Wind, wave and tidal power will not replace traditional sources of electricity in Guernsey, the States renewable energy policy advisor said.
Matt Des Forges said the cost of renewable energy would remain high for some time to come.
He said it would be around eight years before offshore wind power was up and running in Guernsey, and wave and tidal power was not expected before 2020.
Guernsey currently imports its energy from France and generates it on-island.
Mr Des Forges said: “Renewable energy is intermittent, the wind doesn’t always blow and the tides are not always flowing so the cables and conventional on island generation will always be very important to Guernsey.
“But it is really just part of the energy mix so we should be able to have a proportion of our energy from wind or tidal power.”