Overview: Emissions variations and emissions factors

The following page highlights some of the key items that can dramatically influence the emissions levels associated with different materials and activities.

The data shown below is based on current published emissions factors, the values come from national and global bodies as well as indepedent groups focussed on developing the most robust emissions factor estimates.

When estimating emissions for current or future activities its important to understand the ranges of uncertainties and the expected ranges in values. The data below should give you as a sense of the ranges of emissions values to expect for different materials, processes and activities.

Many factors can significantly affect the emissions related to different activities and products. Here we highlight some of the more common ones, which include:

  • Material choices
  • Recycled and feedstock material content
  • Process type, energy consumed and energy sources used for processing
  • Country (and plant) of origin, where the emissions variation result, in part, from the items above
  • Mode of goods transport and distribution
  • Mode of associated business travel.

The examples below show a 5 to 10 times variation in emissions for similar or even identical activities.

This infomation can be used to select more carbon efficient activities to deliver better business outcomes.

It can also highlight key questions to ask when evaluating the robustness or uncertainties associated with emissions estimates being developed, provided or shared.

The data below may well provide insights or ideas relating to which areas you can focus on to drive decarbonisation pathways for your business, your products or your supply chain.


Emission variations observed between different products and materials

The following shows emissions estimates (hover over the data to see the data sources) for common materials widely used in many parts of our global society and across many business activities.

  • Primary metal production typically is asssociated with some of the highest emissions intensity levels (although recycling can have dramatically lower levels as shown later).
  • Primary metal production typically is asssociated with some of the highest emissions intensity levels (although recycling can have dramatically lower levels as shown later).
  • Plastics, typically produced from hydrocarbons, also have a high emissions intensity (even though the hydrocarbon isn't combusted).
  • Cement production generates high emissions, primarily associated with calcination of rock, as well as overall energy consumption.
  • Wood production can have suprisingly high emissions intensities if the wood is not sustainably managed.
  • Moving materials around (rather than aggressively chemically processing them), such as sand, often has relatively and surprisingly low emissions.

Impact of recycling on product production emissions

Recycled materials can often be produced with dramatically lower emissions than primary production. Recycling and using recycled products can represent a low cost and easy way to reduce emissions.

  • Recycled aluminium has ~10% of the emissions of primary produced aluminium.
  • Recycled steel has ~40% of the emissions of primary produced steel.
  • Recycled glass has ~60% of the emissions of primary produced glass.
  • Recycled plastic has ~75% of the emissions of primary produced plastic.

Many products, such as metals, plastics and glass are often produced with a blend of both primary and recycled materials. The blend value is important to understand in order to be able to evaluate the final materials likely emissions intensity (as is the liklihood of recycling at the end of the products life).


Emissions variations from producers from different countries - the example shows emissions for aluminium production

For the same product there can be a very large variation in embedded emissions depending on the country and company (plant and process) of origin.

  • Aluminium for instance shows an ~80% variation in emissions based on the country of origin as documented by the EU.
  • These variations result from many factors, including i) different production processes, ii) varying proportions of recycled feedstocks, iii) varying feedstocks, iv) varying emissions intensities of the energy sources used for production.

Freight transport: Emissions variations by mode of transport

Many businesses have large emissions footprints associated with transport and distribution.

The chart below shows the substantial variations associated with freight transport associated with different modes of transport.

Typically, the most sustainable sequence (from best to worst) is:

  • Marine, then rail, then EV's, then HGV's;, then van (fossil fuel powered), and finally air.
  • Marine is ~75 times better than air freight.
  • HGV's are ~6 times better than van transport.
  • EV's are ~10 times better than petrol or diesel vans.

Passenger transport: Emissions variations by mode of transport

Very large variations in emissions are present due to the mode of transport used.

Typically, the most sustainable sequence (from best to worst) is:

  • EV's, then buses, then rail, then PHEV, then smaller petrol cars, larger cars, economy air transport and then finally business class international air transport.
  • EV's are ~8 times better than fossil fuel powered cars.
  • Rail is ~6 times better than business car travel (fossil fuel powered).
  • International rail is ~50 times better than short haul business aviation travel.
  • Economy air travel is ~2.5 times better than business class.

Electricity: Emissions variations by generation type

Orders of magnitude variations in emissions occur between different electricity production methods. Switching your source of supply can be the easiest and cheapest initial step to start decarbonizing your business and your businesses supply chain.

Note that most electricity grids around the world are rapidly decarbonising, with many aiming for net zero electricity between 2030 to 2040. It maybe for your country that the grid is already decarbonizing or will soon so you may automatically benefit from their efforts.

Most grids in the world are blends of these different types of electricity generation methods. Grids that are dominated by fossil fuel power generation will have very high average emissions, whereas grids dominated by renewable and/or nuclear generation will have dramatically lower average emissions.

  • Renewables and nuclear have massively lower emissions than fossil based power.
  • Coal and oil are typically the worst emitters and natural gas can be as bad depending on the amount of upstream fugitive emissions (which are currently poorly measured).
  • Nuclear, hydro and wind have by far the lowest embedded emissions (just 1 to 2% of fossil based power). And those energy sources are continuously driving to further lower their emissions (something thats not particularly realistic with fossil based power).
  • Solar PV has very low emissions compared to all fossil sources but the production process of the panels does add total life cycle emissions and these can vary significantly between countries of panel production.

Summary

For many businesses (and individuals) large reductions in emissions can be achieved by making relatively minor modifications in material and activity choices. The data above highlight the potentially large emissions uncertainties present in a companies current or future planned emissions pathway if high accuracy emissions life cycle assessments are NOT available for all the major emission related activities. There are many free public and paid for emissions factor databases. These contain 10,000's of different materials and activities commonly used in business.

A number of the more common data sources are show below: Add links to:link add hereFree public data sources include: IPCC, BEIS, CBM, EPA, EU: Add links to: Paid for services: X, Y, Z The GHG Protocol recently recommended using public emissions factor datasets to estimate your emissions. Directly measured, or so-call primary emissions values, can be hard and costly to acquire and can, in some circumstances, provide misleading information. It was for this reason that the head of the GHG Protocol recommended at least starting with secondary or emission factor data from reputable databases (such as the IPCC's).

For businesses starting out on their decarbonization journey the above data will hopefully stimulate ideas about areas to evaluate for future decarbonization strategies. The huge range in values shown above for similar and even identical products will also highlight the importance of assessing the likely uncertainties in any estimates provided, generated or shared through your value chain. The data above highlights that when trying to build robust decarbonization pathways and strategies its critical to focus on the major impactful emissions items and not become overly concerned with items that have a low absolute emissions value (almost regardless of the size uncertainty of those estimates (e.g. a 200% error on a tiny value is still a tiny value)).


Get in touch

We are keen to work with organisations to allow them to build and implement robust and cost effective decarbonization strategies.

We would love to hear from you -info@example.com