What is cheaper: cooking with gas or electricity?

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

18 June 2017

What is cheaper: cooking with electricity or with gas? This is a question that I tackled many years ago – August 2006 – but it resurfaced recently after the Kenya Power and Lighting Company launched a cookery programme on TV christened “Pika Na Power”.

Now the 2006 article was based on an experiment that I did to compare the two energy sources – boiling half a litre of water in an electric kettle and in a sufuria on a gas cooker. The kettle took one minute and 33 seconds to do the job while the gas cooker took 4m:48s. Clearly, the former won the speed test hands down!

At that time, the cost of a 13kg gas cylinder was Sh1,500 while one unit of electricity (1kWh) was Sh10.10 (based on my bill for that month). Using these numbers and costs, it turned out that the kettle spent Sh0.58 (58 cents) to boil the water, while the gas cooker spent Sh1.48. Contrary to popular opinion, the cost of gas was almost three times that of electricity!

Eleven years have now passed since that experiment and it would be interesting to see if the results have changed. My current electricity bill shows that I consumed 265 units and was charged Sh5,131. That works out to Sh19.36 per unit. Did some one say that electricity prices have gone down?

The price of cooking gas has also gone up to Sh2,300 for a 13kg cylinder.

Since 2006, electricity prices have gone up by 92%, so the cost of boiling half a litre of water must increase by the same rate. That is, from 58 cents to Sh1.11.

By the same logic, gas prices have increased by 53%, so the cost of boiling the water in a sufuria on a cooker has increased from Sh1.48 to Sh2.27.

Clearly, it is still cheaper to boil water with electricity than with gas. However, the difference has reduce somewhat because electricity prices have escalated by a bigger margin that those of cooking gas. But boiling water is not the same as cooking – you obviously can’t make ugali in an electric kettle!

Gas cookers are very wasteful: only 40% of the energy from their fire is available for cooking. More than half (60%) is lost to the surroundings. Hot-coil electric cookers are more efficient. When using a flat-base sufuria, they can achieve about 70% energy efficiency.

So, out of the 13kg of gas in a Sh2,300 cylinder, only 5.2kg goes to useful cooking. Therefore, the effective cost is Sh442 per kilogram. Similarly, the effective cost of electricity is Sh28 per kWh.

Now one kilogram of cooking gas has 12.9kWh of energy. So, Sh442 buys 12.89kWh; that is, Sh34 per kWh.

So; you pay Sh29 per kWh to cook with electricity costs Sh34 per kWh to do it with gas. Although it is cheaper, the biggest problem is that electricity it is very unreliable. And when it goes off, you have no clue whatsoever when it will back on again!