Construction of a small dam on the Jadar River, Bosnia and Herzegovina, Western Balkans. In recent developments, reports suggest that a new amendment to the energy law in Bosnia and Herzegovina during July 2022, will now ban the construction of new small hydropower plants. Although the law prevents the issuing of permits for new small hydro pants, projects in the pipeline still remain.

Small hydropower plants below 10MW are generally considered to have less impacts than larger plants and this has led to their rapid spread with a developing potential that is not yet exhausted. As the authors of a new paper published in Water Resources Management explain, the sustainable development of small hydro is still important to minimise any environmental impacts, especially in the case of cascade installations.

In their research, Quaranta et al conducted an assessment to estimate how environmental flow and plant spatial density can affect the small hydropower potential in diversion run-of-river schemes (DROR) in the European Union. 

Under the strictest environmental constraints, the potential of DROR is estimated at 79TWh/yr and 1710TWh/yr under the laxest constraints. This large variation “indicates that the potential for small hydropower is strictly dependent on the objectives of environmental protection set in the permitting of plants”. However, the authors add that their estimates may suffer from some uncertainty in hydrological data and the effects of climate change on hydrology. As, for example, climate change may reduce the ROR production in alpine environments by 3%.

The second part of the study focused on estimating the potential of low-impacting micro hydropower technologies (< 100 kW) and hidden opportunities in existing facilities. Here the authors considered the potential in hydrokinetic turbines in rivers, water wheels in mills, plus hydropower in water distribution networks and wastewater treatment plants.

The economic potential of hydrokinetic turbines in rivers was estimated to range from between 0.17TWh/yr and 1.2TWh/yr. However, the authors warn that despite the performance increase that can be achieved in the future, the potential in undisturbed rivers remains limited, while installations may be of interest if local resources are used when flow conditions are favourable (eg at the tailrace of large hydropower plants the potential may be more relevant) and in specific remote contexts. 

When looking at water wheels in old mills, the authors estimate that the economic potential (only considering those in good status) was 1.6TWh/yr. However, the real potential may be higher since water wheels could be installed at any suitable small weir, and the database considered in this research does not contain all EU water mills. 

Significant obstacles to water wheel installations can include long bureaucratic processes for the water concession (despite the small available power) and the need for large diameters, while the possible acoustic impact due to their free surface operation can be mitigated by engineering solutions. The authors add that the retrofitting of old mills can generate additional incomes and benefits such as valorisation of cultural heritage, tourism and electricity for local and remote activities. 

Although they only considered mill-related barriers, Quaranta et al say that other historic weirs could potentially generate 5.2TWh/yr. 

Finally, the hydropower potential in water distribution networks and wastewater treatment plants was estimated at 3.38TWh/yr. Some civil infrastructure is already in place and electricity can be used to drive local activities (eg remote control of the network), with an almost stable and well predictable production. 

The authors added that although they may add a few hundred-gigawatt hours of generation per year, they did not consider the hydropower potential from pressurised irrigation networks or industrial flows and fish farms in their research.

Quaranta et al conclude that: “The bulk of this potential is borne by small DROR plants, whose development often conflicts with other environmental objectives and requires defining compatibility criteria for their siting, implementation and operation. This study will help policy makers and environmental authorities in setting the optimal strategies and policies to find the optimal compromise between hydropower development and impact mitigation.”

Western Balkans

Pavlakovič et al follow a similar train of thought in their research published recently in Energy, Sustainability and Society. 

“This global shift towards the use of SHPPs is driven by perceptions of their advantages relative to large dams: almost no carbon gas emissions, limited environmental impacts, lower engineering requirements, shorter construction periods, and lower total investment cost. However,” the authors say, “all these advantages that come with the installation of SHPPs, also entail certain consequences.”

In their research Pavlakovič et al focus on small hydropower construction in the Western Balkan countries which has been causing “numerous controversies, opposition, and resistance” in recent years. The authors say that this has led to “mass protests by citizens and a high degree of mistrust so that the future of SHPPs in the Western Balkan is extremely uncertain……Accordingly, this paper provides suggestions for much-needed improvements.”

The authors say that “there is no dispute” about the importance of small hydropower plants “in places where they are cost-effective and where the control of the terrain and obtained permits is regulated by adequate laws”. When a quality study on environmental impact assessment is conducted, when it is determined that the construction of SHPPs will not have a negative impact on biodiversity and will not endanger flora and fauna, as well as water supply to the local population, Pavlakovič et al state “there is no obstacle to its construction”. 

