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Renewable energy technologies at TWI

Connect, no. 126, September/October 2003, p.1

Renewable energy technologies at TWI

The worldwide renewable energy market is growing rapidly and will gain further momentum when the associated generating plants and systems become economically viable. The goal of current development is to reduce life cycle costs to achieve a cost per kilowatt hour of electricity which is attractive to consumers.

TWI's capabilities are central to this goal with its innovative developments aimed at lowering fabrication costs, increasing production rates, enhancing durability and reducing maintenance.

Offshore wind

Current fabrication methods cannot meet the growing demand for large wind turbines. For example, steel thickness in the turbine towers is already around 50mm and increasing so conventional welding methods such as submerged arc will not meet productivity targets.

One solution with major potential is the use of Reduced Pressure Electron Beam Welding (RPEBW). The TWI-developed technique, unlike 'traditional' EBW, does not have to be carried out in a vacuum so is ideal for use on large structures. The autogenous welds are completed in a single pass and estimates indicate that not only will RPEBW halve production cost but will also increase the production speed by 5 to ten times. In addition to fabrication issues, the structural integrity of offshore wind turbine towers is also central to TWI's renowned expertise in integrity standards for the oil and gas industry. UK DTI funding has been recommended for a £250k TWI project to develop a high speed welding process for the construction of wind turbine towers.

The increase in turbine size also brings a need for larger blades. A 5MW machine can need blades up to 100m long weighing around 20 tons each. The blade stress, fatigue and hub loading pose significant design problems. TWI's composite structures group's skills in joint design coupled with expertise in fatigue of large structures and an advanced modelling capability, provides a potent support facility. EU funding has been granted for a £450k TWI-ledCRAFT project to develop innovative NDT techniques and technologies for the inspection of wind turbine blades.

Hydrogen and fuel cells

The hydrogen economy will generate a high demand for many container types and a corresponding need for an equally wide range of rapid, high integrity fabrication methods. Electron beam, laser and hybrid laser, and friction stirwelding all have applications in the production of cryogenic storage tanks and pressurised containers for local power supplies and lightweight composite hybrid containers for transport applications. TWI is unique in being able to coverall associated joining and coating technologies together with expertise in materials performance in hydrogen environments.

TWI's joining and coating technologies also impact on the making of fuel cells to be used with the hydrogen source.

Whether glass-ceramic bonds in solid oxide fuel cells (SOFC) or reliable polymer joints in proton exchange membrane (PEM) fuel cells, TWI can help meet production targets. For integrated fuel cells including reforming of natural gas, TWI has expertise in using ceramics in ultra-high performance reformers.


The performance of Photovoltaic (PV) cells is degraded by ingress of oxygen and water. TWI expertise in coating and sealing can help ensure the longevity and sustained performance of PV systems. And, while plastic substrates would be cheaper and lighter, they are too permeable and too soft. A TWI-developed hard coating, Vitresyn®, offers a route to make such substrates commercially viable.

TWI is planning to increase its capability further in this field with the introduction of its proposed Renewable Energy Manufacturing Technology Centre (REMTEC). The primary focus of REMTEC is to develop, validate and demonstrate innovative fabrication solutions for emerging renewable energy industy.

For further details of how TWI can help your renewable energy problems, please contact us.

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