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Monday, January 30, 2023

Power for Development -a cost comparison with solar power.

EconomyPower for Development -a cost comparison with solar power.

Will we have to pay for the cost of inadequate planning and bad water management, or are there alternative solutions?

Following up on my two previous articles on Lusakatimes, it is clear from many of the comments there that there is a good diversity of opinion as far as our current power problems are concerned. I thank all those that took the time to respond with comments, and can assure those bloggers that I have looked at them all. One thing that has become clear is that some people are not familiar with the history of power generation in Zambia, so here is a short synopsis of how we got to where we are now.

After using coal fuelled power plants for many years, it was decided to move over from coal to hydroelectric power generation. The relics of this era are still visible in our towns. Behind the Zesco building on the Great East road are some concrete towers )( )( clearly visible from the railway overbridge. They are the cooling towers that were used for producing Lusakas electricity in the early days, and are now retired and redundant. Their obsolescence was brought about through the development of hydropower.

By now, most people are well aware of the current source of our electricity, mainly Kariba and Kafue Gorge, constructed at huge cost. Why was this changed from the old coal powered system? The answer here is that, although the capital cost of hydro projects were huge and they took many years to build, in the long term it was the cheapest way of providing power, especially for the copper mines that were Zambias life-blood. When planning power production, it is not only the cost of construction of the facility, but also the expected life of the plant, and the running costs that will be incurred during its lifetime.

Different systems each have their advantages and disadvantages. For example, besides the cost of the power plant itself, there is the cost of distributing the electricity through powerlines to where it is needed, so a diesel generator may be expensive, but if it is placed right at the place where the power is used, the transmission costs are negligible. The same applies for solar panels. Obviously, for hydropower the turbines must be sited where the water is. And for coal, either the plant must be at the mining site as at Maamba, with the additional costs of transmission lines, or the coal must be physically moved to the power plant as was done in the past. That is why the old power stations are next to the railway line. The coal was moved by rail.

The chart below is instructive. The costs of new power stations are broken down into capital costs (shown in the blue section) and the running costs (shown in the red section). From this it is clear that the ultimate costs per kWh are highly variable depending on how the power is generated. The cost of transmission is included in these figures.
From this data it is obvious why the choice was for hydropower for Zambia. As Zambia has no natural gas supplies, the systems that are capable of providing the cheapest power are wind and hydro, and as we do not have a windy environment capable of providing dependable power, but we do have massive water resources, the choice had to be hydro.

The planners that decided to build Kariba were well aware of all this, and therefore it was built in the 1950s. Then, in 1972, an extensive survey was done which included identifying all the potential hydropower sites available. Those that held promise were identified and investigated further. The result was a comprehensive report on Zambias hydropower potential. This is shown schematically in a diagram published by M. J. Tumbare in his excellent book, The Management of the Zambezi River Basin and Kariba Dam.

So what about all the other options? Why are those people who are responsible for our energy security now pursuing solar power and coal? The answer is simple. These are short-term, very expensive fixes to make up for their years of neglect and lack of adequate planning.

Lack of planning

There are two aspects to this. The first one is ignoring simple statistics and our demography. At Independence, Zambia had about four million people. That has risen to about thirteen million at present, and it will increase even further in the future. This is a known fact.
Secondly, to grow our economy, develop Zambia and provide employment, we have to move beyond subsistence agriculture and create an industrialized economy that can provide decent, high paying jobs for upcoming generations. Any economist will tell you that this is only possible with cheap, reliable electricity supplies. And large scale hydroelectric projects take many years to build. One of the biggest mistakes ever made was the cancelling of the Kafue Gorge lower power project in 2011. Although this has now been reinstated, that decision has lost Zambia at least four years of development, and to make up for that disastrous choice we now have to pay for solar power and coal plants that will increase our electricity costs by a huge amount.

The other aspect of our power woes are short term decisions. Currently we have enormous generating capacity already installed! But we are not using it. And the reason for that is lack of water. Is it because of drought? A look at the information below shows we have experienced droughts in the past, without resorting to load shedding.
This was the problem I looked at in my first article. It is one thing to build new power plants, but they take time and cost huge amounts of money to purchase the machinery required. Is it not possible to use the already installed capacity more efficiently and thereby save large sums of money?
In the short term solar power can assist at delivering some of the much needed power to the Nation, but at what cost? Or power can be imported such as has been happening from the Turkish powership in Mozambique that was supplying us with power at such exorbitant prices, but a careful analysis of the situation shows that this is avoidable with proper planning and good water management.

