ISSN 00406015, Thermal Engineering, 2014, Vol. 61, No. 4, pp. 260–264. © Pleiades Publishing, Inc., 2014. Original Russian Text © T.A. Zheliezna, O.I. Drozdova, 2014, published in Teploenergetika.

ENERGY CONSERVATION, NEW AND RENEWABLE SOURCES OF ENERGY

Complex Analysis of Energy Production Technologies from Solid Biomass in the Ukraine T. A. Zheliezna and O. I. Drozdova Institute of Engineering Thermophysics, National Academy of Sciences of Ukraine, ul. Zhelyabova 2a, Kyiv, 03057 Ukraine email: [email protected] Abstract—The results of the energetic, economic, and environmental analyses of technologies of energy pro duction from solid biomass are considered. Examples of the introduction of the technology of the direct com bustion of biomass (straw and wood) in a boiler installation, a domestic boiler, and a combined heat and power plant (CHPP) are considered. The results indicate the energetic and environmental reasonability of implementa tion of such projects. From the economic viewpoint, the introduction of the boilers that use the biomass is profit able with the substitution of natural gas for the statefinanced and industrial consumers, and the CHPP operation with the use of biomass is profitable with selling the electrical energy by the “feedin” tariff. Keywords: biomass, solid biomass, biofuel, straw, wood, bioenergy, renewable energy sources, energy installa tion, boiler DOI: 10.1134/S0040601514030124

The introduction of technologies of energy genera tion from the biomass makes it possible to increase the level of energy supply, especially at a local level, by force of using such renewable fuels as wastes of agri culture and forestry, woodworking, and other types of biomass. Ukraine possesses a large potential of biomass avail able to produce energy. It varies from 25 to 35 million t eq.fuel/yr, largely depending on the productivity of the main crops. Its main components are straw and other wastes of agriculture, energy crops, and wood [1, 2]. The use of biomass makes it possible to cover about 15% of the total consumption of the primary energy in Ukraine. For practical implementation, it is reason able to select the technologies effective from the ener getic, environmental, and economic viewpoints. Technologies and projects, which have the positive evaluation over all three components of the complex analysis, should be recommended for introduction. PROCEDURE OF THE COMPLEX ANALYSIS OF TECHNOLOGIES OF ENERGY PRODUCTION FROM BIOMASS It is proposed to perform the energy evaluation based on the index of cumulative energy demand (CED) and its inverse quantity called energy yield coefficient (EYC). This procedure is selected among other similar ones since it contains the recommenda tions relative to the admissible range of applied criteria [3]. This approach can be used to analyze both the energy installations that use fossil fuels and the boilers that use renewable energy sources. The CED index is determined as the sum of the primary energy con

sumption necessary to fabricate the installation under consideration, supply of its operation for the service life, and utilization after finishing the service life. The dimensionless index of cumulative energy demand (ced) is determined by force of division of the CED by the total energy production by the installation, i.e., the ced shows what the factor is, by which the total CED for provision of functioning this installation (input energy), is larger than the energy produced by its oper ation (output energy). Similar indices with subscript NR (cedNR and EYCNR) take into account the traditional energy con sumption only (fossil fuels) to provide the operation of the energy installation. Thus, they do not take into account the energy of biomass itself as a fuel, i.e., the EYCNR shows what the factor is, by which the energy at the output, is larger than the cumulative traditional energy consumed to implement this technology. These indices for energy installations recom mended in [4] are as follows: ced = 1.32–1.56, EYC = 0.64–0.76, cedNR < 0.2, and EYCNR > 5.0. The admis sible ranges when taking into account only the con ventional energy are cedNR < 0.5 and EYCNR > 2.0. In foreign practice, the analysis of the environmen tal effect is performed when evaluating the servicelife cycle of the installation operating according to definite technology. This evaluation involves a broad set of parameters, which correspond to the influence of functioning of the installation in the earth’s interior, atmosphere, soil, water, and population [3]. We propose to perform the environmental evalua tion of the practical implementation of bioenergy technologies by the balance of greenhouse gases. It is necessary to establish the boundaries of the analysis,

