http://ago.helion.pl ISSN 1733-4381, Vol. 11 (2009) Issue 2, p -01-08
LCA analysis of conventional heat sources as a tool in
environmental management in the building sector
Adamczyk J.
University of Zielona Góra ul. Powstańców Warszawy 14/41 65-807 Zielona Góra
e-mail: J.Adamczyk@wez.uz.zgora.pl
Streszczenie
Analiza LCA konwencjonalnych źródeł ciepła jako narzędzie zarządzania
środowiskowego w sektorze budownictwa
W artykule dokonano krótkiej charakterystyki konwencjonalnych źródeł energii. Dokonano opisu metodyki analizy cyklu życia. Opracowano również analizy LCA najbardziej popularnych, konwencjonalnych źródeł ciepła. Następnie przeprowadzono analizę doboru źródła ciepła w kontekście ekonomiczno-środowiskowym.
Summary
The paper presents a short characteristics of conventional energy sources. It also describes the methodology of life cycle analysis. The most popular conventional heat sources have also been elaborated. The paper also analyzes the choice of heat in terms of economical and environmental aspects.
1. Introduction
Poland has already been functioning in the structures of EU for four years which, on one hand, results in relevant economic, environmental and political benefits, but causes certain obligations, on the other. The need to ensure sustainable development in the territory of EU states, an adequate condition of natural environment as well as safety in energy supply, yet at the same time maintaining the position of competitive Europe. The documents Green Book1 and Directive 2006/32/EC2 introduce requirements concerning a more effective use of fossil fuels and choice of ecological heat sources.
1
European strategy for sustainable, competitive and safe energy
2
Directive of the European Parliament and the EU Council concerning effectiveness of the final use of energy and power-energetic services
There has been no doubt, that renewable energy sources are most environmental friendly, yet in Poland the frequency of their use is rather small. Therefore, the following part of the paper will focus on analysis of non-renewable sources of thermal energy used for heating of detached buildings (single-family houses).
It has been assessed, that the building sector is responsible for consumption of 33% of the total energy generated, the significant part of which is used during the building operation [3].
Effective use of the energy generated, as it has already been mentioned herein, is one of EU priorities, however it is also conditioned by economic effectiveness of this energy potential users. Increase in the prices of energy agents (see figure 1.1) is a significant element motivating to solicit solutions of effective energy use. Determining expenses related to heating of a single-family building should provide for such variables as [1] [5]:
• surface ( cubature) of the building; • type of fuel;
• efficiency of the heat source;
• values of heat-transfer coefficients of building partitions (transparent and non-transparent);
• external temperature of the building (of its surroundings); • required indoor temperature of the building;
• wind strength;
• heat accumulation capacity of building partitions, etc.
Fig. 1.1. Percentage increase of energy prices in the years 1997-2007
Generation of heat by means of fossil fuels is by principle related to the increase on the emission of dust and hazardous gases, the so called „low emission”. The possibility to make choices and use ecological heat sources is furnished by the Life Cycle Analysis (LCA). The present paper illustrates combining this method with the analysis of boiler operational efficiency coefficient as well as with the analysis of expenses of conventional heat sources exploitation.
1. Conventional heat sources
Types of heat sources depend first of all on: type of the material their heating surfaces are made of, type of the fuel used as well as the temperature or pressure of the agent generated. For the needs of the present paper, heat sources in central heating boilers have been divided depending on the type of the fuel used:
• solid fuel, namely: timber, peat, brown coal, hard coal and coke, • gaseous fuels, mainly natural gas and liquid gases;
• liquid fuels in the form of light, medium and heavy heating (fuel) oil.
Another source used for heating is electrical energy, but due to high costs this method is not popular for this purpose. The cost of purchasing a boiler in comparison to other energy sources, is not high [2].
Choosing a particular boiler for the needs of individual users of a detached house is influenced by, first of all, the expected heating power, which is determined on the grounds of the balance of heating needs for a particular building. This depends on the heating power demand of a particular building for: heating, ventilation or air-conditioning and heating water. Depending on the solutions in the project, the overall demand for heating power is not influenced by preparing heating water. (single-function boiler) nor by the heat used for ventilation and air-conditioning (Practical heating).
The demand for heating power for central heating purposes is fixed basing on the building project of the house, where it is calculated following certain standards and norms or where they are determined on the grounds of cubature indices. The demand for heating power for preparing heating water is defined by considering the amount of hot water used, for example, for particular hygienic activities, or according to the average daily use per inhabitant.
Individual investors, when making a choice about a boiler also take into account: type of the fuel chosen and its heating value3, investment costs (purchase of a boiler), central heating use expenses (purchase of a fuel), boiler efficiency (see table 2.1) and central heating system.
