Hydropower Generation of Electricity and Capacity Installed
World production of hydroelectricity has grown steadily by about 2.3 % per year on average since 1980 (EC 2000). The total increase in electricity production has grown 3.1 % per year. Worldwide average growth rates of hydroelectricity generation in the future are estimated from about 2.4 % (Voigtländer and Gattinger 1999) to 3.6 % (Eurelectric 1997a) per year between 1990 and 2010 or 2020, respectively. The highest growth rates are expected in developing or strongly industrializing countries with high, yet unexploited hydropower potential, e.g., parts of Eastern Europe, while in Western Europe, only a 1 % annual increase is assumed (Voigtländer and Gattinger 1999).
Electricity production in the EU-28 from large-scale hydropower is projected to increase to 370 TWh by 2020; this represents an increase of 6.6 % with respect to 2011. Largest additions in large-scale hydropower production are expected in Spain (4.5 TWh), Portugal (3.6 TWh), Austria (3.1 TWh), and Romania
(2.6 TWh). Two countries, Sweden and Italy, expect large-scale hydropower production to decrease by 3.2 TWh (Sweden) and 3 TWh (Italy). Small-scale (<10 MW) hydropower production is projected to be 53 TWh by 2020. Largest addition is expected in Italy (2.9 TWh). Small hydropower plants rated at an installed capacity of 10 MW or less currently contribute more than 37 TWh per annum or 2.5 % of the European electricity market. Modernization, recondition- ing, and the exploitation of new sites will mean that around 50 % of the remaining small hydropower sites in Europe will be exploited by 2015.
Worldwide hydropower accounts for a total of 16.47 % of all electricity gen- erated globally. Today, electricity generation from hydropower makes a substan- tial contribution to meeting the increasing world electricity demand. In 2011, the installed hydropower capacity (949.075 kWh) represents 17.8 % of the total installed capacity for electricity generation (5,331.045 million kWh).
Besides the fact that hydropower currently makes up a substantial share of the total amount of electricity generated in the world, the arguments for the continued and increased utilization of hydropower are based on its advantages when com- pared to other sources of energy. The key positive characteristics of hydroelectric- ity can be summarized as follows:
• Low cost1;
• Effectiveness2;
• Sustainability;
• Stored in large quantities (Lehner et al. 1998).
Electricity generation from large hydropower is characterized also by:
• High exploitation and proven technology: Among all renewable energy sources used for electricity generation, hydropower represents the most explored sources, especially in some EU countries, such as Austria and France. The various conversion technologies applied are common and well proven;
• Low volatility of the power output: Hydropower represents a fluctuat-
ing source of energy. In contrary to wind and solar photovoltaic, the volatility appears in the medium to long term. It is characterized by a seasonal depend- ence, but also high annual differences occur;
• Low social acceptance: Public resistance has been raised in most parts of
Europe since the 1980s when new large-scale hydropower projects have been discussed. For this reason, the environment and social effects of hydropower projects need to be carefully considered. Countries should follow an integrated approach in managing their water resources, planning hydropower develop- ment in cooperation with other water-using sectors, and take a full life cycle approach to the assessment of the benefits and impacts of the projects under consideration. Over the last two decades, decisions on many hydropower devel- opment projects have been affected by the controversy about the environmental and social effects of hydropower. Analyzing the benefits and impacts of such projects is both difficult and time consuming. In deciding on the role of hydro- power within an electricity supply portfolio, which addresses climate change and energy security concerns, energy policy makers have to consider a whole range of issues, including: (a) enhancing economic equity among citizens; (b) protecting the lives and property of citizens from floods and droughts; (c) secur- ing the rights of citizens with respect to expropriation of land to be inundated; and (d) protecting the environment concerning air, land, water, and biodiversity;
• High initial investment costs: A huge hindrance for large-scale hydropower plants represents the high investment costs. However, hydropower is receiv- ing a strong boost from the rising electricity prices that can be expected as a result of increasing internalization of climate costs, the growth in global energy consumption, and the associated growing scarcity of fossil fuel sources. It is expected that the European electricity prices rise by an average of around 4 % per annum up until 2030;
• Run-of-river versus storage plant: In general, a standard classification of hydropower plant distinguishes between run-of-river and storage power plant. In mountainous regions (large-scale), storage plant is applied to meet peak-load demand, and at proper river sites, run-over-river power plant delivers base-load electricity;
• Pump-storage plant: Hence, a further sub-category of storage plant is a pump-
storage plant—in order to be able to store excessive base-load energy. Such plants are commonly used all over Europe to account for peak-load supply. In the EU, the energy produced from such plant is not accounted as renewable. Accordingly, electricity generation as a result of pumping in existing pump- storage hydropower is not taken into account from the achieved potential and not considered in the potential assessment for new hydropower plant.
