Small Hydro Power Plants in Croatia
Zarko Janic
Abstract: This paper provides information about small hydro power plants in Croatia. The MAHE program (National Program of Small Hydro Power Plants Construction) has been described. Hydrological potential, costs and the prospects of small hydro plants in Croatia have been also described.
Keywords: Small hydro power plants, MAHE
1. Introduction
The hydro power plants can be categorized in many ways – type of the turbine, size etc. Small hydro power plants are plants with an installed power smaller than the limit. The limit varies from state to state, in Croatia small plants are those from 10 kW to 5000 kW (5 MW) of installed power. In the European union and in the most countries of the world the limit is 10MW.
Small hydro power plants can also be categorized in several ways but in this paper this issues will not be discussed.
The first power plants and the first steps in the electrification of the world started mostly with small hydro power plants something more than a 100 years ago. Nowadays, the same processes are happening in remote parts of Africa, South America and Asia. [1]
Programs for the energy efficiency and usage of renewable energy sources were started in 1997, by the Croatian government, among them the National Program of Small Hydro Power Plants Construction called MAHE. [1]
2. Small hydro power plants in the world
Among the renewable sources of energy in the world, hydro power plants produce the most electric energy.
Among the hydro power plants, small hydro power plats make about 7% of installed power (approx. 50 GW). The potential for the total installable power is estimated to be about 180 GW, which is about 6% of the estimated total installable power in hydro power plants (for this statistics small hydro power plants were considered those with an installed power less than 10 MW).
Table 1 [3]
Continent / No. of small hydro plants / Installed power (MW)Africa / 165 / 1048,27
Asia / 45720 / 29877,489
Australia an Oceania / 73 / 157,98
Europe (without Russia and Turkey) / 17328 / 2398,42
North and Central America / 615 / 4113,25
South America / 438 / 1175,19
Total / 64339 / 48770,599
Small hydro power plants are increasing its importance in the power systems of the developed countries. There is a very large number of plants built all over the world and because of the good experiences in building and working the interest for them is increasing. Most of the small hydro power plants are private property and the numbers in table 1 show their popularity. There were more than 60000 small power plants in the world in 2002. – the statistics are based on approximately 66% of the countries.
In Europe the countries with most small hydro plants and the most installed power are shown in table 2.
Table 2 [3]
Country / Installed power (MW) / No. of small hydro power plantsAustria / 670 / 1720
Czech rep. / 200 / 1200
France / 1972 / 1717
Germany / 1300 / 6000
Italy / 2000 / 1510
Norway / 950 / 550
Spain / 1540 / *
Sweden / 1050 / 1615
Switzerland / 750 / 1000
* - Data not available
3. Small hydro power plants in Croatia
There are 31 operating small power plants in Croatia with the total of about 73MW of installed power. Nine plants are private property, two are industrial plants and the rest is owned by the Croatian Electric Utility (some of which plants of biological minimum on the dams of large hydro plants) – see Appendix A. There are few more plants constructed and not in use for some time which could be used again.
The first step in planning and building small hydro power plants in Croatia was in 1981. when Elektroprojekt published the “Plan for Development of Small Hydro Power Plants in Croatia until 2000” [4]. The next document made was “Methodology and Guidelines for Design and Construction of Small Hydro Plants in Croatia” [5] in 1982 which set criteria and guidelines for the next elaborates. The “Register of Small Streams” [6], the “Register of Small Hydro Power Plants – Stage I.” [7] and the “Register of Small Hydro Power Plants – Stage II.A” [8] then followed. [1]
4. Croatian hydro potential
The Register of Small Streams (KMVS), which was made in 1985, gave the first assessment of possible locations on 134 streams. From those 63 streams have been judged as suitable for small hydro power plants. On those 63 streams 699 locations were identified. All of them were categorized in 4 categories – see table 3.
