Very good article. Really this is the reverse of what we do right now which is to take a complex hydrocarbon source (oil) and distill it into its constituent parts. Producing hydrogen and using available carbon sources (coal) to synthesize products we currently make from oil seems a very sensible idea.

I am sure it all boils down to economics but it is technically feasible right now. I had considered the idea more in the light of using nuclear energy to produce the electricity needed to break out hydrogen from water but really any non CO2 emitting electricity production process could be used as the "prime mover".

Coal and hydrogen could even be combined to produce methane gas to be used in our present distribution netwroks rather than use hydrogen directly with all of its huge infrastructure costs and implications.

I think modern society will be forced into it since there is a finite supply of oil and we will be using products made from oil for many years to come. It begs the question how we produce all these products when there is no raw material left from which to make them.

You paper proposes the solution to that problem.

In fact any liquid or gaseous fuel we currently use could be manufactures from coal and hydrogen thereby ending reliance on oil.

I would suggest the time is right to promote this idea. It requires very large volumes of hydrogen and therefore very large amounts of electricity but this can be base load or it can use intermittent renewables.

Provides much food for thought Harry.

Malcolm

What's that? Did I hear someone say "sequestration"? The problem there is just the sheer scale of the task. For every ton of coal that is burned, roughly two and a half tons of CO2 are produced. The most likely scheme that anyone has proposed for large-scale CO2 sequestration is to pump it into deep sea sedimants. That would require an infrastructure of deep-water reverse oil rigs many times larger than the current network of deep-water oil rigs. Plus a new infrastructure of pipelines or new rail carriers that can move CO2 from the power and CTL plants to ocean ports, where it can be loaded onto a new generation of supertankers for transport to the deep water pumping platforms. The CO2 supertankers alone would need a tonnage capacity for liquified CO2 that's an order of magnitude greater than current oil carrier capacity. Not going to happen!

There is a workable alternative, however. That's why I only said the title is "nearly" an oxymoron. The alternative is to mandate that any synthetic hydrocarbon production must be driven by carbon-free energy. In most cases, that would mean hydrogen produced by electrolysis from nuclear, wind, or solar. But the key is that production process could not be driven by burning of carbon.

The real economic cost of such a restriction would be small to negative. It roughly doubles the yield of synthetic hydrocarbon per ton of carbon feedstack. It doesn't automatically make for a low carbon economy, because when the synthetic hydrocarbon is burned, it still releases CO2. But in the worst case. when coal is used as the feedstock, the CO2 impact the same as the current oil economy, instead of twice as bad.

If the feedstock is biomass, rather than coal, then the process is carbon neutral. The land area required to grow the biomass is cut by half, since the hydrocarbon yield per ton of biomass is doubled.

The process can be made carbon negative and sustainable over the long term by using low-temperature pyrolysis of biomass, and processing only the volatile fractions driven off in pyrolysis--about 60% of the biomass. The pyrolysis char would be returned to the land as a soil ammendment. It builds long-term soil fertility, and aids retention of fertilizers.

More on this can be found at the Eprida website, here

The renewable energy sector could combine clean renewable energy with coal to develop a competitive North American synthetic hydrocarbon industry. The initiative to curtail carbon emissions in both America and Canada could require that only clean and renewable energy could be used to produce synthetic hydrocarbons intended for non-transportation use.

On a minor note, I would remove "proximity to a source of water to produce hydrogen" from the list of criteria for a location. The bonding energy in a water molecule is so large that the actual quantity of water we're talking about is not all that significant. One nuclear plant dedicated to producing hydrogen from water could easily be fed by a small irrigation ditch. At the levels required, sufficient water could be condensed from desert air without paying a very large energy penalty.

To me having a whole bunch of deadly gas somewhere below me seems to be a lot more scary than Nuclear waste buried somewhere off in a mountain.

A second advantage, particularly when using fossil feedstock, is that the CO2 emissions when burning methane are about 27 % lower than when burning liquid fuels (pure chemistry).

My understanding from some previous research is that the carbon efficiency of both CTL and BTL (biomass-to-liquids) is in the range you cite: 45% - 55%. The energy efficiency, however, is somewhat better. The liquid hydrocarbons contain more energy per carbon atom than the initial carbon feedstock. Also, most of the waste heat is generated in the FT synthesis step. It's given off at a temperature in the range of 250 - 350 degrees C--too low for efficient power generation, but useful for things like space heating, desalination of sea water, or drying.

The 55% - 45% of the feedstock carbon that is lost is lost as CO2, from partial combustion of the feedstock to drive gasification. But if the process is driven by externally supplied energy rather than partial combustion, the carbon efficiency can be virtually 100%. That's why driving it with electrolytic hydrogen and oxygen can double the fuel yield.

I think you're correct, however, that if you produce methane from the synthesis gas rather than liquid hydrocarbons, more of the input energy will remain present in the product gas. But it's not a large difference. You have to consider how you intend to use the synthetic methane. If it's for power generation or firing a stationary furnace, they you're better off just using the raw synthesis gas. If it's to provide transportation fuel, then you have to consider the overall economics of fueling with CNG vs. liquid fuels. You'll get somewhat more energy from CNG, but the heavy fuel tank and refueling difficulties may offset the energy advantage.

Have not been able to respond on account of travelling and will again be 'on the road' for a week. Send me an e-mail at peter@boisen.se and I will asap provide you with requested references.

Bears maximum repetition. Loudly and clearly.

However, I'd judge the whole concept as a VERY long way from a business plan.

I don't see the hydrogen economy that others do simply because the infrastructure replacement costs to use hydrogen are enourmous. They may not be insurmountable obstacles but humand beings always take the easier route. The easier route in this case is to make hydrogen and convert it to something elese that we DO have the infrastructure for. We already have the infrastructure for methane so it makes very good sense to produce hydrogen from water and then convert the hydrogen to methane using a carbon source.

I suspect that the economics of that will heavily favour production from a nuclear power source rather than remote generation sites in the Hudson Strait and similar places around the world. Remote hydroelectric sites may work but if it is too expensive to build a power line to it for a high value commodity like electricicy then I suspect it will be equally uneconomic to build a natural gas pipeline there too to take the produced methane out.

Nuclear plants on the other hand can be built anywhere. Many are already adjacent to natural gas pipelines and it is easy to tap into the existing infrastructure and costs are always lower when the production centre is close to the point of use.

I favour the following scenario. Build multiple new power plants at existing sites. Use the excess nuclear capacity (over and above base load) to produce hydrogen from water (all plants have existing water treatment plants to provide the demin water necessary). Convert the hydrogen into methane and pump the gas into the existing gas infrastructure. A source of Carbon is required and this can come from any source that is conveniently available...maybe even CO2 out of the air although I don't know yet if that is at all feasible eco0nomically.

There is no new technology required. We know how to build and operate large nuclear plants. We know how to build and operate the water treatment plants necessary to provide demin water and we know how to build and operate electrolysers.

Hydrogen also seems a natural "fit" to wind and solar power although I don't think those sources are powerful enough to meet the needs. They could certainly make a contribution though.

Once methane is produced just about any hydrocarbon can be synthesized from it and none of that needs to occur at the nuclear site. Access to a methane gas supply is all that is required.

Joseph is correct in that a business plan is required and it may not be economic at current hydrocarbon availability and prices. But that will not last forever. we might as well start planning now rather than have to do it in a panic when it is too late.

Malcolm