HYDRO POWER: LATEST ISSUES AND DEVELOPMENTS

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1 HYDRO POWER: LATEST ISSUES AND DEVELOPMENTS Nandu D BHULA Power Station Manager, Eskom, Peaking Generation SOUTH AFRICA, nandu.bhula@eskom.co.za 1. INTRODUCTION Eskom has two large hydro power stations in the Generation fleet. This paper introduces these stations and highlights the role they play as part of Peaking Generation, one of the business units of Generation Division. Currently, focus is being placed on refurbishing these stations after 30 years of operation and the opportunity is being taken to upgrade the capacities of these stations and to improve efficiencies. This initiative is in line with current world practice of increasing renewable capacity and limiting Carbon based emissions. The paper highlights the benefits of the Clean Development Mechanism of the Kyoto protocol and how it adds to the financial justification of these refurbishments. The paper will also present the latest positions on the challenge against Large Hydro s as renewable options and Eskom s involvement with the International Hydro Association and their initiatives on Sustainability. 2. BRIEF OVERVIEW OF PEAKING GENERATION Peaking Generation is one of the business units of Eskom s Generation Division which comprises all of Generation s non-fossil and non-nuclear generating capabilities, i.e. Hydro, Pumped Storage, Gas Turbines and Wind Turbines with total installed capacity of 3381 MW over nine Power Stations. Each plant type has a unique advantage or constraint and is required to be operated at its optimal efficiency benefiting the system and the end use customer. Peaking s products are used to reduce the cost of the supply of electricity to the customer and are utilised according to system requirements. Supply of peaking power and absorption of energy during low demand periods. System voltage stabilisation (synchronous condenser operation). Automatic governor control (frequency control). Water transfer for the Department of Water Affairs and Forestry Flood and flow control on the Orange River system Peaking Generation has developed into a totally self-sufficient organisation over the last ten years. A wide variety of hydro and gas turbine experience, expertise and know how is available in Peaking and all its core business activities are conducted in house, i.e. Operating and Maintenance (including the inspection, servicing and overhaul of plant), Engineering, and Project Management. Peaking Generation has also been the latest recipients of the new built Gas Turbine Power Stations Ankerlig and Gourikwa with two further Pump Storage Stations yet to join the fleet. Fig 2.1 below shows the current and potential new additions to the Peaking fleet. 1

2 Peaking: All Stations Pretoria Johannesburg Steelpoort Bloemfontein Ingula Drakensberg Ankerlig Cape Town Acacia Durban Gariep Vanderkloof Port Rex Klipheuwel Gourikwa East London Port Elizabeth Palmiet South Africa Pumped Storage Hydro: Reservoir Gas Turbine Wind Farm National Control Peaking Office Fig. 2.1 Map showing location of Existing and New Peaking Power Stations 3. THE ORANGE RIVER HYDRO SCHEMES The Orange River Hydro Schemes in Peaking Generation namely Gariep and Vanderkloof Power Stations are located on the Orange River. They are situated on the Gariep and Vanderkloof Dams respectively. The two dams are the largest and second largest water reservoirs respectively in the Republic, with Vanderkloof 130 km downstream of Gariep. The dams are components of the Orange River Scheme, operated by the government Department of Water Affairs and Forestry. The Orange river is the largest watershed in SA, 2100 km long with catchments area of more than 1 million km², rising in the Lesotho Highlands, and flowing through South Africa and out to South Atlantic ocean. Water resources are at a premium in South Africa and the two power stations on the Orange River are the only conventional hydro-electric schemes of significance in the country. Due to the multi-purpose nature of the Orange River Scheme as a whole, a balance has to be maintained with regard to water resources for irrigation etc and water available for power generating purposes. In water scarce South Africa they are designed to: - Make provision for irrigation - Stimulate farming production - Provide urban water supplies - Promote economic activity - Create recreation facilities and promote tourism - Level out flood peaks - Generate hydro-electric power 2

