Renewable Energy: Biomass - a burning issue

691 to 720 of 1076

- CommentAuthorJoiner
- CommentTimeSep 22nd 2011 edited
That link has stopped linking for some reason now! Occasionally goes back to the home site but then doesn't open the link there.
- CommentAuthorSteamyTea
- CommentTimeSep 22nd 2011
Works fine for me.
- CommentAuthortony
- CommentTimeSep 22nd 2011
It surprises me how long it has taken them to come to this conclusion.
- CommentAuthorSteamyTea
- CommentTimeSep 22nd 2011 edited
Posted By: tonyIt surprises me how long it has taken them to come to this conclusion.

Took them this long to get through the threads on here about it.

After a quick skim through it is down to land use change then. What a surprise.
- CommentAuthorJSHarris
- CommentTimeSep 22nd 2011 edited
What surprises me most is that an extremely simple, back-of-a-fag-packet, calculation will show that the land area needed to grow biofuel to meet our current fuel needs doesn't exist, by a colossal margin.

Surely someone can do the basic arithmetic that determines how much fuel is produced per square km, it isn't exactly rocket science, as it is just a solar power calculation in essence.

I suppose it is a human trait to want to believe that you can grow your own anything. Anyone with a farming background and who's had a go at making and using biodiesel very quickly gains first hand knowledge of the number of acres needed just to runs a single car.............

Edited to add this back-of-fag-packet calculation that illustrates just the oil impact on agriculture (it ignores gas, coal and nuclear energy replacement):

Assume that the UK domestic oil demand stays around the current 55 million tonnes and that this can all be met by vegetable oil.

A reasonable oil seed rape crop can generate about 1 tonne of oil per hectare.

The UK currently has around 8 million hectares of arable land, mainly growing food. If all of this arable land were to grow oil seed rape for fuel oil instead of food, then it would produce around 8 million tonnes per year, just 14.5% of our current oil requirement.

Put another way, we would need to increase the area of arable land to around 55 million hectares just to meet our oil-based energy needs, without looking at replacing the energy provided by gas, coal and nuclear.

Currently agriculture uses around 75% of our available land area, around 19 million hectares.
- CommentAuthorJoiner
- CommentTimeSep 22nd 2011
Stop looking so smug, Brian!
- CommentAuthorBrianwilson
- CommentTimeSep 22nd 2011
Dave- It would be nice to think that finally there is hope that common sense will prevail, that it is time for joined up thinking, due diligence and duty of care in energy provision and then along comes fracking gas!.
- CommentAuthorSteamyTea
- CommentTimeSep 22nd 2011 edited
Posted By: JoinerStop looking so smug, Brian!

Not just Brian
Now where are those maps I did of Norfolk covered in trees and a tiny bit of Penwith covered in solar farms and houses. They have to be lurking here somewhere
- CommentAuthorJoiner
- CommentTimeSep 23rd 2011
Have any of the number crunchers worked out the proportions of biofuel feedstock from dedicated land-use and that from waste products - the combustible residues after processing for their primary purpose - and seen how that impacts upon the finer details of the report's conclusion?
- CommentAuthorSteamyTea
- CommentTimeSep 23rd 2011
No. But does it make any difference if, to avoid double counting, you separate the stalk from the seed. Seem to remember that was Gordon Browns trick. I have an acre of land and I can grown some corn on it, I also use the straw to make bales. I must have 2 acres of land. The better way I think is to work out the efficiency of conversion for each constituent part with the base being the horizontal plane solar radiation (the W.m^-2).
- CommentAuthorDamonHD
- CommentTimeSep 23rd 2011
An ex-member of the RAB I was speaking to at the w/e shares my hopes for biomass as a major part of 'storage' to fill in gaps in other renewables' output, including the dreaded long/cold/calms of midwinter, and he seems to think that (a) large plants with good ceramic filters would be fine in terms of PMs and (b) that MSW once all available recyclables have been plucked out would make a huge difference in terms of fuel availability.

(I believe that I'm reporting him accurately: I might see if I can get him to sign up here and contribute.)

