Life cycle assessment of an offshore grid interconnecting wind farms and customers across the North Sea



This study aims to contribute to an improved understanding of the environmental implications of offshore power grid and wind power development pathways. To achieve this aim, we present two assessments. First, we investigate the impacts of a North Sea power grid enabling enhanced trade and integration of offshore wind power. Second, we assess the benefit of the North Sea grid and wind power through a comparison of scenarios for power generation in affected countries.


The grid scenario explored in the first assessment is the most ambitious scenario of the Windspeed project and is the result of cost minimization analysis using a transmission-expansion-planning model. We develop a hybrid life cycle inventory for array cables; high voltage, direct current (HVDC) links; and substations. The functional unit is 1 kWh of electricity transmitted. The second assessment compares two different energy scenarios of Windspeed for the North Sea and surrounding countries. Here, we utilize a life cycle inventory for offshore grid components together with an inventory for a catalog of power generation technologies from Ecoinvent and couple these inventories with grid configurations and electricity mixes determined by the optimization procedure in Windspeed.

Results and discussion

Developing, operating, and dismantling the grid cause emissions of 2.5 g CO2-Eq per kWh electricity transmission or 36 Mt CO2-Eq in total. HVDC cables are the major cause of environmental damage, causing, for example, half of total climate change effects. The next most important contributors are substations and array cabling used in offshore wind parks. Toxicity and eutrophication effects stem largely from leakages from disposed copper and iron mine tailings and overburden. Results from the comparison of two scenarios demonstrate a substantial environmental benefit from the North Sea grid extension and the associated wind power development compared with an alternative generation of electricity from fossil fuels. Offshore grid and wind power, however, entail an increased use of metals and, hence, a higher metal depletion indicator.


We present the first life cycle assessment of a large offshore power grid, using the results of an energy planning model as input. HVDC links are the major cause of environmental damage. There are differences across impact categories with respect to which components or types of activities that are responsible for damage. The North Sea grid and wind power are environmentally beneficial by an array of criteria if displacing fossil fuels, but cause substantial metal use.

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  1. 1.

    Table 1 is an aggregate representation of Windspeed results (Huertas-Hernando et al. 2011).

  2. 2.

    Wind turbines have been studied extensively before (Arvesen and Hertwich 2012).

  3. 3.

    See Cameron et al. (2011) for details on how learning is modeled in Windspeed.

  4. 4.

    While 600 MW wind farm capacity is assumed here for the purpose of determining typical array-cabling requirements, the wind farm cluster capacities in Fig. 1 are not divisible into 600 MW units.

  5. 5.

    Scaling is performed because the sum of estimated cable layer weights does not exactly match the known, total weight. Without the scaling, estimated totals amount to 80–90 % of real totals.

  6. 6.

    Tilton and Lagos (2007) present a contrasting view.

  7. 7.

    See Cameron et al. (2011) for details on the scenarios considered in Windspeed.


  1. 4C Offshore (2013) 4C Global offshore wind farms database. Accessed 19 Apr 2013

  2. ABB (2008) Miljörapport för år: 2007 [in Swedish). ABB high voltage cables, Sweden

  3. ABB (2010) XLPE submarine cable systems. Attachment to XLPE land cable systems. User’s guide. Accessed 26 Apr 2011

  4. ABB (2012a) Environmental product declaration. Power transformer TrafoStar 500 MVA. Accessed 5 May 2012

  5. ABB (2012b) Environmental product declaration. GIS type ELK-3 for 420 kV. Accessed 15 Nov 2012

  6. ABB (2013) The NorNed HVDC connection, Norway–Netherlands. ABB High voltage cables. Accessed 17 Apr 2013

  7. Arvesen A (2013) Understanding the environmental implications of energy transitions: a case study for wind power. Dissertation, Norwegian University of Science and Technology

  8. Arvesen A, Hertwich EG (2011) Environmental implications of large-scale adoption of wind power: a scenario-based life cycle assessment. Environ Res Lett 6(4):045102