Hydropower is expected to continue to play an important role in the world energy balance in the future. Worldwide average growth rates of hydroelectricity generation in the future are estimated to be about 2.4 % per year up to 2020. The highest growth rates are expected in developing or strongly industrializing countries with high, yet unexploited hydropower potential, particularly in Eastern Europe. It is important to highlight that since the 1970s, annual energy production of some existing hydropower plants in Western Europe zhas decreased, in particular in Portugal, Spain, and other Southern European countries. This reduction has been attributed to changes in average discharge; but whether this is due to temporary fluctuations or already the consequences of long-term changing climate conditions is not yet known (Lehner et al. 1998). However, it should be noted that hydropower projects have also been known for their negative effects concerning environmental and social issues. These negative effects must be considered when planning the construction of new hydropower plants, particularly within the EU.
The installed capacity of hydropower plants has grown steadily in the EU over the past fifteen years.3 In 1995, the installed capacity was 90.8 GW, and in 2008, it was 102.3 GW. In 2009, the total installed hydropower capacity was 136 GW in the EU-27, an increase of 32.9 % with respect to 2008, with an additional 62 GW
An estimated 30 GW of new hydropower capacity came on line in 2012, increasing global installed capacity by 3 % to an estimated 990 GW. Hydropower generated an estimated 3,700 TWh of electricity during 2012. Once again, China led in terms of capacity additions (15.5 GW), with the bulk of other installations in Turkey, Brazil, Vietnam, and Russia. Joint-venture business models involving local and international partnerships are becoming increasingly prominent as the size of projects and the capacity of hydropower technologies increase (REN 21 2013).
While the installed capacity shows little annual variation, hydropower produc- tion varies from year to year due to hydrological conditions. The annual average hydropower production in the EU is about 350 TWh. When counting renewable electricity shares, Eurostat normalizes hydropower production to average condi- tions. Besides the countries belonging to the EU, Norway and Switzerland also have significant hydropower assets. In 2008, Norway’s hydropower capacity was 29,700 MW, larger than any single EU member state’s hydropower capacity. In 2011, this capacity was 28,367 MW; this represents a decrease of 4.5 % with respect to 2008. In 2008, Switzerland’s hydropower capacity was 15,300 MW (Ruska and Kiviluoma 2011), but in 2011, this capacity decreased 10 % (13,770 MWe).
Investment opportunities in the hydropower sector within the EU lie in countries with huge potential in the Alps and in Scandinavia, where hydropower already has a long tradition. The convergence of regional European electricity markets as well as technical megaprojects such as the offshore North Sea Ring will make hydropower plants even more interesting in the coming years.
