Walter Youngquist: Geodestinies Coal

Preface. Before the excerpt from Geodestinies, I thought an introduction to how coal is formed would be worthwhile, especially since I still thought it was the “once-popular explanation” below (Cottier 2021 How Ancient Forests Formed Coal and Fueled Life as We Know It. Discover).

“Coal doesn’t form at a steady rate. Huge quantities appear now and then in the geological timeline, but small, isolated patches are more typical. This spotty record raises the question of why coal creation isn’t constant throughout Earth’s history. 

A once-popular explanation argued that the Carboniferous was so productive because woody plants had just begun to grow and the fungi of the time hadn’t yet evolved to decompose lignin, the polymer that makes wood rigid. Rather than decay and disappear, these prehistoric trees remained preserved until they were buried by sediment and turned into coal.

It’s a simple, elegant solution, but many experts find it unconvincing. For one, the odds seem low that tens of million of years passed before any fungus hit upon an enzyme that could break down lignin. More importantly, there’s much more to coal than woody plants: In many places, the bulk of the dead plant matter came from lycopods, a giant tree whose living relatives include club mosses and which contained little lignin. 

The way coal is formed is very simple: You need a lot of rain (to form swamps and foster plant growth) and a hole (for the plants to fill).  Which was especially true in the Carboniferous and a few other coal-bearing periods.  During the Carboniferous, as the Earth’s landmasses merged into the supercontinent Pangaea, the collision of tectonic plates forged both mountain ranges and wide basins beside them. Voila — holes to fill. Some of those basins, including the ones in present-day Europe and the eastern U.S., happened to form in the ever-wet tropics. In the global scheme of thingsit comes down to how many large, sinking tectonic basins sit in the appropriate locations and allow deteriorating organic matter to accumulate.

When plants died in these waterlogged regions, many fell into stagnant pools with little oxygen. Since most decomposers (bacteria, fungi, worms and the like) can’t survive in such conditions, the plants never fully decayed. Instead they formed peat, an accumulation of partially decayed organic material. But even this is not enough to guarantee coal — if the wetlands dry out, the exposed peat will disintegrate. One way or another, it must be covered by sediment. 

Sometimes, in swamps located either near the ocean or in flatlands where rising seas can reach them, this happens repeatedly during glacial-interglacial cycles. Peat forms during glacial periods, when the polar ice sheets grow and the sea level falls. Then, when the ice melts and the sea floods into the swamps, the peat is preserved, locked away beneath new marine sediment. In some places, the rock record attests to dozens of these repeating marine and non-marine layers, known as cyclothems. “Then you just have to wait a hundred thousand years until the next cycle begins again,” Looy says. Peat can also be preserved farther inland, as the eroding sediments of the surrounding landscape bury it.

Over time, when new sediment and peat layers compress the buried peat, the increasing weight squeezes out water, gradually leaving behind coal. It hardens slowly into increasingly refined forms, starting with lignite, or brown coal, and proceeding through sub-bituminous and bituminous to anthracite — the black, lustrous lumps you might imagine.

glaciation, rainfall, sedimentation — is actually quite simple. With basins in the appropriate spots, the coal cycle runs almost like clockwork, an hour hand spinning round and round. “Once you see the system as linked together, it’s not that complex,” he says. “The glaciers come, the glaciers go. Peat forms, peat doesn’t form. It makes sense.”

And coal is almost always cropping up somewhere in the world. Even today, in select tropical regions like Borneo and the Congo Basin, peat piles up into what could be the next generation of deposits (though not all peat necessarily makes the transformation to coal). 

But nothing recent rivals the likes of the Carboniferous and the Permian. To create the immense troves of fossil fuel that have driven so much of human activity, you need precise circumstances, and our planet doesn’t often provide them. “You have an alignment of conditions … and those conditions give you all this coal,” DiMichele says. “Getting that set of conditions is not something that just happens again and again.”

Other Youngquist Geodestinies Posts:

Alice Friedemann  author of “Life After Fossil Fuels: A Reality Check on Alternative Energy“, 2021, Springer; “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer; Barriers to Making Algal Biofuels, and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Collapse Chronicles, Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report

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In regard to the “depths of the Earth,” mining at best can get down to only reach a depth of about 10,000 feet because the geothermal gradient is about 2° F for every hundred feet. That means the temperature at 10,000 feet down is about 200° F higher than at the surface. Mines at that depth require expensive cooling systems. A lot of pumps are also needed to keep out the water that would otherwise flood the mine. A major hazard at greater depths is overlying rock pressure. It is so great that walls of the mine are subject to “rock bursts,” in which rocks burst out of the sides of the mine and crush anything in their path, including mine cars and people.

But when it comes to coal, the depth is far less. Coal is usually mined safely at depths less than 3,500 feet; any deeper and the weight of the overlying rock could collapse.

