The Crash Course - Chris Martenson [72]
Why is the net yield dropping? In the past, a relatively tiny amount of embodied energy was contained within the smallish rigs that were used to exploit finds that were massive, plentiful, and relatively shallow. Two of the larger finds in the world’s history, Spindletop in Texas and the Ghawar field in Saudi Arabia, are both only a little over 1000 feet below the surface. The Macondo field in the Gulf of Mexico, which was the site of the Deepwater Horizon incident in 2010, was beneath 5,000 feet of water and a further 13,000 feet of rock and sediment, and held perhaps 1/1000th of the oil in Ghawar. All that drilling, miles of piping, and a massive oil rig were required to find a relatively minor amount of oil, illustrating why the net energy of oil discoveries of today are so much lower than the past. And the Macondo field was neither particularly deep nor disappointingly small by current standards.
Today much more energy is required to find energy. Exploration ships and rigs are massive, requiring significantly more steel to create than the humble drilling rigs of the 1930s. And today more wells are being drilled to greater depths in order to find and produce smaller and smaller fields, all of which weigh upon our final net energy return.
And what about the massive amounts of oil allegedly contained within the tar sands and oil shales? These are often wrongly described as equivalent to “several Saudi Arabias.”8 The net energy values for these are especially poor and are in no way comparable to the 100:1 (or higher) returns actually found in Saudi Arabia. Tar sands have a net energy return of around 5:1,9 and tar shales are thought to be even worse, in the vicinity of 2:1 or less.10 So while there may be the same volume of oil locked in those formations as there is in Saudi Arabia’s magnificent treasures, there isn’t the same amount of useful, desirable, delicious net energy in them. Nowhere near as much.
If we were to try and subsist entirely on the energy offered by a new source that was sporting a 3:1 net energy return, this is the world in which we’d live:
Figure 15.4 The Energy Cliff (3)
Trying to live on 3:1 net energy.
Look at how much less gray area and how much less surplus energy there is in this chart after we’ve begun to slide down the energy cliff, compared to the ones where there were 10:1 or 20:1 returns. The gray area represents how we “fund” our growth and our prosperity. The gray area is the net energy that feeds and supports our economic complexity. If we can appreciate how two societies, one abundantly supplied with food and the other nearly starving, can differ on the basis of their available net food energy, then we can also appreciate how a high-net-energy economy will be fundamentally more robust, complex, and interesting than a lower-net-energy economy.
And what about renewable energy sources (Figure 15.5)? Methanol, which can be made from biomass, sports a net energy of about 2.6:1,11 while biodiesel offers a net energy return of somewhere between 1:1 and 4:1, depending on whether we count just the biodiesel itself or include the energy left in the crushed meal, which can be burned.12 Corn-based ethanol, if we’re generous, might produce a net energy return of just slightly over 1:1,13 but could also be negative, according to some sources.14 Ethanol produced from sugar cane in Brazil has an EROEI of closer to 8:115 (largely because the sugarcane itself can be burned to fire the process), making it a viable proposition there, and some exciting work is being done on cellulosic and other forms of ethanol that might have much higher EROEIs than any other biofuels, but those are not yet out of the demonstration phase. We