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i.e., to determine the set of operations and to calculate the volumes greenhouse gases emissions over all oper ations. Usually, these operations involve the produc tion, collection, preliminary preparation, transporta tion, and storage of the biomass. In addition, the con sumption of the traditional energy resources for proper needs of the bioenergy installation is taken into account. The technology of energy production from the bio mass can be considered environmentally reasonable if its introduction leads to a decrease in greenhouse gases emissions compared with the application of traditional fuel. The Directive of the European Parliament 2009/28/EC [5] on the assistance to using renewable energy sources requires that a decrease of greenhouse gases emissions with the application of biofuels would be no smaller than 35%. Starting on January 1, 2017, this index will increase to 50%; and starting on Janu ary 1, 2018—to 60% for the installations, which will begin to operate in 2017. Since Ukraine is a member of the Energy Community, the fulfillment of the notions of Directive 2009/28/EC is obligatory to it starting in 2014. The key indices of the economic reasonability of the project are the internal profitability norm and the payback period. In bioenergetics, the project is usually considered as economically attractive if the payback period is shorter than 5 years [6]. We further consider the results of the complex eval uation of technologies of energy production from the solid biomass. The combustion of straw bales and wood chips at a boiler house for 350 kW and at a CHPP for 2 MW(el.) + 10 MW(h.) as well as the com bustion of straw and wood pellets in a domestic boiler with power of 100 kW are analyzed. ENERGETIC ANALYSIS OF TECHNOLOGIES OF ENERGY PRODUCTION FROM THE BIOMASS The input energy for the boiler house that uses the straw is calculated by the following components: the energy inputs for the manufacture, transportation, loading–unloading, stacking, and storage of straw bales; the electrical energy consumed by the boiler installation; and the energy inputs for the boiler ser vice by the personnel and holding the installation in the operable state. According to the selected proce dure, we also took into account the energy inputs for the manufacture of the boiler and its utilization after finishing the servicelife period. The components of energy inputs, GJ/yr, in the “life” cycle of the straw fired boiler for 350 kW found as a result of calculations are as follows: The fuel (straw) consumption by a boiler The production of straw bales Loading–unloading, stacking, and storage of straw THERMAL ENGINEERING

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The operation of the boiler installation (the consump 65.1 tion of electric energy, repairs, the maintenance) The manufacture of equipment, and building and 23.6 mounting works Dismounting and utilization of the equipment of the 2.9 boiler installation The transportation of straw bales for distance, km: 0 0 50 75.2 100 150.5 150 225.7 200 301.7

The analysis of the found results shows that the largest energy component at the input is the chemical energy of the fuel (straw). All other components are smaller by one–three orders of magnitude including energy inputs for the transportation of the baled straw in the limits of 200 km (Table 1). All energy indices found in this calculation correspond to the recom mended range cedNR < 0.2 and EYCNR > 5. Thus, we can conclude a high energy efficiency of the project on the introduction of the straw fired boiler of 350 kW. A similar approach was applied to other considered variants of energy generation from the biomass. The results of calculation of the EYC are presented in Table 2. Evaluations performed for a domestic boiler, which uses the straw pellets, show that its energy indices are lower than for the boiler, which uses the straw bales, but correspond quite well to the admissible range EYCNR > 2. A decrease in indices is explained by a comparatively larger laboriousness for the pelletizing of the biomass. When producing the thermal and elec trical energy at the CHPP, the energy indices are also lower than for the boiler house, which is associated with rather large energy inputs for proper needs of the CHPP. When combusting the wood biomass, the boiler house for 350 kW and CHPP for 2 MW(el.)+10 MW(h.) have identically high energy indices. For a domestic boiler, which uses the granules, the indices are noticeably lower, but they are in a range of admissible values when trans porting the biomass for distances up to 200 km. ECONOMIC ANALYSIS OF TECHNOLOGIES OF ENERGY GENERATION FROM THE BIOMASS Three variants are considered for the boiler instal lation, which uses the straw bales. They differ by the type of the enterprise at which the straw fired boiler is mounted. First, this determines the set of the main and auxiliary equipment necessary to implement the process. Second, the price for the natural gas, which is replaced by the biomass, is also different at these enter prises. Statefinanced institutions and industrial consum ers purchase the gas at a high price (437 EUR/1000 m3),

