Issue 36 – March 2012
Since the International Electrotechnical Commission's (IEC's) Technical committee (TC) 4, 'Hydraulic turbines', was set up in 1913, the world's population has multiplied by a factor of 4 – now over the 7 billion mark. Almost a third of the world's population still has no access to basic electricity and world estimates are that current levels of electricity consumption will double by 2030, mainly led by developing countries. Demand for clean renewable energy and proper management of water resources is higher than ever, owing to an increased awareness of global pollution and the need to better integrate and optimise new and existing energy sources.
Importance of clean renewable hydro generation
The United Nations (UN) has put renewable energy at the top of its agenda in 2012 and the UN General Assembly has declared 2012 the 'international year for sustainable energy for all'. By early 2011 at least 118 countries had some type of policy target or renewable energy support policy at the national level, up from 55 countries in early 2005. IEC TC 4 experts are technical contributors to various worldwide organisations, including the International Hydropower Association (IHA). The IHA's recent Congress meeting in Brazil identified a need for increased urgency in addressing key sustainability challenges relating to:
- water security
- energy security
- climate change
- poverty eradication
Sustainable power from water
Hydropower development is at the intersection of these challenges, offering the potential to both mitigate greenhouse gas emissions and to help advance the adoption of renewable energy sources. Equally important are the environmental and social aspects of water that can be included as part of a clean-energy multipurpose water management infrastructure. By essence, a hydropower installation amasses water and thus makes access to water easier for a greater number of people. The IEC's 2010 White Paper, Coping with the Energy Challenge, cites large-scale hydropower as playing a leading role in renewable energy generation, particularly in large transitional and developing countries, where it will make the biggest contribution towards clean-energy generation.
Considering that the other two major sources of renewable energy, wind and solar, are susceptible to availability fluctuation, hydro facilities with large storage reservoirs can also play an important role in balancing power generation and load, thus helping to maintain the security of electrical systems. The ability to provide these services, coupled with low cost and long life expectancy, make hydropower one of the most durable, flexible, and valuable generation assets on the electric grid.
World contributors to hydroelectricity
Since 1990, global hydropower generation has increased by 50%, with highest absolute growth in China which produced 721 TWh in 2010 – roughly 17% of domestic electricity use. According to new research published by the Worldwatch Institute, the use of hydropower increased more than 5% between 2009 and 2010. In 2010, worldwide hydropower use reached 3427 TWh, just over 16% of global electricity consumption. The technically exploitable potential for hydropower is estimated at more than 16 400 TWh/year with China, Brazil, the US, Canada, and Russia accounting for approximately 52% of world installed hydropower capacity in 2010.
Pumped storage hydro the most technically viable
New energy storage technologies are being developed to compensate for the variations in availability and fluctuation of certain renewable energy resources. As a result, there is much ongoing research and debates as to the relative benefits of various forms of storage.
Of all of the energy storage technologies available, pumped storage hydro is the most established and technically viable. Currently, it is also cost competitive due to the low interest rates available for financing it and the wide array of ancillary benefits it provides to a region through the electrical grid. It is able to achieve one of the highest lifespan efficiency cycles at some of the lowest costs. Interest in pumped storage is increasing, particularly in those regions and countries with the most variable renewable resources and where there is less potential for new installations of traditional hydropower. The vast majority of pumped storage installations are currently found in Europe, Japan, and the US.
Technical committee 4 – Hydraulic turbines
IEC TC4, as one of the earliest IEC TCs, is responsible for hydraulic turbines, with some 14 international Standards and guides published. There are eight different working groups (WGs) actively developing new Standards and maintaining existing ones. TC 4 also works closely with other TCs and with the International Organization for Standardization. It is also in contact with the European Committee for Electrotechnical Standardization; American Society of Mechanical Engineers, involved with field flow measurements in hydro installations; and other regional Standards development organisations.
Among the various TC 4 documents under review is IEC 62256, Hydraulic turbines, storage pumps and pump-turbines – Rehabilitation and performance improvement, a guide developed to assist in identifying, evaluating, and executing rehabilitation and performance improvement projects including life extension options of components and improved future efficiency interventions. These result from progress made in new materials and technology and help account for future budgeting and planning needs. The maintenance team is revising IEC 62256 to include further identification methods and details for life extension planning of turbine components.
Upgrading existing hydropower plant projects and reviewing the lifespan expectancy of their valuable equipment offer further options for cost-effective increases in generation capacity. In the context of renewable energies, the notion of rehabilitation is particularly interesting. Many of the centres already in existence, or used in the past, can be modernised with relatively little additional expenditure, not only to increase production of energy, but also to reduce maintenance costs. Extending plans to also include drinking water or irrigation supplies helps generate additional sources of energy that only have minimal environmental impact.
In addition to the high revenues that can be obtained from clean energy generation, there is also the aspect of low maintenance costs. High performance hydropower equipment can frequently run without interruption for extended periods of time. Thus even the smallest improvements in efficiency over this long lifespan have an important financial impact. Indeed, most of the major components of large turbines and hydro generators return to service after their second overhaul and 70 years of continuous operation. Here, two publications within the remit of TC4 stand out as being important.
- IEC 60193, Hydraulic turbines, storage pumps and pump-turbines – Model acceptance tests, at design stage
- IEC 60041, Field acceptance tests to determine the hydraulic performance of hydraulic turbines, storage pumps, and pump-turbines
Other valuable work is being carried out by WGs involved in areas such as design, installation, and particle erosion, to name but a few.
Since any hydroelectric project is by essence a long-term investment, whether it concerns new construction or the rehabilitation, replacement or upgrading of previous installations, relevant Standards have to be technically irreproachable and aim for the highest levels of performance and durability. By striving for excellence, the future of hydropower looks bright and likely to resist the many reorganisations typical of any highly technical industry.
Benefit from performance improvements
As newer and more technically ambitious hydroelectric installations continue to come into existence, so the long lifespan of the present existing installations also provides additional opportunities to benefit from the research and developments made in the efficiency of hydro equipment technology.
As far as normal wear and tear of hydroelectric equipment is concerned, there are several areas where standardisation plays a major role. One of these is pitting due to cavitation. The specification of new design methods and use of numerically controlled manufacturing tools have virtually eliminated this. However, there are as yet no Standards dealing with abrasion from particle erosion and work is underway on defining erosion rates, hard coating effectiveness versus consequent efficiency drop, erosion guarantee evaluation, and unit availability.
There are other areas that also require attention, such as those of vibration and stability, particularly for plant operators of Francis and pump turbines, both for upgrades and new units. Standards have been updated for specifying and testing speed control systems, and those for unit and plant control systems face rapid and constant evolution, both on the hardware side and in communication protocols.
Another element that influences the need for standardisation is the change in manufacturing, specifically the extended subcontracting of work which was formerly done in-house by the supplier. Globalisation of turbine suppliers and subcontractors means that there are newcomers to the market who are not necessarily as specialised as they were in the past. Standards and guides can only help ensure the quality of the equipment and contribute to making the world a more environmentally friendly and sustainable place.
Today, TC 4 has a total of 32 country members, with 18 Participating (P) countries and 14 Observer (O) countries. Together they account for over 115 active technical experts who contribute to the advancement of IEC hydroelectric Standards and represent most of the major contenders of hydroelectricity in the world, including China, Canada, the US, and the Russian Federation.
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Summarised from the International Electrotechnical Commission's e-tech, January/February 2012.