Aug 3 (Reuters) - Australia's Genex Power Ltd said on Monday that Japan's J-Power would invest as much as A$25 million ($17.8 million), finalising a deal that secures funding for Genex's equity component of the Kidston pumped hydro project.

The deal, which had to be renegotiated after delays last year, helps puts the project back on track, and shares in Genex were up 6% on the news.

In March this year, Genex also lined up Energy Australia to buy power from the project, after a failing to reach a similar deal last year.

J-Power will gain between 15% and 19.99% of Genex's enlarged share capital under deal. It will also be able to nominate a director to Genex's board and will provide certain technical services in the operational stages of the project.

Pumped hydro acts like a giant battery, pumping water uphill when energy is abundant and releasing it to create power at night or on a windless day.

Genex's 250 megawatt project, which is being built at an abandoned gold mine in the state of Queensland, is widely seen as a template for projects that could be developed all over Australia at old dams and mine sites.

($1 = 1.4011 Australian dollars) (Reporting by Arundhati Dutta in Bengaluru; Editing by Edwina Gibbs)