Rgds

Damon
- CommentAuthorJoiner
- CommentTimeSep 23rd 2011
And what about all that excess packaging!
- CommentAuthorJSHarris
- CommentTimeSep 23rd 2011 edited
Biomass cannot ever, no matter how the figures are tweaked, be a major part of our energy supply. If you take the most efficient plants (in terms of conversion ratio of sunlight to usable biomass potential chemical energy) then the upper limit for photosynthetic energy conversion is around 11%. In practice few plants (including algae) get better than around 5%.

If you were to assume that all of the UKs available land were given over to growing the most efficient biomass crop possible (say, 5% efficient) then it would only produce around 1/3rd of the energy of that same land area covered in solar panels, or about 1/9th of that same land area covered in solar thermal collectors.

The UK uses around 9.9 x 10^18 J of energy per year. A hectare of biomass might be able to produce about 250MJ with a perfect crop of a high conversion ratio species. To grow enough biomass to meet the current UK annual energy need would require around 40,000,000,000 hectares. We currently have about 8,000,000 hectares of arable land in the UK and around 19,000,000 hectares of agricultural land in total, about 75% of our total available land area. If all our arable land was dedicated to growing biomass for energy, instead of food, we could produce about 0.002% of our total energy needs.

I don't see how the potential to provide an absolute maximum of 0.002% of our energy needs from biomass can ever be considered to be a "major part".
- CommentAuthorJoiner
- CommentTimeSep 23rd 2011
John's either busy with the winter ploughing or doing his sums!
- CommentAuthorrenewablejohn
- CommentTimeSep 23rd 2011
Posted By: JoinerJohn's either busy with the winter ploughing or doing his sums!

John is very busy at the moment and cannot really afford the time to go through all this b******t again. Obviously JSH went to the same school as McKay and making the same mistakes and assumptions.
- CommentAuthorJoiner
- CommentTimeSep 23rd 2011
- CommentAuthorBrianwilson
- CommentTimeSep 23rd 2011
The fundamental problems are land usage and processing/transport impact of a low energy density fuel. At average yield 10t/ha then a typical hospital biomass boiler requires 1000ha dedicated to biomass. With 95% of agricultural land cropped we have little scope for indigenous provision. The DECC/Arup report details 90% import but this could be higher if increased subsidy for biomass burning is implemented.
This report on EU biomass imports illustrates our competition for resources.
http://www.argusmedia.com/pages/NewsBody.aspx?id=751620&menu=yes

I note straw is favoured for UK combustion but presents serious problems not least high chlorine content indicating carcinogenic dioxin formation. There are a number of superior uses e.g. construction, ploughing back in to reduce fossil fuel based fertiliser , cellulosic bio ethanol etc. Current proposals for <50MW straw burning plants in Lincolnshire ignore resource problems when DECC/Arup report confirms major users will divert resources from < 50MW plants in adjacent Counties. Local Council leader reported to claim operators can import straw from Denmark at low cost which then brings in fact that Denmark currently import 85% of biomass plus transport impact. Where is joined up thinking?
Average household waste composition detailed as 32.5% paper and cardboard, 30.3% kitchen &garden, 12.7 % plastic, 4.6% textiles, 3.7% ferrous metal,1.4% non-ferrous with remainder miscellaneous. We know recycling/up cycling saves far more energy than burning, AD is preferred waste to energy stream for biodegradable material and MBT process to provide material for co-firing in coal plants. EFW plants are known to be totally inflexible creating future sustainability problems, Sheffield already suffering 22% 50,000 t feedstock shortfall requiring extended haulage.
Ceramic filters provide superior fine particle reduction but cost appears to deter UK use and biomass will still produce far higher levels of hazardous emissions than alternatives. The UK Energy Strategy document 2009 details 52TWh of biomass energy will add Â£2803 million annually to health costs, note this assumes biomass will produce fine particles level of 20g/Gj of energy but recent reports indicate practical reality will be at least 50% higher with direct correlation to health impact. Current proposals indicate UK biomass burning will be far higher than anticipated.
Recent press reports detail exposure to fine particle pollution directly linked to heart attacks with traffic being demonised when we are aware biomass combustion produces most hazardous size spectrum with levels from small biomass plants equalling billions of additional vehicle km.
Sorry to rant on re biomass but sadly suspect vested interests in UK will push thro massive burning policies ignoring joined up thinking, duty of care and due diligence. Can only hope!
- CommentAuthorrenewablejohn
- CommentTimeSep 23rd 2011 edited
Just to start and redress the balance. JSH assumes 1 tonne of oil per hectare this is only the most usable form of the rape seed crop. In addition rape meal is produced when the oil is extracted which can be fed to animals or used in AD plants. Rape straw is baled and is a valuable biomass fuel. Honey is produced from the rape seed flowers and is excellent fuel when mixed with hydrogen peroxide and finally rape is an excellent break crop supplying essential nutrients for a following crop. In real terms an extra 1 to 1.3 tonnes of wheat per hectare compared to a wheat on wheat crop. If somebody would care to work out the total energy content of these individual components we might end up with an informed discussion.
- CommentAuthorJSHarris
- CommentTimeSep 23rd 2011
<blockquote><cite>Posted By: renewablejohn</cite><blockquote><cite>Posted By: Joiner</cite>John's either busy with the winter ploughing or doing his sums!</blockquote>

