1. Introduction

The current energy policy requires a constant technology development towards more sustainable energy transformation systems. Cogeneration and the use of renewables are two important solutions available to achieve this goal [1]. To analyse such systems from the point of view of resource efficiency, the pure energy analysis is not sufficient since the quality of particular energy carriers is not evaluated. Biogas projects demand high investments. Biogas plants are still experiencing harsh economic conditions [2]. Financing is therefore one of the key elements in order to ensure project viability. The financing scheme of a biogas plant project differs from country to country, but in general, low interest long-term loans are used. Ordinary mortgage loans are not frequently used. The index-regulated annuity loans are low-interest loans, which secure the investor against inflation through a re-evaluation of the unpaid debts according to the inflation rate. The pay-back period is more than 20 years. This type of loans proved to be the most suitable for financing the construction of biogas plants, meeting the demands for long maturity, low interest and low initial installments. The disadvantages of such loans are that they are raised by ordinary sales of bonds at the stock exchange market price, implying a depreciation risk that may induce some uncertainty in the planning phase [3, 4]. In countries like Denmark, biogas projects are e.g. financed by means of index-regulated annuity loans, guaranteed by the municipalities. Most of the past biogas projects received also supplementary government subsidies, representing up to 30 % of the investment costs of the project.

A single farmer, a consortium of farmers or a municipality are usually the entrepreneurs likely to implement successful biogas projects. The success of the project depends on some factors that can be controlled and influenced by strategic decisions concerning investment and operational costs. Very few research studies exist on the positive effects of biogas production on the socio-economics of rural areas [5]. Considerable changes occur regarding the employment level. Additionally, in the majority of areas there is a significant potential for further development of biogas production, which would likewise be reflected in the effects of added value and employment opportunities. Farmers have heterogeneous investment thresholds. Their investment decisions are mainly driven by capital costs and the subjective perception of the risk resulting from the investment. Other decision parameters like sustainability and non-monetary objectives play only minor roles [6]. Choosing the best technology in respect of level of investment and operational costs is very difficult. If tendering a biogas plant, it is important receive offer on operational cost like:

* Operational cost of combined heat and power plant (CHP) incl. all services and spare parts (amount/kWh),

* Maintenance costs of biogas plant in total (% of investment/year),

* Own electrical energy demand, including demand of CHP (kWh/year),

* Average working hours/day of staff (maintenance and feeding the system).

The success of the project is also influenced by some factors that cannot be controlled such as:

* Interest terms,

* Grid access and feed in tariffs,

* World market prices for feedstock (e.g. energy crops),

* Competition for feedstock from other sectors.

Industrial waste collectors face problems securing long term availability of the feedstock. This could be a problem because the waste recycling market is highly competitive and contracts with waste producers are rarely for periods longer than five years.

Quite often, before a bank offers to finance the biogas plant project, the economical long term success of the project must be proven by a study/ calculation of profitability [7]. The calculation is normally done within the preliminary planning by an experienced planning/consulting company, but in many cases, especially in the case of single based biogas projects, this work can be done by the project developer, with two consequently advantages: the project developers/partners are forced to have a very close view to the different aspects of the project and, in case of cancelling the project, no external costs have occurred.

2. Economic forecast of a biogas plant project

In a case of a biogas plant treating municipal waste, it is recommended to mandate an experienced consulting company. Waste treatment plants are much more complex regarding handling of feedstock, biological stability of the system and the whole plant design, compared to a farm based plant (Fig. 1).

For case specific calculation of the economic forecast, a calculation model was elaborated, allowing the preliminary estimation of costs, plant size, dimensioning, technical outline etc. finding an independent and reliable planning partner is mandatory. The framework conditions of organic biogas generation and its monetary implications on production economics must be carefully analysed [8] and [9], with risks evaluation [10]. Renewable energy production is not economically viable by its own, without considering the wastewater treatment function and the associated incomes [11].

