Chapter 15: nonrenewable energy sources, their impacts, and energy conservation. Where will we turn for energy: fossil fuels are finite, nonrenewable, and have become more expensive. Economics determines how much will be extracted: extraction becomes increasingly expensive as a resource is removed, proven recoverable reserve amount of a fossil fuel that is technologically and economically feasible to remove under current conditions. Reaching further for fossil fuels and coping with the impacts. Mountaintop mining extends our reach for coal: economically efficient, but causes environmental disruption, unleashes soil erosion and destroys large areas of habitat, breathing in coal dust and hazardous gases; possibility of black lung disease. Secondary extraction produces more fuel: primary extraction initial drilling and pumping of oil or gas, secondary extraction using new technology to force the remaining oil/gas out by pressure, more costly. Directional drilling reaches more fuel with less impact: directional drilling allows drillers to bore down vertically and then curve to drill horizontally.