A renewable resource is a substance of economic value which can be replenished or replaced either through natural recurring processes or biological reproduction.
Biomass is a biological material taken from plants or plant-based materials.
Biomass is considered a renewable resource because plants and plant-based materials can be found everywhere and once used these plants will continue to grow and supply the demand for biomass consumption.
Differences in the density of water can cause currents to form and move.
Density is affected by temperature and salinity. Cold water or water with dissolved salts (higher salinity) is denser than warm water or water without dissolved salts.
The different densities cause the water to move, forming a density current. In the oceans, the deep,bottom currents are colder and saltier than the surface currents.
