World Commission on Dams / Reuters Media Symposium 14 July 1999

Dams and Energy: Hydropower as the Preferred Alternative

A. Bartle, International Hydropower Association

Alison Bartle is director of Aqua-Media International and editor of the International Journal on Hydropower & Dams. In 1995 she assisted in the launch and development of the International Hydropower Association (IHA), of which she is a board member and one of the executive secretaries. She chairs the IHA permanent committee on public relations, and is also a member of the public relations committee of the International Commission on Large Dams.

The International Hydropower Association is grateful to the World Commission on Dams, IUCN and Reuters for this opportunity to put forward our views on the overall benefits of hydroelectric power. As Prof Asmal said, negative impacts tend to make good headlines in the press, but I hope this morning to adjust the perspective by demonstrating the concern and expertise within the engineering profession for social and environmental issues, and the fact that this has resulted in tens of thousands of hydro projects not reaching the headlines, as they are fulfilling their roles effectively and without controversy.

1. The IHA

The IHA, founded in 1995 and strongly supported by UNESCO, is a non-profit-making, multidisciplinary NGO, with members in 60 countries, which provides a forum for the exchange of views, enhancement of knowledge, and encouragement of good engineering practice in the field of hydropower.

It is important to point out that it is not an organisation for hydropower, without reservation, but one which supports and encourages hydropower schemes which are designed with full respect for social and environmental issues.

Extract from our Mission Statement:

IHA exists to increase awareness of the role hydropower can play in sustainable development as the most important source of renewable energy.
The IHA promotes hydro development which is planned and implemented in an environmentally and socially acceptable way.
Objectives include developing and disseminating information for the public and policy makers, advancing knowledge on various aspects, promoting good practice and international standards in hydro development, encouraging innovation, and selecting and recommending key issues for research.

We do this through the activities of seven Permanent Committees, which cover topics such as Technology, Pumped Storage, Research and Education, but also more importantly - Environment, Economics and Public Relations/Communications.

The Environment Committee chaired by my colleague Richard Taylor, is one of the most active, with Working Groups on environmental impact assessment, social aspects, groundwater management, fish and fisheries, sedimentation, emissions and climate change, water quality, and operational aspects. Much of the information I will present is based on their work.

2. Present role of hydro in the world

First it is important in a debate on dams to point out that hydropower stations are in fact only incorporated at about 20-30 per cent of dams higher than 15 m, and often hydropower is not the primary function.

70 per cent of the world's dams are built specifically for irrigation or water supply, and many of the others have one of these roles as their principal function.

Hydro potential

The world's total technically feasible hydro potential is estimated at 14 320 TWh/year, of which about 8100 TWh/year is currently considered economically feasible for development. About 700 GW (or about 2600 TWh/year) is already in operation, with a further 108 GW under construction. Most of the remaining potential is in Africa, Asia and Latin America.

A study by the Utility Data Institute in the USA predicts that a world total of 695 GW of new capacity will come on line in the next ten years from all sources, 22 per cent of which will be hydro (26 per cent gas, 27 per cent coal).

Hydropower at present supplies about 20 per cent of the world's electricity. If all of the economically feasible potential were to be developed, and it could substitute fossil-fuelled thermal plants, global CO2 production could be reduced by between 4700 to 7000 million tons a year.

It supplies more than 50 per cent of national electricity in 68 countries, more than 90 per cent in 22 countries and more than 99 per cent in 13 countries.

The remaining technically and economically feasible potential, appropriately implemented, could play the greatest role in improving living standards of developing countries, where the population is predicted to increase to 8.6 billion by the year 2050. Realistically energy needs will be met by both renewable and non-renewable sources, but clearly the maximum use should be made of renewable energy to limit pollution.

It is well known that a number of countries, such as China, India, Iran and Turkey, are undertaking large scale hydro development programmes, and there are schemes under way in about 80 countries at present. In this year's survey conducted annually for the World Atlas of Hydropower & Dams, hydropower was specifically mentioned as the key priority for future economic development in a number of developing countries. Examples are Sudan, Rwanda, Guinea, Myanmar, Armenia, Kyrghyzstan, Cuba, Costa Rica, and Guyana.

