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Home , Osmotic power

RRenewableenewable energyenergy booms!booms!

By James Chater

Thermal power plant with parabolic trough technology. Photo: Abengoa KeywordsP OWER GENERATION: Ball Valves • CSP • Materials • Water

little , its wind resources The next few years will be crucial for . Solar power are abundant and increasing. For a few is progressing at an exponential rate, and wind and tidal are not hours in 2011, the country’s electricity far behind. Progress is being driven by not only by government supply was fuelled entirely by renewables! intervention but also by innovation leading to falling prices. Several Spain generates a large amount of its technological breakthroughs are occurring, and this will continue. electricity from wind and solar power and This article surveys solar and (no disrespect meant to is a world leader in Concentrated Solar wind, hydro, geothermal, or ) and fi nds plenty of Power (CSP). resourcefulness and creativity. All in all, an exciting time for suppliers In comparison with these European of equipment and materials to green energy projects. countries, many would accuse the United States of having dragged its feet. Background capacity of 17 GW of solar power installed, Nevertheless, US carbon pollution is Two recent warnings from energy think- the equivalent of 17 plants! down, and on 25 June 2013 President tanks are worth setting side by side. First, We have reached the point where increased Obama announced a plan to cut carbon the IAE has warned that world needs installation rates and falling prices are emissions. Public land has been released USD 48 trillion in investment to meet feeding off one another. for solar and wind projects, agencies have its energy needs up to 2035. Second, True, governments are skewing the been ordered to increase their share of Carbon Tracker and the LSE have stated playing fi eld with tax breaks, loan renewables consumption, electric cars are that known fossil fuel reserves already far guarantees, subsidies and feed-in tariffs. to be increased, and training in the solar exceed the carbon budget to avoid global This is nowhere truer than in Germany, power job sector is to be fi nanced. warming of 2°C, and that a fossil fuel where traditional utilities (E.ON, RWE) bubble is developing as companies pursue are losing out. A telling sign of the times is unburnable carbon. If we accept these that the French oil and gas giant Total just two premises, it is clear that the future lies bought SunPower for USD 1.4 billion. with zero-carbon energy sources. And the future is already here. Depending Renewables by region on such variables as solar power or wind Germany, with its Energiewende (energy power at any given moment, renewables turning), is the undisputed world leader can already generate power cheaper that in renewable energy. The German fossil fuels or nuclear. This is especially government is aiming for 80% renewables Kaplan turbine at the workshop in Heidenheim, true of solar power, where innovation and by 2050, and with solar power able to Germany. Photo: Voith increasing economies of scale are causing satisfy as much as 40% of , it The United States is not the only country prices to plummet. And in terms of speed looks so far as if this goal will be achieved. seeking to transform its energy policies. of installation, solar is beating nuclear hands In the process, it is massively reducing its North of the US border, British Columbia down. In 2013, the world saw an additional greenhouse gas emissions. has passed the BC Green Energy Plan in Not to be outdone by its neighbour, order to achieve a 100% carbon-neutral Denmark has set a target for 100% power grid. In China solar power is renewables by 2050, to include not increasing so fast that it is expected to only power generation but also heating overtake as early as 2016. Even Saudi and transport. For 2020 the target is Arabia has espoused solar: last year, it to generate 35% of electricity from launched a plan to install 41 GW of solar renewables. capacity to serve more than 30% of the Spain and Portugal are not far behind. country’s electricity supply by 2032. As yet PV plant by Isofon in Morocco. Although Portugal generates surprisingly there are few installations, but with the country’s oil reserves fast dwindling, this is Did you know? likely to change. Saudi Aramco is investing • Renewable energy capacity grew 8% in 2011, producing 20.3% of electricity. in several small projects. • In 2000, the world had 1.4 GW of installed solar capacity. By the end of 2013 In Europe, North Africa and the Middle this had grown to 40.7GW, up 2,752%. East, several wind and solar projects • Germany has 75% of installed solar capacity world-wide. are in the offi ng thanks to the of • A solar panel cost USD 60 per watt in the mid 1970s. Today the cost is USD the Desertec Foundation. For the time 1.50 per watt. being, Desertec is focusing on creating • Solar installations are growing by 65% per year. • IKEA has started selling solar panels in its UK stores. the conditions for developing renewable projects in Morocco and Tunisia. It

4 October 2014 www.valve-world.net P OWER GENERATION has been estimated that the world’s deserts receive as much energy from the sun in six hours as the world requires in one year.

