The $70 million would be allocated upfront to accelerate the second stage of a potential dry year pumped hydro storage solution at Lake Onslow in the Teviot Valley, Labour announced today.
It would be subject to the $30m business case the Government announced in July.
The Lake Onslow project would be joined by other smaller schemes to bring Labour's target of 100% renewable electricity generation forward five years to 2030 with a review at the 2025 emissions budget.
Labour Energy Spokeswoman Megan Woods said support for projects like pumped hydro at Lake Onslow was in line with the party's commitment to achieve 100% renewable energy.
Party leader Jacinda Ardern said Labour's Clean Energy Plan was a critical element of Labour's wider Covid-19 recovery plan to prepare New Zealand for the future while boosting jobs and the economy now.
The Lake Onslow plan is one of a raft of energy measures Labour is pledging; including accelerating electrification of transport and industrial sectors, and investing in emerging technologies like green hydrogen.
If the $30 million business case stacked up, Lake Onslow would be New Zealand's biggest infrastructure project since the Think Big projects of the 1980s.
The Lake Onslow project would cost up to $4 billion, take four to five years to build plus two years to fill the reservoir, could employ as many as 4500 workers at its peak, and indirectly produce thousands more jobs.
