It has released a discussion document on two projects and is calling a consultation meeting this Friday, in Wellington, to be attended by interested parties.
One project is to improve transmission lines in the Taupo-Hawkes Bay district and the other project is the lower South Island transmission system.
The document says there is a potential constraint to unlocking substantial wind resource south of the Clyde and Roxburgh area.
"Specifically, the potential resource for electricity generation is likely to be substantially greater than can be accommodated by the current transmission system," the document said.
The use of the transmission system is likely to reach its limits soon, the document said, citing new renewable power projects either given resource consent or in the process of obtaining it.
The document gives a long list of options to be considered to help overcome the transmission constraint.
It does not recommend a preferred option or give the financial cost of each option.
Options included building generation in the upper half of the South Island, switching fuel to gas, and promoting more energy-efficient appliances.
The transmission options include using existing assets, building a new AC transmission line, and using the existing HVDC line or building a new one.
It is hoped to have a proposal with the Electricity Commission, which will approve the project, by the end of the year.