Nevertheless, in order to achieve the forecasted vision of the sector for 20304 and 2050 or surpass, these estimations of the following issues must be tackled:
• Reconciling targets of the Water Framework Directive (WFD) (Directive 2000/60/EC)5 and the RES Directives (Directives 2001/77/EC and 2009/28/EC): The implementation of the WFD is currently restraining the present and future development of the sector, as the interpretation of the directive at a national level is having direct consequences in terms of the approval of new projects and in terms of the allocation of concessions and permissions;
• Environmental measures: Hydropower needs a more objective approach of the environmental community and from stakeholders for current and future legisla- tion could limit in a severe way the benefits of such a source of energy6;
• Removal of administrative and regulatory barriers: Administrative proce- dures to get a hydropower plant operating are still one of the most important barriers for the sector. Longer time periods required for obtaining licenses,
concessions, and permissions discourage developers from bringing projects to an end. A more flexible, simple, centralized, and homogeneous European sys- tem could ease the procedure;
• More attractive incentive regimes (especially in the new EU member
states): Hydropower, and in particular small units, is currently benefiting from European support schemes. Nevertheless, in comparison with other renewables and between countries, the level of support is not satisfactory in terms of cost- benefit and market competition;
• Need for proactive cooperation and better communication at a local level:
In the case of hydropower projects, the rapid establishment of a participatory approach involving the different stakeholders affected by the realization of the project and in particular the environmental and fishing community is a must for the future development of the sector;
• Investment in research and development and change of thinking: The hydropower technology of the next decades will evolve toward more sustainable solutions. However, in order to minimize the environmental impact while at the same time maximizing electricity production, a change of thinking is required and investment in current and future research and development is highly recommended to explore and test different solutions.
According to EU sources, hydroelectric is the most important renewable energy source within the EU from a global perspective. In more than 60 countries, hydropower covers at least 50 % of the electricity supply. In the EU, hydro- power accounts for 11.6 % of gross electricity generation. The top 5 EU countries in terms of hydropower share in the total electricity mix are as follows: Austria
59.3 %, Latvia 49.5 %, Sweden 43.5 %, Romania 29.3 %, and Slovenia 24.3 %. In neighboring Norway, hydropower covers roughly 95 % of electricity supply and there remains significant unexploited potential. Nevertheless, the European hydro- power potential is already relatively well exploited and due to public opposition to build new big hydropower plants in many European countries, it is expected future growth will be rather limited.
On the global level, on the other hand, significant growth is expected with annual hydropower generation reaching between 5,000 and 5,500 TWh in 2050. Strong growth is anticipated during the next decade in China, India, Turkey, Canada, and Latin America (World Energy Outlook 2010). The use of renewable energy sources to generate electricity is expected to expand significantly during the coming years. The use of renewables-based electricity generation worldwide is expected to almost triple, from 3,900 TWh in 2009 to 11,100 TWh in 2035. This expansion is driven largely by government policies, including subsidies, and represents 44 % of the growth in total electricity generation up to 2035. The bulk of this growth is expected to come from four sources: Wind and hydro will provide approximately one-third each, biomass accounts for about one-sixth, and solar photovoltaic for one-tenth.
The global exploitable hydropower capacity exceeds 14,000 TWh, of which some 2,500 TWh is utilized. The potential of hydropower in Europe is well used, but far from being exhausted. In fact, it plays a key role in major, important con- cepts in Europe’s future. For example, the offshore grid initiative of the nation’s lining the North Sea that is meant to produce an additional 100 GW of clean elec- tricity capacities in Europe is also counting on modern hydropower technologies such as pumped-storage generating plants in Norway. These help to better even out the erratic peaks in wind power generation. Without hydropower, Europeans would have a very much more difficult time of carrying through on their ambitious climate protection pledges in the future.
The potential hydropower theoretically to be tapped in Europe (excluding Russia) totals nearly 2,600 TWh per year. Currently, 64 % of the economically via- ble potential is being exploited. It follows that Europe leaves no less than 36 % of its hydropower potential unused, even though related power generation would pay- off. Southeastern Europe utilizes just 40 % of its hydropower potential. Since 60 % of the economically viable hydropower potential is still waiting for investors, it is worth also taking a look at Southeastern Europe. Specifically, because the region’s electricity supply largely relied on centrally planned large-scale structures for more than half a century, it means that there are now lots of interesting project opportu- nities that elsewhere in Europe can only be found in isolated cases (Auer 2013).
