Renewable Energy
Cable routes cleared of boulder hazards E
cosse Subsea Systems (ESS) has completed a £4.7 million boulder clearing and pre-lay trenching
project which it claims has been one of the most successful ever conducted for the wind energy sector. As subcontractor to Siem Offshore
Contractors (SOC), the Banchory-based subsea specialist completed 86 boulder clearing passes followed by 172 first and multi-passes over a 90km route during a 13-week boulder clearing and trenching campaign on the EnBW Baltic 2 offshore wind farm project. The project was on schedule and on
budget and now ESS is looking to secure a frame agreement with SOC for similar works on renewables schemes across Europe.
Several thousand boulders ranging
up to 4m in size were cleared from the individual cable routes and ESS performed 260 individual route passes in varying and sometimes challenging soil conditions. ESS managing director, Mike Wilson, said:
“We created a lot of firsts on EnBW Baltic 2. It was our largest contract to date, our first non-UK trenching workscope and our first project for a German offshore wind farm project. “It couldn’t have gone better and our
client is now convinced that our zero-risk pre-trenching option – where the hard work is done before the cable is present – is the future for cable installation.” Mobilisation on the 86 cable route
workscope started in Gdansk, Poland, with ESS transporting its SCAR ploughing technology by road from Aberdeen. Installation onboard of the SOC operated
DP-2 anchor handling tug and supply vessel AHTS Siem Topaz, including a combined ROV and survey spread, took 48 hours with demobilisation taking place in Sassnitz, Germany, and being completed in 12 hours. ESS deployed a seven-man trenching
Figs 1 and 2. Preparing the SCAR subsea plough for deployment.
crew plus a 10-man ROV and survey personnel, a huge reduction on the 40-strong teams typically used by other cable trenching companies. Mr Wilson added: “Our technology and equipment was easily adaptable for use on the SOC operated vessel and having
our own ROV and survey spreads meant we were able to provide a completely integrated solution. “Performing trenching before the
cable is present removes any risk of cable damage and means we can work faster and use more powerful machinery. Meeting the schedule is hugely important to the client in terms of cost and also brings environmental savings.” EnBW Baltic 2 is an 80 turbine
development 32km north of Rügen island in the German exclusive economic zone of the Baltic Sea and owned by the German utility company EnBW. The 27km² site spans water depths ranging from 20m to 45m LAT and has a wide array of soil conditions from fine sands to glacial tilt with areas of gravels and cobbles with numerous boulders. ●
For more information, visit
www.ecosse-subsea.com
Biogas plants boost green energy in France W
eltec Biopower, together with partner Domaix Energie in Alsace, France, has started
rolling out four agricultural biogas plant projects in France. Apart from agricultural substrates, the
biogas plants, whose construction has already started, will use sludge and food leftovers. This documents the trend that French biogas plants are increasingly fermenting industrial leftovers. Since the introduction of the separation
and utilisation of kitchen waste from large catering establishments in France at the end of 2011, organic waste from schools and company cafeterias must be used for the production of energy.
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www.engineerlive.com Accordingly, Weltec will integrate
hygienisation units in order to utilise the substances of category 3 according to the EU directive. Another common feature concerns the
use of the heat: In all four biogas plants, the residual heat will be used in a digestate dryer in order to reduce the amount of liquid manure and market the dried digestate. Thanks to the heat utilisation concept,
the four biogas plants have an efficiency of at least 70 per cent, enabling the operators to benefit from the heat and power bonus, which is up to EUR0.04/kWh in France. Two 600kW plants are currently being built. The plant in the département of
Charente makes use of a 3,000m³ stainless- steel digester, while the other 600kW plant in Burgundy, central France, will have two digesters with a capacity of 2,000m³ each. The two other plants will have an
electrical output of 190kW and 255kW, respectively. The smaller Weltec biogas plant in
Lorraine comprises a 1,500m³ stainless-steel digester and will be loaded with cattle manure from the operator’s farm as well as whole plant silage and food leftovers. Additionally, the 255kW plant will utilise agro-industrial waste. ●
For more information, visit
www.weltec-biopower.de
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