What do trees have to do with energy? Trees and other plants are energy.
They are the ultimate collectors of solar energy, using the energy of the sun to produce food through photosynthesis. Plants jump-start the entire food chain with this energy, synthesizing carbon-based food by taking carbon dioxide and water and that energy from the sun and producing carbohydrates for their own metabolism. In turn, this food feeds animals such as us, or animals that eat animals that ultimately ate plants.
Second, trees are leafy friends that pay us back by conserving energy in our homes. For example, according to treebenefits.com, a 30-inch diameter pin oak in my yard provides $371 in annual benefits in terms of stormwater remediation, air-quality benefits, carbon sequestration, enhanced property value and energy savings. According to estimates of the Tree Benefit Calculator and the i-Tree suite of software (itreetools.org), those energy benefits for this one tree include estimated savings of 362 kilowatt-hours of electricity and reduced consumption of oil or natural gas by 49 therms. The estimated value of these benefits from this one tree is $75 a year.