Debate Rounds (3)
Now I will begin... Because my opponent has started the debate, stating "i think tidal power is the best power..." the burden of proof is on my opponent, but for Round One, I will work with what I have, providing a few arguments of my own and at the same time to rebuke or prove false any of my opponent's statements.
First off, this, from my opponent's previous agrument, states "...becuase it would not harm the envoirment and also it won't hurt the sea life and it prouduces electrity my favorite tidal power is the seagen turbine it powers up to a 1,000 homes and also it can't hurt sea life the 52 feet blades move so slow that sea life can't be harmed and also it moves all the time..."
In his argument, he failed to explain just how these generators don't harm the enviroment, other than "...blades move so slow". I did some reasearch, and this came up first. Check it out:
"Fish may move through sluices safely, but when these are closed, fish will seek out turbines and attempt to swim through them. Also, some fish will be unable to escape the water speed near a turbine and will be sucked through. Even with the most fish-friendly turbine design, fish mortality per pass is approximately 15%."
Hmmm... I didn't mean to burst your bubble or anything, so sorry, but next time you should check your sources. I found this too:
Turbidity (the amount of matter in suspension in the water) decreases as a result of smaller volume of water being exchanged between the basin and the sea. This lets light from the Sun to penetrate the water further, improving conditions for the phytoplankton. The changes propagate up the food chain, causing a general change in the ecosystem.
As a result of less water exchange with the sea, the average salinity inside the basin decreases, also affecting the ecosystem... "Tidal Lagoons" do not suffer from this problem.
Estuaries often have high volume of sediments moving through them, from the rivers to the sea. The introduction of a barrage into an estuary may result in sediment accumulation within the barrage, affecting the ecosystem and also the operation of the barrage."
The installation of SeaGen in Strangford Lough will be carried out by A2SEA A/S of Denmark, one of Europe's leading offshore installation contractors. The SeaGen 1.2MW commercial demonstrator has been developed on the basis of results obtained from SeaFlow, the world's first full-size tidal turbine installed by Marine Current Turbines off Lynmouth Devon in 2003. It has taken the subsequent four years for Marine Current Turbines to design and build SeaGen and secure the necessary environmental and planning consents.
SeaGen is a commercial demonstration project with permission to operate in Strangford Lough for a period of up to 5 years. It is intended as the prototype for commercial applications of the technology that will follow.
Martin Wright, Managing Director of Marine Current Turbines said: "SeaGen's installation is a very significant milestone for both Marine Current Turbines and the emerging marine energy sector. Following from our previous experience with SeaFlow, our 300kW experimental test system installed in 2003 off the north Devon coast we are confident that SeaGen will show that tidal energy can be truly competitive with other forms of power generation. Decentralized tidal current energy is fundamentally predictable and sustainable. It is also environmentally benign."
Commenting on the future prospects for tidal current energy, Martin Wright added: "We will build on the success of SeaGen to develop a commercial tidal farm, of up to 10MW in UK waters, within the next three years. With the right funding and regulatory framework, we believe we can realistically achieve up to 500MW of tidal capacity by 2015 based on this new SeaGen technology."
Recognizing the special marine environment of Strangford Lough, MCT has undertaken a comprehensive environmental monitoring programme. This program is already active and is managed by Royal Haskoning, a leading environmental consultancy, working in partnership with Queen's University Belfast and the St Andrews University Sea Mammals Research Unit. The program is overseen by an independent body, chaired by David Erwin, a former Chief Executive of the Ulster Wildlife Trust.
The A2SEA jack-up barge, "JUMPING JACK", is planning to mobilize from Belfast's Harland & Wolf shipyard, where SeaGen is already complete and waiting, to Strangford Lough on August 20th. It is expected that the drilling of a single pile into the seabed and the installation of the twin-turbine device will take 14 days, with commissioning and power generation to the local grid shortly afterwards.
Martin Huss, Sales & Marketing Director of A2SEA said: "We are delighted to be working with MCT on this important and challenging project and hope it is the start of a long and rewarding relationship as tidal technology enters the market place in the UK."
The blades are designed for bi-directional flow, so that they turn regardless of which way the tide is rushing. They'll spin 10 to 20 times per minute. The company says this is slow enough to allow fish and other sea creatures to get out of the way if they're swimming on through. But it certainly doesn't sound like anything a diver would want to approach.
This Seagen installation may be just the first step. As part of another project, the company is also hoping to install a farm of underwater turbines off Wales that would be capable of powering thousands of homes.
my sorces are from popsci.com and also alternative-energy-news.com
lenorenomore forfeited this round.