3. Project case

For the purpose of construction of the biogas plant, land in area of 1.4 ha is being purchased. The Ministry of economy has issued a preliminary electricity permission needed in order to construct the plant with bio power of 1 MWh based on prior economic and technological analyses.

collection of waste from farms represents an ecological problem because raw manure cannot be immediately (due to its high concentration and / or vegetation period) used on arable land as fertilizer. The waste is therefore collected or deposited along the fields in inadequate (usually permeable) reservoirs / disposal sites / lagoons from where they penetrate into the surface and ground waters, polluting them. Stench and even more important pollution from glass gases (N[H.sub.3], C[O.sub.2], C[H.sub.4], [H.sub.2]S), that destroy the ozone layer, are expanding.

3.1. Project goals

Three main goals need to be achieved:

* Tackling environmental problems and at the same time exploiting "waste" traits as a renewable source of energy,

* Exploitation of processed and fermented residue as a high caloric organic fertilizer,

* Development of energy crops (silages) with the aim of improving the energy efficiency with partial exploitation of fertilizer produced on site.

The raw material for the biogas plant will be purchased in the environmental field on approximately 10,000 hectares of arable land, which provides a minimum of 10,000 tons of biomass with the price of 17 [euro]/tonne. The production itself is agreed for a reason that it should not endanger food production and should take the arable land. Deficiencies of the contracts for inbounds are identified as price hikes of the raw materials required for the upcoming biogas plant and the price hikes of the agricultural products, corn in particular. In absence of price hikes regarding the biogas production, long-term contracts for period of 10-12 years are suggested to be signed. In terms of the biomass price the following formula is applied:

[C.sub.Goie] = [C.sub.Goie-1] * [ICM.sub.Goie-1] (1)

* [C.sub.Goie] is the purchase price for the current year,

* [C.sub.Goie-1] is the purchase price for the previous year,

* [ICM.sub.Goie-1] is an annual index of growth of the retail prices in terms of the previous year,

* Goie is an annual index, the minimum value in the year.

Plants connected to the distribution network with installed electrical power up to 1 MW, which use renewable sources of energy for its production, sell such energy under the price of 0,174 [euro]/kWh, with no value added tax (VAT) calculated.

The raw material is delivered to the cleaver and the blender by pressure pipeline and/or tanks, where it is mixed with silage, other biodegradable substrates (waste material) and hot water (heated with the surplus of the heat already generated), after what it is dosed in an equalization pool, mixed with a submerging device. The liquid is being pumped from the pool into a hydrolyser, where for 2-3 days a hydrolysis is commencing on temperature of approx. 55[degrees]C. The heating is carried out by heat exchanger of the water heated with the surplus of the produced heat (hot water). The hydrolysate is pumped onwards into a digester--1, where for 15-20 days a thermophilic conversion of hydrolysed organic substances into biogas is commencing on temperature of approx. 55[degrees]C [12]. The heating is carried out by heat exchanger of the water heated with the surplus of the produced heat (hot water). Ferment thickens by passing through the separator and thus condensed, pumps through the reservoir, where the conversion into biogas continues, accumulating in the gas tank / in the dome above the reservoir. In that gas tank, the biogas is dosed from the dome of the digester--1. Reservoir--ferment will be soon built for the phase II as well, thus the initial period of retention of the ferment shall take approx. 30 days, whilst in the second phase it shall decrease [13].

The obtained biogas is purified by aerobic biological conversion of sulphide into elementary sulphur at the top of the dome and by removing the moisture by passing through the capacitors and the filters. Later on the obtained biogas is used for drive of CHP units which are used in the production of electrical and thermal energy.

Processed and fully stabilized fermenter (without odour) is transported through the same reservoirs, which are used for delivery of the substrate to the smaller reservoirs (container, metal or terrestrial), mounted on arable areas as high calorific organic fertilizer with corresponding tractor hitch. Optionally it can be one of the larger reservoirs (which holds fermenter for approx. 90 days, during the vegetation period), from which the fertilizer can be deprived if necessary.

