The ultimate renewable (sustainable) 'geo-energy' source is, obviously, geothermal heat, which is continuously produced radiogenically within the Earth. In marine environments this potential energy source is manifested as hydrothermal vents, associated with emanating hot water, boiling water, or supercritical water (at depths greater than 2900 m, or 300 bars). But, is it equally obvious that the combustible 'biogenic' gases, which are continuously being produced in marine settings may be classified as renewable (sustainable) energy sources?
Dear Martin Hovland,
In my opinion, this question claims great attention and a many-sided study but not hasty answer. It is possible that the answer should be coordinated with the problem of the Solar System formation and origination of hydrocarbons in the vicinities of different celestial objects including the Earth and with the problem of the possible significance of the underground gaseous and liquid substances as the grease that is capable of dampening the fluctuations of the continental and intra-continental platforms.
The fact of the matter is that, according to our works, the underseabed and underground biota originated (and originates) from the underground methane (maybe also, etane and propane), nitrate ions and posphate ions rather than the underground methane was produced by biota. I address you to our works available (in particular) at the RG site, and, I hope, you will find a rather great number of the proofs for our concept.
At least, the major portion of the underground hydrocarbons is of abiogenic origin.
Yes, indeed, Victor Ostrovskii, - thanks for the reply.
This is why I posed the question in the first place. It seems that some of the 'Biogenic gas' we see coming out of marine sediments, is not biogenic at all, it is pahaps better classified as 'Archaeic gas', e.g., gas which is composed of basic molecules accreted from Space during the planet formation stage of our Earth. These molecules have since then been combined with all types of other material in the deep sub-surface, and are slowly degassing from the mantle and through the crust. Some of the gas is undoubtedly formed in the very important serpentinization process, whereby peridotite reacts with water. Large amounts of hydrogen are the result, which then combines with CO and CO2 to form methane and higher hydrocarbons, as is currently being discussed by many researchers, especially on the deepcarbon.net website. Although, the main definition of Biogenic methane is the stable isotope delC13-value, which is supposed to be between -60 and -120, for the gas to be called Biogenic. However, Gretchen Früh Green and others have published papers discussing this definition to be too simplistic.
Dead Martin,
OK!
I am with you.
Like you, I state together with Dr. Elena Kadyshevich that the underground hydrocarbons are, at least mainly, of the Pre-Archaean and of (CO2+H2) origin. The problem of isotopic anomalies is also considered in our papers. Our Life Origination Hydrate Theory (LOH-Theory) uses this statement, I wrote a special paper (in Russian) which is titled in English "Hypothesis of the natural gas abiotic origin in the context of living matter origination”, and a number of our papers, which are dedicated to the problems of living matter origination and of Solar System formation, consider the problem of CH4 origination in more or less details. Almost all our papers are available at the RG site. I think that the recent discoveries of hydrocarbons around different cold celestial bodies count strongly in favor of origination of hydrocarbons over the Solar System with no help from living issues; there are a number of other arguments for this statement.
Thanks, Victor for clarification.
This actually means that the gas we call 'Biotic' (dry) gas, is mostly Archaic, e.g., it is neither considered to be of 'fossil' origin, but belongs to a vast, and in all senses 'renewable' (more-or-less infinite) resource. If we follow this line of thought further, it also probably means that the greatest hydrocarbon resource on Earth, the oceanic gas hydrates, probably are storing this type of gas also, as it moves upwards along plate boundaries, where it forms by serpentinization and migrates to surface, where it is temporarily trapped in combination with water molecules as gas hydrates. Therefore gas hydrates can also be regarded as a renewable and non-fossile combustible gas resource.
Dear Martin,
Yes!
I think, you are right.
But there is the problem of relative rates of the gas (oil)-output and the gas (oil) diffusion from the Earth’s depths.
I am not expert in the geodynamics but I think from the common considerations that, at the equator, the mantle is thinner and warmer than it is near the poles and that the underground equatorial diffusion is more intensive than that near the poles. May be, the data obtained on the basis of the Kola-Peninsula 11-km hole are capable of giving quantitative data about the rates of diffusion of fluids at different depths.
Sincerely.
Dear Martin,
To be objective, I should point one more factor influencing the renovation of the gas deposits in the form of gas-hydrates. The fact is that the processes of formation/destruction of methane hydrates are governed by the thermodynamics and depend on the temperature and gas methane pressure. The gas-extraction is capable of decreasing the methane pressure, destruction of the water structure of hydrates, and liquation of the structured water. The liquation of water can lead to its moving, and, thus, the conditions for formation of new methane hydrate can be changed. In addition, the occurrence of the unclosed boreholes can influence the methane-pressure regime within the methane -hydrate base layers.
In addition, I wrote you that the underground fluids are capable of playing the role of grease between the continental platforms and their intra-continental parts and, thus, of damping their oscillations and movements. This effect, maybe, is capable of influencing the earthquakes.
Therefore, I think that the answer to your question is unobvious and requires an attentive consideration, as I had written in my first answer to your question.
Thanks, H. Gary Greene, I agree, and that means we should harvest it and use it, just like we harvest the wind with windmills. I have some New ideas on how to collect the seeping gas, both from non-hydrate prone and hydrate-prone regions. This discussion, I will start next week. Thanks also to Victor's interesting input on this.
Great. Nice talking to you again Martin. You should plan on presenting your ideas at the GeoHab workshop next May in Brazil.
Cheers, Gary
Dear All,
The underseabed procaryotes should consume methane for their mitosis and DNA replication but not produce it. The source materials for their reproduction are methane, and nitrate- and phosphate-ions. No other source of carbon is in the vicinities of the underseabed biota localizations. For any biota, C, O, P, H, and N are necessary. The chemical laws are very stubborn.
Dear All,
My opinion on the problem of recoverability of the gas and oil deposits is that it is quite possible that they are renewable but it could be through the (CO2 + H2) reaction (CO2 could be, for example, from decomposition of carbonates) or through the CH4 diffusion from the deep layers but not through CH4 formation by prokaryotes.
If the substrates for the reactions that lead to the formations of CH4 and CH3-CH3 are renewable, then these two gases can be safely considered a renewable energy source. In my opinion, the key here is to have a good understanding on how these gases are produced in the marine environment, before jumping into conclusions bases on others opinions.
To my opinion, first one might like to answer the following question: Is the CO2 that will be produced at a rate given by the burning of these marine biogenic gasses, consumed at the same rate as these biogenic gasses are produced? If the answer is yes, then you have renewable energy. If the answer is no, then you are burning fossil fuels, which is not sustainable as long as you cannot mineralize CO2 at the same rate as at which it is produced.
Some work is going world wide to explore methane gas hydrate. The research has been also been initiated to trace the hydrates in India which seems to provide more gases in condensed form.
However, since you have of mixture of 'biogenic' gasses, you might have a case of relative sustainability, even if you are burning fossil fuels on faster rate than your carbon-dioxide mineralization.
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