[Donaldson Tan]

The Three Wise Monkeys

1. Oil Companies - See No Depletion
2. Governments and International Agencies - Hear No Depletion
3. And All Agree it would be best to - Speak No Depletion

[billnotgatez]

There is a projection that the source for petroleum will run out in the near future (let us say 50 years). What then do we do? One solution that would be the path of least resistance would be to convert coal to a gasoline or diesel substitute. Chemists here know that the technology from olden times provides a method for doing so. Not only does it   fit within the current modes of transportation, but also the processing structure would be similar to what is done now for crude. The harvesting of coal is a well-known process.  The coal reserves are far greater than petroleum. So the statement we are about to run out of liquid fuel is not quite correct.

What are the ramifications? Well the process of mining (strip mining) has some consequences that would have to be ameliorated.  The discussion about carbon dioxide emissions will be another post in the near future.

Although coal may not be the best and greenest solution, it still may be the adopted solution since it is the path of least resistance.

[Donaldson Tan]

A lot of coal and gas are burned in the process of converting coal and gas to synthetic diesel and gasoline. I am not sure about the numbers for coal, but I know for certain half the amount of gas coming into a synthetic fuel plant is burned to generate energy to reform the remainder natural gas into carbon monoxide and hydrogen. On top of that, hydrocracking, an energy intensive process, is employed to convert the parrafins formed from the Fischer-Tropsch Process into iso-parrafins. In the end, the total calorific value of the synthetic fuel will be at most 25% of the total calorific value of the natural gas entering the Synthetic Fuel Plant. On top of that, vehicle engines are at 30-40% efficient, so the total energy from the natural gas feedstock being utilised by our transport vehicles would be 8-10% of the total natural gas feed into the synthetic fuel plant.

[billnotgatez]

In days of yore there used to be stuff called town gas. Natural gas replaced it for the most part since it was cheaper. Town gas is made from coal and may have methane, carbon monoxide and other burnable constituents.
Thus I would expect that a gasoline / diesel substitute can be derived solely from coal. I expect, as the petroleum stuff gets more expensive this coal methodology will become an economic contender. Again, I am not necessarily a proponent of coal use, I am just pointing out a likely avenue that will be pursued.

I post here a link about methane hydrates for information purposes.
http://en.wikipedia.org/wiki/Methane_hydrates

[Donaldson Tan]

The classic Fischer-Tropsch Synthesis (FTS) is the backbone of many synthetic fuel synthesis technology. It first involves the gasification of any hydrocarbon feedstock, followed by the fishcer-tropsch reaction.

There are many variants of FTS. Different catalysts are used in each variant and each variant is optimised for the manufacture of a particular product, such as the Methanol (Direct Methanol Synthesis), Ethanol (Pearson Process) and Gasoil (Shell Middle Distillate Synthesis).

[Donaldson Tan]

Another Process that I want to highlight is the BRI Process



Syngas is generated via partial oxidation of the Biomass Feedstock with Air. This is an exothermic reaction and it easily reaches 1280C. The hot syngas has to be cooled to 40C before it can be fed to the Fermentator for Ethanol Synthesis. Hot steam is generated via the cooling of Syngas and this steam can be used to generate electricity in a turbine. The Fermentator contains a anaerobic bacteria which converts the Syngas to ethanol. Chemical energy input to the fermenator is present in the form of nutrient supplement for the bacteria.

This process produces both bioethanol and electricity at the same time. Is this a solution to meet energy demand for fuel and electricity at the same time?

[KLB]

When we ask the question about synthetic fuels from coal, we should ask the question of what is the ultimate objective and what is the most cost effective, most energy efficient and least environmentally damaging method of achieving that objective. Why do we want to produce petrol? We need petrol as it is a convent and portable energy source that can be used to power vehicles.  So when we convert coal into petrol, the petrol is nothing more than an energy storage medium. As was pointed out above coal-to-liquids is a very inefficient and extremely energy intensive process.  It would probably be much more economical, more energy efficient and less environmentally damaging to simply convert coal into electricity, which could be delivered to the consumer via existing infrastructure and stored in the vehicle via either chemical batteries (e.g. lithium ion) or fuel cells (e.g. hydrogen).