The total installed power on those 699 locations could be about 177 MW (natural gross power of 135 MW), and the technically usable annual production of 567,7 GWh (natural gross potential of 1180 GWh).
The first category is the most interesting for investors but they are mostly in areas of protected environment, although they can be very well incorporated with the environment their future is uncertain. Because of the small net head, very high flow and, consequently, a small installed power and small amount of energy, the fourth category can be eliminated.
Table 3 [2]
1 / No. of locations / 108Average net head / 16,62m
Maximum flow / 8,04m3/s
Average installed pover / 791,3 kW
Average annual production / 3564 MWh
2 / No. of locations / 244
Average net head / 5,33m
Maximum flow / 9,81m3/s
Average installed pover / 247,35 kW
Average annual production / 1115 MWh
3 / No. of locations / 231
Average net head / 3,11m
Maximum flow / 6,69m3/s
Average installed pover / 95,47 kW
Average annual production / 430 MWh
4 / No. of locations / 116
Average net head / 0,998m
Maximum flow / 13,08m3/s
Average installed pover / 73,53 kW
Average annual production / 346 MWh
The table 4 shows that less than 3% of the locations would have an installed power between 5 and 1,5 MW but more important is that its installed power would be nearly 1/3 of the total installed power.
Table 4 [2]
Installed power (kW) / No. of locations / Total installed power (kW)5000-1500 / 20 (3%) / 50232 (29%)
1500-1000 / 17 (2%) / 21723 (12%)
1000-500 / 42 (6%) / 28768 (16%)
500-100 / 296 (42%) / 55667 (31%)
Under 100 / 324 (47%) / 20765 (12%)
TOTAL / 699 / 177155
It was planed that the Register of Small Hydro Power Plants (KMHE) would be made in two stages. The first stage gave the designs for plants on 13 streams. 50 possible locations were identified (see Appendix B) and 10 of the possible locations were studied more thoroughly giving basic principles for constructing plants (guidelines for the type of structures, hydro mechanical equipment etc.). The selected 13 streams are Bregana, Brzaja, Buticnica, Cabranka, Jadro, Krupica, Krusa, Ljuta, Orljava, Ovrlja, Ruda Velika, Rumin Veliki and Zrnovnica. It was planed that the Stage II would study all the other streams but it was not carried out according to the plan, so only 4 streams have been studied – Cuckov Jarak, Kupcina, Slapnica and Vitunjcica. In those 4 streams 17 possible locations were identified – see Appendix C.
5. Pilot program
In 1998 the pilot program has been started. The program included 50 locations from the first stage of the Register of small hydro power plants, 17 from the second (II.A) stage and more 10 as a result of interest of investors in some locations. This way the program wanted to encourage building of small hydro power plants. The main goal of the pilot program was to test the procedure of planning, engineering and building small hydro power plants. The more accurate Croatian potential of small hydro power plants would be one of the results as well. [3]
Based on the contact with the institutions the environmental protection and cultural heritage protection restrictions were identified as the more restricting. One of the main reasons is the current approach so that all the restrictions are made for the whole stream and not for specific locations. [3]
Table 5 [3]
Location
1. / Butisnica 12. / Butisnica 2
3. / Cetina - Cikotina lada
4. / Cetina - Vinalic
5. / Jadro 2
6. / Jadro 2
7. / Kupcina 2
8. / Kupcina 3
9. / Kupcina 4
10. / Kupcina 5
11. / Kupcina 7
12. / Ljuta 2
13. / Mirna – bridge
14. / Orljava 1
15. / Orljava 2
16. / Orljava 3
17. / Orljava 4
18. / Orljava 4-1
19. / Orljava 5
20. / Orljava 6
21. / Orljava 7
22. / Orljava 8
23. / Ovrlja 1
24. / Pantana 1
25. / Ruda Velika 1
26. / Ruda Velika 2
27. / Vitunjcica 1
28. / Vitunjcica 2
29. / Vitunjcica 3
30. / Zrmanja Vrelo 1
As a result of space-planning 33 locations have been eliminated. Two projects (Krupa 3 and 4) have been joint into one project so 41 project went to the next level (2 projects were added later on). Based on the cultural heritage and environmental protection more 13 projects have been eliminated, leaving 30 locations in the pilot programs – table 5. [3]
6. Finances
According to the regulations in the energy sector “Besides the Croatian Electric Utility (HEP), persons, companies and other legal persons can also produce and distribute electric power.” so it is a possibility for investors because of the easy construction and maintenance as well as the good rate of return. [9]
One of the key issues is the construction cost. The four categories from the previous chapter give four categories of construction costs. The coefficient of the profitability (Cp) gives an approximate picture of the construction cost. [10]
Ctot – total cost
Pmax – maximum installed power
These are the estimations of the construction costs per installed power for the four categories. [10]
1. Cp £ 2500 US$/kW
2. 2500 US$/kW£ Cp £ 4500 US$/kW
3. 4500 US$/kW£ Cp £ 6000 US$/kW
4. 6000 US$/kW£ Cp
The percentages of specific parts of the total cost are shown in table 6.
