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SWS and Electrification

SWS and Electrification. Lessons from Ghana’s Experience. By: Jabesh Amissah-Arthur, Managing Partner,. Presentation Outline. Electrification in Ghana. Starting Conditions. Accomplishments. Innovating for Rural Electrification. Background and Motivation for SWS.

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SWS and Electrification

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  1. SWS and Electrification Lessons from Ghana’s Experience. By: Jabesh Amissah-Arthur,Managing Partner,

  2. Presentation Outline • Electrification in Ghana. • Starting Conditions. • Accomplishments. • Innovating for Rural Electrification. • Background and Motivation for SWS. • The Shield Wire Scheme (SWS) – Description • Benefits and Savings of SWS. • Cost Comparison with standard MV supply. • Operational Comparison with standard MV supply. • Conclusion. • Successes and Failures. • Lessons.

  3. Starting Conditions • The grid supplies only 240 towns in 1/3rd of Ghana. • Virtually all isolated diesels are non-operational. • Macro-economic indices far from being favourable. • 5yrs of economic decline. • 3yrs of drought, 1982-84. • Project area considered to be very poor. • Project viability doubtful ! • Starting conditions were simply far from ideal.

  4. Accomplishments • 1985: Grid covers only 1/3rd of Ghana’s land area. Access to service = 23%. • 1990: Nine regional capitals and 400 towns have supply from grid. • 1995: 1,000 towns (including 87 of 110 district capitals) have grid supply. • 2000: All districts and 2100+ towns have grid supply. Access = 43.7%. • 2005: 3,200 towns to have supply. Access = 50+%

  5. Innovating for Rural Electrification: Background & Motivation for SWS • The citizens of small communities living near HV transmission lines who had no supply made it a Corporate Social Responsibility and Public Relations issue for the utility, Volta River Authority (VRA). • VRA invited Prof. Iliceto in early 1980s to make innovative proposals for a “Low Cost” solution to serve the settlements near its 161kV transmission lines. • Shield Wire Scheme (SWS) is proposed & implemented: • SWS is serving more than 10,000 households in 30 communities that may not otherwise have been served. • The cost of SWS is only a fraction of standard MV line. • The operational performance of the SWS in terms of outage frequency and time is better than normal.

  6. The Shield Wire Scheme (SWS) • The SWS uses the sky/shield-wire which is normally grounded with no voltage and only shields the power lines below. • The sky/shield-wire in this case is: • Insulated for medium voltage operation. • Energised at 20-34kV from sub-station. • Supplies loads using earth return current. • Still performs power line protection. • No additional environmental impact.

  7. The Shield Wire Scheme (SWS)

  8. Savings and Benefits • Installation Costs are lower because: • Common usage of conductors & grounding rods. • Does not add to the power line right-of-way. • Operational Performance is better as: • Outage rates are low & permanent faults are rare. • Low medium voltage losses due to conductor size. • Maintenance burden is extremely low. • Other Benefits. • Community protection of the transmission line.

  9. Cost Comparison: MV vrs SWS

  10. Comparison of Operational PerformanceTotal Outage Frequency - Standard MV vrs SWS.

  11. Successes and Failures • The massive extension of the HV grid presented an opportunity to deploy SWS on the new lines. • SWS cost is only 15% of equivalent MV line. Yet its operational performance is superior. • SWS is now proven technology which supplies settlements within a 20km corridor of the transmission line at very reasonable cost. • A subsidised connection charge helped many to receive supply initially. But paying the bills to maintain supply has been difficult for some. • In more than a few villages, only the Chief’s Palace has been able to retain supply.

  12. Lessons • SWS is well-suited for medium sized communities (ie total <10MW) located near transmission lines. • When planning electrification for poor communities we need to recognise two affordability thresholds: • Those who can at least afford the variable (operating) cost of supply but not the full capital recovery burden. • Those who cannot afford even the operating cost alone. • Electrification for Group A is sustainable with only an initial connection subsidy which may be justified on social & poverty alleviation considerations. • Access for Group B requires perennial subsidy and so needs cautious consideration of the source of subsidy else “true access” may not be sustainable.

  13. The End Lessons from GHANA’s experiences. Jabesh Amissah-Arthur

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