The biogas plant will be installed at a location with good infrastructure in terms of logistical point of view. At 500 m distance from the bioplant there is a transformer-station with an option to connect to the network.

Possible impacts of the construction of biogas plant on the surrounding area can affect the soil, underground and groundwater, the air and the "production" waste. Negative impact can occur on soil and subsoil in case of outlet of the liquid manure. In that case the liquid manure will penetrate into the underground, in particular into the underground water or it will reach the recipient on the surface, where it can destroy the living world due to lack of oxygen. In order to prevent such negative impact, the manure is deposited into closed reservoirs.

The impact on air is unfavourable odour-stench from the biogas plant because of the silage, the livestock faeces, aggregate pits for wastewater from the silages and the reservoirs for the fermented manure. It is considered that the stench reaches an area of 500 m, whilst in terms of unfavourable weather conditions it can reach an area of up to 1 km. Closest living areas are 1 km away, which means that it shall not affect the area of residential neighbourhoods.

In order to monitor the state of the environment, regular controls and analyses on the underground water shall be performed, whilst once in two years' time analyses on the soil, which are fertilized by the fermented liquid manure from the plant shall be commenced as well. The construction of the biogas plant creates jobs, new values and raises the awareness of the usage of renewable sources.

4. Economic and financial analysis

The input data and the results of the analysis for the observed 10 years are summarised in tables 1 to 8. We have developed the cost model considering all fixed values of parameters (some of them are fixed by the government regulation or market situation) and some cost components giving us some optimisation possibilities.

Consumption of thermal energy for own needs is 55 %.

Consumption of electricity for own needs of the biogas plant is 6 % or 476.505 kWh. During operation, we have a computer control loop, which indicates that we are running within planned costs, within the achievement of the planned objectives and within other technical parameters. All technical parameters and costs, eventual failures are controlled by dedicated software. Any deviations are displayed using visual warning signal, overall control can also be remotely controlled and synchronized with the network. This ensures a stable economic operation of the plant.

5. Conclusion

Production and consequently sales of energy derived from biogas production devices offers economic opportunity for treatment and recycling of many agricultural residues and by-products, a variety of bio-waste, organic waste water from industry and sewage in a sustainable and environmentally friendly manner.

Having done the pre-calculations using the calculation tool as recommended in the result is a model of the economy of the project. As stated before, the operational costs and the investment costs can be influenced by strategic decisions. For example by choosing the best adapted technology. So, if labour is cheap in your country, than it might be cheaper engaging more people than spending money for automation of a plant.

The revenue side of a project is difficult to influence. The feed in tariffs are set by the government. In case of waste treatment plants, the tipping fees are market prices. There are other possibilities of improve the revenue side:

* Using/selling the produced heat,

* Selling digestant as a fertilizer.

If the project obtains an internal rate of return (IRR) lower than 9 %, you should reconsider all the project premises, and improve some of them. If the IRR rate is higher than 9 %, the premises are good and it is worth continuing the project and moving to the next planning phase. It is important to compare the assumptions with the material reality. This helps to get a realistic idea of the biogas plant itself, the needed space, the true mass current and the real building costs. The calculation model is useful for providing the rough information which is necessary to kick start the actual planning phase. Also the earnings before interest, taxes, depreciation and amortization (EBITDA) are very prosperous. For the next steps of project, finding an independent and reliable planning partner is mandatory.

According to the economic indicators, return on the whole investment is anticipated in 5-6 years. The lifetime of the biogas plant is 20 years. The plant itself delivers 5 jobs, whilst it indirectly ensures 20 jobs including production of biomass on the fields. The utilization of the fermented mass as organic fertilizer improves crops contribution for 15- 25 % and reduces the application of artificial fertilizers, which as a result improves the total quality of the agricultural production and decreases the artificial fertilizers expenses. In the biogas plant, the waste is used as bio-renewable source of energy.

