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Proof-of-principle of cost-effective methane cracking technology for H2 production without CO2; 50% cleaner than SMR, comparable to electrolysis

Researchers of the Institute for Advanced Sustainability Studies (IASS) in Potsdam and the Karlsruhe Institute of Technology (KIT) have achieved the proof-of-principle for a innovative technique to extract hydrogen (H2) from methane (CH4) without the formation of CO2 as a byproduct.

At this stage, cost estimates are uncertain, since methane cracking is not yet a fully mature technology. However, preliminary calculations show that it could achieve costs of €1.9 to €3.3 per kilogram of hydrogen at German natural gas prices—without taking the market value of the solid black carbon byproduct of the process into consideration.

Most of the world’s hydrogen production is currently based on conventional technologies such as steam methane forming (SMR), which also uses natural gas as feedstock but releases significant amounts of carbon dioxide in the process. CO2 emissions from the ammonia industry alone amount to approximately 200 million tons per year—by comparison, Germany generates around 800 million tons of carbon dioxide per year. By contrast, methane cracking—the separation of methane’s hydrogen and carbon molecular components—occurs at high temperatures (750°C and above) but does not release any harmful emissions.

The main by-product of methane cracking—solid black carbon—is also an increasingly important industrial commodity. It is already widely employed in the production of steel, carbon fibres and many carbon-based structural materials. The black carbon derived from the novel cracking process is of high quality and is a particularly pure powder. Its value as a marketable product therefore enhances the economic viability of methane cracking. Alternatively, black carbon can be stored away, using procedures that are much simpler, safer and cheaper than the storing of carbon dioxide.

Methane cracking itself is not an entirely new idea: in the last two decades, many experiments in different institutions have been carried out that have proven its technical feasibility. But these past attempts were limited by issues such as carbon clogging and low conversion rates.

The IASS and KIT team built an experimental reactor that could demonstrate the potential of methane cracking and overcome previous obstacles. The starting point is a novel reactor design, as proposed by Nobel Laureate and former IASS Scientific Director Professor Carlo Rubbia and that is based on liquid metal technology.

Fine methane bubbles are injected at the bottom of a column filled with molten tin. The cracking reaction happens when these bubbles rise to the surface of the liquid metal. Carbon separates on the surface of the bubbles and is deposited as a powder at the top end of the reactor when they disintegrate.

This idea was put to the test during a series of experimental campaigns that ran from late 2012 to the spring of 2015 in KIT’s KALLA (KArlsruhe Liquid Metal LAboratory). Researchers were able to evaluate different parameters and options, such as temperature, construction materials and residence time. The final design is a 1.2-meter-high device made of a combination of quartz and stainless steel, which uses both pure tin and a packed bed structure consisting of pieces of quartz.

In the most recent experiments in April 2015, our reactor operated without interruptions for two weeks, producing hydrogen with a 78% conversion rate at temperatures of 1200°C. In particular the continuous operation is a decisive component of the kind of reliability that would be needed for an industrial-scale reactor.

—Professor Thomas Wetzel, head of the KALLA laboratory at KIT

The innovative reactor is resistant to corrosion, and clogging is avoided because the microgranular carbon powder produced can be easily separated. The reactor thus satisfies the technical preconditions that would be needed for the continuous operation of an industrial-scale reactor.

While these remain laboratory-scale experiments, researchers can extrapolate from them to gain insights into how methane cracking could be integrated into the energy system and, more specifically, what its contribution to sustainability could be. To this end, the IASS is collaborating with RWTH Aachen University to conduct a life cycle assessment (LCA) of a hypothetical commercial methane cracking device based on a scaling-up of our prototype.

The LCA assumes that some of the produced hydrogen is used to generate the required process heat. The compared hydrogen production technologies were steam methane reforming (SMR) and water electrolysis coupled with renewable electricity. With respect to emissions of carbon dioxide equivalent per unit of hydrogen, the LCA showed that methane cracking is comparable to water electrolysis and more than 50% cleaner than SMR.

Our experimental results as well as the environmental and economic assessments all point to methane cracking as a clear candidate option in our portfolio of measures to transform the energy system. This could be a gap-bridging technology, making it possible to tap into the energy potential of natural gas while safeguarding the climate and facilitating the integration of a clean energy carrier like hydrogen.

—Professor Carlo Rubbia

In the next phase of the process, the IASS and KIT will focus on optimising some aspects of the reactor design, such as the carbon removal process, and progressively scaling it up to accommodate higher flow rates.

Comments

HarveyD

Using harmful ocean bed methane to produce lower cost H2 without CO2, for future FCEVs, could be interesting?

Arnold

Harvey
It would be nice if we could ignore some of the science you are referring to. "final days" - to coin a phrase.