John is very busy at the moment and cannot really afford the time to go through all this b******t again. Obviously JSH went to the same school as McKay and making the same mistakes and assumptions.</blockquote>

Wow! What a response. I'm a retired scientist, BTW, so I've been to a few "schools" over the years. All taught me pretty much the same core principle - if in doubt go back to first principles and work from there.

Perhaps you would like to produce your own calculations and supporting data to refine these figures?

I fully accept that I may be in error, as I just worked from some basic assumptions that might well be wrong (excepting photosynthetic energy conversion efficiency, as I know this to be correct from work I did myself in the early 70's). If you can provide hard data on, for example, the UK latitude land area needed to provide the 9.9 x 10^18 J of energy per year that the UK needs, then please do so, as I will be genuinely interested to see where I may have gone wrong in my estimates.
- CommentAuthorJSHarris
- CommentTimeSep 23rd 2011
<blockquote><cite>Posted By: renewablejohn</cite>Just to start and redress the balance. JSH assumes 1 tonne of oil per hectare this is only the most usable form of the rape seed crop. In addition rape meal is produced when the oil is extracted which can be fed to animals or used in AD plants. Rape straw is baled and is a valuable biomass fuel. Honey is produced from the rape seed flowers and is excellent fuel when mixed with hydrogen peroxide and finally rape is an excellent break crop supplying essential nutrients for a following crop. In real terms an extra 1 to 1.3 tonnes of wheat per hectare compared to a wheat on wheat crop. If somebody would care to work out the total energy content of these individual components we might end up with an informed discussion.</blockquote>

Indeed, I did use the oil yield, because the specific point being made was regarding fuel oil, not total biomass yield. Around 50% of rape seed goes to animal feed as waste from oil extraction, I believe, plus there are large volumes of rape straw that can be burned to recover energy. The total energy yield from a rape crop may be significantly greater than the oil yield, I agree, perhaps around three times greater at a guess.

Other crops are, I believe, significantly better than rape in terms of energy produced per hectare. Willow is potentially around 45 MWh/ha/yr, but there are large areas of the UK where the conditions aren't suitable for its growth so average production rates will be a lot lower than this.
- CommentAuthorrenewablejohn
- CommentTimeSep 23rd 2011
Posted By: JSHarris
Posted By: renewablejohn
Posted By: JoinerJohn's either busy with the winter ploughing or doing his sums!

John is very busy at the moment and cannot really afford the time to go through all this b******t again. Obviously JSH went to the same school as McKay and making the same mistakes and assumptions.