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Table 1. Energy indices of the boiler with a capacity of 350 kW and the transportation* of straw bales for distances up to 200 km Transportation distance, km Index CED (input energy: the sum of all components of energy intakes)

0

50

100

150

200

4911.00

4986.00

5062.00

5137.00

5212.00

ced** (input energy/output energy)

1.37

1.39

1.41

1.44

1.46

EYC** (1/ced: output energy/input energy)

0.73

0.72

0.71

0.70

0.69

372.00

447.00

522.00

597.00

673.00

cedNR** (nonrenewable input energy/output energy)

0.10

0.12

0.15

0.17

0.19

EYCNR** (1/cedNR: output energy/nonrenewable input energy)

9.63

8.01

6.86

5.99

5.32

CEDNR (nonrenewable input energy: the sum of energy components without fuel consumption)

* Loadcarrying ability of the mean of transportation is accepted as 12 t. The energy capacity of the transport operation [7] is 2.32 MJ/(t km). ** Dimensionless index.

Table 2. Comparison of the energy efficiency of technologies by the energy output coefficient EYCNR Transportation distance, km Bioenergy installation (capacity)

Boiler (350 kW) Boiler (100 kW) CHPP (2 MW(el.)+10 MW(h.))

Biofuel Straw bales Wood chips Straw pellets Wood pellets Straw bales Wood chips

while the enterprises of community heat power engi neering purchase it at a much lower price (125 EUR/1000 m3). Since the profitability of the project is determined by the funds saved when pur chasing the gas, the price for the latter decisively affects the main economic indices. First Variant The boiler is introduced at the enterprise, which is financed from the state/local budget (for example, at a school, at a hospital, or at an industrial enterprise). Such organizations will purchase the fuel (baled straw) from the producer or the distributer and should pro vide the operations on straw stacking and storing at the boiler house territory; consequently, the necessity appears to build a storage facility and purchase a straw loader. Second Variant The boiler is established at the agriculture enter prise, which produces the baled straw, acquires it by the prime cost, and has the loader. It is necessary to build the straw storage only.

0

50

100

150

200

9.63 8.41 3.87 5.69 6.09 8.44

8.01 6.69 3.62 5.24 5.41 7.08

6.86 5.98 3.39 4.87 4.88 6.10

5.99 5.22 3.19 4.54 4.44 5.35

5.32 4.64 3.02 4.25 4.07 4.77

Third Variant The boiler is established at the enterprise of the housing and communal services (HCSs), which pro vides the service on heating and hot water supply to the population. This variant is similar to the first one with the difference in the cost of the natural gas replaced by the biomass. In addition, the transportation of fuel (straw bales) to the boiler installation for distances in limits of 200 km, which affects its cost, should be taken into account for the first and third variants. It is reasonable to transport only the compacted straw (pellets, briquettes, bales) for large distances. The chopped straw has a low apparent density (approximately 40 kg/m3); therefore, its trans portation is more expensive. According to the results of calculations, the first and second variants of the project on the introduction of the straw fired boiler for 350 kW have good eco nomic indices. The payback period does not exceed 3 years, which is attractive to the potential investor (Table 3). A distance in limits of 200 km, for which the straw bales should be transported, does not substan tially affect the project profitability in this case. The third variant corresponds to the introduction of the boiler, on which the straw is combusted, at the com THERMAL ENGINEERING