3. Main characteristics of hydropower

• Its resources are widely spread around the world. Potential exists in about 150 countries, and about 70 per cent of the economically feasible potential remains to be developed. This is mostly in developing countries.
• It is a proven and well advanced technology (with more than a century of experience), and modern powerplant providing the most efficient energy conversion process (> 90 per cent)
• It plays a major role in reducing greenhouse gas emissions in terms of avoided generation by fossil fuels. Hydro is a relatively minor source of atmospheric emissions compared with fossil-fired generating options. (More detail in the next section.)
• The production of peak load energy from hydropower allows for the best use to be made of base load power from other less flexible electricity sources. Its fast response time enables it to meet sudden fluctuations in demand.
• It has the lowest operating costs and longest plant life, compared with other large scale generating options. Once the initial investment has been made in the necessary civil works, the plant life can be extended economically by relatively cheap maintenance and the periodic replacement of electromechanical equipment. (Replacement of turbine runners, rewinding of generators, etc - in some cases the addition of new generating units). Typically a hydro plant in service for 40-50 years can have its operating life doubled.
• Hydro plants are very often integrated within multipurpose developments, which are satisfying other fundamental human needs (eg, irrigation for food supply, domestic and industrial water supply, flood protection). The reservoir water may also be used for other functions such as fisheries, discharge regulation downstream for navigation improvements, and recreation. Hydropower plants can help to finance these multipurpose benefits, as well as some environmental improvements in the area, such as the creation of habitat for birds, fish and other creatures.
• The 'fuel' (water) is renewable, and is not subject to fluctuations in market conditions. Countries with ample reserves of fossil fuels, such as Iran and Venezuela, have opted for a large scale programme of hydro development, recognizing environmental benefits. Hydro can also represent energy independence for many countries.

4. Hydro compared with other generation options

In comparison with hydropower, thermal plants take less time to design, obtain approval, build, and pay back. However, they have higher operating costs, typically shorter operating lives (~25 years), are important sources of air, water and soil pollution and greenhouse gases, and provide fewer opportunities for economic spin-offs.

Other renewable sources of power (wind, solar, etc) are valuable options in addition to hydropower in specific contexts, but cannot produce large amounts of energy in the coming decades, and need back-up supply from other sources.

5. Avoided emissions

Recent research in North America (reported to us by L. Gagnon of Canada) confirms that the GHG emission factor for hydro plants is typically 30 - 60 times less than factors for fossil fuel generation, taking into account emissions from decaying biomass in reservoirs.

Recent research has shown that development of even half of the world's economically feasible hydropower potential could reduce GHG emissions by about 13 per cent, and the impact on avoided sulphur dioxide (the main cause of acid rain) and nitrous oxide emissions is even greater.

Taking into account the fuel required to build hydropower stations, a coal-fired plant can emit 1000 times more SO2 than hydropower systems.

The magnitude of the impact of particulate emissions is also now becoming recognized, and a recent estimate of the environmental cost of this form of pollution is put at US$100-500/t/year (according to E. Oud)

It is known that more research is needed on emissions in the case of tropical reservoirs, but a theoretical calculation has been done for the case of Tucurui in Brazil, including 'worst case' assumptions concerning the decomposition of biomass (that 100 per cent of the biomass would decompose over 100 years, and that 20 per cent of biomass carbon would be emitted as methane) and even in this case the emission factor for Tucurui would be 213 g CO2 equivalent per kWh, a factor five times lower than that for coal.

6. Social and environmental impacts and mitigation measures

Social aspects

(Based on paper of J. Milewski, IHA Working Group Leader on Social Aspects)

As with other forms of economic activity, hydro projects can have both positive and negative social aspects. Social costs are mainly associated with transformation of land use in the project area, and displacement of people living in the reservoir area. As far as resettlement issues are concerned, the IHA Working Group has collected case studies, so that experience can be compared and a constructive analysis made.

Social effects of hydro schemes are variable and project specific. However, if anticipated and tackled early in the planning stage of a project, the negative impacts can be addressed efficiently, or in some cases avoided altogether.

