Kabulasoke: A critique on where and how to use solar electric energy
Kampala, Uganda | ENG. KANT ATEENYI KANYARUSOKE | First, we will congratulate Ugandans and their son Dr. David Alobo for the recent commissioning of a 20 MW photovoltaic power plant. The project follows the 2016 Soroti solar plant of 10 MW, which was famed as the biggest in East and Central Africa then.
As I have argued both locally and internationally in the past, solar energy harnessing is the way to go for countries with a plentiful solar resource and with dysfunctional electric grid systems such as in most of sub-Saharan Africa.
As a primary resource, solar energy is everywhere, free, inexhaustible. It can easily be used to provide different forms of energy: electric – as in these plants; heating – as in solar water heaters; refrigeration – as in solar powered refrigerators and air conditioners; cooking – as in solar cookers; agricultural – as in solar irrigation-water pumping, solar crop drying and perishable foods preservation; transportation – as in solar powered vehicles; biochemical as in solar water purifiers, etc. It is safe, and can be completely free of corrupting tendencies, so rampant in Africa’s energy infrastructure. More interesting, it is a powerful discipliner to users, because the primary source is not directly available at night.
The above narrative notwithstanding, we need to be a bit more careful on how we go about exploiting it than displayed in the above two investments.
This article argues that in sparsely populated Africa, solar electric investments are better if directed to smaller individual home units and to isolated power supplies in remote areas than to feed into the dysfunctional grid systems. There are technical, economic, environmental, social and political reasons for this approach – which I explain hereunder.
Technical – Too many odds are against feeding solar electricity into an existing grid: The uneven power generation from minute to minute creates an unsteady grid voltage and frequency, which badly affects equipment connected to the grid. In the worst of situations, it can also cause death of lines maintenance personnel trying to rectify faults emanating from conventional generators, transformers and transmission lines. To avoid the fatalities, the solar units would have to be simultaneously switched out before maintenance. This means, they do not improve reliability of the supply at all – even as they do increase risks of equipment damage and human life loss. The other issues are to do with actual solar electric energy delivered to the consumer. Solar panels as used in Soroti and Kabulasoke produce direct current (like that in your torch or car battery) at an operating efficiency of about 15-18%. This power is then converted to alternating form at efficiency of about 96% (even though the Kabulasoke investors claim a 99.5% value!). If it is to be transmitted over a long distance it would have to be stepped up to the transmission line voltage at another 96% and then stepped down to 240 V at a further 96%. This means, from say 100 W of solar energy arriving at the panel, only about 14 W enters the grid. Now, if the grid is dysfunctional, even much of this 14 will never reach the consumer.
For Uganda, with a transmission loss of 16.5% (which is a very good performance by the way), the transformer near the consumer will receive only 11.5 W, which will reduce further to 11, after the final step down transformer to the consumer. This is about 73% of what was actually produced by the panels. In other words, from a 20 MW plant, we could reasonably expect the consumers to receive just about 14.6 MW!
Economic – The losses and risks indicated above have serious implications on the economics of the plant. For the Kabulasoke investment running at about 1 US$ per installed Watt power, this works out at over 1.4 US$ per UMEME delivered Watt. This is not to include the cost of added risks. The investor will have of course agreed with UMEME (and government) on a suitable energy sale/purchase rate to ensure he makes a good profit. No problem there – but in the larger scheme of things, for society, the actual investment cost is over 40% more than it would be if the same amount had been invested at household level (i.e. with no conversion and transmission costs). There are also opportunity costs to do with loss of agricultural or other usage of land occupied by the panels when ground mounted as in the two plants.
Environmental – It is easy to romanticise the environmental benefits of the investments, and on which romance, NEMA will have pleasantly approved them. However, considering the ground mounting of the installations, as opposed to roof mounting or home compound installations, there is an issue of loss of alternative use of land. The 120 acres in fertile Luwero and another 33 in Soroti may now look uniformly beautiful to the eye, but the ecology of those acres is irreversibly affected. Does this mean we should never have such plants? No – they are better located in dryer and more barren areas, where it is even easier to justify the 25-30% energy loss than in highly agriculturally productive areas.
Social – My biggest concern here is the lie that feeding this energy into the grid is the easiest and most convenient way to get more rural people to use electricity. It is a lie because you must still expand the transmission and distribution system to reach the peasants. This is not possible for all peasants, and even if it were, it would be dangerous for many of Africa’s peasants, as they would be receiving potentially fatal 220-240 Volt supply. The second point is that this energy would have to be paid for on a recurrent basis. If the peasants do not have sustainable incomes, they cannot pay for it – and in that case, other tax payers would have to pay these bills. It is acceptable to run transmission lines to rural trading centres principally for small and medium scale artisanal businesses which are generating incomes to meet the bills, but not to peasants’ homes. The latter ought to be encouraged to obtain roof-mounted units on which recurrent expenses are minimal. Investors like Xsabo Power Limted would do well to invest in solar PV assembly plants or in direct current devices for use with these panels without having to go through conversions. We should take a leaf from neighbouring Kenya, which within 5 years, has pushed up access to electricity from below 20 to 75% now, not through grid supply, but through small, affordable roof-mounted photovoltaic systems.
Political – here I want to address myself to the independence bit. Reliance on power from the grid keeps people tied to and ‘enslaved’ by a centralised, largely corrupt system, when there is a clear independent alternative. This is not just at individual home level. At national level, African countries are easily held at ransom by so called foreign donors and investors in supplying large and grandiose systems for merely transforming what is naturally and abundantly available to electricity, and subsequent degradation through conversions and transmissions. For some African countries, Uganda inclusive, at present state of home solar energy systems technology development, the truth is that there is hardly a need for many of these foreign vampires to help our people access modern forms of energy.
Kant is a pan-Africanist Engineering Pracademic and Team leader of Progressive Africa Solar Engineering Company.