I'm a retired scientist,

Poor excuse

I fully accept that I may be in error, as I just worked from some basic assumptions that might well be wrong (excepting photosynthetic energy conversion efficiency, as I know this to be correct from work I did myself in the early 70's).

Sounds like a good place to start if you believe it to be correct.
Please explain your scientific experiments which brought you to this conclusion as my field trials over the last decade have shown that heat is far more important than light intensity and that outputs 8 times the "norm" can be achieved in polytunnels as compared to open ground cultivation.
- CommentAuthorJSHarris
- CommentTimeSep 23rd 2011
<blockquote><cite>Posted By: renewablejohn</cite>
Poor excuse </blockquote>

Not an "excuse" for anything, simply a statement of fact. No need to be so objectionable; we're only having a reasoned debate.

<blockquote><cite>Posted By: renewablejohn</cite>
Please explain your scientific experiments which brought you to this conclusion as my field trials over the last decade have shown that heat is far more important than light intensity and that outputs 8 times the "norm" can be achieved in polytunnels as compared to open ground cultivation.</blockquote>

I started my career as a chemist, working in organic radiochemistry for what was then the UKAEA, in the early 70's. I spent around a year studying carbon uptake in a wide range of plant species, grown in controlled, sealed environments where we could vary the amount of C14 labelled CO2 in the atmosphere and could accurately control and measure irradiance, both in terms of magnitude and wavelength.

I found that the best photosynthetic energy conversion ratio I obtained was around 6%, and was highly dependent on light level, availability of nutrients and water and temperature. Others have reached the same conclusion, that 3 to 6% efficiency is typical for plant energy conversion. Your own conclusion that a warm, controlled environment produces better yields in some species tallies with my own findings, and isn't surprising.

A colleague was doing work on the photochemistry of plant leaf cells, specifically the efficiency of chloroplasts in being able to convert light to chemical potential energy. She found that chloroplasts were theoretically able to convert about 11% of the total sunlight they were exposed to into chemical energy, but that loss factors reduced this considerably when considering the whole plant. These loss factors include such fundamentals as the angle of a leaf towards the illuminating source, shading from other leaves and stems etc.

If we were able to recover and use all of the potential energy that plants can derive from the sun over their lifespan, then we could reasonably expect to obtain around 5% of that from the sunlight that had shone on them through life, assuming that they were kept at a reasonable temperature and were provided with adequate nutrients and moisture.

This sets an upper bound on what we might theoretically be able to obtain in terms of energy yield per hectare, a figure that cannot be exceeded because to do so would imply that all the work done on understanding photosynthesis over the years is wrong. We know how much sunlight falls on the surface of the earth and have pretty good data for it by region. East Anglia has the greatest area of arable land in the UK, I believe, and has an annual irradiance figure of around 995kWh/mÂ² (3,582 MJ). If we were able to grow crops all year around, with no break for harvesting or sowing, and if those crops were able to convert available sunlight into usable potential energy at a constant rate of 5% throughout the year, then in theory we could produce around 179 MJ/mÂ², or 1,791,000 MJ per hectare. In practice the yield will be significantly lower, because the growing season may only be half of the year, not all the energy from sunlight gets converted to usable potential chemical energy in the plant and there will be an energy input in the form of producing seed, preparing the land, providing nutrients and water, harvesting etc.

Nevertheless, if we ignore all the practical issues that may affect energy yield, we can still set the absolute upper bound for biomass, in terms of the theoretical potential energy per hectare, at this figure of about 1.8 TJ. Using this upper bound (which is admittedly far from achievable in practice) we can calculate that we would need approximately 5.5 million hectares of perfectly efficient crops, with no energy input other than sunlight, to meet the UKs energy needs. I believe this is the sort of figure that may be convincing some that biomass can meet our needs, but this is a flawed assumption, as the real, practical, date from crop yield testing seems to show.

If we look at some real data for biomass crop yields we find that they are very significantly lower than the theoretical upper bound the above calculations suggest. Willow is a commonly suggested biomass crop, and in suitable conditions can give a maximum yield of about 165GJ/ha. Waste wheat straw can give a maximum of around 60GJ/ha. The average yields across the country will be much lower than these maximum figures, so it would be reasonable to assume that we might get around 100 to 110 GJ/ha for willow (in the right environment - it needs a lot of moisture) and perhaps 40 GJ/ha for wheat straw.