However, in the case of SHPPs in the Western Balkan region (the Republic of Albania, Bosnia and Herzegovina, Montenegro, Republic of Kosovo, Republic of North Macedonia, and Republic of Serbia), the authors claim that the way certain small hydro plants have been built and exploited has led, in a significant number of cases, to an increasing dissatisfaction of citizens “because they threaten water supply, biodiversity, the entire ecosystem (especially when it comes to protected areas), agricultural activities in rural areas, and the survival of the population in the area”. 

The main aim of this study was to review and analyse the construction of SHPPs in the region and define a model for assessing their sustainability in terms of environmental and social acceptability. The authors propose that their model can be used in future decision-making processes to help to avoid identified problems and improve the sustainable energy transition of the Western Balkan region.

Since 2018, almost all countries of the region have seen an increase in the construction of small hydropower plants. The authors say that this has been accompanied with more controversial views and legal, technical, sociological, and environmental problems. Although the construction of SHPPs “certainly has a positive impact on the sustainable energy future….studies on the harmful influences in the WB countries are rare”. It is claimed that the opinions from the local communities are neglected, and concerns over the harmful impact on, biodiversity, flora, fauna, water supply, income-generating activities, nature reserves and world cultural/historical heritage sites are being ignored.

In a large number of cases, the report claims that “the necessary analyses were not performed” and “even if they are, their results are generally not transparent”.

“What characterises the projects of most WB countries,” the report goes on to state, “is the lack of transparency of the documentation, coherence, and corruption.”

Pavlakovič et al say that their research shows that the decision-making process on investing and building SHPPs in the Western Balkans “uncovered great weaknesses, thus leading to a high degree of public distrust in decision making in this respect, with an extremely uncertain perspective”. They add that to find the right solution, and contribute to sustainable energy and economic development, it is necessary to develop a fully transparent and objective policy system, and use contemporary models for decision making with emphasis on the involvement of local communities in the decision-making process.

Model development

The authors developed a model based on the need to perform a multi-criteria analysis which include a number of criteria that are relevant and have not been taken into account so far, the most important of which are (in order of importance): 

  1. Sites for installation of SHPPs. The construction of SHPPs in national parks must not be allowed, and existing SHPPs built in national parks have to be removed. 
  2. The impact of SHPPs on the ecosystem. A comprehensive assessment of the impact of construction works and operation of SHPPs on water, air, land, flora and fauna must be carried out. 
  3. The impact of SHPPs on the quality of life of local residents. This part of the analysis is particularly complex but is claimed to be completely neglected in the existing decision-making system. It includes socio-demographic structure of inhabitants of the area under review, structure of economic activities, size of households, size of holdings, the existing method of water supply, and the existing method of using water potential by households. If the construction of SHPPs endangers the water supply and economic activities of the local community, an acceptable technical solution has to be found. Otherwise, the construction of SHPPs must not be allowed. 
  4. Assessment of sustainable economic development of the area. The construction of SHPPs can affect agriculture, tourism, sport, culture and other factors that can enable the sustainable development of the area. 

“Establishing communication between all stakeholders (investors, municipality, state, local population, and all other stakeholders) is a necessary precondition for the choice of locations and techniques for the construction of SHPPs in the WB territory,” the authors conclude. “Due to the complexity of the issue, it is necessary to apply an adequate decision-making model, expected to constantly improve, and to make the results of the analysis fully transparent. Special emphasis must be given to establishing a relationship of trust and better cooperation with representatives of local governments, their inclusion in construction plans and respect for their requirements, since they have so far been completely excluded.” 

Pavlakovič et al recommend that further science-based research and reporting on this issue is carried out.


Is There a Residual and Hidden Potential for Small and Micro Hydropower in Europe? A Screening‑Level Regional Assessment by Emanuele Quaranta, Katalin Bódis, Egidijus Kasiulis, Aonghus McNabola, Alberto Pistocchi. Water Resources Management (2022) 36:1745–1762 

Small hydropower plants in Western Balkan countries: status, controversies and a proposed model for decision making by Barbara Pavlakovič, Andrea Okanovic, Bojana Vasić, Jelena Jesic and Polona Šprajc. Energy, Sustainability and Society (2022) 12:9