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Table 3. Comparison of the economic efficiency of bioenergetic technologies by the payback period, years Transportation distance of the biomass, km Bioenergetic installation (power)

Biofuel 0

50

100

150

200

Boiler (350 kW)

Straw bales Wood chips

2.3 2.4

2.4 2.5

2.6 2.7

2.8 2.8

3.0 3.0

Boiler (100 kW)

Straw pellets Wood pellets

3.0 3.9

3.2 4.2

3.4 4.5

3.6 4.8

3.9 5.2

CHPP (2 MW(el.)+10 MW(h.))

Straw bales Wood chips

3.0 3.0

3.2 3.2

3.5 3.3

3.8 3.5

4.1 3.7

munity power engineering enterprises. In this case, the project is unprofitable since the price for natural gas for the HCSs enterprises subsided by the state is con siderably lower than the economically substantiated level. The attainment of the payback period of 5– 6 years is possible with an increase the price for gas in this sector by a factor of 2.0–2.5. Biomass pellets are a rather expensive fuel (the market price is about 86 EUR/t); therefore, the project on the introduction of the boiler for 100 kW with the use of straw pellets is economically reasonable only with the condition of the substitution of highcost natural gas. In this case, the payback period is about 5 years. The introduction of the boiler in the house hold sector is unprofitable (the payback period is longer than 10 years) because of a low price for the natural gas for the population. When calculating the economic indices of the strawusing CHPP, the income was determined allow ing for the volume of electric energy purchased by the “feedin” tariff (12.39 eurocents/(kW h)) and the vol ume of heat energy purchased by the weightaverage tariff for the HCSs (5.73 EUR/GJ). The results show that the payback period is 3–5 years in the range of dis tances under consideration for which the straw bales are transported (up to 200 km). A similar approach is applied when evaluating the economic indices of the projects on the introduction of energy installations that use wood biomass (Table 3). The results are similar in principle with the variant of using the straw as a fuel, namely, the introduction of installations that use wood biomass is economically reasonable when substituting highcost natural gas. ECOLOGICAL ANALYSIS OF ENERGY GENERATION TECHNOLOGIES FROM THE BIOMASS The essence of the ecological analysis is in the cal culation of the balance of carbon dioxide when apply ing straw/wood as a fuel and the determination of the reduction volume of СО2 emissions compared with burning natural gas. The biomass is the СО2neutral fuel since the same amount of carbon dioxide is released during its combustion, which was absorbed by THERMAL ENGINEERING

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the corresponding plant during its growth. Thus, when using the biomass for the energy generation, no addi tional contribution is introduced into the global greenhouse effect. When combusting the straw in a boiler with a capacity of 350 kW (the consumption volume is 324 t/yr), a decrease in carbon dioxide emissions compared with burning natural gas is 235 t/yr (the СО2 emission index for natural gas is 56.1 t/TJ). However, this value is not final since the СО2 emissions associ ated with straw packing and transportation as well as other processes, which ensure the operation of the boiler installation, should be taken into account. The components of emission in the “life” cycle of the straw fired boiler with the capacity of 350 kW found by cal culations are as follows, t/yr: Straw baling (CO2 emission index for the diesel fuel is 74.1 t/TJ) Straw loading–unloading and stacking Operation of the boiler installation [CO2 emission in dex for the electrical energy is 1.225 kg/(kW h)] The transportation of straw bales for a distance, km: 0 50 100 150 200

2.5 0.3 10.5

0 5.2 10.4 15.5 20.7

Emission of carbon dioxide when producing the straw is not taken into account in calculations since straw is considered as the byproduct (or waste) of the traditional agricultural production. Allowing for all Table 4. Final decrease in CO2 emissions for the straw com bustion in a boiler with a capacity of 350 kW Final decrease in CO2 emissions Calculated in t/yr Calculated in %

Transportation distance, km 0

50

100

150

200

226 96

221 94

216 92

210 90

205 87

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Table 5. Reduction of CO2 emissions, %, for the biofuel combustion depending on its transportation distance Bioenergetic installation (power) Boiler (350 kW) Boiler (100 kW) CHPP (2 MW(el.)+10 MW(h.))

