The amount of global consumption of plastics is huge and the amount is still increasing rapidly. Unlike metal recycling, plastic recycling is difficult especially in terms of economical feasibility. In today's WEEE (Waste Electrical and Electronic Equipment) recycling schemes, material recycling is prioritized with regard to energy recovery. However, by forcing the recycling rate to increase, material recycling requires much more costs and yields more environmental loads than energy recovery. In the article, the authors claim the following. Material recycling should be applied for such WEEE plastics as: plastic parts that can be relatively easily sorted by plastic material types, large plastic pieces, and plastic parts made of plastics suitable for material recycling. On the other hand, energy-recovery should be applied for other type plastics. For example, plastics used for semiconductor substrates are suitable for energy recovery. As a technique that enables effective energy recovery, 'WEEE Steam Gasification' technique is presented. The implications of the technique for product design are then discussed.