by backstop » Sun 19 Sep 2004, 00:28:23
It seems to me unlikely that devil has any further clarification to offer here as he/she is apparently unable to comprehend the dynamics of the annual through-put and accumulation of carbon, hydrogen and other materials which we call forest, and, further, apparently has no knowledge of the ancient and increasingly popular silviculture known as Coppice.
The critique, such as it was, fails in its first line :
“deciduous forest requires a minimum of 30 years to recycle.”
In several decades of interest in forestry the notion of forest’s recycling of CO2 has been ubiquitous in books and research papers, but I’ve not seen discussion of a period in which a forest itself ‘recycles.’ ‘Regenerates’ yes, from the stump (or ‘stool’) of a coppiced tree, from replanting (mostly for timber) or naturally, even from bare ground; but not ‘recycles.’ This term to my knowledge has no accepted meaning in the study of silviculture.
There are very large areas of forest which take a minimum of around 35 years to ‘regenerate’ naturally and provide sustainability, but this occurs with the human inhabitants’ primary aim being subsistence cultivation under the much-maligned “Slash & Burn” system. This has been practiced for millennia (aeons ?) by indigenous peoples in the Amazon, Indo-China and elsewhere. It is now being recognized by forest ecologists that much of those forests are the long-term result of plots being cleared, cultivated and then abandoned to regenerate naturally for at least 35 years. This approach yields wood for building poles, for artefacts and for fires, but its primary goal is cultivation, i.e. when crop-yields start to decline the community migrates to a new clearing. If this is what devil was referring to it was wholly irrelevant to discussion of a silviculture that yields feedstock for energy.
Coppice is evidently an ancient form of forestry which survives (on a greatly reduced scale) in various forms in various parts of the world, in which deciduous trees are felled and then given from 3 to around 35 years (according to factors including species and local usage) to regenerate from the stump or ‘stool’ before being felled again. To give it some background I'd list the following.
At Mere in Somerset, UK, a bronze age village has been uncovered where a causeway of coppice-wood faggots was laid in the marsh out to a settlement over the lake, with the individual felling tools used still being identifiable by their often notched blades scribing the poles’ cut ends.
In the wetland of the Fens in Norfolk, UK, the remains of a celtic-era causeway have been excavated, running some hundreds of yards from a settlement on raised land through marshes to an open waterway. The structure was of a large number of long straight oak piles driven into marsh in a double row, and was presumably surmounted by framing and a walkway. There were several generations of piles, with the age of the great majority being between 16 and 18 years old when felled. Just as at Mere, the piles’ very straightness declares that they grew as coppice. (Try looking round in a natural (unmanaged) oak forest for hundreds of stems that are straight and all of an age).
The oldest surviving coppice ‘stools’ that I know of are at Ashford in Kent, UK, and have been dated as having been planted during the Roman occupation. These have survived so long only because they’ve been regularly cut ever since those days.
Near the village of Backbeck in Cumbria, UK, there are the massive ruins of an industrial-scale iron foundry from the early eighteenth century which is authoritatively claimed to have been, in its day, the largest industrial building in the world. The iron ore was brought in by ship, primarily from Sweden, for smelting on charcoal made from extensive coppice woodlands across the mountainous region of the lake district. As such, coppice woodland for energy plainly had a direct role in the emergence of industrialism, before being displaced by the peasantry having to work down the mines for coal.
Currently the UK has rather less than 100,000 ha.s of coppice, of which much has been allowed to go derelict (i.e. hasn’t been cut for more than 35 years) and would need harvesting and replanting to get it back into production. Yet a significant area is still worked (until recently much of the yield was used for paper pulp) and the restoration of derelict coppice is slowly gathering pace. By comparison France has a far higher proportion of its far larger land area under coppice, but has faced the same problems of competition with farming (particularly sheep-farming) of loss of traditional markets, and of the absence, until now, of sufficient new ones.
The yield of 5 Tonnes of Dry Wood /hectare /year [5 TDWd /ha /yr] that was in my first post’s example represents a quite good yield from coppice under the temperate forestry conditions in the UK. In passing I would note that the significance of altitude on growth is so central to forest and all other ecosystems that the potential here is very obviously not of reforesting all uplands, but, as suggested my first post, of reforesting parts of the very large areas of the uplands within the UK and elsewhere where it would be appropriate.
A yield of 5TsDWd /ha /yr from temperate coppice is substantially lower that that from “Short Rotation Coppice,” (SRC) which has been rapidly increasing its acreage in various countries as a promising ‘renewable’ energy, mostly in the form of CHP. During its first set of trees, its yields are higher (at up to 7.0TsDWd /ha /yr) as it uses relatively flat arable land for chemically fertilized and biocided monocultures (mostly of poplar or willow in Europe and North America). After around twenty years of being mowed at 3-year intervals (i.e. one third of area per year), the trees are expected (by SRC’s proponents) to be exhausted and to need ploughing up and replanting, thus releasing substantial volumes of CO2 from the soil.
In using a more valuable land type than traditional coppice needs, this modern regime attempts to get higher output per unit of input from high inputs, in the long-debunked economics of intensification which, as usual, fails miserably most tests of sustainability. Using lower-value land to get a modest but sustainable yield per unit of input from lower inputs, by means of a fairly traditional coppice regime, is patently the sane way to go.
