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Americans win latest round of patent war

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A European patent for variable speed wind turbine technology has been secured by Zond Energy Systems of California, part of American energy giant Enron Corp. A document allowing the US company's controversial application for a patent was issued by the European Patent Office (EPO) in Munich at the end of February, according to public documents now available.

The EPO "Proposal for Granting" came after the organisation unexpectedly cancelled an oral meeting with Zond, now part of Enron Wind Power, in early March at its Munich offices (Windpower Monthly, February 1998). According to the standard procedures of the EPO, Enron Wind Power's patent has been in a "granting phase" since the cancellation in February. During this four month phase, which was due to end on the last day of June, the applicant can respond to the EPO's suggested text of the patent. In this case, the scope of the patent suggested is apparently similar to what had been sought by Zond, according to those who have reviewed the document.

Once the applicant has approved the text, the EPO issues a "Rule 51/6 communication" which covers an exact three month period. During this time the applicant must meet a variety of demands, including a series of payments to cover EPO costs. The patent must also be printed and translated into the languages of the countries in which it will apply. A further administration period follows, usually lasting two months, before the final patent is published in the European Patent Bulletin.

From the publication date there is a period of nine months in which the public and other companies may lodge their opposition to the patent with the EPO. The date when the patent is granted, no later than this November, is crucial. From that moment on, Enron Wind Power can sue other parties to protect its patented technology.

Protest period

The "window" for opposition in the case may well be busy. The EPO's action has astonished observers of the process. "I had thought it was unlikely that they would get it," says one, who has watched the application closely. "I had thought the EPO would not grant that broad a patent, given the prior art that exists. But I suppose they didn't know the prior art."

The Danish wind industry seems less concerned. "Until we have seen the patent document we cannot comment on it," says industry association director Søren Krohn. "There is a lot of strategy in this. It might not be in our interest to object to it. There are many different approaches which can be taken, both by the patent holder and others."

Objections to the patent lodged within the nine month period for protest require the EPO to open an "opposition file" and an "opposition division" is set up consisting of three people, one of whom might be a member of the original examining committee. The opposition procedure takes on average two to two-and-a-half years. The proceedings usually start in written form, but often involve oral presentations at the EPO's Munich office.

Variable speed wind turbines are seen by many to hold the key to large penetrations of wind power on electricity systems because they offer greater versatility and can often meet utility technical criteria for grid stability better than pitch or stall controlled turbines. Variable speed technology can also provide vital reactive power to the grid, instead of drawing it from the grid.

German Enercon, which has sold the most variable speed wind turbines in Europe, seems to be the company most at risk if Enron Wind Power chooses to exercise its patent. As well as owning Zond, Enron Wind also owns Enercon's main rival in Germany, Tacke Windenergie. Germany is the largest market in the world for wind turbines. Enercon's Martina Kuhlmann has previously said that until the final patent is issued -- and Enercon has examined its contents -- the company cannot act.

Other wind turbine companies immediately at risk include Lagerwey and WindMaster in the Netherlands, WindWorld of Denmark, and Windtec in Austria. All sell, or are in the process of developing, wind turbines with variable speed technology.

In 1996, Kenetech Windpower of California successfully used its US patent on variable speed wind turbines to prevent Enercon from selling its rival technology in the US. Kenetech lodged a similar patent application at the EPO in 1992. This application was taken over by Zond soon after Kenetech declared bankruptcy. The full text of Kenetech's US patent is a matter of public record and it is believed that Zond's EPO patent application is very similar in content.

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