The magic ratio in the prices of gas and electricity
By MUNGAI KIHANYA
The Sunday Nation
Nairobi,
08 October 2023
Last week, we saw
that an electric cooker is a lot more efficient in energy utilisation
than a gas burner. 59 per cent of the energy supplied to the electrical
heating coil went into cooking while for gas it was just 17 per cent.
Nevertheless, gas is much faster in doing the job – it took just 30
minutes to evaporate 1.7kg of water while, after more than one hour,
electricity only managed 750g!
Two interesting
question arise: first, at what price would gas be cheaper to cook with?
Second, at what price would electricity be more expensive? The
experiment from two weeks ago found that the cost of cooking with gas
was Sh28.35/MJ while with electricity it was Sh15.20/MJ.
This calculation was
done using a price of Sh3,000 per 13kgcylinder. So, the question we are
asking is, what price of gas would bring down the cooking cost to
Sh15.20? The answer is found by first dividing Sh3,000 by Sh28.35 and
then multiplying the result by Sh15.20.
This comes to
Sh1,608. This is how low the price of gas would have to be for it to be
cheaper than electricity – assuming electricity prices remain at Sh32.00
per kWh. Is it reasonable to expect it to get that cheap?
On the other hand, if
the price of gas remained at about Sh3,000, then, by similar
calculation, that of electricity would have to increase to Sh59.68 per
kWh. Is it reasonable to expect it to get that high?
Finally; is there a
quick away of figuring out which of the two is cheaper? The answer is
yes. At Sh1,608 for 13kg gas and Sh32 per kWh of electricity, it costs
the same to cook with either source of heat. Alternatively, at Sh3,000
for gas and Sh59.68 for electricity, again the cooking costs would be
equal.
Now, take your
calculator and divided Sh1,608 by Sh32 and write down the answer. Next,
divide Sh3,000 by Sh59.68 and record the answer as well. Look at the two
answers: they are approximately the same – about 50. Any difference is a
result of rounding in previous calculations.
Thus 50 is our magic
number! If the ratio of the price of 13kg gas to one kWh of electricity
is greater than 50, then gas is more expensive. If it is less than 50,
then gas is cheaper. Currently, that ratio stands at almost 100 (Sh3,000
divided by Sh32) – gas is almost double the cost of electricity.
