Wartsila India has signed a shareholders' agreement with the Tamil Nadu-based Arkay Energy (Rameswarm) to invest Rs 12 crore by subscribing to preference shares not exceeding 14.95% of the equity of Arkay Energy.This was announced in a release issued by Wartsila India to the BSE today."Wartsila will supply certain equipment and engineering services for the 70 MW natural gas based power plant of Arkay Energy (Rameswarm) in Tamil Nadu. The company will also provide operations and maintenance (O&M) services for the power plant," the release added.