Water management

Can we improve on how we manage water for power generation? The simple answer is – YES WE CAN!
To understand the problem it is necessary to know how this works in practice. The managers of a dam like Kariba have a set of rules that they call a “rule curve” as it is essentially a graph, with the rules shown as the R-Curve below. This also stipulates that when rainfall in the catchment area reaches specified levels water must be let out of the dam to make way for incoming water. Based on these calculations the gates are opened for a time that allows the water to be spilled. The problem here is that if there is suddenly no more rain, valuable water will have been wasted and we will have to wait for future years to fill the dam again.
And it takes a long time to fill a huge lake like Kariba! Now, water is being continuously used to generate power. But even before the turbines were installed, and after the dam was constructed, it took SIX YEARS to fill.

The proposal of constructing a second spillway outlined in my second article will eliminate this practice completely. In this way the lake can be left to fill up to its maximum capacity without any fear of excessive inflows. Flushing out and wasting water like what was done in 2011 where a WHOLE YEARS SUPPLY was let out of the lake will end. Safely.

Saving water through cost effective strategies

So can Kariba store excess water in years when there is a surplus and then used by EXISTING POWER PLANTS, that have already been built and paid for? Yes it can. All that is needed is the diversion canal suggested in my first article. Will this solution save money? The cost will be only that of a diversion canal – very much cheaper that building a whole new power plant!


There is enough water in years of high rainfall in the Kafue river to justify the investigation of a diversion canal to Kariba.
A second spillway on Kariba can substantially improve how the water reserves are managed, and contribute to the safety and efficiency.
These interventions, especially when combined, can productively use the already installed generating capacity at Kariba.
In this way we can avoid the huge expense of additional solar panels or importing gas generated power and the loss of forex.

Further reading


By Adrian Piers


    • A good analysis but lacks empirical evidence or references to have a skeleton with stamina.
      Without references to this wonderful article renders it as an educated opinion.
      The Skeleton Key

    • From your own figures, coal is not too far off in terms of cost comparison to hydro. Hydro, coal and nuclear are great for base load, unlike solar. Nuclear may be out unless contracted out to the Russians, Chinese or French who are good with nuclear. Coal offers diversity of power sources. If Zambia has coal (which we do in millions of tonnes in Gwembe Valley), then more large coal power stations is a great alternative when droughts happen (which will be more often going forward). Solar is great for topping up during day time but we do not have storage systems for use of solar power at night. Also micro-solar systems cannot provide reliable three phase power that is required in industry.

    • Please note that all the coal power station cooling stacks were built before Kariba Power Station (pre 1958). The coal used was from Wankie. Nkandabwe/Maamba was only developed in early 1970s and the coal was for NCZ and copper smelters, not for power generation. Coal power can only sensibly provide base load power at scale. Your cost comparison chart clearly shows that coal has slightly lower capital cost but higher operating cost. As a diversity of power sources going forward Zambia needs more coal power stations. It is not true that Maamba coal has too low calorific value for power generation. Thermal coal is not supposed to be of the same quality as for steel making.

    • The proposal to divert water from Kafue to Gwembe Valley may be too costly and irrelevant. The Kafue Flats are too shallow and the ridge of high grounds that ends at Munali Hills is wide and is the backbone on which the road and railway to Lstone runs. Crossing that high ground cannot be a mere 15km(?) as you suggested in your second article. Also, in the year when you would want to divert the water, you may also not have enough for Kafue Gorge and Lower. I am not convinced without prior rainfall historical records and geographical profiles of the land between Kafue and Gwembe. However, your proposal for a second spillway at Kariba is great but will not be supported by Zim because water will be diverted into Zambia where it can be used for agriculture. Zimbos are too selfish to give away…

    • Zimbos are too selfish to give away such an advantage. Sata’s cancellation of the Kafue Lower project in 2011 was pure treason and economic sabotage. Even the financing structure was better then, at no cost to Zambia, with entirely private capital, instead of the current loans on Zambia’s balance sheet. BTW Kafue Lower has always been the number 1 power project ahead of Batoka for Zambia since the early 1970s. While Batoka is important for Zim who do not have alternatives, Zambia can and should do power projects that are entirely within our own borders.

    • Please give links to all your articles so that one can follow your ideas. Why do the curves for Kariba only go to 2006? Is it because the Zambezi River Authority has stopped such technical work or you are an outsider and they are not giving you the data? The 2007 to 2016 period is the most interesting!

  1. Great artjcle non political, factual. Adrian, is it possible that plantings of harvest trees, plantations, is reducing the traditional run offfs and aquifers. Does this have an effect on Lake Kariba.
    This is just question not any form of critique.
    Keep pushing as your informative insights will, hopefully, bear fruit

  2. This man knows the subject. He has very lofty academic credentials on the subject matched only by his humility which forbids him from revealing them to us. Alinwa data, mukali. He gives full value to the intended purpose of a blogging site. Long live, man!

