Germany’s Federal Government committed itself to cut its greenhouse gas emission by 40 % compared to the 1990 baseline levels by 2020, if the European Union Member States agree to a 30 % reduction of European emissions over the same period of time. A comprehensive National “Integrated Energy and Climate Programme” has the potential to bring Germany very close to this goal by achieving a reduction of at least 36 % according to independent studies. Key elements of this programme are amongst others:
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Renewable Energy Sources Act with the goal to increase the share of renewables in the electricity sector from the current level of at least 14% to 25-30% in 2020
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Amendment to the Combined Heat and Power Act with the goal to double the share of high-efficiency Combined Heat and Power (CHP) plants in electricity production by 2020 from the current level of around 12% to around 25%
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Renewable Energies Heat Act with the goal to increase the share of renewable energies in heat provision to 14% by 2020
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Actions for grid expansion in a package of measures to improve the integration of renewables into the grid. The Energy Grid Expansion Act includes a bundled approval procedure for undersea cables connecting offshore wind turbines when new grid construction is undertaken. (IECP Action 2)
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Several actions towards energy saving in the transport and building sectors
In the context with the amendment of the Renewable Energy Sources Act, a new regulation on the demarcation of areas for specific uses at sea within the German exclusive economic zone (EEZ) of the North and Baltic sea, in particular offshore wind energy, came into force in 2009. It reflects the government strategy for offshore wind energy which aims for the installation of wind turbines with a combined capacity of up to 25,000 MW by 2030. Spatial planning includes the designation of priority areas. The legal impact of this status is that any other uses that are not compatible with the designated priority must be disallowed or denied authorisation, thereby ring-fencing potential locations for offshore wind farms. To permit a flexible response to research that remains to be conducted on offshore wind energy use, these demarcations will initially only secure locations for a first tranche (with a total capacity of approx. 10,000 MW). A decision will have to be taken in the medium term as to whether any further priority areas are to be designated and, if so, where, on the basis of an amended or new plan, so that the government’s target of 25,000 MW can be assigned within the appropriate corridor.
In August 2012 the German government adopted the draft for the Third Act Revising the Legislation Governing the Energy Sector. The new legislation aims to speed up the expansion of offshore wind farms. The major focus is on a system change towards a consistent and efficient offshore grid expansion by introducing a binding offshore grid development plan. This will improve coordination of grid connections and offshore wind farms. In addition, a compensation regulation for the construction and operation of grid connections to offshore wind farms will be introduced.
Currently, there are no explicit plans to include wave energy into spatial planning but a study launched by the National Government identified no issues in the legislation which would prevent wave energy projects from receiving approval.
A feed-in tariff for electricity from wave and tidal energy similar to the tariff for small hydropower has been available under the Renewable Energy Act since 2005. These figures were raised in 2009 to 11.67/kWh for power plants below 500 kW and €0.0865/kWh up to 5 MW.
In the public sector, around 15 R&D institutes and universities are involved into developing wave, tidal current and osmotic power mainly in the framework of European research projects. The National funding in the framework of the national energy research programme for renewable energies was approximately €160 million in 2011. This programme is open to ocean energy research. Up to now, six technology projects related to the development of components and concepts for tidal turbines and wave energy components have been funded by the federal Environment Ministry (BMU) with a total amount of around €7 million.
The first two projects operating from 2001 to 2008 were related to the development of a tidal turbine concept and components. Fraunhofer IWES (former ISET) and LTI Power Systems developed a pitch system, the dynamic simulation, control engineering and new drive train concepts for marine current turbines, such as the British Seagen concept, which was successfully installed in 2008. Siemens acquired the complete shareholding of MCT in 2012, which is now operated as a Siemens business under the Siemens Solar & Hydro Division. With this, tidal turbines have become a part of the Siemens energy technology portfolio. There are great expectation about the realisation of the first two farm projects namely, the 8-MW-project Kyle Rhea in Scotlandand the 10-MW farm at the Anglesey Skerries in Wales. These sites have been leased by The Crown Estate.