3 Scheme Specifications Gariep 360 MW (4 x 90 MW) Vanderkloof 240 MW (2 x 120MW) Construction years Gariep Power Station 1967 to 1977 (First unit commissioned 1971) Vanderkloof Power Station 1973 to 1977 (First unit commissioned 1976) Reservoir capacity Gariep million m3 Vanderkloof million m3 Other aspects 1. Resource use: Wet and dry cycles of river flow influence the availability of the power plant. In practice, a sophisticated operating model has been developed by ESKOM and DWAF for optimum management of this precious water resource for both power generating and water supply purposes. Control curves maximise generation of electricity without violating the rights of downstream users. 2. Energy system benefits: The hydros are predominantly used as peaking power stations due to limited water resources and as such do have the ability to provide a swift response to the needs of the South African energy market. The units are able to come on line within three minutes and can be operated by remote-control from Eskom s national control centre. 3. Cost benefits and economic performance. The electricity produced by the Orange River Hydro stations is the cheapest in Generations fleet with average cost of production at almost 5 times less than coal-fired power stations. 4. Environmental aspects: Because the hydros displace a portion of the electricity which would otherwise be generated by Eskom s fossil stations, particulate emissions are reduced. In line with international agreements, the South African government is committed to significantly increase the estimated electricity demand being met by renewable energy resources. Both power stations are IS compliant and comply with relevant national environmental and water management legislation. 4. TYPICAL HYDRO INSTALLATION Hydro power is generated through the conversion of energy from potential to kinetic energy, where water is held in an upper reservoir or holding pond and is released through a water way system to the bottom river or holding pond. The difference in the water levels from the top and the bottom water bodies represent the net head or potential energy that translates into kinetic energy once the water is released. The water, once released passes through a turbine that is connected to a Generator via a shaft. As the turbine rotates due to the pressure and velocity of the flowing water, the generator rotor rotates within the stator and power is produced for export into the connected grid. The power so produced is generally at a low voltage which is then stepped up through a transformer for transmission over the grid. 3

4 Fig. 4.1 Typical components of a Hydropower Installation In the case of Gariep and Vanderkloof, the upper water bodies are reservoirs being the Gariep and Vanderkloof dam and the water is released into the Orange River. 5. CAPACITY INCREASE OPPORTUNITY FOR THE HYDRO STATIONS During the recent Vanderkloof stator rewind project the rewind Original Equipment Manufacturer suggested a possible capacity upgrade at these stations was possible. At the time this was not feasible due to the missed opportunity at Vanderkloof but it was identified as a viable option for Gariep Power Station. The opportunity arises from the fact that the current Peaking Technical Plan contains a number of existing refurbishment projects such as a Generator Refurbishment program for all 4 units, an Excitation Refurbishment program for all 4 units as well as the purchase of two new transformers to replace two existing ageing transformers. These projects present an ideal opportunity to consider the uprating of the turbines to maximise the capacity from Gariep using improved operating knowledge and design and manufacturing techniques. Based on this opportunity, the Generator OEM, was requested to perform a technical feasibility on the uprating of the units at Gariep. The detail of the feasibility found the following: 4

5 The turbine can be upgraded to a maximum of 62.57m if the runner, stay vanes and guide vanes are replaced/modified The turbine can be upgraded to a maximum of 62.57m if only the runner is replaced The turbine shaft can carry a maximum load of ±110MW and hence will be the bottleneck for uprating. Based on these findings, the technical proposal is as follows: Current Rating Turbine: Generator: Transformer: m head 100MVA, 13.2 kv 100MVA, LV: 13.2kV HV: 132kV Proposed Rating Turbine: Generator: Transformer:. Output [MW] 62.57m head min 122.2MVA, 13.2 kv min 122.2MVA, LV: 13.2kV HV: 132kV Unit Capacity Existing Proposed 1 Proposed 2 Proposed Net Head [m] Figure 5.1 Uprated Gariep Output Potential 5

