A £50m wind turbine factory on the shores of Belfast Lough will be completed by the end of the year.
Last year, Danish energy giant DONG signed off on the deal to make Belfast its hub for building wind turbines.
The 450m quay and 50-acre building space at Belfast Harbour is sited on land reclaimed from the sea in 1960 but kept vacant in anticipation of a major development for more than 50 years.
Dunmurry firm Farrans Construction Ltd was selected as main contractor, providing 150 workers.
When completed in 2013, it is expected that the 'offshore wind logistics terminal' will create 300 jobs. The work, which will require one million tonnes of stone from local quarries, is also helping reap huge rewards for the supply chain.
Work will centre on the construction of a £1.6bn offshore windfarm in the Irish Sea, to be known as 'West of Duddon Sands'.
A Belfast Harbour spokesman said that the work is on course for to meet its completion target.
"Construction work to develop a new terminal for the assembly of offshore wind turbines in Belfast is progressing well and is on schedule for completion in late 2012, becoming operational in early 2013," he said.
"The £50m investment represents the largest ever in Belfast Harbour's 400-year history and has provided a major boost for the Northern Ireland construction and aggregate sectors.
"The development is the first bespoke offshore wind installation and pre-assembly harbour in any UK port with DONG Energy's decision to locate in Belfast Harbour a major vote of confidence in Belfast Harbour's long-term investment strategy.
"Expected to take 750,000 man hours to complete, the terminal will initially support the construction of the West of Duddon Sands offshore wind farm - a joint venture between DONG Energy and ScottishPower Renewables - and the facility will then be utilised by DONG Energy for its future Irish Sea operations."
Some £25bn is expected to be spent in the Irish Sea alone over the next 10 years on renewable energy.
Dansk Olie og Naturgas A/S (DONG) Energy was founded in 1972 to manage resources in the Danish sector of the North Sea. The majority of the company (73%) is owned by the Danish government, and it is the largest power producer in Denmark, responsible for 49% of the country's electricity and 35% of its heat. It also owns facilities in Germany, Sweden and Norway, where it focuses on deep drilling, oil and gas production, and hydro and wind power. DONG has built five of the 10 largest offshore wind farms in the world.