1. Introduction
During the last few decades, the consumption of energy has increased, specifically owing to the development of new technology, based predominantly on a limited and unsafe energy structure, composed of such fossil fuels such as hard coal, petroleum and gas [
1]. More than 38% of electric energy globally is generated from hard coal [
2]. For emerging markets such as India or China, hard coal is an attractive source of energy because of its high resources and low cost of mining [
3].
Figure 1 shows total hard coal output in Poland and in the European Union (EU) in the years 1990–2019. The diagram shows that the value has been going down almost incessantly since 1990. In the year 2019, the hard coal production volume for the European Union was 65 10
6 t, which is 77% lower than the value of 277 10
6 t in the year 1990. In 1990, hard coal was produced by 13 member states of the present European Union, compared with only two states (Poland and the Czech Republic) in 2019 [
4,
5]. Poland produced 61.6 10
6 t of hard coal, which was 95% of total hard coal production volume in the European Union, whereas the Czech Republic did 3.4 10
6 t (5%) [
6]. In comparison with 123 10
6 t in the year 2012, when the last peak in the hard coal production volume was observed in the European Union, Poland cut its production volume by 22%, and the Czech Republic did by 70%. All the other former hard coal-producing states had ceased their production by that time.
In the year 2019, 47% of hard coal was used for power generation. Since 2013, hard coal supplies for power generation have clearly been decreasing. This is due to the fact that hard coal tends to be replaced with natural gas and renewable sources of energy [
4].
As regards the consumption of hard coal in 2019, the value for the European Union was 176 10
6 t, of which more than 60% falls to Poland (39%) and Germany (23%), followed by France and the Netherlands (6% each). The decreasing trend in hard coal consumption in the EU is confirmed by the fact that only 37% of hard coal consumption was satisfied from production in the year 2019, compared with 71% in 1990 [
4].
In 2019, the European Commission declared that greenhouse gas emissions in Europe would have been cut down by 50–55% by the year 2030 (in comparison with 1990) and that complete carbon neutrality would have been achieved by the year 2050 [
8]. According to the Polish hard coal industry program, the domestic demand for hard coal by the year 2030 will be running according to one of the three possible scenarios, none of them forecasting a rapid decline in hard coal production (
Figure 2) [
9].
The low scenario is based on the assumption that the total consumption of hard coal in the domestic economy will have been cut down by 15% by the year 2030 in comparison with 2019. This scenario is based on the lowest costs: although it leaves to the market forces the problem of solving any issues arising in connection with investments in the public power sector, it also is a source of problems for the hard coal mining industry, which will have lost much of its market share for its product by the year 2030. On the other hand, according to the reference scenario, the present level of demand for hard coal is not going to change, even though some changes will be taking place in the consumption structure, namely, growth in the public power sector and a decrease in households. The structure of fuel consumption can also be affected if locally available resources, such as gas and municipal waste, are used or if the share of renewable energy sources for generating heat increases.
The high scenario is based on the assumption that the market for power coal in Poland will develop. According to this variant, the total demand for hard coal will be more than 15% higher than in the year 2019. It also permits a higher demand for hard coal in the public power sector and in new hard coal markets. The implementation of this scenario will involve high expenditure to finalize any ongoing or planned investment projects concerning new hard coal-based power plants in the public sector. In other market segments, departing from hard coal at a slower rate may arouse opposition from local communities. Facing an inevitable decrease in power hard coal consumption in market segments other than the public power sector, domestic demand for hard coal will be affected by developments in the public power sector and by the process of its consolidation [
9].
Using a novel approach, based on the time series prediction method, Li et al. predicted the consumption of hard coal in Poland by the year 2030. Based on that method, they found that hard coal consumption would be decreasing gradually until the year 2027 and will then stabilize, reaching a 20% lower level in 2030 than in 2019 [
10].
The use of fossil fuels (hard coal, gas, petroleum) for the production of energy generates significant emissions of CO
2, NO
x, SO
2 and particulate matter, contributing to the death of thousands of people [
11]. Coal, sulfur, oxygen, hydrogen, small amounts of nitrogen and traces of heavy metals are the main components of hard coal. Its combustion generates toxic gases, such as carbon dioxide (CO
2) and carbon monoxide (CO), sulfur dioxide (SO
2) and sulfur trioxide (SO
3), as well as nitrogen dioxide (NO
2) and nitrogen monoxide (NO), which cause health effects and environmental problems [
12]. These gas emissions may cause various diseases which attack the skin, cardiovascular system, brain, blood and lungs, and may lead to various kinds of cancer [
13].
The combustion of hard coal generates the highest amount of CO
2 among all the fossil fuels. Hard coal generates 58% more CO
2 than does petroleum and twice as much as natural gas on combustion [
14]. The use of hard coal as an energy carrier causes phenomena such as smog, acid rain and the emission of particulate matter. High environmental pollution caused by boilers and thermal plants based on the combustion of hard coal is regarded internationally as the main subject of ongoing international research studies, focused on how to reduce emissions generated by the combustion of hard coal as fuel [
13].