The main paper contribution is the development of new structure of cost calculation applying a wide list of influencing parameters which consider the actual state and conditions. Another achievement is the modified system of evaluation of the eligibility of investment. In future research some model expansions are planned, including the generalization of implemented (combined) energy sources.

DOI: 10.2507/28th.daaam.proceedings.018

6. References

[1] Stanek, W.; Gazda, W. & Kostowski, W. (2015). Thermo-ecological assessment of CCHP (combined cold-heat-and-power) plant supported with renewable energy. Energy, Vol. 92, Special issue--Part 3, 279-289, ISSN 0360-5442

[2] Ahlberg-Eliasson, K.; Nadeau, E.; Leven, L. & Schnurer, A. (2017). Production efficiency of Swedish farm-scale biogas plants. Biomass & Bioenergy, Vol. 97, 27-37, ISSN 0961-9534

[3] Glavan, I.; Prelec, Z. & Pavkovic, B. (2015). Modelling, simulation and optimization of small-scale CCHP energy systems. International Journal of Simulation Modelling, Vol. 14, No. 4, 683- 696, ISSN 1726-4529

[4] Kang, J. Y.; Kang, D. W.; Kim, T. S. & Hur, K. B. (2014). Comparative economic analysis of gas turbine-based power generation and combined heat and power systems using biogas fuel. Energy, Vol. 67, 309-318, ISSN 0360-5442

[5] Guenther-Luebbers, W.; Bergmann, H. & Theuvsen, L. (2016). Potential analysis of the biogas production--as measured by effects of added value and employment. Journal of Cleaner Production, Vol. 129, 556-564, ISSN 0959-6526

[6] Reise, C.; Musshoff, O.; Granoszewski, K. & Spiller, A. (2012). Which factors influence the expansion of bioenergy? An empirical study of the investment behaviours of German farmers. Ecological Economics, Vol. 73, 133-141, ISSN 0921-8009

[7] Lai, X. D.; Wu, G.-D.; Shi, J. G.; Wang, H. M. & Kong, Q. S. (2015). Project value-adding optimization of project-based supply chain under dynamic reputation incentives. International Journal of Simulation Modelling, Vol. 14, No. 1, 121-133, ISSN 1726-4529

[8] Blumenstein, B.; Siegmeier, T. & Moeller, D. (2016). Economics of anaerobic digestion in organic agriculture: Between system constraints and policy regulations. Biomass & Bioenergy, Vol. 86, 105-119, ISSN 0961-9534

[9] Krajnc, M.; Dolsak, B. (2013). Computer and experimental simulation of biomass production using drum chipper. International Journal of Simulation Modelling, Vol. 12, No. 1, 39-49, ISSN 1726-4529

[10] Kremljak, Z. (2016). Risk analysis of specific project problems. Proceedings of the 27th International DAAAM Symposium "Intelligent Manufacturing & Automation", October 2016, Mostar, Bosnia & Herzegovina, ISSN 2304-1382, ISBN 978-3-902734-3-6, Katalinic, B. (Ed.), 8 pages, DAAAM International Vienna

[11] Fersi, S.; Chtourou, N.; Jury, C. & Poncelet, F. (2015). Economic analysis of renewable heat and electricity production by sewage sludge digestion--a case study. International Journal of Energy Research, Vol. 39, No. 2, 234-243, ISSN 1099-114X

[12] Voegel, V.; Bertron, A. & Erable, B. (2016). Mechanisms of cementitious material deterioration in biogas digester. Science of The Total Environment, Vol. 571, 892-901, ISSN 0048-9697

[13] Siswantara, A. I.; Daryus, A.; Darmawan, S.; Gunadi, G. G. & Camalia, R. (2016). CFD analysis of slurry flow in an anaerobic digester. International Journal of Technology, Vol. 7, No. 2, 197-203, ISSN 2086-9614