  3. This is pure soliciting for a JOB in ZESCO, their is nothing new what this man is writing apart from copying from hydrology text books and editing some graphs. This is politics , please i challenge you to write a paper we meet at an international forum NOT exposing your mwembeshi on this site that we are used commenting and talking politics ATASE

  4. This is the man that needs to be heading Zesco and not these cadres who have no capacity nor technical know-how on electricity generation. Clearly, this article is one of the best I have ever read on Lusaka times, succinct, full of statistics and clearly lays the solutions right in front of you. This is what we mean when we say their are a lot people with immerse knowledge and one wonders why we fail to utilize them. Imagine you call for an indaba and you are presented with such information, can we fail to come up with a strategic plan to manage our water resources prudently? Hats off to Adrian Piers for such valuable presentation, excellent.

  5. Anyokooo, at degree level and beyond, it’s not called copying, but manipulating data to support your argument or thesis. Apa conversation naikosa for cadres like you who breathe politics every second. Iyi nomba ya bakulu discussion munthu wandi to take Zambia pamulu. Stand aside and watch us talk. Vote Adrian 2021.


  7. Good article and good ideas. Your graphs and data used to do the comparisons of each source of energy need to be updated however as technology for solar has since significantly advanced in the recent past bringing the cost of solar substantially more competitive than even hydro. The recent scaling solar project in Zambia is locked at an average of us6cents compared to us11cents for hydro. A solar plant can be built in just 8 months. Check your numbers again for solar at least!

    • Those costs for solar are without energy storage. You can only access that solar power during the day. But according to Zesco, peak power use is from 18:00 to 22:00.

  8. @Peter, I totally agree. We need to embrace such ideas and come out of this political circus of always bickering everyday, put politics aside and converge to come up with solutions to solve our most pressing challenges. There are people with immerse knowledge in economics as well but because of lack of seriousness, people are now dying fighting for hand outs when we have educated technocrats who can move this country out of this economic quagmire. Economic doldrums are experienced in any economy but, it is the reaction of technocrats and many other experts that will bring about needed change and steer this country in the right direction. Lets stop these politics of the belly and deal with issues magnanimously.

  9. I still think with the Inga 3 mega dam proposed in congo, Zambia would be smatter being part of the consortium.

    The $14bn (£9.5bn) Inga 3 project, the first part of the mega-project, is being fast-tracked by the Democratic Republic of Congo government will span one channel of the vast river Congo at Inga Falls. It involves a large dam and a 4,800MW hydro-electric plant.

    But subsequent phases, together costing about $100bn, could eventually span the Congo river, the world’s second largest by volume. It is expected to have an electricity-generating capacity of nearly 40,000MW – nearly twice as much as the Three Gorges dam in China or 20 large nuclear power stations.

    SA have already signed up to this project and cheap electricity will be in abundance.

    • @ spaka like lilo, this is true. Inga will ultimately be the biggest power source in Central Africa and will dwarf all other hydroelectric schemes, not only in Africa, but in the whole world. Zambia will make money by charging SA for transmission of the power from DRC to Zimbabwe through the Southern Africa Power Pool arrangement, so we should support it.

      But we need to end our load shedding now! And this project will take decades to complete, so the argument here is what can we do that that is cost-effective and quick. Zambias development is on hold while we sit in darkness!

  10. Adrian,
    Your reasurch is enviable and is a much education to many readers like myself.

    As another side to this discussion could you also research , if possible, and explore the Inga dam project in Congo. If zambia can join the cosortium, How zambia can benifit. If zambia can join can we pay by maybe supplying maize and other farm produce to congo in return for a place at the table.

    SA is part of that deal, where will their transmission lines pass through?

    Thanks in advance.

  11. Congratulations to all bloggers not one mention of party politics…this is how zambia can progress…work together and become a NATION in ACTIONS not words.

    WELL DONE now apply the same rationale when we blog on other issues relevant to our economy and future.

  12. This is incorrect. The data you use is from 6 years ago, the cost of solar is now from 6-7 cents for large projects, (Scaling solar Zambia 2016) to 14 cents for projects under 1MW. All new hydro projects here will cost 15+cents. Hydro uses water which is needed by Zambias farmers to ensure food security. Water will become scarce in the coming years, meaning it is vital for the country to diversify into solar. New solar projects are cheaper than new Hydro so that is good news. This report uses old data and spreads misinformation.

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