It is recommended for a baseline study of a project area to be carried out, and for an effective public participation programme to be implemented. Examples of design aspects which can help to modify impact include: dam location, maximum reservoir levels, powerplant design flow, access road routing, etc.

During the construction phase of a hydro scheme (often several years) there may be a large workforce, and access roads can lead to a sudden influx of outside labour and the development of new economic activities, with resulting tensions if the area in question is unprepared. Effective mitigation measures can be implemented if local authorities and project promoters acknowledge and address these issues. On the positive side, the additional economic activities create new employment opportunities.

During the operational stage, the hydro project may represent a significant source of revenue for local communities. The access roads, local availability of electricity and other activities associated with the reservoir are all possible sources of sustainable economic and social development. But there must be good co-operation between proponents, authorities, political leaders and communities, and long-term benefits must be directed to affected communities.

We heard a nice example from Hydro Quebec last week, during a hydropower conference in the USA. HQ's rule for future hydro projects is that they have to meet three criteria: to be environmentally acceptable, socially acceptable and profitable. Socially acceptable means that any proposal for a project must be discussed with stakeholders, adapted to their needs, and consensus must be reached for the project to go ahead.

In the first agreement signed under this rule, for hydro schemes involving four partial river diversions, equity partnership is being established with the local people, the Betsiamites Innu Nation of Quebec. They will have a 17.5 per cent share in the project, and will receive at least $100 million over 50 years. In addition, a Community Development Fund of $10 million has been set up, and an Environmental Mitigation Fund of $11 million.

From a social point of view, the relative success or failure of a hydro project is determined by integrating social consideration into the project design.

Environmental impact assessment

As mentioned earlier, hydropower has a long history, and lessons have been progressively learnt throughout its history. It is clear that not every hydro plant in the world is without environmental problems, but today the profession is aware of the problems to be addressed, the expertise exists to mitigate the known impacts to achieve an acceptable balance, and research is continuing. Reservoirs can in fact focus attention on existing problems in a watershed.

departments on environmental aspects).

It would be virtually impossible today for a hydro plant of significant size to go ahead without detailed studies on its potential impacts being conducted and a comprehensive report of environmental impacts being prepared. (Framework, criteria and the degree of public involvement vary from country to country, the latter depending to a certain extent on the degree of democracy in the country concerned.)

Our Working Group on EIA calls for impact assessment to be an integral part of the multidisciplinary planning approach, and to include a strong element of public consultation. EIAs should cover positive and negative impacts and mitigation measures, and should also identify existing problems in a river basin.

Sedimentation

This is one of the problems to which much attention is being devoted by the profession. While in general large dams and reservoirs are designed for an operating life of about 100 years, there are cases where reservoirs have faced sedimentation problems within a much shorter time. Although a relatively small proportion of the total number of existing dams have a serious problem, many future large dams are likely to be in areas where sedimentation will be a problem, if not anticipated at the planning stage, with appropriate measures being taken.

It is considered imperative to assess as accurately as possible at the conceptual stage of a project the average annual sediment load entering a reservoir, or passing through a run-of-river project, so that appropriate measures can be taken. Efforts also have to be made to reduce erosion in the catchment area. Work is on-going in improving modelling techniques, and improving monitoring systems.

A number of measures can be taken such as periodic flushing or dredging from reservoirs (successful flushing has been reported at Sanmenxia in China). In the case of run of river projects, flow diversion structures can be provided with sediment excluding devices, and sediment (and thus nutrients) can be maintained in the downstream river course.

(More details are available in a paper by S. Alam, a world expert on sedimentation management, who is leader of the IHA Working Group on this subject).

Fish protection

Dr Andrew Turnpenny is our IHA Working Group Leader on this subject.

As hydro schemes are usually designed and dimensioned to make optimum use of available water, a large proportion of the natural flow passes through the turbines and it is inevitable that quantities of fish will enter the generating flow, particularly at the time of natural migration.

Much research has been done on the specific risks to different sizes and species of fish, and on effective methods to control their behaviour to minimize mortality.

