Your browser does not support JavaScript!

Intermittent renewable generation and the cost of maintaining power system reliability

Intermittent renewable generation and the cost of maintaining power system reliability

For access to this article, please select a purchase option:

Buy article PDF
(plus tax if applicable)
Buy Knowledge Pack
10 articles for $120.00
(plus taxes if applicable)

IET members benefit from discounts to all IET publications and free access to E&T Magazine. If you are an IET member, log in to your account and the discounts will automatically be applied.

Learn more about IET membership 

Recommend Title Publication to library

You must fill out fields marked with: *

Librarian details
Your details
Why are you recommending this title?
Select reason:
IET Generation, Transmission & Distribution — Recommend this title to your library

Thank you

Your recommendation has been sent to your librarian.

There have been attempts, using various approaches, to assess the additional cost of running an electricity system when intermittent renewable generation is used to provide a significant proportion of the energy. The key issues are the difference, in statistical terms, between the resource availability of the intermittent source and conventional generation and the contribution the intermittent source can make to meet the system peak demand while maintaining system reliability. There is considerable agreement over the capacity credits that can be attributed to renewable energy sources, that is the amount of conventional capacity that renewables can reliably displace, yet the implications for costs have proved more controversial. Approaches to calculate changes in overall system cost are examined and an expression for the additional cost that intermittent generation imposes on a system that is attributable to its intermittent nature is identified. Further, it is shown that this expression can be reconciled with approaches that look at intermittent renewables on a stand-alone basis and factor in the additional costs of ‘standby’ capacity. It is shown that the main source of divergence between estimates of the cost of intermittency is the load factor implicitly assumed for the conventional plant used as a reference. There is only one consistent way to impute the costs of intermittency when the unit cost of intermittent plant is being compared with that of baseload generation plant.


    1. 1)
      • L. Dale , D. Milborrow , R. Slark , G. Strbac . A shift to wind is not unfeasible (total cost estimates for large-scale wind scenarios in UK). Power , 17 - 25
    2. 2)
      • (2006) The energy challenge.
    3. 3)
      • MacDonald, M.: `The carbon trust & DTI renewables network impact study Annex 4: intermittency literature survey and roadmap', 2003, available at:, accessed January 2007 The Carbon Trust.
    4. 4)
      • (2004) The cost of generating electricity.
    5. 5)
      • M.J. Grubb . The integration of renewable electricity sources. Energy Policy , 7 , 670 - 688
    6. 6)
      • Ilex, , Strbac, G.: `Quantifying the system costs of additional renewables in 2020', 2002, available at: v2_0.pdf, accessed January 2007.
    7. 7)
      • , : `Planning of the grid integration of wind energy in Germany Onshore and Offshore up to the year 2020', 2005, available at: stud_summary-dena_grid.pdf, accessed January 2007 DENA Project Steering Group: Deutsche Energie-Agentur, Berlin.
    8. 8)
      • Auer, H.: `Modelling system operation cost and grid extension cost for different wind penetrations based on GreenNet', IEA Workshop on Wind Integration, 2004, Paris, available at:, accessed January 2007.
    9. 9)
      • Milborrow, D.: `Penalties for intermittent sources of energy', Performance and Innovation Unity Energy Review Working Paper, 2001, available at:, accessed January 2007.
    10. 10)
      • M. Milligan , B. Parsons . (1997) A comparison and case study of capacity credit algorithms for intermittent generators.
    11. 11)
      • J. Skea , D. Anderson , T. Green , R. Gross , P. Heptonstall , M. Leach . (2006) The costs and impacts of intermittency.
    12. 12)
      • Holttinen, H.: `The impact of large scale wind power production on the Nordic electricity system', 2004, Licentiate PhD, Helsinki University of Technology, Department of Engineering, Physics and Mathematics, Finland.
    13. 13)
      • Anderson, D.: `Power system reserves and costs with intermittent generation', UK Energy Research Centre Working Paper, 2006, available at:,com_docman/ task,doc_download/gid,548/, accessed January 2007.

Related content

This is a required field
Please enter a valid email address