Within the space of a year, global installed capacity rose by an unprecedented 44.8 gigawatts (GW) to just under 282.6 GW – or by 48.4 GW to 280 GW, depending on which statistics you believe. The figures come from the Global Wind Energy Council (GWEC) and market-research institute Bloomberg New Energy Finance (BNEF) respectively. Both say that they only included turbines which were actually connected to the grid over the course of the past year. However, BNEF made two exceptions that probably led to the significant eight-percent difference between the two figures for new installations: firstly, it included all installed turbines in China, even those not yet connected to the grid, as these were the data available. Secondly, it counted projects which had been partially completed in the previous year. “For example, if a 100-megawatt (MW) project was half-completed in December 2011 and the installation was finished in January 2012, most wind-energy associations would count 50 MW for each year – but the whole 100 MW would appear in our statistics for 2012,” explains Justin Wu, head of wind-energy research at BNEF.
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The inconsistent calculation methods are also a hot topic for the Paris-based international Renewable Energy Policy Network for the 21st Century (REN21). “Different organisations use different methods,” says executive secretary Christine Lins. “In some studies, the final figure is based on the number of turbines delivered, while others use the installed or grid-connected turbines as a basis.” Lins says that REN21 is now proceeding to combine the varying figures in its own publications, in an effort to provide readers with a comprehensive overview. The Renewables Global Status Report for example provides an estimate for installed capacity, and then cites the exact figures from individual analyses in the footnotes at the end of the study. “These divergent results are confusing for policy makers. But what is ultimately crucial is that the strong growth trend in the field of renewables is made clear – and this does not depend on the digit in the last decimal place,” says Lins.
This is an abridged version of the article – the complete text is available in issue 4/2013 of new energy.