Decarbonization of Coal

If the problem is Carbon Dioxide, wouldn't it make more sense
to simply NOT Oxidize the Carbon in the first place?

We can reduce emissions from coal by 80% by using less than twice as much coal and take CO2 emissions from coal to ZERO by using maybe two or three times as much coal, all with existing technology.

The actual path to zero will involve rapidly increasing efficiency and renewables in response to higher energy prices such that overall coal use actually remains flat while efficiency makes up the difference.

The recognition of the possibility of doing this is based on two key insights:

1. Carbon emissions from coal can be reduced by almost 80% by simply repurposing and adapting an existing 150 year old technology, namely the coke oven still used to derive coke from coal for use in smelting iron into steel. An updated thermal volatile extraction (TVE) process can now instead be used for the thermolysis of coal whereby the volatile gases and liquids are separated from coal for energy, leaving the carbon as a solid in the form of coke. The resulting solid carbon can be used as a building material, industrial feedstock, or simply buried.

The remaining carbon emissions from coal can be completely eliminated using another existing technology, thermal decomposition of methane (TDM), to separate off the hydrogen from methane and other hydrocarbons, leaving solid carbon by deposition.

2. The value of CO2 necessary to make it cheaper to use this method to totally eliminate carbon emissions from coal is roughly equal to or less than the price of the coal. Therefore, at CO2 prices of less than $9 to $50 per ton we can completely eliminate CO2 emissions from coal.

The possibility of doing this has not been previously recognized for a number of reasons:

• Everyone has erroneously assumed that the penalty for not burning the carbon from coal for energy is so high that it cannot even be considered.
• Therefore most people thinking about the atmospheric carbon problem have never even considered the possibility of decarbonization by thermolysis.
• Carbon emissions have been priced by their weight in CO2 rather than carbon, which has masked the actual relationship between the price of CO2, the price of carbon and the price of coal in most people’s minds.
• The magnitude of the threat of catastrophic climate change, and therefore value of not emitting CO2 in the first place, had not reached its current level.

The two core insights above lead to a third key recognition:

3. If it did take almost four times as much coal to make carbon-neutral electricity from coal, then the actual cost of carbon-neutral electricity from coal would be on the order of four times the current cost. However, by making use of existing combined cycle combustion technology, burning the gases may be as much as twice as efficient as burning the coal, meaning only half again the cost to get to an almost 80% reduction, and perhaps only double the cost in coal to go to a 100% elimination of CO2 from coal.

Coal is a hydrogen-rich ore.

The Basic Numbers
These are still theoretical numbers based on well understood chemistry and thermodynamics from the coke oven gas process, however, they do not yet include the capital cost that will need to be amortized over the life of the investment to do this. Never-the-less, this suggests the only plausible path to actually eliminate our emissions from coal in the time required.

Coal currently sells for $9 to $45 per ton in the U.S. (the range has been as low as $6 and as high as $66 in the last two years). Anywhere from 50% to 92% of the total weight of coal is carbon, and the example coke oven gas was derived from relatively high carbon coal. Each CO2 molecule actually weighs 3.66 times more than one carbon atom, so for each ton of coal there are anywhere from 3.66 x .5 = 1.8 tons, to 3.66 x .92 = 3.36 tons, or an average of around 2.75 tons of CO2 produced from the carbon in coal when it is burned. To pay for the energy value of the carbon not emitted would require about an extra three tons of coal to be used for each ton currently burned.

If there were an average 3 tons of CO2 per ton of coal burned, and about 1/4 of the energy if not burned, then not burning the coal would require a total of 4 tons of coal, or an extra 3 tons of coal.

To achieve zero CO2 emissions using these very rough numbers:
At $9/ton coal it would be 3x $9 /3 => $9 per ton of CO2.
At $30/ton coal it would be 3x $30 /3 => $30 per ton of CO2.
At $50/ton coal it would be 3x $50 /3 => $50 per ton of CO2.

