Thermal radiation provides radiative access to all heat sources, with the sun representing the most important renewable energy resource and the universe representing the ultimate heat sink. Thermal radiation could have many applications such as solar energy harvesting and radiative cooling. In our quest to utilize various thermodynamic resources including both heat sources and heat sinks, the ability to control thermal radiation plays a fundamentally important role. Here, we will take advantage of the emerging tools at the intersection of photonic materials and metamaterials, thermal science and energy applications, namely coupled-mode theory to tailor the thermal radiation behaviors from multiple arbitrary numbers of resonators, radiative cooling for freezing desalination and radiative cooling atmosphere water harvesting.