This site uses cookies. By continuing to use this site you agree to our use of cookies. To find out more, see our Privacy and Cookies policy.
Skip to the content

[IOP] A community website from IOP Publishing

environmentalresearchweb blog

Hydro – and beyond

By Dave Elliott

Hydro plants are the largest existing renewable source of electricity, with around 874 GW installed worldwide, providing almost all of the electricity for many developing countries, for example, in 2008, nearly 100% in Albania, Angola, Bhutan, Burundi, Costa Rica, D R Congo, Lesotho, Mozambique, Nepal, Paraguay, Tajikistan and Zambia, as well 60–90% in 30 other developing countries. In addition, it provides nearly all the electricity in Norway, most of it in Iceland, and up to 60% in Austria, Canada New Zealand and Sweden. See

Since the energy output is dependent fundamentally on the head height, sites that can accommodate taller dams can produce more energy and it is a square law: double the head gives you four times more energy on average. So in energy terms at least, the bigger the better, and trapping a large mass of water in the reservoir behind the dam will help to give a guaranteed supply, although there will be cost trade-off and site limitations.

The energy source is ultimately solar heat, which drives the hydrological cycle, but since that is climate and weather related, the energy resource at any particular location and time can vary. Indeed, with decreased rainfall in some areas in recent years, output from some hydro plants has fallen. This is likely to get worse with climate change.

The interactions between hydro projects and the environment are also two-way: large projects can have significant environmental impacts. Many environmental/development organisations, while backing smaller scale hydro, have opposed large hydro projects because of the large social and environmental impacts.

The social dislocation resulting from flooding areas for new reservoirs is an obvious issue, but there are also wider ecological issues. For example, the World Commission on Dams NGO has claimed that, in some hot climates, biomass carried down stream can be collected by the dam and can rot, generating methane, so that net greenhouse emissions can be more than from a fossil plant of the same energy capacity. It is not just a matter of any initial biomass trapped when the hydro reservoir was first filled, but a continuous ongoing process of fresh biomass decay.

The industry does not accept this. It says emissions are not a general problem, and in any case there are remedial options and there remains a strong push for more hydro, and large schemes. See

While it is clear that Africa and other places in the developing world need energy, there are counterviews about whether hydro, especially large hydro, is the best bet. Large projects are expensive and involve large companies who, some fear, may not be that concerned about local impacts. Certainly there have been some bitter battles fought over some projects and large-scale hydro remains a politically contentious issue in many parts of the world. Quite apart from local impact issues, it is sometimes argued that large centralised projects may in any case be the wrong answer for Africa and other similar locations. The very large distances involved make it unlikely that grids could ever cover the entire continent. As with the 40 GW Grand Inga project on the Congo, much of the electricity seems likely to be exported on HVDC links to remote markets, not used locally. Local decentralised power may make more sense. That can be micro hydro, or wind, or biomass or solar, technologies which can be installed quickly with low local impacts and a potential for direct local involvement, and also possibly for the creation of local manufacturing enterprises to build the equipment.

Large hydro obviously plays a major role in Egypt, the Aswan Dam supplying 10% of its electricity, although it is now diversifying into solar and wind, with a target of getting 20% of its electricity from renewables by 2020. Large hydro is dominant in many sub-Saharan African countries, but in addition to wind, micro-hydro is seen as attractive in some locations, while village-level PV projects have spread widely, for example in Uganda, Tanzania, Chad, Rwanda, Angola, Gambia and Congo. Niger aims to get 10% of its primary energy from renewables by 2020, Senegal 15% by 2025. Kenya has large wind, solar and biomass resources, and is planning a 10 MW wave plant. It already has more than 200 MW of geothermal capacity, and aims to meet 50% of its electricity needs with geothermal by 2018. Nigeria’s 2006 Renewable Energy Master plan has renewables supplying 13% of electricity in the short term, and 36% long term. Ghana has introduced a Feed-In Tariff for PV, and its 155 MW PV project, launched in 2012, is the largest so far in Africa

Renewable energy feed-in tariffs (REFiTs) are clearly helping roll-out renewable technology across Africa, as they have in the EU, but a recent NGO report argued that, to meet Africa’s needs at the speed and scale required without burdening the energy poor, costs must be distributed across the population fairly, based on usage and ability to pay, while the international community can provide extra financial support, such as through “top-up” payments via a Global REFiT Fund, in line with obligations under the UNFCCC/Kyoto protocol for repayment of climate debts. See

There has certainly been no shortage of high-level initiatives on renewables in the region. In 2009 the Africa–EU Energy Partnership and the EU, together with the African Union, launched a 10 year Renewable Energy Cooperation Programme. and the UN’s new Sustainable Energy for All initiative, includes €50m EU backing. See But Africa needs more than top–down aid programmes. It needs local involvement, training and skill development, to support the growth of local jobs, and technical and economic capacities.

For a good overview see IRENA’s new report on Renewables in Africa:

In my next post, I will be looking at the situation in South America, where large hydro also dominates, but alternatives are also emerging.

This entry was posted in General and tagged , . Bookmark the permalink.
View all posts by this author 

Leave a comment

Your e-mail address will not be published.


  • Comments should be relevant to the article and not be used to promote your own work, products or services.
  • Please keep your comments brief (we recommend a maximum of 250 words).
  • We reserve the right to remove excessively long, inappropriate or offensive entries.

Show/hide formatting guidelines

Tag Description Example Output
<a> Hyperlink <a href="">google</a> google
<abbr> Abbreviation <abbr title="World Health Organisation" >WHO</abbr> WHO
<acronym> Acronym <acronym title="as soon as possible">ASAP</acronym> ASAP
<b> Bold <b>Some text</b> Some text
<blockquote> Quoted from another source <blockquote cite="">IOP</blockquote>
<cite> Cite <cite>Diagram 1</cite> Diagram 1
<del> Deleted text From this line<del datetime="2012-12-17"> this text was deleted</del> From this line this text was deleted
<em> Emphasized text In this line<em> this text was emphasised</em> In this line this text was emphasised
<i> Italic <i>Some text</i> Some text
<q> Quotation WWF goal is to build a future <q cite="">
where people live in harmony with nature and animals</q>
WWF goal is to build a future
where people live in harmony with nature and animals
<strike> Strike text <strike>Some text</strike> Some text
<strong> Stronger emphasis of text <strong>Some text</strong> Some text