* Power conversion and distribution will always be needed.
* Knowledge of motors and motorized devices (small and large) is always needed.
* Solar panels are coming down in price per watt, making them viable for wide-scale use. Problems still go with them, which need knowledgeable experts to cope with them.
* Battery technology. Fuel cell technology. How to increase Watts-per-weight. How to eliminate risk of fire and explosion if abused.
* Computer technology. Networking methods. Internet access. Increased reliability. Ease of use. Miniaturization.