Is desalination of seawater viable in Kenya?


The Sunday Nation


26 February 2023


Is it practical to pump water from the Indian Ocean and Lake Victoria and supply it to Kenyans in the interior of the country? Fabian Muli, the member of parliament for Kangundo thinks so. He was recently reported saying that “it is high time we stop this nonsense of building dams and drilling boreholes…[and] pump water from the Indian Ocean!”

Apart of the obvious challenge of desalination, water from the Indian Ocean would need to be pumped to an average of at least 1,500 metres above sea-level (ASL)because that’s where the majority of Kenyan’s live. In May 2020, I discussed the feasibility of pumping water from Lake Victoria (1,135m ASL) to Nairobi (1,795m ASL).

It turned out that it would take about 1.8 units of electricity (kWh) to pump one unit of water (1,000 litres). In shillings, the cost comes to about Sh45 at today’s power prices. Remember: this is the price of pumping alone.

Knowing this, it is easy to extrapolate and estimate how much it would cost to pump desalinated water to the average of 1,500m. It is 1,500 divided by 660, and the result is multiplied by Sh45. The answer is Sh102 per unit of water. To this, we must add the cost of desalination.

Many cities around the world are desalinating sea water. The average cost is varies widely between $0.50 and $1.50. Thus, we can use the middle-ground of one dollar per 1,000L. That is, about Sh125. This brings the total cost of desalinated water to about Sh227 per 1,000L.

Let’s compare that with what, say, Nairobi residents are paying for water that is collected in a dam. My current bill shows that I consumed 16 units and I was charged Sh1,359. This works down to Sh85 per unit. Desalinated water would cost about three times this: that is, about Sh3,600.

Desalination plants are also very expensive: Kenya is spending Sh82 billion on the construction of Thwake dam in Machakos/Kitui counties. This will produce about 150 million litres of water daily. A desalination plant of similar capacity would cost about $2.5 billion; that is, over Sh300 billion.

So, it turns out that building dams is not nonsense, as the MP would put it. It is actually very sensible. The regions of the world that are desalinating seawater have not other option. They are desert regions near the sea with no rivers and no viable underground water.

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