A description of the application
Optimising cable size has multiple applications, including for example small and large offices, industrial areas and large industrial plants. Small and large offices typically use low voltage copper cables whereas for industrial plants, which have higher power demand, it is more common to use medium voltage copper cables.
There are relatively significant differences in power losses between standard cables and optimised cables, which arise from the fact that cables with larger cross-sectional area are subject to lower distribution losses.
When considering different applications, it is also important to consider collection rates and end-of-life of the cables, in order to have a life cycle perspective.
The challenges that appear regarding this application
The main challenge relates to the question whether the energy saving potential justifies a larger cross section. Sometimes, end-users are concerned that the environmental impact of producing additional copper makes the use of larger cable sizes environmentally disadvantageous. The studies referenced below have calculated the energy, carbon and cost balances from optimised conductor sizing.
How copper serves as a key factor to overcome this hurdle
These studies considered different environmental impact categories focusing on global warming potential and others such as acidification potential or summer smog.
Focusing only on the production phase of the cables, for most of the categories, 60% to 90% of the environmental burden has origin in the production of the copper required; the rest has mainly origin in the production of the plastic components. The exception is the summer smog (photochemical oxidant creation potential, POCP), for which 44% of the impact stems from copper production, as plastic production releases significant nitrogenous emissions, which are relevant for this category.
Considering the entire life cycle of the cables (production, use, and end-of-life), it becomes clear that within few years of use the impact from the production of the cables is overshadowed by the impacts due to energy losses during the use phase. These impacts are represented by the emissions associated with the production of the same amount of electricity.
Cables with smaller cross sections have lower starting (production) impact but greater annual energy loss rate. Optimised cables, delivering equivalent electrical function, have higher starting (production) impact but lower annual energy losses.
Therefore the cumulative impacts for different impact categories intersect at a certain point before which the standard cables are advantageous and after which optimised cables become environmentally advantageous.
The key message as a conclusion
Overall, there are clear environmental advantages on using optimised copper cables. The mitigation of increased production impact by the use-phase savings is visible in the early inflexion point (often within 1 year[1] compared to average cable lifetimes of about 30 years).
References
An investigation into the environmental effects of upsizing of copper cables in commercial applications. European Copper Institute, thinkstep; 2015
Modified Cable Sizing Strategies Potential Savings vs Copper Usage. European Copper Institute, Egemin Consulting NV; 2011
[1] Assumptions:
- Application in large offices is considered; operating hours: 60 hours of day time load per week
- EU-27 power grid mix (GaBi 6, database 2013)
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