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.
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.
By Adrian Piers