Of course it would be better if it were to stay where it is in it's proper place in the natural carbon cycle.
We would be very ignorant to believe we can do work on the scale of natural CCS.

Loosely held hydrocarbons I.E. soil sequestered , leaky coal and associated gases (most CSG is held a bit tighter and deeper), gassy mines, abandoned CSG wells etc peatlands,forests, tundra's etc are a major headache and will be the canary in the mine.

It will be a clear message to make shure you have a toothbrush and one way ticket.

Planet earth Earth will no longer support many life forms we can recognise.

Harvey, I see this will be the gas chamber scenario, the only question is not whether it will be peaceful or will people take these matters into their own hands and turn on themselves blame followed by revenge, but to what extent.

I think the short answer is it's an academic problem only to be resolved by the next intelligent lifeform.

Eternal optimists as you and I will (rightly) never change thats not an option but we do need to look reality right in the face.




Davemart

Solid black carbon is very different to leaky gases.
As a first approximation it should perhaps be compared to very high grade coals like anthracite, which have successfully sequestered carbon for tens on millions of years, although it is of course purer than even them,

Davemart

'However, preliminary calculations show that it could achieve costs of €1.9 to €3.3 per kilogram of hydrogen at German natural gas prices'

If that works out it is pretty much:
'Game over'

as what the heck is the cost at US natural gas prices which are far lower than those in Germany?

It is clear that there are ginormous amounts of methane available, from both methane hydrates and coal gasification, the problem has been how to extract and use it without having a fried planet.

Alain

... or any biomethane from anaerobic digesters.
The pure carbon black is probably more valuable than the energy that would be produced by burning it.

Engineer-Poet

What DaveMart said.

I started writing a story about a desperate attempt to convert methane clathrates to less-potent GHGs before they escaped by themselves.  This would fit even better.  If methane was converted to what's essentially carbon black it would be thermally and chemically stable on a scale of hundreds of millions of years.

Davemart

Yo,EP!

I hate it when my comments criticising some who don't really understand the issues about what they see as the flaws in hydrogen and fuel cells based on incomprehension of the real energy flows and carbon balance of the energy alternatives get confounded with my very real respect for 'proper' critics such as yourself.

On subject, I was somewhat disconcerted by the staggering quantities, planet frying quantities, available by low grade coal gasification and methane hydrates.

UCG I think can likely be done in situ with minimal gas releases, as they are to trial in the UK.

Methane hydrate gas releases are still to be proven, and could prove problematic.

I would value your initial comments on these issues, and also the possible use of direct carbon fuel cells for the 'waste', although of course that has total life cycle issues.

SJC

"production of steel, carbon fibers and many carbon-based structural materials.."

They use it for lithium ion battery anodes.

HarveyD

Regardless of adverse believers, ocean bed and tundra methane will be released and/or harvested (or both) before the end of the current century.

It would be better for mankind that it be harvested and used or converted (to H2), stored and used, instead of letting it escape into the atmosphere as a very powerful GHG.

This is no science fiction but our existence may very well depend on how our grand children and their off springs directly or indirectly deal with it.

Engineer-Poet

Harvey didn't mention that tundra methane is a real thing already.

Arnold

Davemart,

"UCG I think can likely be done in situ with minimal gas releases, as they are to trial in the UK."

I had the same thought 10- 15 years ago.

I was advised by those who knew it's history it to be filthy old Fischer–Tropsch process.

Bureaucrats knew better and the experiment proceeded.

The outfit were dodgy mining entrepreneurs and smelt rotten.
The comments I was making were borderline defamitary sufficient to need legal consideration.

Our (.au) Link energy trialled ucg in Queensland.
It was old soviet tech and already discredited. But they let happen with disastrous out of control groundwater outcomes.
UCG is now banned in Queensland (+A.U?) never to be revisited. The mess remains.

I can say for me that gasification door tech is well and truly shut. They are total scammers thieves greedy and very wealthy.

I suggest extreme skepticism on the subject.

Marketers and company sprukers show us the bells and whistles take the money and leave the mess.

Davemart

Arnold:

My mentioning a technology does not necessarily indicate support for it, and certainly not unqualified support.

Quite often I am trying to peer into the crystal ball and see what is likely to be developed, regardless of whether I approve of it.

In my view unless very low cost alternatives are developed in one way or another the gigantic reserves of low quality coal will be exploited, and if we are going to do that I would prefer it with some form of carbon capture however imperfect it might be.

Fortunately hydrogen production either direct from solar or via electrolysis seems likely to very cost effective, and capable of competing with the costs given here for methane.

Davemart

I should add that the pathway in the article would also greatly reduce the emissions associated with BEVs.

It would seem a bit silly not to use it in fuel cell cars directly in many or even most cases, but its a benefit to both.

ICE is the only loser, if this works.

