In some ways, being a marine renewable technology is kind of like being Ginger Rogers. Just as Ginger Rogers ably executed the same steps as dance partner Fred Astaire but backwards, so too, marine renewables technologies must address siting and environmental and operational challenges just like conventional energy projects and on top of all of that, figure out how to get the power transported to, and interconnected with the onshore grid in an economic and efficient manner.
As marine renewables move towards more widespread commercial use, resolving transmission issues assumes increased urgency. As described at the Environmental Research Web , now that the U.K. has 600 MW of offshore wind and more on the way, there’s a debate over whether companies should construct their own transmission or cooperate on a uniform grid.
Thus far, the ad hoc approach has prevailed, with each wind company planning its own parallel and expensive transmission lines back to shore. Indeed, Ofgem, which regulates energy in the U.K., supports development of transmission by individual arrangements had pointed out that the advantage of the individual approach is that companies can proceed individually and avoid delays caused by third parties.
However, the downside is that multiple transmission lines are costly and potentially duplicative. Moreover, some contend that individual transmission arrangements will not suffice to enable the U.K. to reach its target of 33 gigawatts of offshore wind by 2020. Green MEP Claude Turmes, the European Parliament’s lead negotiator for the Renewable Energy Directive, has said that the using a competitive approach to bring cable to shore delays development in the long run and that a networked approach is preferable:
The UK approach, imposed by Ofgem, for competitive bids for chunks of 40 km cables for offshore, is not very productive, to put it mildly. Much better is the Danish model and the German model, where you have one system operator, the Danish grid company or the regional grid operator in Germany. This company is in charge of delivering the cable to the offshore platform where you then have to plug in your wind turbine. You have to get rid of Ofgem’s over-liberalised idea, by which you can have competition on grid installation.
A recent New York Times piece discusses another transmission-related topic: whether to transport power through alternating current (AC) or direct current (DC). Though the nation’s electric system is built on AC, DC is gaining popularity to to the expansion of renewables like wind and solar. Both the 175 mile Hydro-Quebec line, which will transport hydropower from Canada to New Hampshire and a proposed underwater cable that will carry wind from Maine to Boston will use DC. Steve Holliday, CEOs of National Grid told the Times that DC will become the choice for delivering power from large offshore wind farms, because “anything beyond 6 or 7 miles will be DC.”
The article summarizes the pros and cons of a DC line:
“There are three advantages to direct current,” Ed Krapels [CEO of Anbaric Holdings LLC] said. The line losses [of electric power in transit] are very small, particularly in a point-to-point situation. It’s controllable and that adds a lot of benefits if you’re injecting power into a particular market.” DC lines can be built with somewhat shorter towers, and they do not raise the concerns about risks from electromagnetic radiation that occur with AC transmission lines, he added.
DC’s drawback is cost. When a DC line connects into the AC grid, conversion stations must be built to switch the power to DC and then back again at the other end. The stations cost $50 million or more, Krapels said.
If the line is long enough, then the advantages of DC transmission become significant, said Rich Logan, technology director for power systems at the Electric Power Research Institute in Palo Alto, Calif. “There is a break-even point, and people argue about where that is. It’s in the ballpark of 100 miles.
While it’s important to track these transmission issues, my view is that marine renewables projects won’t have to grapple with them for another few years. Power from smaller, pre-commercial marine renewables projects can be readily incorporated into electric grids without much system impact. Further, given that early stage wave projects are being sited closer to shore (most are now slated for state submerged lands less than three miles from shore to avoid remaining uncertainty regarding projects on the OCS), transmission costs won’t run as high as those for offshore wind projects situated five, seven or as far as twelve miles offshore. By the time marine renewables reach full blown commercialization and requires added transmission capacity, I expect that transmission questions such as AC versus DC or individual lines versus a network or multi-use merchant line will have been worked out by the offshore wind industry.
My name is Carolyn Elefant, owner of the Law Offices of Carolyn Elefant in Washington D.C. and I do FERC Fights. Whether a matter requires an appeal of a FERC ruling in federal circuit court, a request for rehearing, a vigorous defense in an enforcement action, the pursuit of a refund or general protection of interests in a FERC proceeding, I act as a tenacious, thorough and persistent advocate for my clients.
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