Eliza Buglar

Mar 29, 2021

These days, it seems as though we spend much of our time charging our trusty smartphones, and the rest complaining about how often we need to!

But have you ever stopped to consider how much electricity you use to charge your phone each year, and the environmental impact of that electricity?

We thought we’d investigate the carbon footprint of charging phones on a personal scale first, before ‘zooming out’ to see how this footprint fares at a country and then global scale.

What is a carbon footprint?

‘Carbon footprint’ is used to refer to the total amount of greenhouse gases emitted through a person’s activities, usually measured in tonnes.1 Greenhouse gases include:2
• carbon dioxide
• hydrofluorocarbons
• methane
• nitrous oxide
• perfluorocarbons
• sulphur hexafluoride.

Carbon dioxide equivalence (CO2e), which comprises the above greenhouse gases, is used to measure the emissions of those gases.3

Want to see how we arrived at our results? We’ve broken this information down for you below.

The estimated carbon footprint of charging one phone

If we assume that you recharge your phone using a five-watt (W) charger for one hour each day, this means you’ll use a total of 1.825 kilowatt-hours (kWh) of electricity to charge your phone in one year.

To put this number into perspective, the average annual electricity consumption of a US residential customer was 10,649 kWh in 20194 – making the annual electricity use of charging one phone equal to 0.01% of the total annual use of a home.

So now we’ve estimated how much electricity phone charging uses, let’s find out how much CO2e this produces.

In proper carbon footprint calculations, this number will change depending on which country you live in. However, for our estimations, we’ve broken it down by continent instead. You can find out how and why we did this below.

Africa – 1.69 kgCO2e emitted per year by charging one phone each day
Asia – 1.07 kgCO2e per year
The Middle East – 0.99 kgCO2e per year
Australasia/Oceania – 0.81 kgCO2e per year
North and Central America – 0.62 kgCO2e per year
Europe – 0.54 kgCO2e per year
South America – 0.35 kgCO2e per year

To put these numbers into perspective, let’s return to our average annual electricity consumption of a US home (10,649kWh) and see how much CO2e is produced from this.

Combining this number with the emissions factor for North and Central America tells us that the average electricity use of a US home produces 3,664.03 kgCO2e per year.

So, the greenhouse gas emission of charging your phone doesn’t sound like a lot in the grand scheme of things, does it?

But let’s see what happens when we expand our scope to look at how much greenhouse gas is emitted per year by charging every phone in every country around the world, based on just one hour of phone charging per day.

 

Calculations

Electricity consumption of charging a phone

5 W of electricity for one hour per day = 5 watt-hours (Wh) of electricity per day

5 Wh x 365 days = 1,825 Wh of electricity per year

1,825 Wh = 1.825 kWh of electricity

CO2e emissions per continent

To work out the CO2e emissions of electricity consumption, we need to multiply it by the emissions factor. Emissions factors are different for every country, so we’ve used the average of each continent instead.

Africa: 1.825 kWh x 0.928 kgCO2e (emissions factor) = 1.6936 kgCO2e emitted per year

Asia: 1.825 kWh x 0.587975 kgCO2e = 1.073054375 kgCO2e per year

The Middle East: 1.825 kWh x 0.546266667 kgCO2e = 0.996936667 kgCO2e per year

Australasia/Oceania: 1.825 kWh x 0.44385 kgCO2e = 0.81002625 kgCO2e per year

North and Central America: 1.825 kWh x 0.344073333 kgCO2e = 0.627933833 kgCO2e per year

Europe: 1.825 kWh x 0.29932303 kgCO2e = 0.54626453 kgCO2e per year

South America: 1.825 kWh x 0.1935 kgCO2e = 0.3531375 kgCO2e per year

 

Calculations

To convert greenhouse gas emissions into CO2e, we need to multiply the amount of greenhouse gas (e.g. methane) by its global warming potential (GWP).5 GWP is the measure of how many kilograms of a particular greenhouse gas is needed to produce the same warming effect as one kilogram of CO2 over 100 years.

 

Passenger vehicles

• Average annual emissions from one passenger vehicle = 4.6 metric tonnes CO26
• 4.6 tonnes of CO2 x 1 GWP = 4.6 tonnes CO2e
• 8,088,324 tonnes CO2e ÷ 4.6 tonnes CO2e = 1,758,331 passenger vehicles

Cows

• Average annual methane (CH4) emission from one dairy cow = 100kg7
• 100kg of CH4 x 28 GWP = 2,800 kgCO2e
• 2,800 kgCO2e ÷ 1,000 = 2.8 tonnes CO2e
• 8,088,324 tonnes CO2e ÷ 2.8 tonnes CO2e = 2,888,687 cows

Eiffel Tower lights

• Approximate annual electricity consumption of the 20,000 lights on the Eiffel Tower = 8,800 kWh8
• 8,800 kWh x 0.03895 kgCO2e (France emissions factor) = 342.76 kgCO2e per year
• 342.76 kgCO2e ÷ 1,000 = 0.34276 tonnes CO2e
• 8,088,324 tonnes CO2e ÷ 0.34276 tonnes CO2e = 23,597,630 sets of Eiffel Tower lights