6 The uprating of the turbine is limited to 112MW due to the limits of the turbine shaft. This will ensure a generator output of 110MW taking into account approximately 2MW of generator efficiency losses. The justification for this upgrade would be to make available an additional 80MW of peak and emergency generation to the national grid. This can be extremely important to the grid at this stage in our supply crisis and given the fact that this is considered to be renewable energy makes it more environmentally friendly as well. But there are risks and these are detailed below. Project Risks Utilisation Factor - One of the major risks to the feasibility of upgrading Gariep is that of the availability of water in the Orange River system. This currently has a significant impact on the load factor of both hydro stations on the Orange River with the average load factor for the preceding 7 years at Gariep being only 18.8%. Level of the Gariep Dam - The full increase in capacity will not always be available but only when the level of Gariep is above a certain level. This level is at 74.6% of full supply level. Below this dam level the total increase drops proportionately to dam level. Gariep has been above this level 69.1% of the time over the past 7 years, which is the positive news. However, the Load Factor for the additional capacity is likely to in the region of 5% only thus putting further pressure on the financial justification of the upgrade. 6. CDM, KYOTO & THE CHALLENGE AGAINST HYDRO AS A RENEWABLE 6.1 The Clean Development Mechanism The Clean Development Mechanism is a mechanism available to new and refurbishment projects in the renewable category. This mechanism was formulated during the meetings that lead to the Kyoto protocol. It allows project developers to register their projects as environmentally friendly and then trade the energy produced as carbon credits in order to raise financing capital for their projects. Generally, the qualifying projects will be those that have no carbon foot print and would typically require additional finance to bring them to fruition as shown in Fig 6.1. This means that the project would not be financially feasible or would not reach the required IRR threshold to make it lucrative to invest in. This is typical of many projects in Developing countries currently. The Gariep capacity upgrade project would fall in this category and does qualify to be registered for carbon credit trading. However, for hydro projects both new and upgraded to qualify they have to be considered to be renewable options and this has been the subject of several debates over the past few years until finally sanity prevailed and hydro power was indeed reaffirmed as a renewable option to the relief of many developing countries. 6

7 Project IRR Impact: CDM finance The gap between the project return and the required return on investment threshold CDM cash flow Threshold for the required return on investment Project return excluding CDM revenue Project return including CDM revenue Info Sources: Vattenfall Power Consultant Fig. 6.1 The benefit of CDM finance 6.2 Hydro Reaffirmed As Renewable Some recent attacks against Hydro, and in particular, large hydro as shown in figure 6.2 have taken the technology back many years and has also negatively influenced the developing potential of many Asian, African and South American countries. It is for this specific reason that the outcome of many ministerial conferences in favour of Hydro as renewable is of so great importance. In particular The International Conference for Renewable Energy in Bonn 2004 and The African Ministerial Conference on Hydropower and Sustainable Development in Johannesburg in 2006 have focused on and agreed to Hydro as a renewable option. The role of hydropower in meeting the world s growing water and energy needs as a clean, renewable and sustainable technology should not be down played. It is for this reason that the International Hydropower Association was formed under auspices of UNESCO in Its aim being to promote good practice and knowledge and to advance hydropower s role in meeting world s water and energy needs by: 1. championing continuous improvement, and sustainable practices 2. building consensus through strong partnerships with other stakeholders, 3. driving initiatives to increase the contribution of renewables, especially hydropower 4. increasing awareness of role hydropower can play in sustainable development as important source of renewable energy This they are accomplishing by Identifying and documenting International good Practices, Developing Sustainability Guidelines for hydropower and Repositioning hydropower in the Renewables Sector. 7