Apart from the substantial experience behind its development, SeaGen is more efficient both in the amount of energy it can extract from the current and in cost. This is because it uses a pair of pitch-controlled axial flow rotors, which for good reason are the technology of choice in the closely analogous low-head hydro and wind generator industries. In fact virtually 100% of all commercial sized wind turbines use pitch controlled open axial flow rotors. Many other, sometimes "weird and wonderful", rotor concepts have been tried both as wind turbines and as hydro-turbines but in the end the elegant simplicity and unsurpassed efficiency of the axial flow pitch-controlled rotor has been shown to make it superior in all respects to any other method of kinetic energy conversion. What applied in the fields of hydro and wind power seems unlikely to be significantly different in the field of water current kinetic energy conversion because similar laws of physics apply.
The rotor design also provides the capability for controlling a large power system as the rotor blades may be pitched into a neutral position to stop the turbine gently even at full flow – an essential requirement for any power generation system; by comparison fixed pitch turbines require a powerful brake to stop them and if the brake fails they cannot be stopped.
Moreover SeaGen's rotor blades can be pitched to limit the power to a pre-chosen "rated power" at times when high velocities are experienced; this greatly reduces the loads on the turbine structure, the rotor blades and the power take-off – and reduced and controlled loads translate into reduced costs and safer and more reliable operation. These days no major wind turbine manufacturers use fixed pitch rotors for the aforementioned reasons.
What is more SeaGen's rotor blades can be pitched through 180 degrees so that the rotor can run efficiently in a bi-directional flow (on both the ebb and the flood tides) – this allows high lift/drag ratios to be developed (through using cambered high lift foils) which in turn are essential for high rotor efficiencies. MCT's patented rotor blade pitching system has been shown to permit rotor efficiencies of similar quality to the best in the wind turbine business.
Fixed pitch rotors and rotors in ducts, as have been proposed by others, can never compete effectively for such high levels of efficiency or energy capture as can be gained from conventional pitch-regulated axial-flow rotors. This has been comprehensively demonstrated over several decades by the wind industry under closely analogous flow conditions.
Apart from using the rotor technology of choice, MCT's SeaGen system is mounted on a structure securely seated on the seabed. This makes it easier to maintain and more steadfast in the challenging marine environment.
The technology for placing monopiles at sea is well developed. The patented design of the SeaGen turbine is able to be installed and maintained entirely without the use of costly underwater operations. A unique, and also patented feature of MCT's technology is that the turbines and accompanying power units can be raised bodily up the support pile clear above sea-level to permit access for maintenance from small service vessels. This is an important feature because underwater intervention using divers or ROVs (Remotely Operated Vehicles) is virtually impossible in locations with such strong currents as are needed for effective power generation. The artist's impression indicates a row of turbines such as MCT is planning to install (subject to consents) off the north Anglesey coast and shows one raised for maintenance from a small workboat.
Inexpensive access is particularly important for minimising the risks of running up unexpected maintenance costs.
How do you fix the system so it cannot move? It is often not well understood that the act of taking energy out of a flowing water current generates a major thrust reaction, typically in the order of 100 tonnes per MW, which in turn demands competent foundations. Anchors, relying on gravity and friction with the seabed, and other such seemingly simple solutions are generally inadequate for commercially sized tidal turbines. Perhaps the most difficult engineering problems are the high structural loads to be dealt with and in effect solving the question of "how do you nail it to the floor?" The weakest material to which the turbine is attached is the seabed itself, even if it is rock, so the foundations need to be sized so as not to overstress the seabed and cause the turbine to move or break loose. This is where piles drilled deep into the bedrock of the seabed, as used by MCT are probably the only reliable solution.
Comparisons with other technologies
MCT's SeaGen is the only tidal current turbine world-wide to be ready for deployment in commercial projects. There are many web sites claiming to have developed such technology, but in reality there are very few other designs which have even been tested in the sea, and with one exception these are all small-scale demonstration projects that will need to be scaled up significantly before they could be capable of commercially viable operation. This is because the fixed overhead costs of an offshore project are high and therefore a large system is essential so as to collect enough energy to cover its costs and make a profit. Just as no wind farm developer these days will consider using windturbines of less than 1MW similarly it is uneconomic to consider using very small tidal turbines.
These devices can also be compared in terms of the rotor swept area (or where a duct is used, the entry cross sectional area of the duct) since the swept area or entry area governs the cross-section of current energy that can be captured. Given devices of similar efficiency, the energy capture at any given site is proportional to swept area just as solar panels deliver in proportion to their array area and windturbines in proportion to their rotor area. MCT's economic analysis suggests that at least 300 square meters of rotor area are about the minimum that could realistically generate commercially competitive power; this is regardless of the kind of technology. For reference, MCT's SeaGen system with 16m rotors has a swept area of 402 square meters. Most of the few competitors who have demonstrated systems in the sea have devices with rotor diameters in the order of 5 to 9m, which would be 15 to about 60 square meters.
lenorenomore forfeited this round.
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Vote Placed by lenorenomore 7 years ago
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