Davemart

In much of the world including the US solar would be a great candidate to replace the hydrogen used as process heat, so increasing the usable output.

It works because there is no alteration of energy states is needed, and solar thermal stays as thermal, which is more efficient than pv.

Since the hydrogen is stored anyway then the intermittent nature of solar is more acceptable, although it may not be desirable to ramp the process up and down too much and an intermediate such as molten salt storage might be desirable to increase the hours of output.

Engineer-Poet

The heat of formation of methane is −74.8 kJ/mol.  This is roughly 5.2 kWh/kg(H2), which has to be input at upwards of 700°C to crack it back to H2 and carbon.  You're not going to get this with solar thermal except in the most optimal haze-free conditions.

There are two ways to do this:

  1. Electric power converted directly to heat (induction heating works nicely).  At perhaps 40-70¢ per kg(H2), this is actually affordable (doubly so if it can be managed as a dump load).
  2. High-temperature nuclear.

gryf

E-P,

Interesting that your point of using "High-temperature Nuclear". When I first read about this process in 2013, Dr. Carlo Rubbia (Director of IASS) pointed out that the original research was based on work by Dr. Manuela Serban's team at Argonne National Lab which proposed utilizing the heat generated in the Gen IV nuclear reactors.

Also, you noted about direct electric induction heating which is how carbon fibers are produced by the SGL Automotive Carbon Fibers (a joint venture between the BMW Group and SGL Group) that is producing low cost fiber at Moses Lake, WA using low cost hydroelectric power.

It would be great if we could use hydroelectric power to produce both hydrogen and carbon fiber.

gryf

Correction: low cost electricity at Moses Lake, WA @ 2.8 cents/kwH.

Engineer-Poet

I'm not sure hydroelectric power would do much.  It doesn't travel well (otherwise Ireland and the UK would be buying power from Iceland) and neither do hydrogen or methane for that matter.  Aluminum works much better as a product for surplus/stranded hydropower.

Hmmm, perhaps cracking bio-gas to H2 and using it to make e.g. urea nitrate, then using the urea nitrate as a binder for the carbon as a combined fertilizer and carbon-sequestering soil amendment?

HarveyD

Yes, tundra methane release has started in Northern Russia and Alaska and will probably soon expand to Northern Canada and other places.

Can we learn to use it quickly enough?

It may be the right time to start measuring the total effects on the climate. How will it contribute to global warming in the next decades?

It seems that our e-energy consumption, for our 100% electric home in 2015, will be the lowest on records. Will the on-going trend keep up for 2016? We had record mild temperatures for many months in 2015.

SJC

1.2-meter-high device

Maybe they could make a point of use device. With less than $1 worth of natural gas at wholesale rates you could make some hydrogen and sell the carbon.

$2.47 per million BTUs

Davemart

EP:

Some types of concentrated solar have high enough temperatures.

You were probably thinking of parabolic troughs, which don't.

However:

'A solar power tower consists of an array of dual-axis tracking reflectors (heliostats) that concentrate sunlight on a central receiver atop a tower; the receiver contains a fluid deposit, which can consist of sea water. The working fluid in the receiver is heated to 500–1000 °C (773–1,273 K (932–1,832 °F)) and then used as a heat source for a power generation or energy storage system.[20]'

https://en.wikipedia.org/wiki/Concentrated_solar_power

Just above that, Dish Sterling are also referenced, which verge on adequate temperatures, up to 700C.

gryf

FYI,
The Langeled Pipeline is an underwater pipeline transporting Norwegian natural gas to the United Kingdom. Norway has significant Hydroelectric resources.

Engineer-Poet

Yes, but you need very clear skies for any of those things to reach your minimum required temperature.  Deserts, essentially.  And you can't use the Ivanpah cheat of burning natural gas when a cloud rolls by or your CO2 emissions go south very rapidly.  Oh, and you need to be able to endure daily thermal cycling... and you have to ship your natural gas TO the desert, then ship the H2 back again.

People pushing solar-thermal for this scheme haven't thought it through.

gryf

There are quite a few projects planned to connect the electric grid in Norway and Iceland to the UK, e.g. the NSN interconnector to connect Norway and British markets
(http://www.statnett.no/en/Projects/Cable-to-the-UK/). Also http://www.power-technology.com/features/featureinterconnectors-the-key-to-bringing-more-renewables-to-the-uk-grid-4466121/.

Engineer-Poet

But not even a Norway interconnect is done yet (a Norway gas pipeline is in operation IIRC).  If it's that hard to connect Norway with the British isles, the feasibility of connecting Germany with Australia and Chile to provide overnight heat and electricity in winter has to be dismissed as total fantasy... but that is practically what some of these claims amount to.  They cannot withstand any degree of scrutiny.

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