Caption: Fig. 1. Main components and general process flow of biogas production

Caption: Fig. 2. Technological process of the biogas plant

Table 1. Total investment costs
                                       Amortization       Annual
Description         Equipment value       period       depreciation

Construction works   707.616 [euro]         20        35.381 [euro]
Equipment           2.153.164 [euro]        10        215.316 [euro]
Cogeneration unit    739.220 [euro]         7         105.603 [euro]
Total               3.600.000 [euro]                  356.300 [euro]

Table 2. Total infrastructure costs

Description                                  Price ([euro])

Construction works                              707.616
Electro-mechanical equipment and works         2.672.384
Engineering                                     220.000
Silage purchase in first year of business       220.000
Total                                          3.820.000

Table 3. Detailed specification of equipment, material and labour

No.   Service / Equipment               Capacity            Value

1.    Design / Construction                             135.000 [euro]
2.    Commissioning (Momentum)                          65.000 [euro]
3.    Design of plans for location                      20.000 [euro]
      permit
4.    Static budget                                           V
5.    Apparatus for receiving                           149.838 [euro]
      solids
6.    Reception reservoir of                            16.977 [euro]
      liquid manure
7.    Digester charging room                            105.596 [euro]
8.    Digester 1                     3.115 [m.sup.3]    406.403 [euro]
9.    Digester 2                     3.115 [m.sup.3]    406.403 [euro]
10.   Post reservoir with                               230.792 [euro]
      associated gas-tank
11.   CHP                              Approx. 999      739.220 [euro]
                                       [kW.sub.el]
12.   Safety torch
13.   Desulfurization of biogas
14.   Scale (quantity: 1)                 30 t
15.   Measuring, monitoring and                         284.625 [euro]
      control equipment
16.   Dehydration of sludge                             53.590 [euro]
17.   Laguna for post-fermented                         100.000 [euro]
      mass
18.   Condensing pool
19.   Design of pipelines                               117.300 [euro]
20.   Insurance, transport                              61.640 [euro]
      Plant expenses                                   2.892.384 [euro]
      Infrastructure expenses                           707.616 [euro]
1.    Silage silo                                       274.700 [euro]
2.    Earthworks and asphalt bases      40 [euro]       80.000 [euro]
      (quantity: 2000)
3.    Other earthworks                                  54.000 [euro]
4.    Foundations                                       138.966 [euro]
5.    Substation                                        125.000 [euro]
6.    Starting cost                                     34.950 [euro]
      Total investment                                 3.600.000 [euro]

Table 4. Profit and loss statement (part 1)

Structure \ Year      1          2           3           4

Revenue

Thermal energy        0       31.906      32.864      33.850

Electricity        730.037   1.417.548   1.460.074   1.502.601

Value of the
organic
fertilizers

Total revenue      730.037   1.449.455   1.492.938   1.536.450

Costs

Loan repayment

Interest

Depreciation       178.150    356.300     356.300     356.300

Maintenance                   16.802      16.802      33.605
of the plant

Maintenance        47.875     119.689     123.280     126.870
of the CHP

Insurance          10.000     10.000      10.300      10.609

Fuel                5.833     10.000      10.300      10.609

Fermented mass                38.245      39.010      39.790
supply costs

Raw materials      110.000    220.000     226.600     233.398
costs (Silage)

Monitoring of                  2.340       2.410       2.483
the biological
process

Workforce          12.775     21.900      22.557      23.234

Spare parts         9.946     19.893      20.091      20.292

Total costs        374.579    815.169     827.650     857.190

EBITDA             355.458    634.285     665.288     679.261

Structure \ Year       5           6           7           8

Revenue

Thermal energy      34.865      35.911      36.988      38.098

Electricity        1.545.127   1.587.654   1.630.180   1.672.707

Value of the
organic
fertilizers

Total revenue      1.579.992   1.623.565   1.667.169   1.710.805

Costs

Loan repayment

Interest

Depreciation        356.300     356.300     356.300     356.300

Maintenance         33.605      33.605      33.605      33.605
of the plant

Maintenance         130.461     134.052     137.642     141.233
of the CHP

Insurance           10.927      11.255      11.593      11.941

Fuel                10.927      11.255      11.593      11.941

Fermented mass      40.586      41.398      42.226      43.070
supply costs

Raw materials       240.400     247.612     255.040     262.692
costs (Silage)

