* Low interest rates not translating into cheap loans
* EU austerity measures increase political risk
* Emerging offshore sector can add capacity rapidly (Adds detail on offshore)
BRUSSELS, Sept 27 (Reuters) - Installed EU wind capacity has reached the 100 gigawatt mark - the equivalent of power generated from 39 nuclear plants or a train of coal stretching from Buenos Aires to Brussels - but financial risk threatens growth, industry body EWEA said.
"We have just in the past couple of weeks passed 100 gigawatts of total installed capacity in Europe," Christian Kjaer, CEO of the European Wind Energy Association, told a small group of reporters.
"We have been adding about 10 gigawatts per year for a couple of years and it will be around the same this year," he added. "Whether that will continue in 2013, I can't say. There's too much political uncertainty."
The capital-intensive industry faces a challenge after banks shortened the maturity of loans and increased costs for lenders, meaning wind power has not benefited from low interest rates, Kjaer said.
It is seeking long-term investors, including pension funds and insurers to make up the shortfall.
At the same time, the EU economic crisis means austerity measures have led to abrupt changes in government policies on funding for renewable energy, increasing political risk across the bloc.
The growth in wind power this year has included 400 megawatts (MW) developed by DONG Energy, off the coast of Denmark, and 48 MW developed by EDF Energies Nouvelles Polska in Poland, EWEA said.
Most of the overall 100 gigawatts so far are onshore wind.
The emerging, huge-scale offshore sector has the potential to deliver the next 100 gigawatts much faster, if it can overcome its much bigger financing and grid issues.
Industry cost estimates for installing offshore are 3-4 million euros per megawatt, compared with around 1.2-1.4 million euros for onshore.
To help spur future investment, EWEA wants the European Commission and member states to agree on a policy beyond the existing target of a 20 percent share of energy from renewable sources by 2020. It also wants to ensure major investment in the European grid, as part of a single energy market, in which supplies can easily cross national borders.
"The biggest potential show stopper for us is we need better infrastructure," Kjaer said.
The Commission has said it wants the single energy market across the European Union to be completed by 2014, but it has also said it is not on track to meet that deadline.
It is expected to publish a document in the coming weeks that will lay out strategies to accelerate progress and that discussions on the multi-annual EU budget include debate on earmarking funds for grid infrastructure that benefit more than one nation. (Editing by James Jukwey)