Materials cycle   (NOT YET FULLY EDITED)

An important aspect of hydrogen production is the introduction of a closed cycle of minerals. The gasification of biomass offers the best conditions. In order to close the mineral cycle, minerals from the ash must be returned to the fields in a form usable by plants.

Mineral cycle

Ash from fluid bed gasification can easily be taken up by arable land. Innovative biomass gasification has two ash fraction byproducts. Ash from the cyclone can in principle be scattered directly on fields, and makes up 95% of the ash. The fine filter dust contains poisonous heavy metals, and must be disposed of, processed or used by the building sector. This separation of ash is suitable for detoxification of arable land. Heavy metals introduced from traditional mineral (synthetic) fertilizers or sewage sludge are removed from fields in this way. This method is also suitable for freeing contaminated soil from long term radioactive substances such as Cesium (¹³⁷ Cs) and Strontium (⁹⁰ Sr) released in the disasters of Chernobyl and Fukushima. Nitrogen compounds are largely destroyed by gasification. Nitrogen fertilizers can however be harvested from the the hydrogen produced. These are bio-nitrogen fertilizers, which are approved for use on organic farms.

The same amount of CO2 taken up by the plants can be released into the atmosphere. Gasification of biomass is therefore climate-neutral. There is also the option to store this CO2 underground, for example in spent oil and gas fields or deep aquifers (water-bearing sand layer).  The plans of the energy economy have meant that the population is strictly against this type of CO2 storage, as it has been planned for coal fired power stations, and they are generally no longer accepted. People are prejudiced against the option of CO2 storage (CCS) - maybe it cannot be used for years to come.

There is however a further option to remove CO2 from the air. The innovative gasification plant can be regulated such that a small portion of the carbon formed is transferred from the plant and ploughed into arable land together with the ash. The effect this has is explained in the following paragraph.

Biochar

The graph below shows the carbon bound by planting a forest of pine and beech. In comparison with that the long-term storage of carbon in arable land is shown. The example used here is for a dry mass harvest of 30 t/ha where around 10% of the carbon is not gasified, but introduced into arable land. If the arable land continues to be used for agriculture, then just as much carbon is bound in these fields as would be bound by planting a forest. The biomass coke is a better solution though, because this carbon may remain in the soil for over a thousand years. Storing carbon in a forest however is reversed after 50-150 years from energetic use of the wood.

The introduction of biomass coke is well known in the advanced civilizations of the Amazon basin. It is from there that the term biochar comes for this coke enriched soil. The enrichment depends on whether this biomass coke is available in a porous form. These types of particles are easily produced from thermo-chemical gasification. The porosity is then comparable with activated charcoal, which is made by gasification of wood. Carbon particles from hydrothermal gasification (HTC) are not porous, and therefore only have the effect of black sand.