    Article  Google Scholar 

  9. Arvesen A, Hertwich EG (2012) Assessing the life cycle environmental impacts of wind power: a review of present knowledge and research needs. Renew Sustain Energy Rev 16(8):5994–6006

    Article  Google Scholar 

  10. Arvesen A, Bright RM, Hertwich EG (2011) Considering only first-order effects? How simplifications lead to unrealistic technology optimism in climate change mitigation. Energy Policy 39(11):7448–7454

    Article  Google Scholar 

  11. Arvesen A, Birkeland C, Hertwich EG (2013) The importance of ships and spare parts in LCAs of offshore wind power. Environ Sci Technol 47(6):2948–2956

    CAS  Article  Google Scholar 

  12. Azau S (2011) Focusing on 2050. In: EWEA wind directions: the European wind industry magazine. European Wind Energy Associations (EWEA). Accessed 7 June 2013

  13. Bengtsson S, Andersson K, Fridell E (2011) A comparative life cycle assessment of marine fuels. J Eng Marit Environ 225(2):97–110

    Google Scholar 

  14. Beurskens LWM, Hekkenberg M, Vethman P (2011) Renewable energy projections as published in the National Renewable Energy Action Plans of the European member states. Energy Research Centre of the Netherlands and the European Environment Agency. Accessed 10 Jan 2012

  15. Birkeland C (2011) Assessing the life cycle environmental impacts of offshore wind power generation and power transmission in the North Sea. Dissertation, Norwegian University of Science and Technology

  16. Blanco MI (2009) The economics of wind energy. Renew Sustain Energy Rev 13(6–7):1372–1382

    Article  Google Scholar 

  17. Bumby S, Druzhinina E, Feraldi R, Werthmann D, Geyer R, Sahl J (2010) Life cycle assessment of overhead and underground primary power distribution. Environ Sci Technol 44(14):5587–5593

    CAS  Article  Google Scholar 

  18. Callavik M, Blomberg A, Häfner J, Jacobsen B (2012) The hybrid HVDC breaker. An innovation breakthrough enabling reliable HVDC grids. ABB Grid Systems.$file/hybrid-hvdc-breaker---an-innovation-breakthrough-for-reliable-hvdc-gridsnov2012.pdf. Accessed 24 Apr 2013

  19. Cameron L, van Stralen J, Veum K (2011) Scenarios for offshore wind including spatial interaction and grid issues. Windspeed. Accessed 20 Mar 2013

  20. Carvalho MG (2012) EU energy and climate change strategy. Energy 40(1):19–22

    Article  Google Scholar 

  21. Crawford RH (2009) Life cycle energy and greenhouse emissions analysis of wind turbines and the effect of size on energy yield. Renew Sustain Energy Rev 13(9):2653–2660

    Article  Google Scholar 

  22. EC (2010a) Energy infrastructure priorities for 2020 and beyond—a blueprint for an integrated European energy network. COM (2010) 677 final. European Commission (EC), Brussels

  23. EC (2010b) State of play in the EU energy policy. Accompanying document to COM (2010) 639. European Commission (EC). SEC (2010) 1346 final, Brussels

  24. Ecoinvent. Life cycle inventory database v2.2 (2010). Swiss Centre for Life Cycle Inventories

  25. Erdmann L, Graedel TE (2011) Criticality of non-fuel minerals: a review of major approaches and analyses. Environ Sci Technol 45(18):7620–7630

    CAS  Article  Google Scholar 

  26. EWEA (2009) Oceans of opportunity: harnessing Europe’s largest domestic energy resource. European Wind Energy Association (EWEA), Brussels

    Google Scholar 

  27. Fripp M (2012) Switch: a planning tool for power systems with large shares of intermittent renewable energy. Environ Sci Technol 46(11):6371–6378

