Hooray! I am carbon dioxide neutral; What about you?

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

02 June 2019

How many trees should a person plant in order to soak up all the carbon dioxide that they generate? First of all, it is important to point out that the carbon dioxide we breath out does not add anything to the concentration in the atmosphere.

The reason is that plants breath in Carbon dioxide, then we eat the plants and breath out the same carbon dioxide. The net result is zero.

However, as we go through our normal activities, we do add a significant amount of carbon dioxide to the atmosphere that was not there at the beginning. I think that for me, these additions mainly come from cooking gas, petroleum and electricity.

In my house, a 15kg gas cylinder lasts for about a month and a half. Thus, in one year, we consume about 8 cylinders which equal to 120kg of liquified petroleum gas (LPG). Burning one kilo of LPG produces about 3kg of carbon dioxide; so, my household generates about 360kg in one year through cooking.

The next major source of carbon dioxide is the family car. Over the last few years, I have been keeping an accurate record of the petrol consumed. From my notebook, I see that  I the car has consumed 638.03 litres in last 12 months. Yes; it is that accurate – to the second decimal place!

Burning one litre of petrol produces about 2.4kg of carbon dioxide. So, in the last one year, this car has emitted 1,531kg of the gas. This about 1.5 tonnes!

Next comes electricity. Now only a small portion of our electricity comes from the burning of fossil fuels. Most of it is from non carbon dioxide emitting sources – geothermal, hydro, wind and solar.

The Kenya Power and Lighting Company’s annual report for 30 June 2018 (the latest) shows that we consumed a total of 10,702GWh (Giga-Watt-hours) in the 2017/18 financial year and, out of this, 8,325GWh was from the clean sources. In other words, 78 per cent of our electricity is clean.

This proportion must be the same for my house. According to my electricity bills, we have consumed 3,802kWh (kilo-Watt-hours) in the last 12 months. 22 per cent of these were from fossil-fuel sources. That is, 836kWh

The thermal generators in Kenya use either diesel or gas. The average emission from these fuels is about 0.75kg per kWh. Thus I produce about 627kg of carbon dioxide from electricity.

Adding all the numbers together, it turns out that, in one year, my household generates about 2,500kg of carbon dioxide. There are six people in the house, so each person’s share is about 420kg.

Now a tree absorbs about 3kg of carbon dioxide in one year. So, to remove the 2,500kg that we are generating I need to plant about 840 trees. I am happy to report that I have planted many times that number!