Monitoring of        2.557       2.634       2.713       2.794
the biological
process

Workforce           23.931      24.649      25.388      26.150

Spare parts         20.495      20.700      20.907      21.116

Total costs         870.190     883.460     897.007     910.841

EBITDA              709.803     740.105     770.162     799.964

Structure \ Year       9          10

Revenue

Thermal energy      39.241      40.418

Electricity        1.715.233   1.757.760

Value of the
organic
fertilizers

Total revenue      1.754.474   1.798.178

Costs

Loan repayment

Interest

Depreciation        356.300     356.300

Maintenance         50.407      50.407
of the plant

Maintenance         144.824     148.414
of the CHP

Insurance           12.299      12.668

Fuel                12.299      12.668

Fermented mass      43.932      44.810
supply costs

Raw materials       270.572     278.689
costs (Silage)

Monitoring of        2.878       2.964
the biological
process

Workforce           26.934      27.742

Spare parts         21.327      21.541

Total costs         941.771     956.203

EBITDA              812.703     841.974

Table 5. Profit and loss statement (part 2)

Structure \ Year         1          2           3           4

I. Revenue            730.037   1.449.455   1.492.938   1.536.450

1. Total revenue      730.037   1.449.455   1.492.938   1.536.450

2. Rest of project       0          0           0           0

2.1. Fixed assets

II. Expenditures      319.979    787.306     798.688     822.059

3.Fixed assets
investments

4. Operating costs    200.596    458.869     471.350     500.890

4.1.Tangible costs    177.821    426.969     438.493     467.047

4.2. Service costs    10.000     10.000      10.300      10.609

4.3. Intangible
costs

4.4. Gross salaries   12.775     21.900      22.557      23.234

5. Profit tax         79.589     218.958     218.225     214.112

6. Reserves           39.794     109.479     109.113     107.056

III. Net revenue      410.058    662.148     694.250     714.392

Structure \ Year          5           6           7           8

I. Revenue            1.579.992   1.623.565   1.667.169   1.710.805

1. Total revenue      1.579.992   1.623.565   1.667.169   1.710.805

2. Rest of project        0           0           0           0

2.1. Fixed assets

II. Expenditures       833.899     845.909     858.234     870.813

3.Fixed assets
investments

4. Operating costs     513.889     527.159     540.707     554.541

4.1.Tangible costs     479.031     491.255     503.726     516.450

4.2. Service costs     10.927      11.255      11.593      11.941

4.3. Intangible
costs

4.4. Gross salaries    23.931      24.649      25.388      26.150

5. Profit tax          213.340     212.499     211.685     210.848

6. Reserves            106.670     106.250     105.842     105.424

III. Net revenue       746.093     777.656     808.935     839.992

Structure \ Year          9          10

I. Revenue            1.754.474   1.798.178

1. Total revenue      1.754.474   1.798.178

2. Rest of project        0           0

2.1. Fixed assets

II. Expenditures       895.414     908.522

3.Fixed assets
investments

4. Operating costs     585.471     599.903

4.1.Tangible costs     546.239     559.494

4.2. Service costs     12.299      12.668

4.3. Intangible
costs

4.4. Gross salaries    26.934      27.742

5. Profit tax          206.628     205.746

6. Reserves            103.314     102.873

III. Net revenue       859.060     889.656

Table 6. Economic flow of project

Structure \ Year          1           2           3           4

I. Revenue            4.330.037   1.449.455   1.492.938   1.536.450

1. Total revenue       730.037    1.449.455   1.492.938   1.536.450

2. Funding            3.600.000       0           0           0
sources

2.1. Own               720.000
resources

2.1. Loans            2.880.000

3. Rest of project        0           0           0           0

3.1. Fixed assets

II. Expenditures       200.596     883.634     896.115     925.655

4. Investments in
fixed assets

5. Operational         200.596     458.869     471.350     500.890
costs

5.1. Tangible          177.821     426.969     438.493     467.047
costs

5.2. Services          10.000      10.000      10.300      10.609
costs

5.3. Intangible           0           0           0           0
