Attachment 2
Assessment of the Advantages and Disadvantages of Buried High Voltage
Power Lines
Administration has not completed a comprehensive study of this subject, but for the
purposes of this report has utilized information available from industry and web sources.
The following is a summary of information compiled from these sources.
Advantages of Buried High Voltage Power Lines

Technology - The technology to bury transmission lines has been available for
several decades with 41 projects being completed in 17 countries around the
world. This includes a 500 kv cable buried in Tokyo, Japan in 2000, and another
in the works in China. EPCOR recently buried a 240 kv power line in Edmonton.

Safety - No electric fields are emitted from buried cables. The magnetic field is
greatly reduced in intensity directly above the line and declines with distance
from the buried cable.

Environmental Benefits - There are fewer impacts relative to abutting land uses,
visual aesthetics, property values, tourism, and a lower carbon footprint.
Underground cables eliminate the potential for bird contacts, which could cause
avian injury or death.

Security and Reliability of Service - Security and service reliability are enhanced
as compared with overhead power lines. Service failures are lower in buried lines
versus overhead lines.

Efficiency - Buried lines are considered to be more energy efficient than overhead
lines.

Affordability and Overall Cost – Although there is a higher initial capital cost to
burying lines, possible lower line losses (amount undetermined) could
compensate for the initial development costs.

Health Impacts - There are potentially fewer health impacts (including noise) with
buried power lines; however, existing research is inconclusive.
Disadvantages of Buried High Voltage Power Lines

Cost – Costs for 500 kV underground cables are more difficult to estimate as there
are currently relatively few underground 500 kV cables in service in the world.
The initial capital costs for buried cables are estimated to be 4 to 20 times more
than for overhead cables. The operating costs for buried lines over their life cycle
are on average 1.5 to 2.5 times higher than for overhead lines. The higher costs
associated with underground cables are due to materials (more underground
cables are required to carry the same amount of power as one overhead line),
construction labour and time inputs, and maintenances costs.

Immature Technology - The technology is not mature in Alberta. Also it is
unknown whether a buried system can be integrated into an existing transmission
system and operated dependably.
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Report: 2009PPP031 Attachment 2
Attachment 2

Reliability of Service - The consistency and amount of time a buried transmission
line is available to transport electricity is very difficult to determine. Longer
repair times for underground cables may result in a significant difference in
overall reliability of performance.

Environment - There are some environmental impacts to burying lines, including
underground vaults. Localized heating of the soil, and alterations in ground and
surface water drainage patterns as well as localized impacts on vegetation can also
occur. The construction process for underground installation requires soil
stripping, continuous trenching and underground vaults every several hundred
metres. The underground vaults can be 10 metres long by 4 metres wide. After
construction is complete, the heat produced by energized cables dissipates into the
surrounding soil and may result in localized impacts on vegetation. Drainage may
require temporary or permanent alteration depending on the construction of
underground cable trenches.
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Report: 2009PPP031 Attachment 2