The clean, renewable sources of energy are the wind, water, and the sun. Geothermal energy from the Earth is a good source of energy for electricity generation that has not been fully utilized. Sustainable energy sources must have “respect for environment” in the center of the 4-cornered diamond. Respect for the environment is very critical for the energy sources to be long lasting and thus sustainable. Respect for the environment needs to be the central philosophy of keeping the three components of the environment clean and healthy. These components—air, water and the land, overlap three of the four sources of clean energy. Mankind has to be responsible custodians of these three natural resources. One main cause of the energy–water nexus is that about 90% of the world's electricity is manufactured following the Rankine cycle for power generation, and water is used for the removal of heat from the condenser. The energy–water–food nexus arise in some parts of the world mainly because of the local climatic conditions. High population density involved mainly with agriculture and adverse climatic events (floods from melting glaciers owing to climate change) are the major factors that cause these energy–water–food nexus problems. Areas identified to have these energy–water–food problems include several parts of Saharan Africa, Sub-Saharan Africa, the Arabian Peninsula, Japan, and the Punjab.

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