Table 2.1. Comparison of operating costs of heating with different energy agents
3
Heating value – amount of heat when burning a fuel mass or volume unit when completely burnt, assuming that water vapour included in combustion does not liquefy
Type of thermal energy Operational efficiency, % Heating (calorific) value Heating cost 4 [zł/kWh] Natural gas GZ 35 93 25946 kJ/m3 0,142
Liquid gas propane 98 23613 kJ/dm3 0,360
Liquid gas propane/butane 93 26421 kJ/dm3 0,288
Liquid fuels 90 36120 kJ/dm3 0,249
Electrical energy night rate 100 3600 kJ/kWh 0,217 Electrical energy (round the clock
rate)
100 3600 kJ/kWh 0,373
Hard coal 60 28000 kJ/kg 0,071
Coke 60 29000 kJ/kg 0,103
Source: website: http://www.gazownia.pl/dowload/porownanie_eksploatacyjnych _ kosztów. Pdf
Operational efficiency of boilers may vary even from 50% to 100% and they especially depend on working parameters (temperature, power), and these are influenced by the heat demand function. Reference books state that heating efficiency of small boilers vary within wide ranges and depend on the boiler type and its operation duration [6].
3. LCA methodology
LCA analysis defined in the standards ISO 14040 requires at start formulating the objective as well as the range of the analysis. On the next stage an inventory analysis (stock analysis) is made, which reviews unit processes in terms of input and output information concerning materials and energy related to a particular product. This stage results in product material-energetic balance. Environmental impact is the next stage of the analysis which is made by valuating by means of environmental indices – EI. References name two approaches to environmental indices (eco-indices): one assumes that index should comprise all possible environmental impacts and ecological effects (eleven categories of impact). The other states that indices should only include such effects, which express results of comparable types of environmental damages (three categories of damages). Presently the most frequent index used for environmental evaluation is Eco-Indicator 99, which takes into account the problem of decreasing natural resources often neglected by other environmental indices. The last phase of LCA analysis is interpretation of the product life cycle, which studies the results obtained, explains limitations as well as indicates the product life cycle phase with
4
The cost of heating for individual house about very good heat insulation, the surface 120 m 2, 20.09.2008 r.
the highest environmental impact as the area claimed for the possible remedy and improvement [4].
LCA analysis uses numerous computer programmes, the most popular of which are, among others, Umberto and SimaPro. The software SimaPro 7.1 version uses in its evaluation the above-mentioned Eco-Indicator 99. The evaluation which follows this procedure, gives a possibility of presenting the results of the impact with reference to the eleven impact categories and the three damage categories including characterization, normalization as well as weighing. The final evaluation (weighing) makes it possible to present the result of environmental intervention of a product expressed in Pt units (eco-index point)5.
4. LCA analysis of conventional sources of heat
System limit for the heat sources under analysis comprises generation of a defined thermal energy unit (fuel use and material and energy emissions) excluding the impact on the environment in which boilers were produced as well as the phase of their future recycling. The functional unit is 1 kWh of thermal energy.
Table 4.1. Result of LCA – three categories of damages Damage category Unit Electrical heating Gas heating Coal heating Coke heating LPG propane heating Fuel oil heating Human health Pt 0,020754 0,002013 0,007502 0,005525 0,00214 0,002579 Ecosystem quality Pt 0,002562 0,000413 0,002166 0,000946 0,001393 0,000594 Resources Pt 0,022252 0,01421 0,013908 0,010436 0,009899 0,011407 Total Pt 0,045568 0,016635 0,023577 0,016906 0,013432 0,01458
Source: Author’ own research based on the computer programme SimaPro.
When analyzing the results of LCA (see table 4.1 and figure 4.1), we come to the conclusion, that the highest environmental impact in terms of six heat sources is presented by the material damage category. It seems to be obvious due to the use of fossil fuels (indirectly or directly) for production of thermal energy. The highest environmental impact when considering the six heat sources in this damage category is shown by electrical energy (22,252 mPt). It may be related to the necessity of processing a greater amount of hard coal, causing a bigger environmental impact at the same time, when generating electrical energy, due to energy losses when transferring this energy from electrical power plant. It should be stressed, that this heat source can be characterized by its greatest operational efficiency.
5
Pt - eco-index point (Pt) – value 1 represents one thousandth of the annual environmental load of a single inhabitant in Europe
Figure 4.1. LCA result – three damage categories, graphic form
Source: Author’ own research based on the computer programme SimaPro.
