Electricity fastest growing energy source; renewables more cost-effective
According to IEA (International Energy Agency) data, electricity has been the world's fastest-growing form of end-use energy consumption in the past four decades. It increased by 246 % between 1973 and 2008, whilst overall energy consumption from all sources went up by 31 %
Where production is concerned, the energy payback – that is the ratio of total energy produced during a system’s normal life cycle, divided by the energy required to build, maintain and fuel it – is much higher for electricity generated from renewable sources than that produced using fossil fuels. Hydropower achieves ratios of 170 – 267, assuming a lifespan of 100 years, the return for large wind turbines is 34, whilst fossil fuels have energy payback ratios of between 1,6 and 7.
Water was a source of energy long before its power was harnessed to produce electricity. Watermills and waterwheels have been used since ancient times in many parts of the world, initially for irrigation, then to mill grain and cut wood and stone, and later to power machinery in mining and other industries.
Hydropower was first used to produce electricity in the early 1880s. By 1889, 200 electric plants in the US used water power for some or all of the electricity they generated. Today, hydroelectricity forms the basis of around 16 % of global electricity production and accounts for some 85 % of the total output from renewable sources; most of the production is from large-scale systems.
As many countries are reassessing, curtailing or even cancelling their nuclear power projects, hydropower’s share of electricity generation is bound to increase significantly given the huge untapped resources of water that exist. Some countries, such as Norway and Brazil, already derive the vast majority of their electricity from hydropower (around 99 % and 85 % respectively).
IEC TC 4: Hydraulic turbines, established in 1913, was one of the very first IEC TCs. It is “responsible for the preparation, periodic review and updating of standards and technical reports covering the design, manufacturing and rehabilitation, commissioning, testing and operation of hydraulic machines including turbines, storage pumps and pump-turbines of all types as well as related equipment.”
Its Chairman Elect, Jean-Paul Rigg, outlined for e-tech some of the challenges that face the sector as well as the opportunities it offers.
"Generating equipment used in hydroelectric installations is a mature technology, achieving efficiency rates of 93 % or even more," Rigg said. "Recent improvements have concerned materials, turbines, bearings, lubricants and instrumentation to ensure the longest possible lifespan of equipment and optimize maintenance," he added. Initial construction costs are high, but installations last much longer than is the case for other power-generating systems.
Small is powerful
Mentions of hydroelectricity invoke images of large dams and of massive and costly installations. The huge potential of smaller installations is often overlooked.
Small hydro systems may offer attractive alternatives where the construction of dams proves impossible, impractical or too costly. They can provide electricity for centralized or isolated grids as well as for off-grid power supplies.
The generally accepted definition of SHP (Small Hydro Power) systems includes micro (5 to 100 kW), mini (100 kW to 1 MW) and small (1 to 50 MW) projects that can be run-of-river or reservoir-based. They are reliable, have minimal operating costs, a small environmental impact and use scaled-down versions of existing large hydro turbines.
China offers a striking illustration of the potential of small hydro systems, Rigg told e-tech. A survey of SHP development by the Hangzhou International Center on Small Hydro Power, which describes the three phases of this development, confirms this.
The first phase (1950s-1970s) saw SHP being used mainly for domestic lighting. In 1949 there were only 52 SHP stations, by the end of 1960 the number had reached 8 975 – most with a very small installed capacity, 28 kW on average (for a total capacity of 252 MW).
The second phase (1980s-1990s) saw SHP being installed to alleviate poverty in poor areas. By the end of 1996, 45 174 SHP stations were in operation, with an installed capacity of 19,2 GW, representing 34.5 % of China's total hydropower capacity.
The third phase of China’s SHP plan was launched in the early 2000s; its declared aim was to introduce an ecological protection programme to replace firewood with SHP. Further expansion is possible as the exploitable SHP potential of the country is estimated at 120 GW. Many other countries in Asia and Latin America also have a significant SHP potential.
From rivers to the sea…
Electricity production from water resources is not limited to inland lakes and waterways, but extends to the marine environment too. Research into harnessing the energy from waves, tidal and water currents has been on-going for over 30 years, yet the technologies developed to install systems are still at an early stage.
The IEC established TC 114: Marine energy – Wave, tidal and other water current converters, in 2007. The scope of this TC is to prepare international standards for marine energy conversion systems and to ensure that the technologies employed have a low environmental impact in highly sensitive marine locations.
The future is bright, the future is sunny…
According to research published by the IEA in September 2011, solar energy from PV (photovoltaic) systems and CSP (Concentrated Solar Power) sources could provide the bulk of the world’s power by 2060. Most heating and transport applications could switch their power source from fossil fuels to electric power within 50 years.
CSP systems are employed in solar thermal electric plants to produce electricity. Reflective material is used to concentrate the sun's heat which then drives steam or gas turbines, or other engines, to produce electricity. The systems offer good predictability and reliability of production as installations are located in areas with high daily levels of sunlight. They also benefit from efficient storage and backup possibilities, are cost-competitive compared with other renewables and offer potential for significant technological progress.
After more than 25 years of testing, CSP has moved from a research phase to industrial deployment. To reflect this development, the IEC established TC 117: Solar thermal electric plants, in 2011.
Going with the wind
Like water, wind has been used as a source of energy from ancient times, to power ships, to grind grain in windmills, or to pump water. The introduction of small wind turbines to pump water and produce electricity for a home or small cluster of houses dates back to the late 19th century. The modern wind power sector started in the early 1980s, with turbines that would be considered small by today's standards (20-30 kW each). Work is currently under way on 10 MW turbines and commercial wind farms are now installed in some 80 countries.
IEC TC 88: wind turbines, was established in 1987. Its scope is "to prepare International Standards for wind turbines that convert wind energy into electrical energy". Indications of the global potential of wind energy can be deducted from an IEA 2010 reference scenario for wind power. It forecasts capacities of 415 GW for 2020 and 573 GW for 2030 (from 185 GW in 2010).
Wind turbines may also be adapted to the landscape. In Japan, for instance, wind turbines with tilting heads are being installed in mountainous regions to enable them to benefit from different wind directions on slopes. Another example of technological development, the "wind lens" aerodynamic innovation being developed by Japan's Kyushu University, is said to triple the output of a typical wind turbine, making it less costly than electricity from nuclear power.
Wind power generation is not limited to large installations with dozens of huge wind turbines spinning slowly in land-based or offshore wind farms. To circumvent the environmental and physical limitations of large wind turbines, smaller systems that are often unobtrusive, such as vertical axis wind turbines, have been developed to fit in urban environments.
One of the shortcomings of solar or wind as renewable energies is the unpredictability of their output, which requires regulation. Hydropower has the ability to deliver power on demand and at very short notice, enabling power production to be matched to supply requirements.
The IEC and its TCs will help renewable energies to expand rapidly, ensure that they complement each other and integrate seamlessly into the future electricity production mix.