Limitations The benefi ts of renewables are obvious, but what about the shortcomings? The main one is probably the bottleneck Gemasolar plant, owned by Torresol Energy. Photo © Torresol Energy Investments, S.A. Heliosdtats (turning mirrors) refl ect the suns rays onto a receiver on the tower. caused by limited supply of super- conductive materials (supermagnets) to absorb; anything higher, and the grid In CSP, mirrors or lenses concentrate such as neodymium and other rare system would need to be transformed. the sun’s rays. The concentrated light is earths. Another is the skills shortage: Grid integration remains a major challenge converted into heat, which drives a turbine as house owners have learnt to their that is only just beginning to be addressed. to produce electricity. The medium used cost, not everyone who claims to be to transfer and store the heat is molten able to fi t solar panels correctly and Solar salt. Heat can be stored for up to 15 hours safely can actually do so! Solar power falls into three main types: without any solar feed, allowing a solar water heating/cooling, photovoltaic (solar plant to run both day and night. Examples panels) and CSP. include Crescent Dunes, Nevada, and Of these water heating is by far the largest Gemasolar, near Seville. The medium of sector, and China is the largest user. It molten salt requires control valves, solenoid provides ample opportunities for supplies valves of special materials to withstand the of 300- and 400-series stainless steels and high temperatures and steam. of duplex grades. Weather proofi ng and The solar sector is bristling with the possibility of achieving thin gauges for innovation. For instance, NREL has aesthetic reasons are two factors that often invented a black silicon that can be Power-to-gas unit, Falkenhagen, Germany. infl uence the choice of stainless steel. used to coat solar cells to increase the Photo: E.ON Stainless steel is used for inner and outer absorption of sunlight. Another idea is Another challenge is storage. Renewables shell of water tanks in direct thermosiphon to instal solar panels in public spaces are often viewed as a “top-up” energy systems; in the heat exchangers of indirect such as roads, pavements, car parks and source because the sun does not shine pressurized systems; for absorbers that playgrounds. Additional features could nor the wind blow all the time; therefore transfer thermal energy to the fl uid; for include heating elements to melt snow we still need more traditional sources of glazed cushion absorbers; for the frames; and ice, LEDs to make road lines and energy. However, the industry is gradually for the cushion absorbers of unglazed signage, and an attached cable corridor. turning the tables on this argument. CSP roofi ng panels. solar plants allow storage of solar heat Photovoltaic is a for up to 15 hours. E.ON is engaged smaller sector, but on a project, P2G (power-to-gas), that fast-growing: between uses wind or solar power to transform 2009 and 2011 water into via electrolysis; this the sector almost hydrogen is then injected into the gas doubled in size. In network. Another way to capture energy PV panels, fasteners is to store it as heat. The British fi rm are usually made of Isentropic is developing PHES (pumped- stainless steel, even heat electricity storage), an ingenious when the frames technology which not only stores energy are made of another as heat but exploits the temperature material. Types 304 difference between two chambers to and 316L are used generate more electricity. on the substrata that Another challenge is posed by the support the cells, on The SeaGen installation in the strait of Strangford Lough, Northern Ireland, fl uctuations in power load resulting from fasteners, and on the uses tidal forces to generate electrcity with the aid of two axial-fl ow turbines with a combined capacity of 1.2 MW. Two underwater rotors attached to a the intermittent nature of solar, wind and joints with which the tower structure drive the marine current turbine. The twin rotors turn with the tidal (Variable Renewable Energy or VRE). panels are welded tidal current and optimally track the fl ow thanks to their 180-degree-pitch Fluctuations of 5-10% are relatively easy together. blades. Photo: Siemens

www.valve-world.net October 2014 5 P OWER GENERATION

Solar energy is synergistic with other industries such as water treatment. Desalination projects are often fueled by solar power. A sophisticated example is Qatar’s Sahara Forest Project, which exploits sea water to produce electricity and grow crops. Saltwater cools the greenhouses, while steam-driven turbines desalinate the water used to irrigate crops. Electricity is produced by a CSP plant.

Ocean energy Energy from waves and tidal/ocean currents is at an earlier phase of development than wind or solar. The potential is vast and still relatively untapped. Ways of harnessing the oceans’ energy include wave energy conversion; tidal lagoons and barrages that capture The Invanpah installation in the Mojave desert, California, said to be the largest in the the energy of rising and falling tides; and world, became operational in early 2014. Photo: NRG Solar turbines that capture the kinetic energy of tidal currents. facility is located. Among the participants turbine. Statkraft’s osmotic power plant Tidal energy has an advantage not are Ireland’s OpenHydro, the UK’s Tidal in Tofte, , has been running since shared by wind, or solar: it Generation and Atlantis Resources. The 2009. Progress has been held up because is predictable and consistent. Also the UK also has one tidal lagoon, at Swansea no membrane had been specifi cally turbines used have smaller rotors than Bay, Wales, and more are envisaged. designed for the application. Now, those used in wind. They can therefore Ocean energy provides plenty of scope however, French researchers have invented be bunched closer together, resulting in a for innovation. For instance, energy is nanotube membranes made of boron smaller environmental footprint. now being generated by the collision nitride that are thousands of times more The seas off the UK boast many of the of and freshwater. In osmotic effi cient because their surface structure can best sites in the world for tidal energy. power, the energy is derived from the create stronger electrical charges. The UK’s tidal power resource probably difference in salt concentration between Material selection in ocean energy will be exceeds 10GW, about half of Europe’s seawater and river water. The two types driven by the corrosive action of seawater tidal energy capacity. It is thought that of water are funneled into separate and by the need to keep components free Pentland Firth, near the Orkney Islands, membranes divided by a semi-permeable of biological fouling. It is therefore likely could one day provide half of Scotland’s membrane. The salt molecules in the that large amounts of stainless steel valves electricity. It is here that the European seawater then pull the freshwater through will be used as well as check valves to Center (EMEC) testing the membrane. Pressure builds, driving a rectify the fl ow.

Sources Our thanks to Nigel Ward of the Nickel Institute for providing us with copies of Gary Coates, “Emerging demand for nickel in renewable energy” and Richard Matheson, “Emerging markets for nickel and stainless steel in the 21st century”. Other sources include: www. madehow.com/Volume-1/Wind- Turbine.html; “Stainless steel in solar energy use” (published by the ISSF); “Pumping heat”, The Economist, 7 June 2014, p. 5; Wikipedia. Statkraft’s osmotic power prototype at Tofte in Hurum, Norway.

6 October 2014 www.valve-world.net