From 2008 to 2011 another public funded project was executed by Voith Hydro Ocean Technologies GmbH & Co. KG in cooperation with Loher GmbH for the development of a tidal turbine concept. It is based on a fully submerged horizontal turbine equipped with a variable speed direct drive permanent magnet generator and symmetrically shaped fixed blades which allow the operation in two opposite flow directions. A first 110 kW pilot installation has been installed within 2011 at a site off the coast of South Korea near the island of Jindo. This test facility was built as a 1:3 scale model and is used primarily to demonstrate the new technology developments under real operating conditions. The turbine has a rotor diameter of 5.3 m, and achieves a rated capacity of 110 kW with a current speed of 2.9 m/s. The test power plant fully met the expectations of Voith’s engineers. The calculated power curves have been confirmed. In addition, the system is able to keep the turbine running at the optimum power generation point at all times, even in the exceptionally turbulent currents that occur at this location.
The Jindo power plant stands on a gravity base foundation due solely to its intrinsic weight. For recovery during maintenance, a special recovery module on a drive chain slides down to the turbine nacelle, grasps it from below and then lifts it out of the gravity structure. The nacelle is then lifted by winding up the guide chains to the water surface.
A second device with 1 MW capacity is planned to be installed at the European Marine Energy Centre (EMEC) for testing with funding from the UK Marine Renewables Proving Fund (MRPF). The construction and installation of the full-size machine was the consequent continuation of Voith’s test program. It allows the low-maintenance current turbine systems to be developed in a commercial size. With the exception of a number of small modifications, the EMEC turbine is basically an up-scaled version of the system in Jindo. The simplicity and sturdiness of the optimized system has been consistently maintained. The turbine reaches its rated capacity of 1 MW at a current speed of 2.9 m/s. It has a rotor diameter of 16 m. Unlike the Jindo turbine, the test system is mounted on to a monopile drilled into the seabed. The turbine rests under its own weight on the support structure and is installed and removed with the help of crane ships.
Voith Hydro Ocean Current Technologies, Heidenheim, is a Center of Competence for the development of ocean current power stations. Voith Hydro Ocean Current Technologies is an 80:20 joint venture with the RWE Innogy Venture Capital Fund I.
Voith Hydro Wavegen in Inverness, Scotland is a “Center of Competence” in wave power, driving forward research and development in wave power systems. Voith Hydro Wavegen focuses on the conversion of wave energy using the principle of the oscillating water column (OWC). In the year 2000, the 250 kW trial system Limpet was brought into service on Islay at the Scottish west coast, where it has been generating electricity and feeding it into the network ever since. Limpet is the only wave-powered plant worldwide to have continually produced power over the past 10 years, feeding it into the network on the Isle of Islay. Up until the end of 2011, it had been running for more than 75 000 operating hours. System availability stands
at over 98 %, and has been so continuously since 2009.
The world’s first breakwater wave power plant was commissioned in the summer of 2011 on the Spanish Atlantic coast at Mutriku using Voith Hydro Wavegen technology. It has a nominal output of some 300 kW, and can supply around 250 households. The system consists of 16 Wells turbines, each with a rated performance of 18.5 kW. It was built into the breakwater around the harbor at Mutriku, which was re-built by the local municipality. The Mutriku power plant has been operated successfully since its opening by the Basque energy agency, EVE, and is currently the only commercially operated wave power station in the world. (source: Voith Hydro)
In 2011 the chair of structural analysis at the Technical University Munich started a collaboration project with Ed. Züblin AG on the numerical simulation and optimisation of the foundations of ocean current turbines with a focus on the fluid structure interaction. The public funded project will be completed in 2013.
