Fossil and even nuclear fuels depletion is virtually certain. Long-term solutions must rest on technology that economically harvests wind, solar and other renewable energy sources.
There is constant research on propulsion and materials, neighborhood and road geography, travel pricing and impact of telecommuting. Studies like UC Davis's Transportation Publications help improve urban planning for optimal traffic flow.
Current biotech questions span genetics, protein dynamics, cancer research and biomedical engineering. For example, biomedical engineering deals with materials used for the likes of tooth fillings and artificial hips.
Waste disposal research entails isolating garbage within safety, budget, space and political ("Who wants to live next to a dump?") constraints.
Space research presents a cornucopia of science questions. In September/October 2009, NASA slammed a probe into a shadowy moon crater under suspicion that detectable amounts of water/ice are present.
It is difficult to exaggerate the high-cost/high-ambition nature of energetic physics. Current problems facing CERN scientists involve proving the existence of a theorized particle (Higgs particle) that endows matter with mass.