Table 6 [2]
Preparation and construction / 40-70%Hydro-mechanical equipment / 1-2%
Electric and machinery equipment / 20-40%
Connection with the electric system / Up to 20%
Other (studies, project, buy offs etc.) / 5-10%
The Croatian Electric Utility guarantees the buying of the entire production of electric energy. The price is set by the regulations. For plants whose installed power is under 500kW is 75% of the average price of electric energy and for plants with an installed power grater than 500kW is 65% of the average price of electric energy for buyers [2]. Calculations for a pilot project (Krupa-3), done by MAHE, show that the project is profitable.
The MAHE program suggests that because most of the locations are located in rural undeveloped areas and areas of special state care (occupied areas or areas on the first line during the war), the local government should encourage such programs to gain advantages for the local community (through taxes, concessions etc.). Such facilitations should be introducing the possibility of power plants in urban plans, permission for the building etc even prior to the interest of investors.
7. Environmental impact
Small hydro plants, as all other types of plants, have environmental impacts. Because of their small size, if constructed taking into account all factors, they can have a really small impact or even improve it. The basic impacts on the environment are the change in the parameters of water (percentage of oxygen in the water, decrease of speed of the flow, level of the water, possible decrees of biodiversity etc.).
The most important is to estimate correctly the biological minimum. If it is not calculated correctly it can result in extinction of plants and animals, especially in the zone between the intake and the exhaust. There are a lot of endemic and rare species in Croatia, which makes these calculations even more important.
For example Switzerland the Mattheyes equation is used for calculating the biological minimum [10].
Vmin – biological minimum (l/s)
V347 – water flow in 347 days in year (l/s)
There is always the possibility of the contamination by various types of oil and other liquids used during construction and use of the plant. Knowing that the most profitable locations in Croatia are those in National parks and other areas of protected environment, the standards for these plants should be set high and the authorities should strictly control their appliance.
Because of the small size of small hydro power plant accumulation lake, it should not have a big impact on the level of underground water, which can have a significant impact on the surrounding vegetation.
Level of noise produced by the equipment, nowadays, is considerably under the recommended levels so no noise contamination should be experienced.
There are a lot of possible good impacts. First of all is the decrease of the possibility of floods.
Small hydro plants as one of the renewable types of plants do not use fossil fuels. For example a 5 MW plant using fossil fuels uses 1400 toe (tons of oil equivalent) per year. It also produces about 16000t of carbon dioxide (CO2) and 1100t of sulfur dioxide (SO2).
The structure itself (the dam and the powerhouse) can be a degradation of the environment but not necessarily. The powerhouse can be built underground or well integrated in the environment. The dam can also be well integrated in the surrounding environment. Special attention should be given to road construction, used during building of the structure and for later maintenance.