costs

5.4. Gross salaries    12.775      21.900      22.557      23.234

6. Profit tax 20 %        0           0           0           0

7. Reserves               0           0           0           0

8. Annuities              0        424.765     424.765     424.765

III. Net revenue      4.129.441    565.820     596.823     610.795

IV. Cumulative        4.129.441   4.695.261   5.292.084   5.902.880
net revenue

Structure \ Year          5           6           7           8

I. Revenue            1.579.992   1.623.565   1.667.169   1.710.805

1. Total revenue      1.579.992   1.623.565   1.667.169   1.710.805

2. Funding                0           0           0           0
sources

2.1. Own
resources

2.1. Loans

3. Rest of project        0           0           0           0

3.1. Fixed assets

II. Expenditures       938.655     951.925     965.472     979.306

4. Investments in
fixed assets

5. Operational         513.889     527.159     540.707     554.541
costs

5.1. Tangible          479.031     491.255     503.726     516.450
costs

5.2. Services          10.927      11.255      11.593      11.941
costs

5.3. Intangible           0           0           0           0
costs

5.4. Gross salaries    23.931      24.649      25.388      26.150

6. Profit tax 20 %        0           0           0           0

7. Reserves               0           0           0           0

8. Annuities           424.765     424.765     424.765     424.765

III. Net revenue       641.338     671.640     701.696     731.499

IV. Cumulative        6.544.217   7.215.858   7.917.554   8.649.053
net revenue

Structure \ Year          9           10

I. Revenue            1.754.474   1.798.178

1. Total revenue      1.754.474   1.798.178

2. Funding                0           0
sources

2.1. Own
resources

2.1. Loans

3. Rest of project        0           0

3.1. Fixed assets

II. Expenditures      1.010.237   1.024.669

4. Investments in
fixed assets

5. Operational         585.471     599.903
costs

5.1. Tangible          546.239     559.494
costs

5.2. Services          12.299       12.668
costs

5.3. Intangible           0           0
costs

5.4. Gross salaries    26.934       27.742

6. Profit tax 20 %        0           0

7. Reserves               0           0

8. Annuities           424.765     424.765

III. Net revenue       744.237     773.509

IV. Cumulative        9.393.290   10.166.799
net revenue

Table 7. Production balance of thermal energy (in KWh)

                   Monthly         Own        Energy
Month             production   consumption   for sale      Rest

January            662.400       198.720      463.680        0
February           662.400       198.720      463.680        0
March              662.400       198.720      463.680        0
April              662.400       158.976      302.054     201.370
May                662.400          0         264.960     397.440
June               662.400          0            0        662.400
July               662.400          0            0        662.400
August             662.400          0            0        662.400
September          662.400          0         198.720     463.680
October            662.400       59.616       361.670     241.114
November           662.400       99.360       563.040        0
December           662.400       198.720      463.680        0
Total per annum   7.948.800     1.112.832    3.545.164   3.290.804

Table 8. Production of electricity (in KWh)

                   Monthly     Capacity       Daily
Month             production     (kW)     production (h)

January             674.505      999           21,78
February            609.230      999           21,78
March               674.505      999           21,78
April               652.747      999           21,78
May                 674.505      999           21,78
June                652.747      999           21,78
July                674.505      999           21,78
August              674.505      999           21,78
September           652.747      999           21,78
October             674.505      999           21,78
November            652.747      999           21,78
December            674.505      999           21,78
Average             661.813      999           21,78
Total per annum   7.941.750       --          7949,7