Last week we looked at the science of climate change and how electricity used to run computers and telecommunications can contribute to greenhouse gas emissions. This week we look at estimates of how much ICT contributes to Equivalent carbon dioxide (CO2e) to calculate the global ICT Carbon Footprint from use of telecommunications, data centres and desktop PCs.
The carbon footprint is an estimate of the amount of CO2e emitted by activity, in this case the use of ICT. The carbon footprint can be estimated from the embodied energy used to produce the ICT product and the energy used to operate the equipment.
Embodied energy (or Embodied carbon) refers to the energy used to manufacture, and supply to the point of use, a product or service. This includes the energy necessary to extract the raw material, to transport, manufacturing, assembly, installation as well as disposal of the equipment. ICT professionals would not normally be required to carry out detailed analysis of embodied energy for specific products, but use estimates supplied for a class of products, such as desktop computers or laptops.
Operating energy is a measure of the energy used to operate the ICT equipment. This can be measured directly using an energy meter (electric meter) which measures the electricalenergy used. Alternatively the energy use may be estimated from the power the equipment uses (specified in Watt), multiplied by the estimated amount of time the equipment will be used (in Hours) to give the energy (in Kilowatt hours).
A Greenhouse gas conversion factor can then be used to convert energy consumed in kWh to kg of equivalent carbon dioxide. For example a computer using 200 W of power for 10 hours per day uses 2 kWh of energy. Multiplying by a conversion factor of 0.537 Kg CO2/kWh produces a total of 1.074 Kg CO2 per day.
Energy and greenhouse gas measures are only approximate. There have been attempts to estimate these for industry sectors, nations and the world.