol, bio diesel, and gaseous fuels such as hydrogen and methane. Bio fuels research and development is composed of three main areas: producing the fuels, finding applications and uses of the fuels, and creating a distribution infrastructure.

4.2 Liquid bio-fuels

Unlike the solid and gaseous bio-fuels the liquid bio-fuels are used to drive the motorcars. There ate the following liquid bio-fuels:

* Alcohol fuels (Ethanol and Methanol) are the most used liquid bio-fuels worldwide and they are produced mainly from grain, maize and sugar cane.

* Bio-oil may be produced from more than 300 plant kinds such as colza, sunflo-wers, olives, soya etc.

The bio-oil importance consists in the fact that almost each oil motor may be, in principle, converted to be driven by the bio-oil. In the countries of the European Union, the portion of the bio-oil driven cars to the classically driven cars is 15-40%. The bio-oil, under which the pure vegetable oil or MERO shall be understood, has almost the similar quality in one litre as the classical oil with this values being higher than the energetic density of other alternative fuels which fact is documented by the following table 2.

Main advantages of the bio-oil may be summarized as follows:

* Positive energetic balance.

* Low pollution emissions and CO2, emission reduction.

* Agricultural and ecological usage of the soil extracted from the production of food commodities.

* Safe when loading.

* Rapid degradation in soil without any contamination etc.

4.3 Gaseous bio-fuels

The biogas is acquired mainly from the deposits of municipal and agricultural wastes at the present. The reaction of the biogas origin may be expressed as follows:

BIOMASS + BACTERIA [right arrow]

BIOGAS (C[H.sub.4], C[O.sub.2] ...)+NUTRITIVES (N, P, K, S ...)

The biogas composition depends on the input raw materials and biogas production conditions. The biogas may be valued when producing electric energy and heat.

[FIGURE 3 OMITTED]

Traditional use of biomass is more than its use in modern application. In the developed world biomass is again becoming important for applications such as combined heat and power generation. In addition, biomass energy is gaining significance as a source of clean heat for domestic heating and community heating applications. In fact in countries like Finland, Austria and Sweden the per capita biomass energy used is different higher than it is in Slovakia.

5. Solar thermal energy

Solar power is one of the first things that come to most people's minds when the subject of alternative energy comes up. Solar radiation can be chance into other kinds of energy--heating, mechanical, chemical, electricity, light, see figure 3. Solar power first gained wide public awareness during the 1970's energy crisis, and while it may not be such a hot topic these days, solar technology has made great advances since then.

5.1 Solar Photovoltaic Power

As the technologies for the photovoltaic energy are compatible with those of semiconductors, the human and material resources to achieve international competitiveness in this area are domestically attainable. Standalone photovoltaic system has been utilized in the form of an unattended lighthouse and emergency highway lighting and as demonstration photovoltaic electrification.

There are many applications for the direct use of solar thermal energy, space heating and cooling, water heating, crop drying and solar cooking. It is a technology, which is well understood and widely used in many countries throughout the world. Most solar thermal technologies have been in existence in one form or another for centuries and have a well-established manufacturing base in most sun-rich developed countries. The most common use for solar thermal technology is for domestic water heating. Hundreds of thousands of domestic hot water systems are in use throughout the world, especially in areas such as the Mediterranean and Australia where there is high solar isolation (the total energy per unit area received from the sun). As world oil prices vary, it is a technology that is rapidly gaining acceptance as an energy saving measure in both domestic and commercial water heating applications. Presently, domestic water heaters are usually only found amongst wealthier sections of the community in developing countries. Other technologies exist which take advantage of the free energy provided by the sun. Water heating technologies are usually referred to as active solar technologies, whereas other technologies, such as space heating or cooling, which passively absorb the energy of the sun and have no moving components, are referred to as passive solar technologies. More sophisticated solar technologies exist for providing power for electricity generation. We will look at these briefly later in this fact sheet.

[FIGURE 4 OMITTED]

5.2 The nature and availability of solar radiation

Solar radiation arrives on the surface of the earth at a maximum power density of approximately 1 [kWm.sup.-2] (kilowatt per metre squared). The actual usable radiation component varies depending on geographical location, cloud cover, hours of sunlight each day, etc. In reality, the solar flux density (same as power density) varies between 250 and 2500 [kWm.sup.-2] per year. As might be expected the total solar radiation is highest at the equator, especially in sunny, desert areas. Solar radiation arrives at the earth's outer atmosphere in the form of a direct beam. This light is then partially scattered by cloud, smog, dust or other atmospheric phenomenon. We therefore receive solar radiation either as direct radiation or scattered or diffuse radiation, the ratio depending on the atmospheric conditions. Both direct and diffuse components of radiation are useful; the only distinction between the two being that diffuse radiation cannot be concentrated for use. There are many other uses for solar thermal technology. These include refrigeration, air conditioning, solar stills and desalination of salt water and more. There are also solar panels which convert sunlight directly into electricity, using some sophisticated scientific technology, see figure 5.

