Last Word
Zimbabwe, as everyone on the national grid is well aware, does not generate enough electricity to meet demand for all consumers 24/7 with heavy load shedding in most residential areas, which includes suburban shopping centres, as efforts are made to feed power to commercial users.
Zesa itself does not at present generate much more than 1000MW reliably from its two power stations, Hwange Thermal and Kariba South Hydro. There is a growing supply of solar from independent producers sold to Zesa distribution subsidiary, ZETDC, but it is still low, not much more than 100MW.
Zesa itself has started the renovation and rebuilding of the first six units at Hwange Thermal, one at a time, but this is not going to take Hwange to much more than 1 400MW when complete.
While a lot more rain in southeast Angola, where most of the water in Lake Kariba originates, will allow more generation at Kariba South we need to recognise that Angolan rainfall has been well below normal for at least the last three years, and there is no guarantee of sudden surges.
So doubling present average output is on the cards, and a return to normal flows could allow a tripling, we would be betting on better rainfall patterns than we have been seeing in recent years.
Supreme optimism will see around 2000MW maximum from these two stations when the refurbishment is completed, but with capacity at Kariba South to push up the maximum demand so long as we could cut back sharply at slack times, since that station has more capacity, 1 050MW, than the average we can reasonably expect, under 750MW, with normal flows.
A major reliance on hydro no longer seems the obvious solution. If Batoka had been built and commissioned a few years ago we would not be getting 1 200MW for Zimbabwe this year, more like less than 200MW at the low flow rates at this time of year.
Solar is the renewable energy for Zimbabwe and while there are plans by some potential investors for large stations, most of the solar capacity now installed, and it is a lot, is a huge collection of small domestic and commercial installations on roofs of houses, businesses, factories, schools and the like that do add up to a surprising output although reserved for the panel owners rather than the grid.
But all that extra output is, in one sense, helping to meet national demand with panel owners having power when Zesa is load shedding and even if there was no load shedding cutting back demand on the grid supply.
Some owners of solar arrays have already been fitted with the meters and connections required that they can sell their surpluses, generally small surpluses, during the day after charging batteries, but we still have a long way to go with this.
One problem is the cost. The rich are ever less reliant on Zesa. You can see large houses in say Harare’s northern suburbs that have substantial arrays of solar panels on their roofs, and have solar water heaters, which are now selling a lot better in hardware stores.
Such households can basically generate their own power for non-heating purposes, that is run their fridges, lights, computers, televisions and other non-heating solid state appliances, and heat their own domestic water, at least in summer although many will want grid power to top up the geysers, especially in winter.
But there are many, who manage without Zesa supply with their solar panels and batteries and water heaters and who cook on liquid petroleum gas and many others who only need Zesa power to top up after midnight for a few hours when there is hardly any load shedding.
Efforts by the then Solar Energy Society of Zimbabwe to get law changes in the 1980s that would have seen all new building being fitted with solar water heating failed.
Israel put in such a law in 1980, and Spain has gone even further with solar water heating from 2006 and solar panels a year earlier on all new construction, so we could do the same.
We are building a lot more flats, but generally only four or less floors, so there is enough roof for panels and hot-water systems and a law could be enacted soon, especially if there was some sort of finance available. Fitting this at the construction stage is a lot cheaper than retrofitting.
Solar panels are continually falling in price, and can be imported duty free. Batteries are now the expensive part of a solar system, and it is time for the Government to remove duty on these.
If there was high local demand this might also be the market required to kick start lithium battery manufacture in Zimbabwe.
Already some of the retailers have credit schemes, although these are limited to customers with assured US dollar income, but civil servants and others are able to sign up with their pay slips for modest installations, at least enough for the fridge, tv, lights and a computer.
A similar scheme is needed for hot water and some sort of arrangement for those not on US dollar pay slips, starting with the old.
Heating chews up most of a household’s power demand, which is why rural households are encouraged to look at biogas, but this is not an urban option, although the water heaters can take over a chunk.
Running stoves off solar panels and batteries is not really an option, hence the surge in gas, but widespread fitting of basic panel arrays and water heaters would allow three quarters of urban domestic demand to come from the roof, and even when Zesa has more capacity that would still be a large slice knocked off the demand, and especially at peak hours if electric stoves were limited to off peak cooking.
The cut back in electricity bills should, in theory, help to provide the income most people would need to finance credit schemes for the solar installations, although some extra would probably be needed.
So we need a lot of innovative solutions if we are to cope with present demand and then boost capacity to take into account the desperate need to increase output to feed the new mines, the mineral processing and the industrialisation that everyone in Government and the private sector sees as the only way to accelerate economic growth, plus the extra power needed to pump the extra irrigation water we are talking about for farming.
Hwange Thermal has a theoretical capacity of 1 520MW, comprising 4x120MW in the first phase of the early 1980s, 2x220MW in the second phase in the late 1980s and 2×300 in the third phase completed last year.
In practice, even if everything was working perfectly, the output would be a little over 1 400MW because of the cooling deficiency in the first two phases and the fact that no unit is ever at 100 percent.
But at present the first six units need a great deal of rebuilding, which for much of the mechanical and most of the electrical equipment means replacement of many parts.
Generally on a thermal unit the “dirty” end, the coal feed and the boiler, sees the greatest wear and replacement or complete refurbishment is more frequent than in the middle section, the steam feed and turbine, and the final section, the generator and transformer, usually lasts the longest.
Zesa is busy rebuilding using its own resources one of the 220MW units, and is arranging finance for the other five.
Even if there is extensive replacement of parts it is still a lot cheaper to completely rebuild a unit than abandon a power station as the civil engineering at least lasts far longer than any mechanical or electrical equipment, and in many cases at least some of the electrical equipment at least has a reasonable lifespan.
Building new coal stations, rather than refurbishing and maintaining older ones, is going to become more difficult. Even when Zimbabwe can access cheap global finance, say World Bank loans, there is a good chance that money will not be available for coal stations as stronger climate change policies come into effect. So we are back to solar.
Hydro is now too uncertain to provide new base load and it is noticeable that Zesa no longer talks about Batoka and instead is concentrating on refurbishing the old units at Hwange and pushing investment by others into solar, with its smart meters so it can buy power in the daytime, and is now talking about battery complexes so this day power can be stored.
We still need a lot of investment for solar, but we need to work with the fact that solar arrays can be broken up into small domestic and business installations. Some service businesses and many shops could use solar, although mineral processing and factories need big power stations for the heavy machines and furnaces. Even some of the small industries need grid power for power tools and the like.
So our future appears to be a stronger grid, but with a lot of the light demand coming from the individual solar arrays on roofs and a huge jump in smart metering so the small surpluses in daytime can be combined into something useful for industry.
But we need to start moving a lot faster to organise that panelling of our roofs and combining it with the new thrust on housing so that panels are automatically fitted to new buildings.