    CAS  Article  Google Scholar 

  28. Gordon RB, Bertram M, Graedel TE (2006) Metal stocks and sustainability. Proc Natl Acad Sci U S A 103(5):1209–1214

    CAS  Article  Google Scholar 

  29. Harrison GP, Maclean EJ, Karamanlis S, Ochoa LF (2010) Life cycle assessment of the transmission network in Great Britain. Energy Policy 38(7):3622–3631

    Article  Google Scholar 

  30. Hauschild M, Goedkoop M, Guinée J, Heijungs R, Huijbregts M, Jolliet O, Margni M, Schryver A, Humbert S, Laurent A, Sala S, Pant R (2013) Identifying best existing practice for characterization modeling in life cycle impact assessment. Int J Life Cycle Assess 18(3):683–697

    CAS  Article  Google Scholar 

  31. Hegger S, Hischier R (2010) ReCiPe—Implementation. Assignment of characterisation factors to the Swiss LCI database ecoinvent (version v. 2.2). Midpoint method, hierarchist version. PRé Consultant and Swiss Centre for Life Cycle Inventories

  32. Huertas-Hernando D, Korpås M, van Dyken S (2011) Grid implications: optimal design of a subsea power grid in the North Sea. Windspeed. Accessed 27 Sept 2012

  33. IEA (2012) World energy outlook 2012. International Energy Agency (IEA), Paris

    Google Scholar 

  34. ISO (2006) Environmental management—Life cycle assessment—Principles and framework (ISO 14040: 2006). International Organization for Standardization (ISO), Geneva

  35. Jacquemin J, Butterworth D, Garret C, Baldock N, Henderson A (2011) Inventory of location specific wind energy cost. Windspeed. Accessed 21 Mar 2013

  36. Jones CI, McManus MC (2010) Life-cycle assessment of 11 kV electrical overhead lines and underground cables. J Clean Prod 18(14):1464–1477

    Article  Google Scholar 

  37. Jorge RS, Hertwich EG (2013) Environmental evaluation of power transmission in Norway. Appl Energy 101:513–520

    Article  Google Scholar 

  38. Jorge R, Hawkins T, Hertwich E (2012a) Life cycle assessment of electricity transmission and distribution—part 1: power lines and cables. Int J Life Cycle Assess 17(1):9–15

    CAS  Article  Google Scholar 

  39. Jorge R, Hawkins T, Hertwich E (2012b) Life cycle assessment of electricity transmission and distribution—part 2: transformers and substation equipment. Int J Life Cycle Assess 17:184–191

    CAS  Article  Google Scholar 

  40. Kleijn R, van der Voet E (2010) Resource constraints in a hydrogen economy based on renewable energy sources: an exploration. Renew Sustain Energy Rev 14(9):2784–2795

    Article  Google Scholar 

  41. Majeau-Bettez G, Strømman AH, Hertwich EG (2011) Evaluation of process- and input–output-based life cycle inventory data with regard to truncation and aggregation issues. Environ Sci Technol 45(23):10170–10177

    CAS  Article  Google Scholar 

  42. Moe E (2010) Energy, industry and politics: energy, vested interests, and long-term economic growth and development. Energy 35(4):1730–1740

    Article  Google Scholar 

  43. Mudd GM (2010) The environmental sustainability of mining in Australia: key mega-trends and looming constraints. Resour Policy 35(2):98–115

    Article  Google Scholar 

  44. Nexans (2011) 60–500 kV High voltage underground cables. XLPE insulated cables. Accessed 26 Apr 2011

  45. Pettersen J, Hertwich EG (2008) Critical review: life-cycle inventory procedures for long-term release of metals. Environ Sci Technol 42(13):4639–4647

    CAS  Article  Google Scholar 

  46. Prior T, Giurco D, Mudd G, Mason L, Behrisch J (2012) Resource depletion, peak minerals and the implications for sustainable resource management. Global Environ Chang 22(3):577–587

    Article  Google Scholar 

  47. Riahi K, Dentener F, Gielen D, Grubler A, Jewell J, Klimont Z, Krey V, McCollum D, Pachauri S, Rao S, van Ruijven B, van Vuuren DP, Wilson C (2012) Energy pathways for sustainable development. In: Global energy assessment. Cambridge University Press, Cambridge, p 1205–1306

