Final answer:
Coal is the largest secondary resource we have been using, significantly contributing to the manufacturing sector and economic growth. As a high CO₂ emitter, coal use presents environmental challenges. The shift from high-grade to lower-grade coal impacts energy extraction efficiency and necessitates adaptations in resource management.
Step-by-step explanation:
The largest secondary resource that we have been using is coal. As a secondary sector resource, coal undergoes various manufacturing processes that transform it into energy and other byproducts. Historically, coal has been a significant energy source for industries and remains a valuable secondary resource used in manufacturing and producing electricity, despite being a major contributor to CO₂ emissions. The extraction and usage of coal exemplify a key aspect of the secondary sector: turning primary resources into finished products that have a significant economic impact. However, as resources like coal are consumed, we face the challenge of needing to shift towards harder-to-reach deposits or alternative energy sources, thus affecting the energy output in terms of the mass of coal removed for the same energy yield.
The United States saw its economic growth tied to manufacturing during the Industrial Revolution and this sector continued to grow until it peaked in the late 20th century. In the broader context of resource utilization and the economy, it is evident that resources fuel prosperity, and their extraction and transformation remain fundamental to economic expansion. As we have progressed from using premium Anthracite coal towards the lower-grade Lignite, we have had to adapt to the changing availability and quality of this key secondary resource.