* Dutch aim to reach 4,500 MW offshore wind capacity by 2023
* Shell, Eneco, van Oord NV in bid consortium
* Germany teams up with Macquarie Capital to bid
* Vattenfall submits bid alone (Updates throughout)
By Karolin Schaps
LONDON, May 13 (Reuters) - Some of Europe's biggest energy companies, including Shell RDSa.L , RWE RWEG.DE and Vattenfall VATN.UL , are competing in a Dutch offshore wind tender seen as one of the biggest green energy projects on offer in Europe this year.
The Dutch government has an ambitious target to more than quadruple its offshore wind energy capacity by 2023 to lower climate-harming carbon emissions from energy production.
Many other European governments lack a clear framework to deliver renewable energy projects after 2020, making the Dutch tender an attractive one for investors.
In a first round, the government has offered two offshore wind sites at Borssele that can each house wind farms with a capacity of 350 megawatts (MW).
A second tender for two further sites at Borssele will close in September, making the entire project of 1,370 MW one of the biggest European offshore wind tenders in recent years. A fifth site of 20 MW is set reserved for innovation projects.
Anglo-Dutch oil major Shell in partnership with Dutch energy supplier Enerco ENECO.UL and contractor Van Oord NV. German utility has found a co-investor in Macquarie Capital MQG.AX , while Swedish utility Vattenfall has announced a bid on its own. media have named Denmark's Dong Energy IPO-DONG.CO as another potential bidder.
Dong Energy declined to comment but said the Dutch market was interesting because it is a consistent programme with five tenders.
The Netherlands has a yearly offshore wind tender programme in place out to 2019 that aims to push installed capacity to 4,500 MW by 2023.
Offshore wind energy is one of the most potent forms of renewable energy as technological advances have allowed developers to build offshore wind farms bigger in capacity than a small gas-fired power plant.
However, constructing these huge projects in treacherous conditions and the relative infancy of the industry means it is one of the most expensive forms of energy to build.