Since hard coal and fine coal are widely used as energy sources in Poland, catalysts are required to enable the reduction of the noxiousness of these fuels on combustion.
A number of catalysts have been described in the literature, which are used with hard coal or fine coal for reducing atmospheric emissions. Their reducing effect on emissions was reported in [
15,
16] for CO and NO
x and in [
17,
18] for SO
2. On the other hand, Yu et al. and Doggali et al. described the inhibitory effect of the catalysts on the combustion of hard coal [
19,
20].
In their earlier paper [
21], the present authors studied the effect of polymetallic catalysts comprising a mixture of metal compounds at concentrations of 100, 200, 250 and 350 ppm on atmospheric emissions in the combustion of type IIA fine coal, which is intended for use in heating boilers. Based on these studies, it was found that the optimum additive is composed of Cu, Na, Mg, NH
4+, Ca urea, and is used at the level of 350 ppm [
22].
There is not much information in the literature on the economic effects of the use of catalysts for solid fuels. Therefore, the present authors chose to perform economic analysis for the system, which improves the fine-coal combustion efficiency of power boilers based on a preselected catalyst. The market of the potential users of the system is also characterized.
2. Materials and Methods
Information on savings in energy during the hard coal combustion process in which the system for improving energy efficiency had been implemented was analyzed based on data collected in the project [
23]. The system comprises an additive that improves combustion and a control and supervision system that enables an optimum operation of the boiler.
The existing metering infrastructure and provisional instruments, installed by a company that offers the system for the tests [
22], are used for the settlement of the economic and ecological effects resulting from the use of the catalysts. Computer-based remote control handling the catalyst dosage system, boiler operating parameters and long-term archiving of measurement data is also available [
24]. The company that offers implementation of the system guarantees boiler servicing as well. The company that offers the implementation of the system to improve the solid-fuel combustion energy efficiency is competitive also as regards the innovative method of settling accounts with customers, based on the ESCO concept (Energy Saving Company): a remuneration for using the system is covered from savings in the cost of energy [
25,
26]. The total savings comprise the following components: improved energy efficiency, lower costs of overhaul and lower environmental costs.
The system comprises an additive that improves combustion and a control and supervision system that enables an optimum operation of the boiler. The necessary data required for assessing hard coal consumption for energy production in the Polish market in the year 2019 were obtained using Desk Research [
27]. The method is based on the analysis of records in available data sources, comprising specifically their compilation, mutual verification and processing. Desk Research helps arrive at conclusions about the problem of interest [
27]. There are a number of papers in the literature in which research methodology is based on that type of analysis [
28,
29].
The analysis was based on the following data sources:
hard coal output and consumption in Poland, based on statistical data;
the National Bank of Poland’s website (
www.nbp.pl, accessed on 20 February 2021)—PLN/USD conversion based on the exchange rate of 24 February 2021 (USD 1 = PLN 3.69);
websites that provide solutions to problems with fuel combustion.
The diagram in
Figure 3 shows the respective steps of data acquisition for a Desk Research analysis.
The next step was to carry out an analysis of the final users’ preferences and expectations using CATI (computer-assisted telephone interview). The method provided some reliable and valuable information on the chances of implementing a system to improve energy efficiency in the Polish market. CATI is used for gathering information in quantitative market research and public opinion polls by means of computer-assisted telephone interviews [
30]. This method also helps find many research papers in which methodology was based on CATI [
31,
32].
To have a preliminary view of the scale of interest the energy-efficiency system may arouse, the study was carried out among its potential users. To begin with, the highest prospects were identified based on interviews with experts. As the result of such consultations, it was found that the prospects are: “combined heat-and-power plants (CHPs) and power plants,” “auto-producing thermal plants” and “agriculture.” Moreover, such a group includes some of the companies in the category “construction and other industries,” namely, cement plants.
Next, the authors attempted to contact 221 entities representing the above groups. The respondents were those responsible for the combustion process in such entities (chief power engineers, boiler room managers, thermal plant foremen, boiler operation coordinators, maintenance managers and employees of the environmental protection department). The purpose of such conversations was to initiate contact with those responsible for making decisions on issues connected with the combustion system and to present essential information on the offered solution. An attempt was made to obtain the person’s declaration concerning their willingness to cooperate or to be provided with more detail. Definitely more often than not, those responsible for the above matters provided a positive response to the information they had been offered, were willing to have a look at the materials provided to them, and, in some cases, a preliminary declaration to cooperate was obtained from them.
In the case of CATI, there exist non-random errors resulting from failures to perform part of the sample. Such errors are found also in other research methods, and they may result from a refusal to take part in the survey, indecision, or from other circumstances. CATI is a very attractive technique from the researcher’s point of view because it takes much less time to collect data compared with direct interview techniques. On the other hand, it has the drawback that the sample performance percentage is usually much lower than in direct interviews. It is estimated that, on average, only 1/3 of the pre-selected phone numbers called the result in a conversation [
33].