Natural gas as a heat source can be characterized by the lowest impact it has on the damage category – human health (2,013 mPt). The damage category – quality of ecosystem, is characterized by the minimum level of environmental impact from all the heat sources. Table 4.2. LCA result – eleven categories of impact
Damage category Unit Electrical heating Gas heating Coal heating Coke heating LPG propane heating Fuel oil heating
Carcinogens Pt 0,003309 1,83E-05 0,001407 0,001057 2,33E-05 5,07E-05 Respiratory
organics
Pt 1,94E-06 4,41E-06 1,72E-05 1,84E-06 1,27E-05 1,85E-05 Respiratory organics Pt 0,013791 0,000746 0,003754 0,002712 0,001093 0,001179 Respiratory inorganics Pt 0,003646 0,001233 0,002316 0,001747 0,001011 0,001305
Radiation Pt 5,77E-06 1,03E-05 6,69E-06 6,39E-06 0 1,68E-05 Ozone layer Pt 9,01E-08 5,47E-07 1,54E-06 1,82E-07 4,75E-09 8,97E-06 Ecotoxicity Pt 0,000587 4,93E-05 0,0014 0,000376 0,001138 0,000155 Acidification/
Eutrophication
Pt 0,001468 0,000196 0,000467 0,000369 0,000255 0,000222 Land use Pt 0,000507 0,000167 0,000299 0,0002 0 0,000218 Minerals Pt 3,69E-05 5,29E-05 1,11E-05 5,99E-06 0 0,00016 Fossil fuels Pt 0,022215 0,014157 0,013897 0,01043 0,009899 0,011247 Total Pt 0,045568 0,016635 0,023577 0,016906 0,013432 0,01458
LCA analysis in terms of the eleven categories of impact6, like in case of its reference to the three damage categories, leads to the conclusion that fossil fuels have the greatest impact of all the heat sources. The impact category – climate change is also characterized by a high value as compared with all the types of heating. Heat sources based (see table 4.2)on hard coal, coke and electrical energy contribute with the impact falling within the category of cancirogenic compounds (1,407 mPt; 1,057 mPt; 3,309 mPt respectively), the impact of the other sources can be regarded as minimum and can be omitted.
5. Conclusions
Fluctuation of the prices of energy agents in the Polish market does not facilitate making choices of heat sources that could be economically justified. The truth is that it is impossible to expect what the prices of heat agents can be, even in the near future, they depend on economic, political, ecological factors and also on depletion of natural resources. The highest efficiency of all the types of heating under analysis is shown by electrical energy heat source, however due to economic (0,373 zł/kWh) and ecological (45,57 mPt) reasons its use is unjustified.
Heat source based on hard coal is an economically most justified solution (0,071 zł/kWh), and also the fluctuation in the prices of this agent throughout the last decade has maintained at the medium level. However, its environmental impact is second as far as its size is concerned (23,58 mPt).
Liquid gas heating – LPG propane – can be characterized by the lowest environmental impact (13,43 mPt), yet the prices of this type of energy are one of the highest in the Polish market (0,360 zł/kWh). To a great extent, it is due to a road transport of this fuel to a consumer.
The most optimal, regarding economy and environmental impact (author’s opinion) is the choice of heat source based on natural gas. Its environmental impact is found out to be average (16,63 mPt). Changes of the prices of energy agent in the last decade has also maintained at the average level, whereas the cost of heating is below the average (0,142, zł/kWh) of all the heat sources under analysis. There are also other factors that speak for this heat source, such as, first of all, the furnace is automatic and does not require any service, thus it is very convenient to operate, and also there is no need of storing fuel. When inside a building there is no facility that could serve as a boiler room the furnace can be installed in any other place (this refers to gas boilers with a closed burning chamber). However, application of this heat source can be limited in the situation when there is no local access to a gas system.
LCA analysis is a universal instrument and necessary in every sector of the national economy. The above-mentioned example of this instrument application in the building
6
Due to a high amount of data the LCA diagram of the eleven impact categories is not precisely readable and has not been included in the paper
sector illustrates how incomplete the analysis of heat sources would be if it only were made in terms of economical aspects.
References
[1] Chorzelski M.: Analiza cen ciepła uzyskiwanego z różnych nośników energii, Ciepłownictwo, Ogrzewnictwo, Wentylacja, 10/2006
[2] Głowacz K., Ze stanu stałego w ciepły, Budujemy Dom 7-8/2008
[3] Kasperkiewicz K., Zużycie energii w sektorze budowlanym – teraźniejszość i
przyszłość, Izolacje, 3 (114)/2007
[4] Kowalski Z., Kulczycka J., Góralczyk M., Ekologiczna ocena cyklu życia procesów
wytwórczych (LCA), PWN, Warszawa 2007
[5] Mikoś J., Budownictwo ekologiczne, Wyd. Politechniki Śląskiej, Gliwice 2000
[6] Nantka M., Ogrzewnictwo i ciepłownictwo, tom 1, Wyd. Politechniki Śląskiej, Gliwice 2006
