Select Committee on Science and Technology Appendices to the Minutes of Evidence


Memorandum submitted by Thropton Energy Services


  A water current turbine converts the kinetic energy in a flowing body of water. Unlike a conventional hydro powered scheme, its installation requires no civil engineering work apart from an anchor or mooring post. This flexibility makes the turbine suitable for use in tidal streams and estuaries. The turbine looks like an underwater windmill with a three bladed rotor. The rotor is suspended from a floating pontoon, with the transmission, generators, pumps etc. above the water. The two designs of water current turbines developed by Thropton Energy Services are the Garman Turbine and the Amazon Aquacharger which meet the needs of different, specific markets.

  Both turbines are decentralised power generators applicable to areas without access to a large grid system. They have been designed for manufacture and maintenance in regions where they are likely to be used. As such, they are more likely to be of interest to private users and development agencies working internationally in the developing world. Detailed specifications and applications are given in the attached documentation[4] but the main advantages are:

    —  It uses renewable energy and needs no fuel or oil,
    —  It is easy to operate and maintain,
    —  It has proved highly suitable for use in isolated locations,
    —  It is non-polluting and almost silent when running,
    —  It needs no large scale civil engineering work,
    —  It can be moved should site conditions change,
    —  It is designed for local manufacture and maintenance,
    —  It can operate 24 hours per day without a full time attendant.

  The Garman Turbine was designed primarily as a water-pumping machine for agricultural or community water supply as this was viewed as the main need in its initial market, North Africa. This turbine design has been adapted to generate electricity and can also be used as a dual purpose machine, pumping water or generating electricity as required by the user. Depending on the resource available, it can produce up to 2kW output and is a replacement for the three-inch diesel pump used in many agricultural situations.

  The Aquacharger is a battery-charging turbine for domestic electrical supply or for use by village health centres, schools or similar facilities. It is smaller than the Garman Turbine and can produce up to 500W electrical power.

  When manufactured in the region where they will be used, the capital cost of the turbines is low compared to other renewable energy systems. Its very low running cost means that it becomes competitive with a diesel pump set after between one and three years depending on local price of fuel and materials. The extent of the resource available worldwide has yet to be established but surveys completed in target countries have shown that the resource and the need are sufficient to sustain local manufacturing bases (see attached paper "Water Current Turbines for Pumping and Electricity Generation" by PG Garman & B A Sexon).[5]

  At present the Garman turbine is being manufactured and used on a small scale in the Sudan. The Aquacharger is manufactured by Marlec Engineering of Corby, under licence. It is undergoing field trials in South America where it has been enthusiastically received by the initial users.

  The main obstacle to the widespread use of this technology is the high initial cost of establishing the infrastructure required to support its installation and maintenance. The majority of renewable energy systems are site specific and thus accurate site surveying is essential to ensure appropriate system design. Although running costs are low, the capital cost of a renewable energy system is higher than an equivalent diesel generator. To compensate for the initial high cost, long service life and high reliability are a requirement and so a very high standard of installation with meticulous attention to detail is essential. When something does go wrong there must be back-up readily available in the form of qualified technicians and spare parts. The hardest task in the dissemination of any renewable energy system is to put in place the infrastructure required for surveying, installation and maintenance without adding unacceptable amounts to the unit cost.

  The provision of these services for such small and of necessity low cost systems is not an attractive commercial proposition for the large companies in capital cities which are capable of manufacturing complete sets (including generators). Thus, if a significant fraction of any renewable energy resource is to be exploited, investment in training of local technicians will be required (eg the staff of small engineering firms, that are already providing services). It is at this point that assistance from external government and international agencies can play an important role.

  After completing the design to production standard, Thropton Energy Services was able to establish local manufacture in Sudan because we were in a position to incorporate the turbine into existing systems within that country. Financial assistance from the Sudan government and the German Development Service made it possible to provide equipment and additional training to qualified technicians already working for a local farming organisation. With the support of Thropton Energy Services standard procedures were set up that enabled the technicians to survey potential sites, install and maintain turbines. The turbines are manufactured in an industrial unit attached to an engineering college in the region. This industrial unit had been set up in the 1980s as part of an unrelated British government funded project at the engineering college. Without the direct and incidental support of the above agencies it is unlikely that the manufacturing base for the turbine would have been established or sustained at any level.

  In conclusion, for this type of technology to be widely adopted, financial support is needed to assist projects beyond the demonstration phase. It is in the area of dissemination of an existing technology that aid from government and other agencies can be of real benefit to small development companies.

9 February 2001

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