Another advantage focusing R&D efforts on electrical energy storage is that the technology is not beholden on just coal.  Any energy source that can be used to generate electricity could be used.  This includes point of use generators like solar panels on consumers' homes.  Our best short term hope for reducing the need for crude oil based energy is plug-in hybrids.  Plug-in hybrids would allow vehicles (e.g. passenger cars) to be mostly powered via batteries (or fuel cells), with petrol only being used for longer trips.  Since most drivers drive less than 35 miles per day even existing battery storage technology can handle most driving needs.

One great advantage to plug-in hybrids over coal-to-liquids is that because these vehicles would be mostly charged at night, when demand on the electrical grid is at its lowest, it is estimated that the current U.S. electrical production capacity could handle up to 75% of the U.S. vehicle fleet being converted to plug-in hybrid WITHOUT adding new power generating capacity.

This is not to say that there wouldn't come a point in time where we might need to begin to convert coal-to-liquids to power things like jet turbines of aircraft, but that we could simply limit the consumption of CTL petrol to those uses that CAN NOT be powered by stored electric power.

We should also remember that CTL is no magic bullet to our dependence on crude oil.  By the coal industry's own estimates it will cost around $200 billion and take 20 years to build enough CTL capacity to replace just 10% of the current U.S. crude oil needs.  Plug-in hybrids on the other hand could probably replace this amount of crude oil needs within a few years for a fraction of the cost and would save the consumer considerable amounts of money in terms of recurring energy costs.

[billnotgatez]

KLB -
Just out of curiosity, would you support the building of 300 nuclear power plants to replace the need for coal?

[KLB]

billnotgatez, no I would not support building that number of nuclear power plants to replace coal. You would be trading one environmental nightmare for another.  Given current technological capabilities. We can not replace coal power plants, so we should make them as clean as is possible and sequester the CO2 they produce.  At the same time coal should not be used in inefficient ways to replace other energies like oil.

For the foreseeable future we will need a mix of energies to supply our energy needs.  This includes fossil fuels, nuclear power, and renewable energies.  What we should be doing is working to develop ways to reduce the environmental impact of energy sources like coal and nuclear, working towards increasing renewable energies' share of of the energy mix AND increasing the efficiency of our energy consuming stuff.  For instance:

• The energy requirements for new and/or renovated homes could be cut in half if stricter energy codes were implemented.
  We were able to cut our household electric bill by 20% by changing our lights over to compact florescent lights.
• The average American home has enough roof area to install enough solar panels to replace 60% of their energy needs.  Excess power produced by the solar panels during the day could be fed back into the electric grid helping supply electricity during the time of peak needs.  This would help reduce the need to build new power plants as peak needs determine needed power generation requirements
• The fuel efficiency of vehicles absolutely sucks.  According to the DOE, only around 15% of potential energy in fuel gets converted into forward motion.  A lot of energy gets wasted in city driving because of idling, and starting/stopping in traffic and for traffic lights. Technologies like hybrids and fuel cells that use electric motors could eliminate a lot of this wasted energy.
• Electronic devices are a huge waste of energy.  The average household electric device (e.g. microwave, DVD player, etc.) consume more electricity over life while not in use and/or turned off then they do while actually being used for their intended purpose.  Devices could be engineered to not consume as much power while in standby mode and/or they could be engineered to be truly turned off when not in use.  Power supplies for battery chargers, computers, etc. still consume power when plugged in even if their parent device is not plugged in to them. These could be engineered to stop drawing power when not actually in use.

Many people have called efficiency the other energy source because improving the efficiency of our stuff would significantly reduce our need for more energy sources. Quite literally we could become closer to eliminating our need for imported oil with plug-in hybrid technologies and more fuel efficient vehicles  than we could ever do with coal-to-liquids technology and the cost to the end consumer would be a lot less.

What we should not be doing is using the least efficient most environmentally destructive method of providing us with the energy we need and coal-to-liquids is one of those technologies that we should not be using when there are more efficient ways of achieving the end objective (powering our vehicle fleet). There is no upside to CTL and while the technology has existed since the 1920's it has always been the technology of last resort by the most desperate of nations (Nazi Germany & apartheid era South Africa)  because of how costly and energy intensive it is. We need to be focusing our research and development on ways to eliminate our need for petrol before we are forced into using CTL to help supply our petrol needs.