8 Talk about negative press!!! Fig. 6.2 Negative Press regarding Hydro The Caption: On Paper, dams may seem like a good idea. The truth is dams kill river s ecosystem by cutting off its flow. But that s after the locals have lost their homes. Spare a thought too, for those downstream of the dam where there s less water to irrigate crops and catch fish. Then there are the green-house gas emissions due to vegetation rotting in the reservoir. Not good. But let s talk money. The projected financial cost is rarely accurate. The World Commission on Dams found that, on average, large dams go over budget by 56%. They are high-risk investments. So how can you navigate this moral and economic mindfield? By getting hold of WWF s Investor s Guide to Dams. It outlines good dam practice and alternatives for supplying water and energy. That way you can go into any project with your eyes wide open. DAMS, THINK AGAIN. WWF publication sourced from IHA 6.2 Other IHA Initiatives: The IHA has driven the development of the Hydropower Sustainability guidelines and Assessment Protocol. The purpose of the guidelines is to promote greater consideration of environmental, social and economic aspects in the sustainability assessment of new hydro projects and the management and operation of existing power schemes. The introduction of the IHA Blue Planet Prize has resulted in hydro schemes around the world being recognised for their excellence in environmental, social and economic aspects and highlighted them as role models for sustainable development. Palmiet Pumped Storage Scheme received this coveted accolade in Sharing of knowledge, experience and best practices in sustainable development is also a predominant focus and the IHA sustainable Hydropower Website is serving as the portal for utilities and power project developers to obtain the latest practises and insights for sustainable hydropower development.. 8

9 7. THE ROLE OF HYDROPOWER IN AFRICA The African continent is blessed with a huge water resource and hydropower remains the dominant potential source of energy for the economic development of the continent. Unlike South Africa, where we have a limited water resource and thus are reliant on fossil fuels to serve the bulk of our energy requirements, the rest of Africa have an abundance of untapped hydro resources. Figure 7.1 shows the world s realistic hydro potential and what is already developed. It is clear that the huge untapped resources in the developing continents are likely to be the secret to their economic rise. With Asia and Africa boasting untapped resources of 1000 to 3000 TWh per annum, it is of vital importance that the efforts of organizations like the IHA are successful. Even more important is the fact that hydro has been recognized as a renewable option and as such each project that has been untapped has the benefit of attracting finance through the CDM facility set by the Kyoto protocol. (Realistic) Hydro Potential versus Developed Output Feasibility (TWh/y) Production (TWh/y) Africa Asia Australasia Europe N+C America South America Source: IHA, based on European model Fig. 7.1 World s undeveloped Hydro Potential 7.1 The African Dream: Westcor and Grand Inga The Inga River in the Democratic Republic of Congo, fig 7.2, has potentially the largest single source of hydro power on the continent. With a potential installed capacity of 39 GW resulting in 288 TWh per year, the prospects are unbelievable. It is for this reason that it is essential that large hydro gets the go ahead as a renewable resource and the Grand Inga scheme comes to fruition. This project could single handed lead to the African Economic Renaissance. To make this a reality Eskom has joined an inter-utility joint venture called Westcor that would drive the project s power delivery network through the five participating countries and eventual customers, DRC, Angola, Namibia, Botswana and South Africa. The first aim is to finalise the Inga 3 scheme of 3500 MW. Timescales for this project are as yet unconfirmed but sufficient organisational structures have been set up to make this project a reality. 9

10 Fig. 7.2 The Inga River in the DRC with a potential of MW and 288 TWh/annum 8. CONCLUSION South Africa is clearly not rich in terms of water resources however the two large hydro schemes in Eskom s fleet still play a major role in both power generation and river management. Focus is currently being place on improving on the efficiencies of these stations and upgrading the capacities through sustainable development. Hydropower remains the key to economic development of the three major developing continents and as such continual efforts at confirming hydro power as a renewable option to tap the as yet undeveloped potential on these continents, is vital. The efforts of organisations like the International Hydropower Association and their Sustainability guidelines will guide the selecting, designing, building and operating of hydro schemes based on sustainable development principles and ensures that hydropower remains the renewable option of choice for Africa. 9. REFERENCES o Gariep Capacity Upgrade Eskom Exco Investment Sub Committee submission 2006 Paul Nel o Orange River Development Project South Africa World commission on Dams s.org o UNFCCC Clean Development Mechanism Website o Vattenfall Power Consultants: Sara Nordström, Sustainable Energy and Carbon Finance Analyst: sara.nordstrom@vattenfall.com o Hydropower Sustainability Assessment: Latest draft released in July 2006 on the IHA website 10