At the core of devil’s misrepresentation of this option lies an apparent incomprehension of the feedstock’s accumulation in each hectare in each year, giving a standing stock of hectare-years’ growth. This is best illustrated in some examples, with the first being on a small scale.
Suppose:
12 ha.s of coppice are managed in twelve plots of 1 ha. each on a 12 year cycle.
Each plot gains the Equivalent of 5 TsDWd /year. [5 TsDWdEq /yr]
(This is around 7.8 tonnes of Green Wood /ha /yr [7.8 TsGWd /ha /yr]).
Each year the plots gain overall 12 ha.s x 5Ts = 60TsDWdEq /yr.
One plot is cut each year so in Year 13 the first plot is ready to cut again.
This holds 12 years’ growth x 1.0 ha = 12 x 5 = 60TsDWd Equivalent.
Thus the annual output from the fraction of the total area that is harvested equals the annual overall gain.
There is a somewhat more subtle regime of quite long precedence (at least mediaeval) known as ‘Coppice with Standards,’ which offers significant advantages over Coppice alone, particularly if the ‘Standards’ (trees grown to maturity) are planted as shelter belts to assist coppice growth-rates while also yielding thinnings to the feedstock output. However, to keep this post simple that option must be left to another post, should people be interested.
To scale up the example above, the area of 375,000 ha.s gaining 5TsDWDEq /ha /yr is repeated from the first post as being needed at 55% material conversion to supply 1.03MT methanol, in order to replace 1.0MT petrol.
Suppose:
375,000 ha.s are managed on a 12-year cycle and thus (notionally) in twelve plots of 31,250 ha.s each.
Each plot gains 31,250 ha.s x 5 TsDWdEq /yr = 156,250 TsDWdEq /yr
Each year the 12 plots gain overall 375,000 ha.s x 5 TsDWdEq = 1,875,000 TsDWdEq /yr.
One plot is cut each year so at Year 13 the first plot is ready to cut again.
This now holds 12 years’ growth x 31,250 ha = 12 x 5 x 31,250 = Annual yield of 1,875,000 TsDWdEq.
1.875 MTsDWdEq with a 55% material conversion efficiency, yields 1.03125 MT methanol. Annually.
Thus 375,000 ha.s of coppice gaining 5 TsDWdEq /ha /yr, yields a sustainable annual supply of feedstock for 1.03 MT of methanol (for use in FC vehicles) to replace 1.0MT of petrol (now used in ICE vehicles).
BTW the processing plant or station is of course stationary within the area of coppice woodland. I’ve seen no mention anywhere (apart from devil’s post) of the idea of a mobile methanol plant, and, short of some unforeseen breakthrough in miniaturizing plant for wood gasification and its conversion to methanol, and I see no prospect of such for a host of reasons.
To sum up, 0.375 Mha.s at good temperate coppice yields will supply feedstock for enough methanol to replace about 1.0MT of petrol annually. This equates to 0.93 acres of the same supplying feedstock for enough methanol to replace about 1.0T of petrol annually. I.e. about 1.08 tonnes of petrol-equivalent is produced per acre of coppice. These figures are of course predicated on a degree of shift from petrol ICE vehicles to methanol Fuel-Cell Electric vehicles.
I can’t tell why devil chose to cop out of this thread. Looking through it I don’t see anything like the attitudes he/she complains of, and, given the employment merits and exceptional biodiversity of sustainable coppice woodland for methanol, it is amply proof against the slur of lacking benign ‘holistic consequences.’ Meanwhile devil's own unconstructive and wilfully uninformed position does him/her no credit, as before sounding off he/she could simply have looked up the Mitsubishi website; among a lot else this includes remarks on their plant’s wood-sourced methanol becoming cost-competitive with some forms of diesel usage. For all that is after research dating back to the 1600s, the funding that has gone into this option globally since 1990 would be laughable (if it weren’t tragic), and yet already that competitiveness is being achieved.
In reacting to my first post on this thread devil chose to describe it as ‘twaddle,’ yet if that is so, then Mitsubishi and others are spending tens of millions of dollars on twaddle in biomass methanol production and in its use in fuel cells, and are getting very positive results for doing so. The term ‘twaddle’ was not given any definition in devil’s post, but the current usage (taken from Heinemann English Dictionary) defines it as “meaningless or foolish talk or writing.”
I hope that people will investigate the web addresses in my first post and conclude for themselves that these two posts are by no means ‘meaningless or foolish.’
I’m intrigued by the fact that I’ve seen just this reaction of utter unquestioning denial of the coppice-methanol option on various occasions since I began researching it in 1987 after the Great Storm over southern England. Yet that denial has usually been by people with an interest in the fossil status quo, including oil-men and car-makers, politicians and diplomats. In addition I’ve not previously seen such an obfuscation of the issues (muddying the waters) whose only effect, as far as I can see, might be to discourage those who aren’t conversant with the issues from looking at the websites to make up their own minds. Being directly anti-educational this would plainly conflict with the ethos of the peak oil website.
And as to why nobody in commerce has been interested in coppice methanol for so long ? Ask yourself just how many countries around the world could have been producing methanol from upland coppice woodlands all these years to enjoy national self-reliance in an high quality liquid fuel, and then ask what that would have cost the beef industry in curtailed expansion and the oil industry in lost sales and influence, and the dollar in hegemony ?
Regards,
Backstop