  48. Rosenbaum RK, Bachmann TM, Gold LS, Huijbregts MAJ, Jolliet O, Juraske R, Koehler A, Larsen HF, MacLeod M, Margni M, McKone TE, Schuhmacher M, Van de Meent D, Hauschild MZ (2008) USEtox–the UNEP-SETAC toxicity model: recommended characterisation factors for human toxicity and freshwater ecotoxicity in life cycle impact assessment. Int J Life Cycle Assess 13(7):532–546

    CAS  Article  Google Scholar 

  49. Steen B (2006) Abiotic resource depletion: different perceptions of the problem with mineral deposits. Int J Life Cycle Assess 11(1):49–54. doi:10.1065/lca2006.04.011

    Article  Google Scholar 

  50. Strømman AH, Solli C, Hertwich EG (2006) Hybrid life-cycle assessment of natural gas based fuel chains for transportation. Environ Sci Technol 40(8):2797–2804

    Article  Google Scholar 

  51. Tilton JE, Lagos G (2007) Assessing the long-run availability of copper. Resour Policy 32(1–2):19–23

    Article  Google Scholar 

  52. Tukker A, de Koning A, Wood R, Hawkins T, Lutter S, Acosta J, Rueda Cantuche JM, Bouwmeester M, Oosterhaven J, Drosdowski T, Kuenen J (2013) EXIOPOL—development and illustrative analyses of a detailed global MR EE SUT/IOT. Econ Syst Res 25(1):50–70

    Article  Google Scholar 

  53. Unruh GC (2000) Understanding carbon lock-in. Energy Policy 28(12):817–830

    Article  Google Scholar 

  54. Veum K, Cameron L, Hernando DH, Korpås M (2011) Roadmap to the deployment of offshore wind energy in the Central and Southern North Sea (2020–2030). Windspeed. Accessed 27 Sept 2012

  55. Wagner H-J, Baack C, Eickelkamp T, Epe A, Lohmann J, Troy S (2011) Life cycle assessment of the offshore wind farm alpha ventus. Energy 36(5):2459–2464

    Article  Google Scholar 

  56. Wiedmann TO, Suh S, Feng K, Lenzen M, Acquaye A, Scott K, Barrett JR (2011) Application of hybrid life cycle approaches to emerging energy technologies—the case of wind power in the UK. Environ Sci Technol 45(13):5900–5907

    CAS  Article  Google Scholar 

  57. Windspeed (2014) Windspeed. Supporting decisions. Spatial deployment of offshore wind energy in Europe. Accessed 19 Mar 2013

  58. York R (2012) Do alternative energy sources displace fossil fuels? Nat Clim Chang 2:441–443

    Article  Google Scholar 

  59. Zhai P, Williams ED (2010) Dynamic hybrid life cycle assessment of energy and carbon of multicrystalline silicon photovoltaic systems. Environ Sci Technol 44(20):7950–7955. doi:10.1021/es1026695

    CAS  Article  Google Scholar 

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The work was supported by the Research Council of Norway through the Centre for Sustainable Energy Studies (CenSES). Huertas-Hernando acknowledges financial support from FME NOWITECH. The analysis builds on the MSc thesis by Nes supervised by Hertwich and Arvesen, Arvesen’s wind power LCAs, and Huertas-Hernando’s work on Windspeed. We thank the anonymous reviewers for many helpful comments and suggestions.

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Correspondence to Anders Arvesen.

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Arvesen, A., Nes, R.N., Huertas-Hernando, D. et al. Life cycle assessment of an offshore grid interconnecting wind farms and customers across the North Sea. Int J Life Cycle Assess 19, 826–837 (2014).

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  • Carbon footprint
  • Grid integration
  • Hybrid LCA
  • HVDC transmission
  • Variable renewable energy
  • Windspeed