The Institute for Fluid and Thermodynamics (IFT) of the mechanical engineering department at the University of Siegen started a 3 year public funded research project on the development of a bidirectional radial air turbine for application in OWCs at the end of 2011. Based on analytical, numerical and experimental methods using a specially designed air turbine test facility a radial turbine design is developed and optimised. The university collaborates with Voith Hydro on the design optimisation of Wells turbines. The Limpet site can be used for field tests of the new design.
Since 2012 Andritz Hydro GmbH develops drive train concepts for tidal turbines with around €1 million funding from the BMU. The focus of the project is the economic and technical optimisation of a variable pitch mechanism for bidirectional operation and the blade connection to the hub. The design will aim at full scale rotors with maintenance intervals of 5 years. Under the Andritz Group based in Austria Andritz Hydro Hammerfest established in 1997 in Norway represents the technology provider in the tidal power business. Based on a 300 kW tidal turbine, tested in Norwegian waters, a 1 MW tidal device was developed and tested at EMEC site before becoming part one of the world’s first tidal arrays, planned for installation in Scottish waters in 2013. (source: Andritz Hydro)
The German marine propulsion specialist Schottel placed a an investment into the UK tidal-power technology developer TidalStream Ltd. in 2011. For Schottel renewable energy is an interesting and forward-looking addition to the traditional product range portfolio. The Triton platform technology comprised of a semisubmerged turbine-carrying catamaran structure is expected to enable efficient installation of large power arrays and provides easy maintenance access. The Triton S concept is tailored to operate totally submerged for “non-surface piercing” applications by using a rigid swing-arm tether foundation, designed to be towed to site, mated with turbines and deployed into operating position via water-ballasting. After completing the ongoing 1:10 scale field test, upscaling of the technology is ongoing with the Triton 3 for intermediate water depths with the capacity to generate up to 3MW from a single installation followed by the Triton 6 designed for deep water sites to accommodate turbines of up to 10MW capacity.
At the occasion of the International Tidal Energy Summit in November 2012 in London, Schottel presented its first TIDAL Generator STG 50. The light-weight and robust tidal generator is based on the fact that reducing turbine size leads to a better ratio of power and material use. High overall power can be reached with a higher number of turbines. STG 50 is a horizontal free flow turbine with a rotor diameter of 4.0 to 4.5 m and a rated power of 45 to 50 kW. It is designed to be composed in arrays of various types and sizes depending on the available space and the output expectations. The turbine is equipped with speed
increaser and an asynchronous generator. Each of the turbines is connected to a frequency converter feeding into a common DC bus installed on the tidal platform. Finally a common frequency converter together with a large transformer is used to produce grid-ready electricity. Due to the modular approach, the turbine can be implemented in rivers, sea straits and offshore in jetty or floating platforms as they are developed by TidalStream.
The turbine design has been supported by various model tests and RANS-CFD simulations. The drive train was subjected to extensive laboratory tests. Two complete STG drive trains were installed in a submerged back-to-back configuration. Full-scale tests have been performed with the entire converter including the rotor. For this purpose, the unit was fixed to a tug (see photo). This setup allowed for the adjustment of various flow conditions. Different sets of rotor blades as well as the entire power generation chain have been tested. (source: Schottel Group)
Schottel stg50 prototype
Other German suppliers such as Bosch Rexroth, Schaeffler, Contitech, Thyssen Krupp, Hunger Hydraulik and Hydac deliver components and parts for a number of ocean energy devices – for wave as well as tidal turbine technologies mainly in Europe. Certification companies and consultants are contributing to the technology and project development in the sector. This international collaboration demonstrates the technology export opportunities which exist in the ocean energy for the German industry.
A national Master Plan Maritime Technologies has being prepared under the coordination of the Ministry of Economics and Technology to support the development of the maritime technology industry in the coming years. The goal is to develop recommendations for a future coordinated maritime technology policy, at federal and state level, and the clustering of the core competencies of industry and science through enhanced networking and clustering. It is anticipated that ocean energy technologies will play a role in the plan.
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