Although most of the best sites for hydropower plants have already been devel- oped in Europe, at present, only about half of its technically feasible potential has been developed and only about one-third in Albania, Bosnia-Herzegovina, Moldova, Former Yugoslav Republic of Macedonia, Montenegro, Serbia, and Ukraine. There is thus additional potential of 600 TWh a year in Europe, of which 276 TWh a year in the EU-27, and of about additional 60 TWh a year in the non- EU member states—more than 650 TWh a year in total (World Atlas and Industry Guide 2010).
Figure 3.6 shows developed and still available technically feasible hydropower potential per country in TWh. Denmark, Estonia, and the Netherlands have a very small hydropower generation today and with comparatively little development potential. Malta has neither hydropower generation, nor any potential. In total, the four countries make up only 0.178 TWh of hydropower generation a year and rep- resent 0.6 TWh of hydropower potential that could still be developed. They are therefore not included in Fig. 3.6.
Hydropower has the potential to become more economically attractive via improved turbine designs and cost-effective plant construction in combination with new technologies for control and operation. From an operational standpoint, a hydropower plant can start very quickly and the power output can be controlled accurately.
Hydropower is an extremely flexible technology for power generation. Hydro reservoirs provide built-in energy storage, and the fast response time of hydro- power enables it to be used to optimize electricity production across grids, meet- ing sudden fluctuations in demands. However, large-scale hydropower projects can be controversial because they affect water availability downstream, inundate valuable ecosystems, and may require the relocations of populations. Despite being a mature technology, in comparison with other renewable energy sources,
hydropower has still a significant potential, even in the European region. New hydropower plants can be developed and old ones upgraded, especially in terms of increasing efficiency and electricity production as well as environmental performance. In particular, the development of low-head or very low-head small hydro plants hold much promise.
A small hydropower plant is not simply a reduced version of a large hydro- power plant. The category of small hydropower plants includes all the hydropower plants with a capacity below 300 kW (BFE 2010). In other definitions, hydro- power plants with a capacity up to 1 MW are included. A lot of them have been constructed during the industrialization period. First, they were used as a mechani- cal driving mechanism; later they were converted to generate electricity. When the larger power plants were built and the production cost fell, the small hydropower plants were abandoned (Programm Kleinwasserkraftwerke 2010).
Small hydropower plants generate electricity or mechanical power by convert- ing the power available in flowing waters in rivers, canals and streams with a cer- tain fall (termed the “head”) into electric energy at the lower end of the scheme, where the powerhouse is located. The power of the scheme is proportional to the flow and to the head. Small hydropower schemes are mainly runoff river with no need to create a reservoir. Because of this fact, small hydropower systems can be considered an environmentally friendly energy conversion option, since they do not interfere significantly with river flows and fit in well with the surroundings. The advantages of small hydropower plants are numerous and include grid stabil- ity, reduced land requirements, local and regional development and good opportu- nities for technology export.
According to the Situation Report on Hydropower Generation in the Alpine Region Focusing on Small Hydropower (2001), small hydropower plants were in place in the 27-EU countries with a total installed capacity of over 13,000 MW bottleneck capacity. They produce 41,000 GWh electricity per year. According to the European Small Hydropower Association (ESHA) data, in the EU-27 countries, more than 90 % of the installed capacity is concentrated in six EU member states. The leading countries with respect to installed capacity in the EU-27 are Italy (21 %), France (17.5 %), Spain (15.5 %), Germany (14 %), Austria (9.4 %), and Sweden (7.7 %). Small hydropower has also great importance in the non-EU countries Switzerland and Norway.