Thus, at a price per ton for CO2 roughly equal to the price per ton of coal, CO2 emissions from coal can be completely eliminated. However, with the efficiency gain of combined cycle this might even be cut in half.

A Huge Reduction First
A reduction of about 78% in CO2 emissions can be achieved by means of the first stage (TVE) thermal volatile extraction alone using basic coke oven type technology that yields a mixture of hydrogen, methane, carbon monoxide, BTX liquids and coal tar, along with solid coke. Simply burning the resulting gas mixture in a boiler to produce electricity would yield approximately 31% of the high heating value that would have been produced by burning the coal, while emitting only 7% of the CO2. Doing so would require about 320% of the coal burned to produce the same electricity, but emit only 22% of the CO2 as burning one ton of coal. However, if the gas is instead used in a combined cycle power plant the efficiency could double, meaning that it will only require on the order of 150% as much coal to reduce emissions by almost 80%. The (TVE) process is energy neutral at 800 to 1000 degrees C, i.e. the reaction itself does not consume any energy beyond the sensible heat required to maintain the reaction vessle at temperature.

Zero Carbon Coal
The overall process may be made fully carbon-neutral, thereby emitting zero CO2 from coal, by adding a second stage, whereby the methane, and/or small amounts of other hydrocarbon liquids, are converted into pure hydrogen and carbon using thermal decomposition of methane (TDM). The solid carbon derived from this vapor deposition process is the high value feedstock necessary for the manufacture of carbon fiber materials. At the completion of the full decarbonization process virtually 100% elimination of CO2 emissions from coal can be achieved while delivering approximately 26% of the total energy that would have been derived from burning the coal. This would theoretically require about 380% of the coal that would have been burned to produce the same energy, but again with combined cycle technology could mean perhaps double the coal to take CO2 emmissions to zero. The net energy yield for the TDM stage is 55%.

A New Carbon Market
The value of the new carbon dioxide elimination trade credit will be based on the current price of CO2 and carbon from the lowest cost coal will actually be negated first. In practice this will mean installing sufficient TVE thermolysis capacity on power plants burning the cheapest coal first. TVE will remove almost 80% of the carbon, thereby avoiding creation of almost 80% of the CO2, but would also only require roughly an extra 2 parts of coal (instead of an extra 3 parts) to achieve that 75% to 80% CO2 reduction: (2 x coal price) / (total CO2 per ton x .8) i.e. (3 x .8 = 2.4).

For $9 coal the minimum CO2 price would be roughly: 2 x $9 / 2.4 = $7.50/ton
For $30 coal the minimum CO2 price would be roughly: 2 x $30 / 2.4 = $25/ton
For $50 coal the minimum CO2 price would be roughly: 2 x $50 / 2.4 = $41.50/ton

Again, with the efficiency gain of burning the gas in a combined cycle power plant these prices might also be cut in half, so $9/ton coal might actually require a CO2 price of only $7.50 / 2 = $3.25/ton, while $50/ton coal might be 80% negated at CO2 prices of close to $20/ton. CO2 is already trading at well above that price in Europe. Global CO2 elimination credits will be fungible so, the first place to find the cheapest coal for the most attractively priced carbon credits will most likely be Chinese and Indian coal plants.

A Unified Carbon vs. Electricity vs. Coal Market Model
Because the price of other existing CO2 credits has not been directly linked to the price of fossil carbon energy, the actual corresponding price of carbon-neutral electricity has not been directly connected to the price of CO2. This system integrates these three variables into one coherent model of the energy and carbon market.

Generalized Credit for All Fossil Fuels
A similar decarbonization approach may be applied to all fossil fuels, and thus the same CO2 credit trading market can also be extended to other fossil fuels by leveraging the decarbonization of oil and/or natural gas using TDM thermal decomposition of methane and similar technologies. Completely decarbonizing natural gas will effectively double the cost of gas, while decarbonizing oil should fall somewhere between the cost of coal and natural gas.

