Long Term Implications of Lignocellulosic Biomass Conversion: The NPT Fractionation Process

Introduction:

Lignocellulosic biomass has long been recognized as the best (if not the only) renewable source of future liquid transport fuel. It is also the best (and probably only) potential source of renewable organic chemicals. In other words it is a renewable petroleum substitute.
However, in focusing on an immediate need, the longer term implications of large scale utilization have been neglected.
This preliminary note suggests some implications that NPT is evaluating.

Scale:

Existing biomass residues, from published sources, suggest that more than 100 MBPDOE could be produced. But, because biomass production in many areas is well below potential yields and densities, there is considerable scope for an increase in this capacity. However, this would require utilization of a large fraction of the available biomass, so that most estimates of potential are below 100 MBPDOE.
But these figures exclude marine and fresh water algae, which, whilst not containing lignin, do contain significant polysaccharides (and protein). The potential for conversion of this biomass would permit a conservative estimate for total biomass of well in excess of 100 MBPDOE (perhaps more than 200-300). This would be comfortably in excess of all forecast demands.
The timescale for any such development is likely to be at least 40 years, assuming a suitable process is demonstrated within 3-5 years (which is considered realistic). For that development period, biomass conversion would co-exist with and supplement or complement (rather than compete with) mineral petroleum, gas and coal resources.
The cost of the biomass derived petroleum should not exceed $70-80 per bbl, and should be $40-60 per bbl, even paying full fuel values for the feedstocks (current world coal prices). This would necessitate larger scale bio-refineries than generally considered, but undoubtedly feasible – ie. oil industry scale.

Implications for Food:

Obviously no human foodstuffs are required as feedstocks. Similarly, animal feeds can be largely excluded, or replaced.
There is no requirement for conversion of existing arable land from food production to fuel biomass production.
There is no requirement for conversion of native (wild) forest or encroachment on wildlife preserves.
There is, however, a requirement for a review of global agricultural practices – both at subsistence level and in intensive Western agriculture. But, the additional income from sale of residues (which may be more valuable than the associated crops in some cases), will both cover costs and provide incentives. Monoculture, with a few exceptions, would be discouraged, since year round supply of feedstock is required.
Biomass conversion utilizes only the hydrocarbon content (deriving from atmospheric CO2 and water), returning minerals and trace elements to the agriculture and all proteins for human or animal foodstuffs.
This, together with increased income, could encourage a significant increase in crop yields (up to 200-300%) that would be an enormous uplift for subsistence based areas economies.
Together with protein, fats and carbohydrates generated as by-products or co-products of biomass conversion, global food production could be increased by 200-300% overall.

Implications for Water:

Biomass production requires large volumes of water – but it does not have to be of potable quality. In fact biomass can be employed to treat waste waters and provide potable water. A more extensive utilization of this process can generate significant quantities of potable water, which would be especially valuable in arid regions or areas with poor infrastructure.
But, a more interesting potential source of potable water from biomass is through the use of transpiration. Biomass utilises only a fraction of the water fed to it – a large part evaporates from the leaves. This gives rise to the phenomenon of condensation in greenhouses, but has also been used for small scale survival kits. Using solar powered refrigeration and large scale, low cost (renewable) plastic tunnels, significant potable water production is feasible. This can also be used to recycle water to the plant, thereby reducing overall water loads.
Improved cultivation techniques can also increase water retention, and thus utilization, in the soil.
However, there are other implications of large scale biomass conversion, such as regional effects due to changes in biomass type and density, which may affect the albedo and regional weather patterns. This may be of particular interest in semi-arid regions where cultivation of native non-food plants for biomass may be encouraged.
In addition, the revenues from biomass residues should permit more efficient, and extensive, irrigation techniques, without a requirement for additional water – indeed, a significant reduction in water per unit area can be obtained.
Finally, most current biomass conversion processes use large quantities of external water. However, it is possible to employ fresh biomass, without any additional water, and generate potable water within the conversion process.
Implications for Atmospheric CO2:
Much of the biomass residues, from agriculture and forestry in particular, are left to decompose on or in the soil. This decomposition is, at least partially, anaerobic and generates large quantities of methane and nitrogen oxides, which are potent greenhouse gases.
Whilst some biomass is required to maintain soil carbon levels, it is the excess which is employed for biomass conversion. This conversion either locks the carbon away for some period, in some cases a considerable period (as with some renewable plastics), or leads to oxidation back to CO2. But methane alone has some thirty times the impact of CO2, so that conversion can directly dramatically reduce the equivalent greenhouse impact.
In addition, the potential increase in biomass production will also require larger quantities of CO2 to be removed from the atmosphere. Whilst some of this is cycled back, some again is locked away as soil carbon or chemicals with an extensive lifespan.
The use of algae increases dramatically the potential for CO2 removal.
Ultimately, with total replacement of mineral oil and large scale substitution (if not total replacement) of gas and coal, the potential impact on global CO2 levels will be significant.
Implications for Subsistence Agriculture:
At present much of the Third World has a per capita income of less than $1,000/a. and is largely agriculturally based. With the revenues from residues, these communities can invest in better equipment, fertilizers, seeds, etc. to increase their crop production (and thus primary income). But this also generally leads to an increase in biomass residues – and yet more income. A virtuous cycle is created which could be expected to increase per capita incomes, over 40 years, to ca. $5,000-10,000/a.
But there are further implications:
• Migration from rural to urban communities should be reversed.
• Production of fuels and chemicals will increase industrialization potential in these areas.
• Dependence on external aid can be reduced.
• Unemployment can be reduced.

The NPT Process:

Up to this point, the analysis has not required a specific process, but is, in principal, generic for any lignocellulosic process.
However, there are clear implications as to the characteristics of any process that is going to succeed.
These include:
• Scale: it must be capable of oil industry scale ie. 50,000-500,000 BPDOE
• Product Slate: it must produce both transport fuels and a range of platform chemicals
• Cost: both capital and operating costs must be of the order of the oil industry
• Feedstocks: it must utilize the full range of lignocellulosic and algal feedstocks
• Water: it should not require significant external water.
These characteristics imply a thermochemical fractionation process (this can be more clearly explained in other papers).
The NPT process was designed specifically to meet all these characteristics and avoid the weaknesses of all existing processes.
It was also assembled from proven component technologies and is now ready for demonstration at semi-commercial scale.

Peter H. North June 2014

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