Laptops are designed to be fairly power-efficient. I don't know what yours does. But mine goes down to only a very few watts if idle and the display is switched off. There's the Linux tool "powertop" which shows power consumption and it can also tune most components to go to low power. Sometimes there's also a power profile setting. That shouldn't be on "performance" or anything like that. I don't think Linux has more to offer, except sleep with wake-on-lan.