The engineering giant likes the predictability of marine power—which can be "calculated for centuries in advance."
Marine energy has long looked to be a niche area, capable of meeting just a few percent of global power demand. But this seemingly limited energy source is drawing some big players, the latest being Siemens. The German engineering giant boosted its stake this month in Bristol, U.K.-based tidal energy developer Marine Current Turbines from under 10 percent to 45 percent. The attraction, according to Michael Axmann, chief financial officer for Siemens's solar and hydro division, is the predictability of marine power.
Scaling up: This dual-rotor tidal turbine has been feeding up to 1.2 megawatts of power to the Irish grid since 2008. Commercial versions will generate two megawatts.
Solar and wind farm operators struggle to predict tomorrow's output, and bad forecasts can wreak havoc with power transmission planning and market prices. In contrast, the gravitational pull of the moon and sun that controls tidal cycles provides a sure means of anticipating the output from tidal generating stations. Says Axmann.
"Power output of the systems could be calculated for centuries in advance."
The result could be higher revenues. Axmann notes:
"Tidal power is not subject to volatility. This increases the value of the energy produced, and hence makes the business case more reliable for the investor and operator."
Axmann declined to say how much value would be added by that predictability. But he anticipates that, by 2020, marine turbines will deliver power at a cost that's competitive with today's offshore wind farms—in spite of the challenges involved in engineering for underwater operations.
SeaGen - The world's only commercially operational tidal turbine, feeding 10MMh per tide into the UK grid
Marine Current Turbines CEO Andrew Tyler says a combination of cost reductions and government incentives will ensure the profitability of his firm's tidal power parks. He expects a return on investment for the company's first two offshore power parks: a proposed four-turbine array off Scotland's Isle of Skye and a five-turbine array off the northwest coast of Wales.
Cost reductions will come in part from scaling up its dual-rotor units to two megawatts from the 1.2 megawatts generated by its demonstration turbine, which has been producing power in Northern Ireland's Strangford Lough since 2008. Future cost reductions, Tyler says, will come primarily from efficiency in equipment assembly and logistics, drawing on Siemens's expertise in these areas.
Artist's impression pf tje [;ammed SeaGem 10<W ocean wave turbine installation
The company also anticipates incentives in the form of U.K. and Scottish installation grants. The tidal power parks will also provide the company with renewable generation credits, which utilities need to acquire to comply with the U.K.'s renewable power standard. Last month, the U.K. announced plans to boost the credits for wave and tidal energy plants from two to five for every megawatt-hour of electricity generated. In comparison, offshore wind farms will earn two credits, and power stations burning biomass will earn one.
Animation of SeaGen Tidal Wave Turbine Farm
Tyler estimates that his first power parks will produce 15,000 to 20,000 megawatt-hours per year, meaning the tidal turbine arrays could earn £3.75 million ($6 million) in incentive payments annually.Tyler says Siemens's backing will be crucial to raising the £100 million in private investment needed to finance the projects:
"It completely changes their perception about our credibility"
Paris-based Alstom Group, which competes against Siemens in power equipment and high-speed trains, also expects to make a splash in tidal power next year. Alstom is building a one-megawatt demonstration turbine using technology licensed from Canada's Clean Current Power Systems. At a meeting in Bali last month, Phillippe Gilson, Alstom's ocean energy manager, affirmed that Alstom plans to install the 20-meter-tall, fully submersible turbine in Nova Scotia's Bay of Fundy in 2012.
COMMENTARY: Marine Current Tuirbines Ltd is both first mover and world leader in its field. The world's first tidal turbine, tested as long ago as 1994 in Loch Linnhe Scotland, has recently been donated by the Company to the Museum of Scotland. From it have emerged first the 300kW Seaflow turbine installed in May 2003 and decomissioned in October 2009, and more recently the full-scale commercial system known as SeaGen which was installed in May 2008.
SeaGen is by far the largest and most powerful tidal turbine in the world with twin rotors each sweeping over 200 square metres of flow. It also uses the most efficient type of turbine rotors, namely axial flow pitch controlled rotors, the technology of choice in the wind industry. As such SeaGen's rotors can achieve over 48% efficiency over a broad range of current velocities and they also offer complete control over the machine - it can be shut down in less than three seconds even with the current at full flow. More details follow.
Tidal turbines such as those developed by Marine Current Turbines Ltd work much like submerged windmills, but driven by flowing water rather than air. They can be installed in the sea at places with high tidal current velocities, or in places with fast enough continuous ocean currents, to take out copious quantities of energy from these huge volumes of flowing water.
The commercial system under development by MCT is known as “SeaGen” . The prototype is operational in Strangford Narrows, Northern Ireland, and uses twin 16m diameter rotors to develop a rated power of 1.2MW at a current velocity of 2.4m/s. The system is accredited to OFGEM as an official UK generating station and regularly runs at full rated power. It has the capability to deliver about 10MWh per tide, which adds up to 6,000MWh per year. This is approximately the rate of energy capture that a wind turbine of about 2.4MW rated capacity can typically produce. So SeaGen shows that the tides are not only more prodictable than wind but twice as productive.
SeaGen is intended for widespread commercial use and future projects can use variants with twin axial flow rotors of 14m to 20m in diameter (the size depending on local site conditions), each driving a generator via a gearbox much like a hydro-electric turbine or a wind turbine. These turbines have a patented feature by which the rotor blades can be pitched through 180o in order to allow them to operate in bi-direction flows – that is on both the ebb and the flood tides. The twin power units of each system are mounted on wing-like extensions either side of a tubular steel monopile some 3m in diameter and the complete wing with its power units can be raised above sealevel to permit safe and reliable maintenance.
Marine Current Turbines is not the only wave energy startup company. There are dozens of them around the world trying to harness energy from the power of the sea. Click HERE for a comprehensive listing.
Courtesy of an article dated November 14, 2011 appearing in Technology Review
Now this is something amazing. Using nature to provide energy for the common person.
Posted by: Nash Stevens | 11/17/2011 at 01:20 AM