Environmental indicators

kg CO -eq/boe

300

250

200

150

100

50

Product transport

Refining

Crude transport

Methane

Flaring

Energy for extraction

kboe/d

kg CO -eq/boe

Extracting oil and gas from the ground, processing it, and bringing it to consumers is an important component of global energy demand today. The process of getting these fuels to consumers is also an important source of global GHG emissions. These can be CO2 emissions from the energy consumed along the oil and natural gas value chains as well as leaks of CO2 and methane to the atmosphere.

These emissions associated with oil and natural gas are often divided into three different “scopes”. Looking from the perspective of the oil and gas industry as a whole, while avoiding any double counting, this report approaches the issue as follows.

“Scope 1” emissions are emissions that come directly from the oil and gas industry itself. This includes, for example, emissions from powering the engines of drilling rigs, or from leaks of methane in the upstream or midstream, or emissions from ships used to transport oil or gas overseas.

“Scope 2” emissions arise from the generation of energy that is purchased by the oil and gas industry; for example from the generation of electricity taken from a centralised grid to power auxiliary services, or from the production of hydrogen purchased from an external supplier to be used in a refinery. The sum of scope 1 and 2 emissions is often referred to as the “well-to-tank” or “well-to-meter” emissions.

The IEA World Energy Model tracks a barrel of oil or cubic metre of natural gas from where it is produced to where it is refined or processed and finally consumed. As a result, this report can estimate total GHG emissions from the multitude of different production and trade routes that exist in global oil and gas markets today.

On this basis, it is estimated that 95 kilogrammes of CO2 equivalent (kg CO2-eq) is emitted in bringing an average barrel of oil to end-use consumers. There is a broad range of emissions for different types of

oil. The lowest 10% production has an average emissions intensity of less than 45 kg CO2-eq per barrel of oil equivalent, while the highest 10% has an emissions intensity of over 200 kg CO2-eq/boe.

For natural gas, global average scope 1 and 2 emissions are around

100 kg CO2-eq/boe. As with oil, there is a large spread between different sources of gas and different trade routes. The highest 10% of production is around four times more emissions-intensive than the lowest 10%.

The main differences between resource types is a function of: the natural complexity and location of the resource, the technologies and engineering used, the age of assets, and the processes and measures in place to minimise flaring and methane emissions. For example, lower-emitting sources of oil tend to be easy to extract, have tight controls on methane leakage and flaring, are light oil or NGLs (which can be processed by simple refineries or bypass the refining sector entirely), and are refined and consumed close to where they are extracted.

“Scope 3” emissions occur during combustion of the fuel by end users. Scope 3 emissions from oil products can vary substantially: liquefied petroleum gases (LPGs) emit around 360 kg CO2/boe, while heavy fuel oil emits around 440 kg CO2/boe. The global average array of oil products produced from a barrel of crude oil equivalent in 2018 results in around 405 kg CO2 when combusted. There is a much smaller degree of variation in CO2 emissions from the combustion of natural gas, but on average, emissions are 320 kg CO2/boe (average combustion emissions for coal, expressed on a comparable basis, are around 540 kg CO2/boe).

On average, scope 1 and 2 emissions account for almost 20% of the full life-cycle emissions intensity of oil; for natural gas, scope 1 and 2 emissions account for around 25% of its full life-cycle emissions.