The statistical sampling error is an unavoidable component of any survey. It exists simply because, in an induction survey, conclusions regarding a whole population are drawn based on a sample. Such inference is, per se, exposed to error, but the magnitude of such statistical error can be determined from the assumed confidence level [
34]. In the survey performed by the present authors for 221 companies, the statistical error for the assumed confidence level of 0.95 was 6.4%.
In the case of CATI surveys, the survey group is usually 1000–2000 respondents [
31,
32]. If the respondents are a specialized group, the number is definitely lower than that, depending on the size of the target group in the territory covered by the survey.
The number of interviews is much lower in a survey involving a specialized respondent group compared with that obtained in a social survey. Mays et al. used an online survey questionnaire concerning the advantages and barriers found in QSAR methods for REACH [
35]. Having sent 280 questionnaires with 8 questions addressed to potential respondents, the authors obtained only 33 completed questionnaires. The group was then extended, and a questionnaire with only 3 questions was used to obtain 29 completed questionnaires. Unfortunately, the survey took 8 months. The authors concluded that the total sample was too small to represent a whole population and that the trends shown by the results enabled its correct interpretation.
The study has resulted in 41 complete CATI interviews with information that is useful for the subject matter of the study.
The interviews indicate that the highest prospects among the potential customers are (in decreasing order):
thermal plants, CHPs and district heating companies/enterprises;
housing co-operatives and cement plants;
horticultural production (market gardens producing fruit and vegetables, other agricultural farms using large-scale greenhouses).
It was also found that the manufacturers of bituminous mixes are not to be regarded as prospective customers simply because they typically operate gas-fueled production plants.
The other entities, contacted by the authors, have failed to respond, either because they were not interested or because they are not to be regarded as prospective customers because (starting from the most frequently stated reasons in decreasing order):
they were too busy or unwilling to talk on the phone, even after being contacted again at the appointed time, suggested by them (in most cases, the person seemed to believe they were being contacted about an acquisition, which had an adverse effect);
the person contacted believes their system does not need any improvement (harmful emissions within the standard range, advanced high-efficiency systems);
the entity operates a gas-fueled system;
there are ongoing refurbishment works, an overhaul of the combustion system, maintenance or other works aimed to improve the system.
The nature of the reasons stated above indicates that some of the respondents could definitely be encouraged after the system has been implemented in several sites. This would provide references and information on the specific sites where the system is working (case-study descriptions), and it would create foundations on which to build the system’s market position, resulting in stronger interest among potential customers. Just as important is a suitable marketing campaign aimed at providing potential customers with information on the specific profits they may have after installing the solid-fuel combustion energy-efficiency system.
The main objective of the CATI study was to obtain information on the following:
- -
the most frequent problems in boiler operation;
- -
the respondents’ awareness of the profits the implementation of catalysts for their combustion system will bring;
- -
the degree of the respondents’ willingness to implement a system that improves energy efficiency and solves other issues related to operation in their company;
- -
determinants of their decision concerning the implementation of catalysts for their combustion system.
For the purpose of the introduction of the new system improving fuel-combustion efficiency, the authors carried out an economic analysis by assessing savings in the fuel and the extra amount of energy.
The economic assessment was carried out for the company that is responsible for marketing the system on the one side and for the company that has chosen to implement the system in its operation. Both the revenue side and the cost side were taken into account. Calculations were made using the equations shown in
Supplementary Materials.
4. Conclusions
The combustion of coal-based fuels is the source of environmental pollution. These emissions can be reduced with the help of catalysts being introduced straight into the fuel. This paper presents the cost-efficiency analysis of a system that improves solid-fuel combustion in power boilers.
In a market study, it was found that the target user group (thermal plants, CHPs, cement plants, horticultural production) uses mainly hard coal or fine coal as solid fuels. Their combustion efficiency can be improved by using a dedicated device comprising a control and supervision system for better accuracy in controlling the boiler operating parameters and in improving combustion efficiency due to the use of catalysts, addressing specifically the issue of fine-coal combustion.
Economic benefits from the use of the system are achieved both by the vendor and by the user. The study was carried out for system capacities ranging from 3 to 100 MW. It was found that, depending on the size of the system ranging from 3 MW to 100 MW, fuel savings were from 2% to 8% due to the refurbishment improving the boiler plant operation and from 2% to 6% due to the use of the combustion catalysts. Apart from boosting energy efficiency, the use of the catalyst and the efficiency-boosting system resulted in the costs of overhaul being cut by about 20%.
It was assumed that the economic effect of the system implementation was shared between the vendor and the user in the ratio of 30%/70%. The vendor’s profit was calculated by subtracting the costs involved in the system implementation from the vendor’s revenue obtained from the user. The system user’s costs are the cost of purchase and implementation of the system plus the cost of purchase and implementation of the catalyst applicators plus the costs of employing system operators. The payback time for the user depends on system capacities: it varies between 6.75 and 1.74 years for capacities ranging from 3 to 75 MW and is 2.0 years for a 100 MW plant.