[FIGURE 5a OMITTED]

[FIGURE 5b OMITTED]

Many of the active solar technologies rely on sophisticated, exotic modern materials for their manufacture. This presents problems in developing countries where such materials have to be imported. Some countries do have a manufacturing base for solar thermal products but it is often small by no means widespread throughout the world. The market for solar products, such as solar water heaters, is small and growing only slowly. Solar passive technology, especially solar cooling, tends to be used traditionally in developing countries.

Many technological advances have been made in design of 'solar buildings' in developed countries during the last two decades but again the level of technology is often high and expensive and out of reach for rural communities in developing countries (figure 5b).

6. Wind and water power

Wind turbines are one of the oldest forms of renewable energy use in the world. From medieval windmills that actually milled grain, to traditional farm windmills that pumped water for livestock and irrigation, to the modern alternator--driven electric wind generator, wind turbines have helped mankind for centuries. Wind turbines are recommended for any year-round energy system. Often the best days for wind energy are the gloomy days when solar panels aren't at their peak. Take advantage of bad weather with a wind power system.

Not everyone is lucky enough to have a source of running water near the homes. But for those with riverside homes or live-on boats, small water generators (micro-hydro turbines) are the most reliable source of renewable energy available. One relatively small water turbine will produce power non-stop, as long as running water is available, no matter what the weather.

7. Combine Power Systems

The renewable energy hybrid power systems consist of wind turbines and Photovoltaic modules. Upwards of 70% can be supplied with the renewable energy equipment and the balance with diesel generators. The wind blows the propeller round, which turns a generator to produce electricity. The more towers, the more wind, and the larger the propellers, the more electricity we can make. The best places for wind farms are in coastal areas, at the tops of rounded hills, open plains and gaps in mountains--places where the wind is strong and reliable. Recent advances in technological reliability and generation capacity have made wind turbines more attractive than other energy generation facilities.

8. Conclusions

From the total balancing consumption of the primary energetic sources, the necessity to use alternative renewable energetic sources is resulted. Their importance consists in relative inexhaustibility of them and as the most perspective source of them, the energy recovered from the bio-mass using the wooden material wastes, agricultural wastes, excrements of agricultural animals, plant, household and other biologic wastes may be considered. Renewable energy sources are forward energetic sources of domestic origin with the minimum environmental impacts and they are one of the suitable alternatives to solve the energetic and environmental problems of the present time. The use of renewable energy sources has many unique qualities that provide environmental benefits. It can help mitigate climate change, reduce acid rain, soil erosion, water pollution and pressure on landfills, provide wildlife habitat, and help maintain forest health through better management.

This paper continues to the grant project VEGA "Simulation of factors for working environment and their optimalization in specific conditions of mechanical engineering plants (100%), solved at Department of Environmental Studies and Control Process of Technical University of Kosice.

9. References

[1.] KRALIKOVA, R.- BADIDA, M. (2003): GIS and GPS--new technologies in the field of Waste Management, Wokshop "Research and development in waste management" 8th Internatonal conference on flexibile technologies MMA 2003, Novi Sad, p.127-128

[2.] KRALIKOVA, R.--LUMNITZER, E. (2003): Perspektivy v oblasti vyuzitia vyroby Sistejsich energii, Stroj rstvo, 3/2004, roSnik 8, str. 56-56, Media/ST Bratislava, ISSN 1335-2938

[3.] KRALIKOVA, R.--LUMNITZER, E.(2003): Trends in the area of alternative energy sources utilization, 6th International Conference MTeM 2003--Modern Technologies in Manufacturing, Cluj-Napoca Romania, 2003

[4.] http://www.solarelectricpower.org/

This Publication has to be referred as: Kralikova, R. & Wessely, E. (2006). Sustenable Energy Sources Utilisation, Chapter 30 in DAAAM International Scientific Book 2006, B. Katalinic (Ed.), Published by DAAAM International, ISBN 3-901509-47-X, ISSN 1726-9687, Vienna, Austria

DOI: 10.2507/daaam.scibook.2006.30

Authors' data: doc. Ing. PhD. Kralikova R.[uzena], doc. Ing. PhD. Wessely E.[mil], Technical University--Kosice, Faculty of Mechanical Engineering, Department of Environmental Studies, Park Komenskeho 5, 041 87 Kosice, Slovak Republic, Ruzena.Kralikova@tuke.sk

Table 1. Potential of renewable energy sources

 Total energy From it:
 production electric energy

Source (GWh/y) (TJ/y) (%) (GWh/y)

Bio-mass 2727 9817 39,7 5

Water energy 3800 13680 55,3 3800

Small water Power 202 727 3 202
Plants
up to 10 MW

Geothermal energy 338 1217 4,9 0

Solar energy 7 25 0,1 0

Wind energy 0 0 0 0

Total 6872 24740 100 3805

Table. 2. Energetic value of the alternative fuels

FUEL Energy [MJ/I]

Crude oil 35,1
Vegetable oil 34,3
MERO (bio-oil) 33,1
Ethanol 21,1
Methanol 18,0
Hydrogen 8,5