Embodied energy and carbon RSS icon

In order to reduce the carbon footprint it is important that we account for the energy that is embodied in the materials that we use. With Cableizer you can calculate the embodied energy and carbon of any cable.

Posted on June 8, 2018
Categories: New feature Theory



Introduction

Embodied energy is the amount of energy consumed to extract, refine, process, transport, and fabricate a material or product. It is often measured from cradle to factory, cradle to use, or cradle to grave (end of life). Likewise, the embodied carbon footprint is the amount of carbon (CO2) emission to produce a material.

Plastics

Because different production paths consume different amounts of energy, the energy used in the production of an organic chemical depends on its so-called feedstock which is derived from crude oil refining and natural gas processing. Chemicals obtained from the cracking and distillation of petroleum or inorganic sources are called raw materials. The total energy consumed in the production is the sum of the energy inputs for itself and all its predecessors, starting from the raw material. It takes about 2 kg of fossil fuels to produce 1 kg of plastics.

Shaping processes

Energy is not only spent and CO2 released in producing the material but also in shaping it into its desired form. Primary shaping processes are e.g. casting, rolling, extrusion, molding, etc. Secondary processes are e.g. welding, heat-curing, painting, coating, etc. The listed values are supposed to contain the energy and CO2 for materials and processes specific to cable production.

What sources did we use?

The search for correct values was most important in order to create this new feature. To find and collect verified material parameters for embodied energy and embodied carbon was very difficult. The found values of some materials had big variations. The most important sources are listed here:

  1. The world's leading source of embodied energy and carbon data, the Inventory of Carbon & Energy .
  2. 'Useful Numbers for Environmental Studies and Meaningful Comparisons, Chapter 1 Materials' by B. Cushman-Roisin and B.T. Cremonini (2017)
  3. 'Materials and the Environment: Eco-informed Material Choice' by M. Ashby, 2nd edition (2012)
  4. 'Carbon Footprint and Sustainability of Different Natural Fibres for Biocomposites and Insulation Material' by M. Barth, M. Carus (2015) (used for Jute)
  5. 'Environmental Impact of Membrane and Foil Materials and Structures' by J. Cremers (2014), Technical Transactions (used for ETFE)
  6. 'Sustainable Engineering and Eco Design' by Chaouki Ghenai, intechopen.com (used for PTFE)
  7. 'Life Cycle Assessment of the Transmission Network in Great Britain' by G. P. Harrison et.al. (2010) (used for Mineral oil)
  8. 'Material Selection in Mechanical Design' by M. Ashby, 5th edition (2018). This book provides the rule of thumb for embodied energy as 26 x price in USD/kg for metals and ceramics and as 7 x price + 65 for oil-based polymers. For embodied carbon, the rule of thumb is 0.06 x embodied energy for metals, polymers and ceramics.

What are typical materials in a cable

First let's look at some materials typically used for insulation, filler/bedding and jacket of cables.

Non-metallic materials
 
Energy
[MJ/kg]
Carbon
[kgCO2/kg]
Source / Comment
 
Polyvinyl chloride (PVC)77.22.61(1) general type
Low density polyethylene (LDPE)78.11.69(1)
High density polyethylene (HDPE)76.71.57(1)
Polypropylene (PP)89.53.69(2) production + extrusion
Natural rubber (NR)88.03.6(2) production + forming
Butyl rubber (isobutylene isoprene rubber IIR)140.08.3(2) production + forming
Bitumen51.00.43(1)
Jute10.04.05(4) ≈hemp
Compounded jute (Jute fiber reinforced polypropylene)41.83.9160% jute + 40% PP

Let's have a look now at some typical metals in a cable, used for conductor, screen/sheath and armour.

Metallic materials
 
Energy
[MJ/kg]
Carbon
[kgCO2/kg]
Comment
 
Copper (Cu)55.02.6EU tube & sheet type
Aluminium (Al)155.08.24general type
Lead (Pb)25.211.57general type
Steel20.11.37general type, 59% recycled content

These are only the most common materials. We have values for much more, all listed in the documentation.

Example

As an example, we want to compare two cables. Note that the insulation thickness is larger for cables with smaller conductor diameters, therefore the cable with copper conductor shows higher values for embodied energy and carbon in the insulation. Bedding and jackets have the same thicknesses, so differences in bedding/filler and jacket are only due to the difference in overall diameters.

2XS(FL)2Y 1x500mm2 Cu 110/64kV A2XS(FL)2Y 1x800mm2 Alu 110/64kV
2XS(FL)2Y 1x500mm2 110kVmass of the copper cable A2XS(FL)2Y 1x800mm2 110kVmass of the aluminium cable
energy and carbon of copper cable energy and carbon of aluminium cable

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