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In the past, the generation of electricity by wind force was of interest to a few scientists and environmentalists only. In the 1970's, wind-generated electricity was as costly as it was impractical, and has continued to be so until recently.
(Published on January - February 2008 – JEC Magazine #38)
ROBERT TSAI, PRESIDENT Swancor IND. CO., LTD.
The soaring price of oil continues to push up the cost of electricity generation, and the environmental cost of pollution is also steadily increasing.
As a result, vast resources have been allocated worldwide to develop alternative sources of power, including wind power, solar energy and hydro-electric generation. Wind power is now becoming a viable alternative to generate electricity. With the support of governments worldwide, the cost of wind-generated electricity is falling.
At present, it costs less than coal-generated electricity, and the same as natural gas or oil.
New epoxy resin for optimized blades
A critical component for wind-generated electricity is the wind blade. Optimizing the blade leads to higher powergenerating efficiency and lower costs. Although open moulding and wet lay-up are still used, longer blades (in excess of 37.5 m) now have two alternative modes of production. Vacuum-assisted resin transfer moulding (VARTM) and infusion are those two popular ways. As blade design has improved, epoxy resin systems are now commonly used. These resins harden at low temperature (reacting between 5~50°C) and have a low shrink rate (1~3%). They offer excellent adhesive, mechanical, insulating and corrosion-resistance properties, are stable (can be stored more than one year without hardener), and exhibit excellent mechanical strength.
Generally speaking, epoxy resin performs well. However, in some cases, the resin viscosity is too high and the operating time too short to be suitable for the VARTM process.
Therefore, these shortcomings must be corrected in order to improve quality and produce larger blades. Swancor has already developed a new generation epoxy resin system, SW2511-1, for VARTM production of wind blades. SW2511-1 has excellent functional characteristics, such as low viscosity (200-300cps), adjustable gel time to satisfy the requirements of any manufacturing process, and lower exothermic temperature; it also combines well with glass fibre and reacts at room temperature without extra pressure.
The SW2511-1 system has earned GL 2000 (Germanischer Lloyd) certification for epoxy resins that meet wind-blade manufacturing requirements.
Production of sleepers for high-speed railway
High-speed railways have far greater capabilities than traditional ones. There has already been an upsurge in construction of high-speed railways in areas such as Japan, Europe and Taiwan. Mainland China started developing its own high-speed railways after 2004.
Making passengers feel safe and comfortable while constantly improving driving speed involves not only high performance of the train itself but also key technology to lay the sleepers of highstandard rail, for which track requirements are obviously far higher than for traditional railways. When the train passes at a high speed, the sleepers are subject to powerful shocks and great stresses, under which splints and bolts can break and the rail would creep. The rail joint is the origin of the noise; the bigger the rail gap, the louder the noise. Greater damage to the wheel, rail, splint and bolt will cause increased rail creep. Therefore, high-speed railway design must allow for strength and stability in the track structure to reduce vibrations at high speed, shock attenuation, and low noise.
Rail gauge, height and direction also influence the quality of the track. Track height adjustment requirements are especially strict. Basically, the method of adjusting splint and interval is changing the distance and height between the sleepers. Design in Taiwan follows the pattern of the Japanese Shinkansen, with SMC mould pressing products used as the splint material. Mainland China’s key technology is mostly localized. China has already succeeded in developing a high-performance spacer and improving its railway technology to become one of the most advanced countries in the world.
Swancor devotes considerable resources to resin development, and there is always a case story for any type of construction. In 1998, Swancor already had met Taiwan’s requirements for making SMC craft. Since then, its mouldpressing vinylester resins have been used in the sleepers for Taiwan’s high-speed railway and have met the Japanese Shinkansen’s requirements for surface finish.
In China, Swancor has developed high-performance resins which meet or exceed the relevant requirements for highspeed railway, with excellent tensile, flexural, impact strength and elongation properties. These products have been successfully applied there; for instance, an experimental section three kilometres long was built in 2002 for the Tianjin Jing-Shen railway; the Qin-Shen experimental section (1.9 kilometres), where all railway backing boards used Swancor resin, was built in 2004; and the Ping-Yu railway also successfully applied the same resin to some railway sections in 2006.
Swancor continues to innovate. Research and development activities are of prime importance for new resin development. With domestic railway construction burgeoning, Swancor products will be used extensively in China railways.