For years, they have built monitors, the biggest drains on energy, that are more energy-friendly. Most monitors today use lower energy displays and can shut themselves off after extended periods of idling. The drive is also there to make computers smaller. And that means fitting more of the hot parts of the computer closer together and getting rid of the big fans that are required to keep it cool. With that, computers may not need any additional cooling or temperature controls.
Solar energy is still a viable option.
Perhaps one day, one day soon even, there will be a solar powered labtop. It happened for calculators. It can probably happen for computers too.