Audit Verification
To assure that the resulting coke is actually used to achieve negation and not used in metallurgy, cooking, heating or other combustion causing CO2 emissions, the coke must be mixed with sand or dirt to render it non-combustible. This process of mixing the coke with sand and/or burial or use as a building material filler will require an audit verification regime.

Value Added Gases
Approximately 55% of coke oven gas is hydrogen, and 25% is methane. The market value of the hydrogen and methane appear to be so much higher than the value of the electricity currently made by burning coal, and cheaper than the H2 currently made from natural gas, that initially it should be economically attractive to install thermolysis to produce the gases even before counting the value of CO2 elimination. However, the supply of H2 should be expected to rapidly rise to the point where the price falls and the value of CO2 negation will become the driving force for installing additional thermolysis capacity on coal plants.

High Sulfur Coal Solution
To make it even more attractive, the decarbonization process will also remove both the sulfur and nitrogen, retaining them as separate products along with the solid coke. Hence the process also solves local air pollution issues, allowing otherwise unmarketable high-sulfur coal to be used. This dirty coal may offer the lowest possible carbon negation price until the new market pushes the price of them up. In addition, low grade coal sometimes contains a higher percentage of volatiles representing non-carbon energy and thus could yield more energy and less carbon per ton of coal. This coal is often not suitable for making coke, but may have a higher yield of H2 than the example numbers from coke oven gas used here.

Comparison with Coal Gasification
This can be compared with alternative proposals for so-called clean coal, involving coal gasification, that would only reduce net CO2 emissions by 50%, require advanced technology, and depend upon the geologically questionable and as yet unproven underground sequestration of gaseous CO2 to even achieve that 50% reduction. Current estimates suggest that without subsidies coal gasification would only start to become economically feasible at $20-40/ton for CO2.

Internalizing Externalities from Coal
In the language of sustainability this is a market mechanism for internalizing many of the most serious externalities from coal, related to climate change and local air pollution from emissions.

If the bulk carbon were actually used to refill the hole where the coal was mined it might even begin to also address some of the collateral costs of that aspect of coal mining as well. If the externalities of the entire coal life cycle could be fully captured in the cost of the energy derived from it, coal might become a legitimate component of a truly sustainable energy future.

Efficiency Gains and Renewables
While at first glance the price increases implied might seem challenging, consider how the market will react once a price trend has been projected and discounted. Once it is universally known that electricity rates will roughly double in five years, everyone will choose to finance, purchase and install improved efficiency at every opportunity to make a capital decision. The savings from massive efficiency gains and resulting demand reductions driven by steady price increases will help compensate to keep the net cost of actual electrical usage growing far more slowly. Even if electricity prices doubled in five years, and then doubled again in the next five years, at the end of ten years the system as a whole would be far more efficient and resilient. The net positive effect on the economy as a whole, and efficiency and renewables in particular, would far outweigh the actual challenges of increased energy costs.

New Carbon Materials
Solid carbon is stronger and lighter than many of the materials in current use, such as concrete and steel, and together steel and concrete account for over 10% of global CO2 emissions. Large quantities of high quality carbon can be used as a construction material. In the short term, carbon based masonry made from coal tar and coke can supplant bricks and concrete. If this construction material sold for even half the price of concrete it would pay for the reduced energy yield even without carbon credits. In the long-term TDM carbon could be the feedstock for new carbon fiber based materials technologies that promise to replace steel in products from cars to buildings, and cars made of carbon fiber could be an order of magnitude more fuel-efficient than steel cars.

Coal is a carbon-rich ore

This idea was developed by Jim Fournier and he has filed a business method patent on it in the U.S. to form a venture backed company, Carbon Zero, Inc. to develop and deploy a demonstration plant. These credits may also be deployed first in other parts of the world where carbon is already trading well above the price necessary to make it attractive to avoid carbon dioxide emissions this way.

v3.5