Pairs of jeans

• Approximate greenhouse gas emissions of the process to make one pair of jeans = 33.4 kgCO2e9
• 33.4 kgCO2e ÷ 1,000 = 0.0334 tonnes CO2e
• 8,088,324 tonnes CO2e ÷ 0.0334 tonnes CO2e = 242,165,389 pairs of jeans

People at a barbecue

• Emissions for one person at a typical barbeque (featuring 125 grams of charcoal, two bread rolls, two tablespoons of butter, two burgers, two slices of cheese, a tomato, two tablespoons of ketchup, some strawberries and two tablespoons of cream) = 5.8 kgCO2e10
• 5.8 kgCO2e ÷ 1,000 = 0.0058 tonnes CO2e
• 8,088,324 tonnes CO2e ÷ 0.0058 tonnes CO2e = 1,394,538,620 people

Seats on the Shinkansen

• CO2 emissions per seat on the Tokaido Shinkansen between Tokyo and Osaka = 4.2 kgCO211
• 4.2 kgCO2 x 1 GWP = 4.2 kgCO2e
• 4.2 kgCO2e ÷ 1,000 = 0.0042 tonnes CO2e
• 8,088,324 tonnes CO2e ÷ 0.0042 tonnes CO2e = 1,925,791,428 seats

How we calculated the carbon footprint estimations

Carbon footprints can be difficult to accurately and precisely calculate (due, in part, to lack of information and data surrounding the complicated processes of emissions).3 Furthermore, everyone charges their phone for a different amount of time each day and using chargers of various wattages, so we can’t be sure of the exact amount of electricity people around the world are using to charge their phones.

So, instead, the carbon footprint we calculated is more of a theoretical estimation.

Here’s how we did it:

  1. We calculated the amount of electricity one phone uses to charge in one year.
  2. We then multiplied the electricity consumption by the number of phone subscriptions in each country.
  3. Using a basic carbon footprint equation, we determined how much CO2e is emitted by that electricity for one person, each country and the world in one year.

We needed to make several baseline assumptions before we got started, though.

  • You use a five-watt charger (which is the current standard for phone charging)12 to charge your phone
  • You charge your phone for one hour per day, every day of the year
  • Every phone subscription (sourced from the World Bank’s DataBank of World Development Indicators) belongs to an individual phone.

These assumptions helped us calculate an amount of electricity in kilowatt-hours (kWh) that phone charging consumes each year, which is one half of the equation for calculating CO2e. The other half is the emissions factor.

Emissions factors are the amount of greenhouse gas emitted per unit of energy (e.g. kWh of electricity).5 They’re different for every country because they’re based on the fuels used to make the country’s energy. For example, a country that relies heavily on fossil fuels for energy would have a higher emission factor than one that uses renewable or nuclear energy.13

Therefore, the equation for calculating CO2e, according to Inventors in the Environment (iiE) in the UK, is activity data (i.e. kWh of electricity) multiplied by the emissions factor.2 To convert the CO2e (which will be in kilograms [kg]) into tonnes, this number is then divided by 1,000.

We used this equation to work out the carbon footprint for charging one phone, all the phones in each country and then all the phones in the world.

Brought to you by Compare the Market: Making it easier for Australians to search for great deals on their energy plans.

Sources
• Emissions factors = Carbon Footprint Ltd – Country Specific Electricity Grid Greenhouse Gas Emissions Factors. Last updated September 2020. Accessed November 2020.
• Mobile subscriptions data = The World Bank: DataBank – World Development Indicators. Last updated October 2020. Accessed November 2020.
• GWP values = Australian Government: Department of Industry, Science, Energy and Resources – National Greenhouse Accounts Factors (October 2020). Published September 2020. Accessed November 2020.

 

  1. CO2 Australia – Defining ‘Carbon Footprint’. By Rebecca Enright. Published November 2013. Accessed November 2020.
  2. Investors in the Environment (iiE) – How to calculate a basic carbon footprint. Accessed November 2020.
  3. Youmatter – Carbon Footprint Definition. Last modified February 2020. Accessed November 2020.
  4. U.S. Energy Information Administration – How much electricity does an American home use? Last updated October 2020. Accessed December 2020.
  5. Australian Government: Department of Industry, Science, Energy and Resources – National Greenhouse Accounts Factors (October 2020). Published September 2020. Accessed November 2020.
  6. United States Environment Protection Agency: Office of Transportation and Air Quality – Greenhouse Gas Emissions from a Typical Passenger Vehicle. Published April 2018. Accessed November 2020.
  7. Government of Western Australia: Department of Primary Industries and Regional Development – Carbon farming: reducing methane emissions from cattle using feed additives. Last updated November 2020. Accessed November 2020.
  8. TourEiffel.Paris – the Eiffel Tower’s Illuminations. Accessed December 2020.
  9. UN Environment Programme – Cleaning up couture: what’s in your jeans? Published December 2018. Accessed December 2020.
  10. The Royal Society – How much is your summer BBQ damaging the environment? Press release. Published July 2019. Accessed November 2020.
  11. Central Japan Railway Company – Annual Report 2019: Engagement in Global Environmental Preservation. Accessed December 2020.
  12. Belkin – Fast charging and why you need it. Accessed November 2020.
  13. Carbon Footprint Ltd – International electricity factors. Accessed November 2020.