What was Mr. Curtain doing with the tidal turbines?

Mr. Curtain was utilizing the tidal turbines to collect and save their power specifically for messages. This action reflects his broader scheme related to communication and control, which is central to his character and the plot. By harnessing the power generated by the turbines for messages, he was effectively manipulating information and communication, which aligns with his desire to maintain power and control over others. This strategic use of technology plays a critical role in the story, as it helps Mr. Curtain execute his plans while also posing challenges for the protagonists. The focus on messages underscores the theme of manipulation and deceit woven throughout the narrative.