Without any doubt, hydropower along with other renewable energy sources is expected to be an important component of the energy mix of many EU coun- tries.7 Why? It is well known that the electricity system can only function properly if electricity generation (supply) matches electricity demand (consumption). Planning generation, according to the forecasted demand is, therefore, essential because electricity demand is variable throughout the year and it depends of the period of the year under consideration. For example, more electricity is con- sumed in winter than in summer. However, daily electricity demand always fol- lows a similar pattern. These plans, however, are not always met. Therefore, any change in electricity demand or generation needs to be met by an equivalent adjustment either on the supply or the demand side. In other words, there is a need for balancing the plans. This is done through market actions or in some cases via TSOs.
In addition to these well-known variations in demand patterns, an increasing amount of renewable energy sources contributes significantly to the challenge of keeping the electricity system in constant balance. In a purely conventional power plant portfolio, the load or the required/delivered amount of electric power falls into three categories: Base load, intermediate load, and peak load.8 Base load refers to a relatively constant output of power plants over a period. It is typically delivered by power plants that are designed to generate electricity at a constant rate of output. In contrast, peak load refers to surges in electricity demand that occur at specific, usually predictable periods (i.e., evening peak load, when con- sumers simultaneously switch on lighting and other electric appliances). Due to their greater responsiveness, peaking power plants are able to provide electricity when demand is at a high. Finally, intermediate load refers to a situation where power output increases every morning and throughout the day and decreases in the evening. Intermediate load power plants run considerably more hours than peaking units, but fewer hours than base-load power plants (RESAP 2011).
With the scene set for an increasing share of renewable energy sources in the energy mix of EU member states, storage facilities will become more important. By 2020, a fifth of all energy consumption in the EU member states must come from renewable sources, particularly hydro, wave, solar, wind, and biomass. This mandate, which EU leaders signed in March 2007, is part of a proposal designed to cut greenhouse gas emissions by 20 % compared with 1990 levels. For hydro- electric power, this mandate translates to significant growth in the development of new capacity and upgrading of existing facilities throughout Europe. Several new conventional hydroelectric projects entered commercial operation in the past years something not seen in several decades. Examples of new projects include Sonna in Norway (270 MW), Glendoe in the UK (100 MW), and Blanca in Slovenia
(42.5 MW). For small hydropower plants (less than 10 MW), development opportunities are significant. Provided the mandate by EU member states is implemented on a timely basis, the ESHA estimates that installed small hydro capacity could reach 16,000 MW by 2020—a more than 4,000 MW increase over current levels.
Another area of significant growth for the hydropower sector in Europe, espe- cially in the central region of the continent, is in pumped storage. In addition to supplying additional electricity during times when demand for power is highest, pumped storage’s ability to balance power production and regulate the transmis- sion network, in light of increased use of intermittent renewables, particularly wind, is attractive. As many as ten pumped-storage facilities are under construction, including 178 MW Avce in Slovenia, 540 MW Kopswerk 2 and 480 MW Limberg 2 in Austria, and 141 MW Nestil in Switzerland. Several more potential projects are being investigated.
Maintaining and, in many cases, upgrading, this existing infrastructure con- tinues to be an important focus throughout Europe. The emphasis in Western Europe is retrofitting hydropower plants with modern equipment, usually upgrading the capacity of the plant. In Eastern Europe, the focus is rehabili- tating aging plants that often were allowed to deteriorate during the era of the former Soviet Union. Numerous utilities are committing significant resources to upgrade entire portfolios. For example, in France, national utility EdF is investing more than €2 billion as part of France’s economic stimulus pro- gram, including spending on modernization of hydroelectric projects. In recent months, EdF has issued several solicitations for hydropower equipment and other work for its many projects, including up to 50 turbine generators over five years.
Hydropower storage plants are the only large-scale storage technology available today. They are also the most efficient and economical way to store potential electricity. While pumped-storage hydropower has a short- to medium-term storage capacity depending on the size of its reservoirs, conventional storage hydro- power plants can offer significant long-term storage capacity. Although pumped storage is a net electricity consumer, it provides valuable regulatory services to stabilize the electric system. Moreover, it can be used to store excess production of renewable energy sources. Compared to all other storage technologies, pumped storage represents the most cost-efficient option9 (RESAP 2011).