If we could grow willow over all of the UK arable land area for fuel (an unlikely assumption) then it looks like we could get around 8.8 x 10^17 J, against the UK energy requirement of 9.9 x 10^18 J, around 8.8% of our requirement. However, willow won't grow well over large swathes of the UK, so we cannot get close to this figure in practice.

Wheat straw might be a better example to use, as even though the energy yield per hectare is lower, it will grow pretty much anywhere. If we were able to recover wheat straw with no energy input (other than sunlight) and use it as fuel, and if all of the 8 million hectares of UK arable land were growing wheat, then it could provide around 3.2 x 10^17 J p.a. or around 3.2% of our energy requirement.

Even these figures are very optimistic though, as they ignore the significant energy input, in the form of land preparation, sowing, irrigation, pesticides, harvesting, crop preparation into fuel etc. In the specific case of growing oil seed rape for biofuel, some researchers are indicating that the net energy output can be only a small percentage of the gross energy output, because of relatively high energy input in growing and harvesting. Some have even indicated that growing crops like these can produce a negative overall energy output.

I'll accept that the estimates I made in that post to which you so vehemently expressed objection may be overly pessimistic, but suggest that even a very optimistic view of biomass potential shows that it simply cannot produce more than a tiny amount of our energy needs, even if we stopped growing food on all our arable land.
- CommentAuthorSteamyTea
- CommentTimeSep 23rd 2011
Re John's statement about heat and light on growth, does the upper and lower bounds of a plants temperature range just set one of the conditions that make it grow. Outside of those bounds yield will drop off rapidly regardless of light intensity. Within those temperature bounds, as long as there is enough light, yields are fairly stable. Or is it the other way around. Serious question that needs a solution, I suspect that the term 'solutions to partial differential equations' will soon creep in.
- CommentAuthorJSHarris
- CommentTimeSep 23rd 2011
<blockquote><cite>Posted By: SteamyTea</cite>Re John's statement about heat and light on growth, does the upper and lower bounds of a plants temperature range just set one of the conditions that make it grow. Outside of those bounds yield will drop off rapidly regardless of light intensity. Within those temperature bounds, as long as there is enough light, yields are fairly stable. Or is it the other way around. Serious question that needs a solution, I suspect that the term 'solutions to partial differential equations' will soon creep in.<img title="" alt="" src="/forum114/extensions/Vanillacons/smilies/standard/wink.gif"></img></blockquote>

It's a long time ago now, but I recall that my data for carbon uptake (analogous to total energy) were highly variable. 6% was the best I saw, but even small variations in temperature, moisture etc made massive differences, with it not being uncommon to see uptake rates down around 1% at times. I was able to change the total CO2 ratio in the growing cabinets, and this, too made a significant difference in uptake rate, although I wouldn't expect the predicted change in atmospheric CO2 to have a massive impact on plant growth at our latitude for some years.

I'm not a plant biologist, so can't claim to fully understand the response of plants to temperature, but I strongly suspect that each species has an optimum temperature for best growth and even small changes either side of that are likely to result in poorer yields. This paper <url>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569569/</url> seems to support that view. I know from experience that yields of common arable crops can vary by 20% - 30% or more, just from seasonal variations in temperature, sunshine and rainfall, so I think we also have to factor that level of variability into any biomass crop that we might be reliant upon.
- CommentAuthorrenewablejohn
- CommentTimeSep 23rd 2011
Sorry JSH but I do find a lot of scientists are great in theory and the lab but when they get down to the practical application there common sense goes out the window. Obviously unfair to tar you with the same brush so I apologise.
From your knowledge then you may be able to explain why I have been very successful at growing better crops under 75% shade netting than in full sunlight. From my practical research plants have a very high built in redundancy factor and can quite easily survive and grow healthy on only 25% of direct sunlight therefore if you have a stacked cropping system you can get 4 times the crop per m2. Add to this the increased growing capacity of a polytunnel due to the increased all the year round temperature this allows a minimum 2 crops per annum instead of the normal 1. Which overall gives an 8 times better performance then open arable land.
- CommentAuthordjh
- CommentTimeSep 23rd 2011
Many naturally trailing crops are grown vertically to get a greater weight of produce, and of course crops are heated and fed with extra carbon dioxide to increase yield. Tomatoes are the classic example and there are good and bad examples of how to do it:

http://www.britishsugar.co.uk/Tomatoes.aspx
http://www.dailymail.co.uk/sciencetech/article-1025689/Welcome-Thanet-Earth-The-biggest-greenhouse-Britain-unveiled.html
- CommentAuthorJSHarris
- CommentTimeSep 23rd 2011 edited
<blockquote><cite>Posted By: renewablejohn</cite>Sorry JSH but I do find a lot of scientists are great in theory and the lab but when they get down to the practical application there common sense goes out the window. Obviously unfair to tar you with the same brush so I apologise.
From your knowledge then you may be able to explain why I have been very successful at growing better crops under 75% shade netting than in full sunlight. From my practical research plants have a very high built in redundancy factor and can quite easily survive and grow healthy on only 25% of direct sunlight therefore if you have a stacked cropping system you can get 4 times the crop per m2. Add to this the increased growing capacity of a polytunnel due to the increased all the year round temperature this allows a minimum 2 crops per annum instead of the normal 1. Which overall gives an 8 times better performance then open arable land.</blockquote>

Plants can only make use of a small range of wavelengths for photosynthesis; they don't need full spectrum light in order to drive the chloroplasts to convert energy at the maximum rate. Plants get rid of the 95% waste energy that falls on their leaves by reflecting some of it away (which is why they look green) transpiring a lot of it away by evaporating moisture from their leaves and losing quite a lot through wind forced convection and radiation. If you can provide a screen that limits the range of light wavelengths that reach the leaves, then provided you are letting enough light at the right wavelengths through to allow photosynthesis to work at its maximum rate, then you are helping the plant by reducing its need to cool itself. In particular, you're significantly reducing transpiration loss, which both reduces moisture demand and also the rate at which water has to pass through the plant just to remove waste solar energy.

The UN Food and Agriculture Organisation have some interesting data on plant growth, photosynthesis, etc. Interestingly they give data that match mine from nearly 40 years ago:

<blockquote><cite> FAO paper on biological energy production</cite>1.2.1 Photosynthetic efficiency

Photosynthesis can be simply represented by the equation:

CO2 + H2O + light !â€™ 6 (CH2O) + O2

Approximately 114 kilocalories of free energy are stored in plant biomass for every mole of CO2 fixed during photosynthesis. Solar radiation striking the earth on an annual basis is equivalent to 178,000 terawatts, i.e. 15,000 times that of current global energy consumption. Although photosynthetic energy capture is estimated to be ten times that of global annual energy consumption, only a small part of this solar radiation is used for photosynthesis. Approximately two thirds of the net global photosynthetic productivity worldwide is of terrestrial origin, while the remainder is produced mainly by phytoplankton (microalgae) in the oceans which cover approximately 70% of the total surface area of the earth. Since biomass originates from plant and algal photosynthesis, both terrestrial plants and microalgae are appropriate targets for scientific studies relevant to biomass energy production.