The world’s reserves of hard coal (bituminous and sub-bituminous) and low-grade coal (lignite) are about the same, but their consumption trends are different. Demand for hard coal is rising, while the use of lignite for fuel is essentially flat. Lignite has a high-water content making it more costly to ship per unit of energy than for hard coal. The result is that the world will run out of higher quality coal much sooner than it will run out of lower quality coal.

It has been estimated that 90% of the total energy in coal, oil, and natural gas deposits in the United States, is in the form of coal. These coal deposits are already known; there is no expensive exploration work involved as there is for deeply hidden oil reservoirs.

Coal, however, has some substantial problems, starting with the fact that underground coal mines are dangerous. Each year miners are killed, and many others have their health permanently impaired. In the United States, most western coal, and considerable eastern coal, now is mined by open-pit methods. Underground mines are becoming less common. In mountainous areas such as the Appalachians, surface or strip mining and mountaintop removal mining of coal can have severe impacts on scenery, hydrology, water quality, local air quality, flora, and fauna.

Scientific American (2007) examined the U.S. government’s recent push to promote coal-to-liquid as a partial answer to the problem of oil supply. Their conclusions were: …liquid coal comes with substantial environmental and economic negatives. On the environmental side, the polluting properties of coal — starting with mining and lasting long after burning — and the large amounts of energy required to liquefy it, mean that liquid coal produces more than twice the global warming emissions as regular gasoline and almost double those of ordinary diesel…. One ton of coal produced only two barrels of fuel [gross return, not counting the energy input to produce it]. In addition to the carbon dioxide emitted while using the fuel, the production process creates almost a ton of carbon dioxide for every barrel of liquid fuel….Which is to say, one ton of coal in, more than two tons of carbon dioxide out…. Liquid coal is also a bad economic choice. Lawmakers from coal states are proposing that U.S. taxpayers guarantee minimum prices for the new fuel, and guarantee big purchases by the government for the next 25 years…. The country would be spending billions in loans, tax incentives and price guarantees to lock in a technology that produces more greenhouse gases than gasoline does….

Coal to oil to coal — in less than 100 years.  For energy measured in terms of barrels of oil equivalent (boe), world oil energy domination over coal only happened in 1963. Given current trends of increased coal production (especially in China and India) the reverse crossover point of coal becoming once again the dominant world energy source appears likely to occur no later than 2050. Some estimates put it as early as 2013. This means that oil will have reigned as the top energy source for less than 100 years. Yet another example of how the “oil interval” will be only a passing moment in human history. But coal is also a finite fossil fuel whose use will end within a century. Europe is going back to coal, with new coal-fired plants now scheduled for Italy, Germany, and in the United Kingdom. “Europe’s power station owners emphasize that they are making the new coal plants as clean as possible. But critics say that ‘clean coal’ is a pipe dream….” (Rosenthal, 2008).

Coal is still vital to U.S. economy in 2030 In spite of its environmental drawbacks and the decline in quality of coal being mined, the Energy Information Agency projects coal will still be a major source of fuel for electric power generation in 2030. Other sources of electricity (wind, solar, etc.) are still regarded to be very minor sources, in total, supplying less than half the fuel energy that coal will provide. Gas, however, will replace coal to some extent for a limited time.

Fossil Fuels — A Brief Flash. The fuels just mentioned are fossil fuels, the accumulation of myriad animal and plant remains during a period of more than 500 million years. It is sobering to realize that the most useful fossil fuels, coal and petroleum, which took geologic ages for nature to produce, will be consumed in a brief flash of Earth history, probably lasting less than 500 years. Even in terms of human history this will be a very short and unique time.

Coal exists in 37 states, and is mined underground in 22 states. It is estimated that eventually underground coal mining in the United States will involve 40 million acres, eight million of which already have experienced underground mining. Ground subsidence over coal mines is already occurring on more than two million acres. The U.S. Bureau of Mines estimates that nearly 400,000 acres of land in urban areas in 18 states may be subject to subsidence, and the total costs to stabilize these lands would be about $12 billion (Johnson and Miller, 1979).

In the East, coal companies have more recently been removing the tops of mountains and mining coal by the open pit method. The overburden is dumped in adjacent valleys, and has severe adverse effects on both the landscape and the environment that will be visible far into the future. In some regions of West Virginia where mining accounts for almost all the jobs, miners and environmentalists have clashed. There seems to be no happy resolution to this problem. In whatever form and by whatever means energy is produced (“captured” would probably be more accurate) in some energy forms more than others, there is always an environmental impact.

David Hughes (2007) reports that 50% of all coal consumed has been used since 1970, and 90% has been used since 1909. Hughes says world coal production will peak by 2025, as do several other recent studies, much earlier than those who have been saying the significant production life for coal is hundreds of years. These consumption patterns also generally apply to the consumption of all metals and nonmetals.

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