What an exciting and informative adventure to browse in old copies of IWP&DC!

We found interesting articles on the repowering of Europe, but also papers on power stations in Asia and Africa which are of recent interest because of their potential for uprating and rehabilitation. Voest Alpine, for example, recently received an order to retrofit Akosombo power station, which was discussed in an IWP&DC issue in 1949.

It is amazing to compare the tools available to the industry 50 years ago with the modern tools of numerical simulation, high precision laboratories and numerically controlled machining and fabrication. Today we see levels of performance which were considered to be absolutely unattainable goals 50 years ago.

A Nichtawitz, K Wolfartsberger, Voest-Alpine MCE

In common with other industries, over the last 50 years hydro power has seen dramatic advances in efficiency, cavitation resistant materials, computerised operational sensing and control systems. For example, dramatic advances in computational fluid mechanics helped improve shaping of runner blades for greater efficiency, and variable speed turbines are increasing the operating range of high efficiencies.

Of greatest impact to the industry, however, has been the realisation that hydroelectric projects, with their attendant dam and water control structures, do have environmental effects. Recent social and regulatory challenges to project relicensing range from costly remedial measures to potential dam removal. Traditional benefits are no longer balanced against cost alone but also against concerns for social and environmental impacts. This paradigm would have been considered radical (or even subversive) in the forties and illustrates how far we have come, and provides the main challenge for the future.

George E Hecker, Alden Research Laboratory

With regard to concrete dams, special achievements have been the development of theories and knowledge on the behaviour of concrete (including alkali reactions), the design and analysis of arch dams, the invention of roller compacted concrete, the analysis of rock foundation deformations and the definition of reliable safety procedures.

In the last half-century the industry has built numberless dams in many countries, providing the basis for electrification, irrigation, navigation, flood protection and drinking water. These activities contributed substantially to improving the lives of the population. Now, too many artificial constraints are slowing down the construction of dams. These are mainly the consequence of overestimating costs and environmental impacts, and underestimating benefits. The result has been a substantial increase in costs.

G Lombardi, Lombardi Engineering

Although significant global achievements could be mentioned, for me it is natural to take the example of Norway, where hydro power means more than in possibly any other country.

When the technologies for producing and using electricity on a large scale emerged, Norway was being rapidly industrialised and quickly began harnessing the power of its rivers, waterfalls and high-altitude lakes. There is a very favourable distribution of hydro resources throughout this mountainous country. Development was on a small affordable scale to begin with, increased as demand broadened, and accelerated after the second world war. As most sites were in remote regions, dams and reservoirs were built without significant negative impact on the environment or need for resettlement.

Hydro power has made an essential contribution to Norway’s economic development: even in overall terms, this country of only 4.5M people ranks with the world’s top hydro power nations.

Kaare Høeg, international-commission-on-large-dams

The most important development in the last 50 years is one that has changed the whole business — as well as our lives. The development of semiconductor and digital technologies has made possible on one side the development of computer systems. On the other side, it has opened new possibilities with respect to control of drives, rectification of current and voltage etc.

The most important development for us at Elin Energieversorgung was the bulb-type generator set. With this machine the civil construction costs have been reduced, construction time made shorter and efficiency increased. What is more, it has allowed power plants with a very low silhouette to be introduced that fit much better into the landscape.

Christian Jacob & Walter Scheidl, Elin Energieversorgung

Hydro power is the world’s largest source of renewable energy, and one of the cleanest energy forms available. A hydro power plant can achieve a higher generating efficiency than any other plant, capturing more than 90% of the energy in water flow. These are reasons enough to invest in hydro power, but the most important fact for me is that the lifetime of hydro is much longer than any other power plant.

Our ancestors harnessed hydro power towards the end of the last century. This century hydro power was developed on a larger scale. Many of the schemes our grandparents built are still in operation, providing valuable energy at the lowest cost. We should always keep the long term benefits of hydro power in mind when discussing new projects. The next generation will be grateful: investment in hydro power plants today have benefits which last beyond the next decade, and far into the next century.

José Reis, General Manager, ABB Hydro Power Plants

In recent years the water power market has been distinguished by deregulation and liberalisation, and it has become an extremely competitive market in the field of renewable energy. Worldwide discussion of the climate problem and carbon dioxide emissions supports our opinion that water power will play a more important role in the future than it does now.

As regards the achievements of the last 50 years, they are numerous. The most essential were: in 1955, introduction of a self-pumping thrust bearing; in 1960, introduction of synthetic resin insulation; in 1963, the first direct cooled rotor winding; and in 1964, the first reversible thrust bearing for pumped storage plants.

Michael Olschewski, KWU Group of Siemens

From my personal short list of dams considered as international ‘stars’, I would finally choose Aswan.

Aswan was not fully understood and at the start was strongly criticised, but its sustainability, like that of practically all dams, is now improved. Egypt is now more than ever — through Aswan — a ‘gift’ of the Nile river which is able to support the drought years with a minimum of inconvenience.

But we should not forget that some territories or countries exist only through dams, which are providing safety in the face of floods, tides or storms. Most dams are not famous: they are not of great size and are a natural result of the meeting between local needs and the development of tools for food production or hydropower.

Jacques Lecornu, International Commission on Large Dams

A major development in water power during the last 50 years was the single stage, Francis-type, reversible pump turbine. The introduction of this type of design significantly reduced the capital cost of pumped storage, when compared with the earlier tandem design, and this made them an ideal cost-effective choice for power and grid management.

Kvaerner Boving played a significant part in the development of the RFT with their machines at Cruachan in Scotland, commissioned in 1966. With a pump head of 358m they were the first high-head RFTs in the world.

Stephen Arotsky, Kvaerner Energy