Measures commonly used include fish screens at turbine inlets, and many countries require this by law. Finer meshed screens can be placed at times of year when fish are actively migrating. Various types of self-cleaning screen have been developed to cope with the build-up of debris.

Behavioural methods have also been developed to defer fish from the intake, and guide them to the safety of a bypass channel. These include: louvre screens (which generate turbulence), bubble curtains, acoustic barriers, electrical fields, and underwater lights.

Well designed behavioural systems (eg, louvre screens or the latest acoustic screening techniques), can achieve better than 90 per cent exclusion for certain species.

Knowledge from experimental studies about the mechanisms of fish damage in turbines has in recent years led the development of 'fish-friendly' turbines. (Pressure and velocity characteristics within a rotating turbine can be modelled and the probability of different risk conditions estimated). This R&D is being pioneered in the USA.

Water Quality

This is another important aspect to be included within an EIA. The Working Group within IHA is headed by R. Zwahlen of Switzerland.

Some of the issues associated with reservoirs are dissolved oxygen, modified nutrient levels, thermal modification and ammonia levels. Relatively few reservoirs have acute problems, and mitigation measures can be adopted if necessary. Examples are multi-level drawoff works so that better quality water near the surface can be used, and to induce mixing of the water body at lower levels, and oxygenation of the water by auto-venting turbines.

Many reservoir projects in fact improve or safeguard the water quality downstream.

Longer term water quality problems generally reflect land use in the watershed. A recent study sponsored by the Environmental Protection Agency in the USA identified agricultural practices to be the source of the majority of incidents, with industrial and municipal waste treatment and discharge being a major contributor.

7. The small versus large debate

Measures favouring renewable technology and "green" energy; often exclude 'large' hydro, and small projects are perceived as having low impacts.

Research has been done on this subject by a number of organizations, including the World Bank, and a paper was recently presented by a member of the IHA Working Group on Social Aspects.

This paper points out that valid comparisons must compare impacts per unit of output. The impacts of a single large hydro project must be compared with the cumulative impacts of several small projects yielding the same power and level of service.

Small projects generally require a far greater total reservoir area than a single large project, to provide the same stored water volume.

It is concluded that the most fundamental determinant of the nature and magnitude of impacts of hydropower projects are the specific site conditions and not the scale of the project. It is also important to optimize development with respect to the complete river system.

8. Conclusion

This presentation was intended to give a brief overview of the important role hydro can play in the future, and its benefits in comparison with other options. I also wanted to demonstrate the awareness within the profession of the social and environmental impacts of hydropower to be addressed, the expertise which exists to mitigate them, and the research that is on-going.

The world's remaining hydroelectric potential should be developed to the maximum possible extent, with projects planned taking full consideration of social and environmental impacts, so that the necessary mitigation measures can be taken. Clearly, the population affected by a project should enjoy a better quality of life as a result of it.

Hydro development should go hand in hand (rather than in competition) with further research and development in the field of other renewable options such as solar and wind power, although it must be recognized that the role to be played by these other options will be modest. Energy conservation measures should also be optimized and encouraged.

Any development involves change and some degree of compromise, and it is a question of assessing benefits and impacts at an early enough stage, and in adequate detail, with the full involvement of any people to be affected, so that the right balance can be achieved.

We have three options: sustainable development - unsustainable development - sustainable underdevelopment.

The most vocal of the environmental groups campaigning against hydropower, on the basis of relatively few projects where negative impacts have been conspicuous (and valuable lessons have indeed been learnt), are based in developed countries with a comfortable standard of living and a very high per capita consumption of electricity. These groups, and the media they use as their mouthpiece, undoubtedly have altruistic aims. But I would appeal to them to take a balanced view, and keep in mind the many tens of thousands of hydroelectric plants which are fulfilling their role as well-designed, efficient, renewable sources of electricity - and those of the future which will have the ability to improve living standards significantly in the developing world.

Two billion people in developing countries have no reliable electricity supply, and especially in this part of the world, in the foreseeable future, hydropower offers the only option as a renewable energy source on a realistic scale.

Impacts of hydro schemes are well understood, and appropriate mitigation measures can be taken to ensure that the project represents a net gain for the population.