Water and energy systems are inextricably linked: water is needed to generate and transmit energy, and energy is consumed to collect, purify, move, store, and dispose of water. Both resources are limiting the other-and both may be running short. Our main research projects in water energy nexus include advanced water treatment, sustainable brackish water desalination and low cost drinking water purification for rural residents, innovative solutions for solar energy capture and storage, as well as integration of renewable energy with water treatment and desalination.<br><br>Energy is essential for economic and social development but also poses an environmental challenge. In comparison to fossil fuels, biofuels have the advantages of being renewable, nontoxic, and biodegradable and have a much lower risk of contaminating the environment. Generally, the raw materials that are exploited commercially to produce biofuel consist of edible fatty oils derived from rapeseed, soybean, palm, sunflower, and other plants. However, biofuel from edible oils is controversial due to the increase in global food prices, depletion of ecological resources, and intensive agricultural practices in crop cultivation. The second generation biomass production and utilization minimizes these concerns because second generation biofuels are derived from non-food feedstock, such as algae.<br><br>Much like the energy crisis, a shortage of drinking water is another major global issue. Freshwater is becoming a scarce commodity, especially in arid and semi-arid regions, requiring treatment of impaired waters in order to satisfy ever-increasing demands. In desalination process, waste concentrate generated from the process requires disposal. On-going research in concentrate utilization includes its use for second generation biofuel production. This waste-to-fuel process is one of the many benefits of sustainable approach to water-energy nexus.