Biofuel Straw bales Wood chips Straw pellets Wood pellets Straw bales Wood chips

the components, the final decrease in emissions of carbon dioxide will be 205–226 t/yr depending on the distance for the boiler house into which the straw is transported (Table 4). The analysis of these results shows that a decrease in the CO2 emission is considerable (87–96%) when transporting the straw for distances up to 200 km. Thus, this project is reasonable for this parameter and can be recommended for introduction. The indices of lowering the CO2 exhausts for the pel letusing boiler and the strawusing CHPP are somewhat lower (63–73%); however, they are quite acceptable according to the requirements of the Directive of the European Parliament 2009/28/EC. The results of the ecological analysis of operation for energy installations using wood biomass are similar in principle with the vari ant of using straw as a fuel (Table 5). CONCLUSIONS (1) The results of a complex analysis of technolo gies of energy production from straw and wood biom ass for conditions in Ukraine indicate the energetic and environmental reasonability of implementation of these projects. (2) The introduction of the biomassusing boilers is profitable with replacing the highcost natural gas for the budget and industrial consumers (the gas price is 437 EUR/1000 m3), while the operation of the biomass using CHPP is profitable with the purchase of electrical energy by the feedin tariff (12.9 eurocent/(kW h)). (3) The implementation of each project leads to the creation of new job sites, which is also a positive factor.

Transportation distance, km 0

50

100

150

200

96 86 74 90 83 84

94 84 72 88 80 81

92 82 70 86 78 79

90 79 68 85 76 76

87 77 66 83 73 74

REFERENCES 1. G. G. Geletukha, T. A. Zheliezna, N. M. Zhovmir, et al. “Evaluation of the Energy Potential of Biomass in Ukraine. Part 1. Agricultural Wastes and Wood Biom ass,” Prom. Teplotekhn., No. 6, 58 (2010). 2. G. G. Geletukha, T. A. Zheliezna, N. M. Zhovmir, et al. “Evaluation of the Energy Potential of Biomass in Ukraine. Part 2. Energy Crops, Liquid Biofuels, Bio gas,” Prom. Teplotekhn., No. 1, 71 (2011). 3. G. G. Geletukha, T. A. Zheliezna, and O. I. Drozdova, “Complex Analysis of Energy Production from Biom ass,” Prom. Teplotekh., No. 1, 87 (2012). 4. T. Nussbaumer and M. Oser, Evaluation of Biomass Combustion Based Energy Systems by Cumulative Energy Demand and Energy Yield Coefficient: Final Report Pre pared for International Energy Agency (IEA), Bioenergy Task 32: Biomass Combustion and CoFiring and Swiss Federal Office of Energy (SFOE) (Verenum, Switzer land, 2004). 5. Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009 on the Promotion of the Use of Energy from Renewable Sources and Amending and Subsequently Repealing Directives 2001/77/EC and 2003/30/EC, Off. J. Eur. Union, 5 (6), L 140/16 (2009). 6. M. Kh. Gazeev, A. P. Smirnov, and A. N. Khrychev, Efficiency Indices of Investments in Market Conditions, (AllRussia Res. Inst. Organ. Develop. Econ. Oil Gas Industry, Moscow, 1993) [in Russian]. 7. V. Yu. Il’chenko, O. D. Derkach, and V. O. Kolbasin, “Investigation into the Energy Capacity of the Trans port Operation,” Vestn. Dnepropetrovsk. Gos. Agrarn. Univ., No. 2, 63 (2008). Translated by N. Korovin

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