written 25 April 2021
published 2 May 2021
Traditional fiscal advice for a sustainable life style is to preserve your capital and live on your interest income. The cautionary tale is a person who burns through an inheritance, living beyond their income, and eventually winds up bankrupt. This same basic idea can be applied to natural resources and energy systems.
Natural resources have a rate of renewal, and harvesting at less than that renewal rate is a prudent, conservative strategy, sustainable in the long term. Harvesting above that rate eventually destroys the resource and whatever society it supports. The history of civilization is littered with societies that collapsed after exhausting one or more of their critical natural resource systems. This can be food resources, water resources, or energy resources.
All societies throughout history have depended on solar energy. Biologic systems convert the daily solar flux into carbohydrates or structural fiber, and the stored energy is used by humans in the form of crops, for food and fiber, and timber, for construction and heating. Food and fiber are generally an annual solar harvest, while timber can have several centuries of stored solar harvest.
Air heated by the daily solar flux moves around the planet as wind, which has been used for nautical transportation for over 5,500 years, and for mechanical power for over 2,200 years. Water evaporated by the daily solar flux eventually falls as rainfall, and flowing water has been used for mechanical power for over 2,400 years.
Fossil fuels are stored solar energy in the form of decomposed organic material, which were deposited long ago, buried by subsequent sedimentation, and transformed by pressure and geothermal heat. Oil and natural gas were deposited between 65M-540M years ago, and coal was deposited between 100M-400M years ago. The large-scale commercial extraction and use of fossil fuels began about 300 years ago.
Coal was the first to be developed, and powered the rise of the British Empire, giving their navy superior speed and maneuverability relative to wind powered fleets. Coal currently supplies 27 percent of global energy. With the lowest hydrogen to carbon ratio of the three fossil fuels, it is inefficient and contributes more greenhouse gases per unit of energy. Consequently, it is losing global economic competitiveness. At current consumption rates there are 133 years of global coal reserves left, but it is likely much of that will remain in the ground.
Global development of oil began about 200 years ago. With a higher ratio of hydrogen to carbon than coal, it is a more efficient fuel, and more versatile as refined transportation fuels. America's abundant reserves allowed us to supplant the British Empire after World War 2. Oil now supplies 33 percent of global energy. However, global oil reserves are smaller than coal reserves, and depletion of existing fields has outpaced discovery of new fields for half a century. America's production peaked in 1972, and most other large global oil fields have peaked since then. Shell Oil recently announced their entire reserve will be depleted by 2040. Global reserves could support current consumption for 42 more years, but not all of that can be recovered economically.
Natural gas is generally found with oil, and began commercial development at the same time. Natural gas lighting revolutionized civilization beginning about 200 years ago. It has the highest ratio of hydrogen to carbon of the three fossil fuels, and has been touted as a greener "bridge" fuel. But natural gas is mostly methane, a greenhouse gas 80 times more potent than CO2 over the short run. Because it can't be refined into as many products as oil, it isn't as versatile. The fracking boom of the last decade boosted natural gas production, but these wells deplete quickly, making it a relatively expensive energy source. Reserves can support current consumption rates for another 52 years.
Like the spendthrift burning through his capital, humanity has grown our economy by burning through our rapidly diminishing supplies of stored fossil solar energy. Independent of climate concerns, to avoid an economic collapse of unprecedented proportion, we must shift our economy to living on our solar income within the next few decades, before we exhaust our stored fossil solar capital completely. Fortunately, our solar income is enormous: 10,000 times our current global energy consumption. Does humanity have the wisdom and commitment to make such a shift?