Any analysis of biomass energy production must consider the potential efficiency of the processes involved. Although photosynthesis is fundamental to the conversion of solar radiation into stored biomass energy, its theoretically achievable efficiency is limited both by the limited wavelength range applicable to photosynthesis, and the quantum requirements of the photosynthetic process. Only light within the wavelength range of 400 to 700 nm (photosynthetically active radiation, PAR) can be utilized by plants, effectively allowing only 45 % of total solar energy to be utilized for photosynthesis. Furthermore, fixation of one CO2 molecule during photosynthesis, necessitates a quantum requirement of ten (or more), which results in a maximum utilization of only 25% of the PAR absorbed by the photosynthetic system. On the basis of these limitations, the theoretical maximum efficiency of solar energy conversion is approximately 11%. In practice, however, the magnitude of photosynthetic efficiency observed in the field, is further decreased by factors such as poor absorption of sunlight due to its reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels. The net result being an overall photosynthetic efficiency of between 3 and 6% of total solar radiation.</blockquote>

When it comes to crop growing schemes, all they can do is increase the period during which the solar energy impinging on the ground produces usable potential energy in the form of plant biomass. You cannot exceed the figure of around 5% of the solar energy falling on a given ground area being converted into usable biomass, unfortunately, even with stacked systems. As soon as you include a vertical component the level of solar energy impinging on the surface reduces. Even though plants don't need full wavelength sunlight for growth, unless you can find a means for converting the unused wavelengths into useful ones, and then directing that in some way to another layer of crop, the system wouldn't produce yields that were greater than that 5% maximum bound figure.

To be frank, it makes more sense to use land for solar PV or solar thermal, as you can get an awful lot more usable energy doing that than you can by growing biomass.
- CommentAuthorSteamyTea
- CommentTimeSep 23rd 2011
Posted By: JSHarrisTo be frank, it makes more sense to use land for solar PV or solar thermal, as you can get an awful lot more usable energy doing that than you can by growing biomass.

Think this has been mentioned a few times

Purely out of interest and to see how good your memory is, I have a book called 'Enery Exchange in the Biosphere' by David. M. Gates. Its a Harper Collins publication from 1962 with my version being 1965 (was well in short trousers then as I am still). Interestingly it covers exactly what you were saying about light intensity, wavelengths, temperature ranges, CO2 absorption, expiration and the likes. Seems little has changed on the basics, but then the 60's was the height of the agricultural revolution with rapidly expanding yields and improvements in techniques.

Renewable John
Out of interest how do you measure your percentage increase in yield, is it relative or absolute. Could be we are working to different figures. Worth having a read of this article to help clarify this point:
http://www.guardian.co.uk/commentisfree/2011/sep/09/bad-science-research-error

Actually well worth reading Ben every week (he is even better when he gets excited with Tim Hartford on R4)
- CommentAuthorJSHarris
- CommentTimeSep 23rd 2011 edited
<blockquote><cite>Posted By: SteamyTea</cite>Purely out of interest and to see how good your memory is, I have a book called 'Enery Exchange in the Biosphere' by David. M. Gates. Its a Harper Collins publication from 1962 with my version being 1965 (was well in short trousers then as I am still). Interestingly it covers exactly what you were saying about light intensity, wavelengths, temperature ranges, CO2 absorption, expiration and the likes. Seems little has changed on the basics, but then the 60's was the height of the agricultural revolution with rapidly expanding yields and improvements in techniques.</blockquote>

The programme that I was working within back in the early 70's was for agricultural research, I believe. We were looking at techniques for measuring carbon uptake, using CO2 labelled with C14, that could be used by the agricultural research bods. They were, I believe, working on crop growth research at the time; as you say it was a boom period for agricultural research. The technique we developed allowed the quantity of carbon in any mass of plant tissue to be measured simply by measuring the C14 emissions, usually as bremsstrahlung, as C14 is a weak beta emitter. It was a method that could be used on whole plants with a bit of cunning, so the agricultural research bods could make regular measurements of carbon uptake on the same plant through life, rather than burn it in a calorimeter to find out. My measurements were calibrated this way. I'd stick a plant in a chamber and take a bremsstrahlung count, then dessicate it, chuck it in a bomb calorimeter and measure the carbon content from the energy in the plant. Interestingly, one of the plants I used (because it grows quite quickly under artificial light) was cannabis sativa. Unfortunately, because all the plants were pretty radioactive we didn't get the chance to nick any.............
- CommentAuthorJoiner
- CommentTimeSep 23rd 2011
Wow! Atomic weed!!

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Renewable Energy: Biomass - a burning issue