Biomass - where is all this energy coming from?

[admin]

Phil,

Thanks for your views on biomass - I did say a guess - figures are nowhere near set in stone within FOE. My guestimate did include imports not just UK - though that is wide open to critique too. If '
sustainable' UK biomass resource (indigenous + imported) is maybe more like 2 or 20 TWh/y then fine - I await your collated figures and will pass them on to relevant FOE campaigners. We are not impressed with the large (300 MW+) 'electricity-only' biomass schemes beginning to get proposed at UK ports (ie imported biomass from around the world). Biomass really should be CHP fired only (and we may do more on the 'pyrolysis and charcoal back to land' technology ?).
Re tidal stream - I asked MCT Ltd what they thought about Mackay's view - and they were not inclined to agree. Also regarding the enhanced pumping of lagoons that Dr Mackay wrote a paper on (ie greatly increased energy generation) as far as I can tell most pumping either 'moderate' (additional 25 - 30 % ) or 'enhanced' (2 to 4+ times !) is mainly 'storage' in reality. Its not extracting 'virgin' additional tidal range energy from the Severn. The input pumping energy and the output received back is probably in parity (ie little NET gain). The benefit is a potentially considerable capability for 'dispatch-on-demand'. This is good for grid integration particularly in a renewable world - and lagoon owner income (sell when 'pool' prices are high).
Neil

[admin]

Mark,
Fine - I will suggest round figures of 20 el + 20 th to my colleagues.
Re CCS - I agree post-C capture cost cause a big efficiency hit. I think energy loss (from coal and or biomass resource) could be greatly reduced in pre-C gasifiers with CHP.
Neil

On 9 Dec 2008, at 11:30, Mark Barrett wrote:
> Dear Phil
>
>
>
> I think about 20 TWh(e) + 20 TWh(th) is what one can expect from
> biomass CHP (p 11 of first attached).
>
>
>
> Pressures on biomass for food (and maybe materials) and habitats for
> other species make it unlikely that much biomass will be grown for
> energy. Some studies show that biocrops (i.e. not waste) can cause
> more GW through non-CO2 gases such as N2O than is reduced through CO2
> reduction.
>
>
>
> Biomass should be used in smallish CHP plant near source, otherwise
> precious transport energy costs large, though optimum scaling/
> location will vary.
>
>
>
> And I think CCS with biomass (or anything!) is not good because of
> efficiency hit – biomass elec/heat output reduced by 15-35% - what
> will replace lost bioenergy - coal? Not to mention cost...
>
>
>
> Other studies attached in case useful.
>
>
>
> Best wishes
>
>
>
> Mark
>
>
>
> Dr Mark Barrett, Principal RCUK Academic Research Fellow
>
> Bartlett School of Graduate Studies, University College London
>
>
> Site : www.bartlett.ucl.ac.uk/markbarrett/Index.html
>
>
>
> Skype: MarkAlexBarrett (Mark Barrett)
>
>
>
> From: Philip Harris [
> Subject: Biomass RE: Where is all this primary energy ...
>
>
>
> DAVE A WROTE (re gas supply scene )
> ** Can I congratulate Neil on a well thought out, carefully written
> and hence
> readable piece. We need more of this style of writing.**
>
> ----------
> I agree with Dave A.
> However in a later piece, following Fred's excellent questions
> about sourcing all primary energy supplies, Neil writes
> ** sustainable biomass - anybody's guess say 40 -80 TWh/y ? **
> I think that Neil, (and Dr Czisch?) could be massively over
> estimating the potential for UK or even for EU biomass supplies.. I
> hope FoE can revisit estimates for biomass.
> I am updating and checking my earlier round-up of estimates of
> biomass energies before posting to "Conference Presentations". I am
> only looking at ball-park figures derived from official data.
>
> Defra yield figures suggest that a million hectares of miscanthus
> could substitute not much more than 10% of coal presently burned in
> UK power stations:- or ~4% of total electricity, or under 16TWh(e)
> of total ~406TWh(e) per year (2006 figures).This would be 1Mha of
> precious ploughable surface (maximum around 7Mha was ploughed in
> WWII) if allocated to highest yielding biomass (miscanthus) . The
> UK imports up to 50Mt (2006) of coal for power generation per year
> and used ~57Mt coal to produce around 148TWh(e) per year in 2006.
> Obviously TWh heat would be higher number, if heat could be used in
> district heating.
>
> I am also looking at a case study for Wales with projections for
> lower yielding willow coppice on land unsuited to arable cropping,
> where 0.7Mha maximum surface could supply perhaps 8TWh(e) per year.
> More realistically, the study projects that farmers might actually
> be persuaded to grow energy coppice on only 10% of that max.
> possible suitable surface in Wales, with an annual yield of around
> 0.5Mt of oven dry wood, (lower energy density than coal) providing
> perhaps around 0.8TWh(e) per year. This study's perhaps realistic
> very low figure is matched with even lower estimates for "existing
> forest wastes" in Wales. Greater future use of forests and
> woodlands for biomass, rather than for timber or pulp, could be
> expected to boost these very low figures. Nevertheless, total
> 'woodland' in the UK does not appear to be more than 2.8M ha, and
> harvestable yields per annum from forest and woods seem potentially
> lower than yields from dedicated energy crops.
> I will try to collate these figures in a fully referenced and more
> easily accessed form.
> To echo Fred, where is it all going to come from? 40TWh e per year
> from biomass seems a huge stretch.
> best
> Phil
> (apologies if I am copying to wrong people - I do not yet
> understand the email system for Claverton.)
> - ---------- By the way, David Mackay is a hotshot physicist, and
> if his recalculation of Tidal Stream is correct (apparently
> somebody thinks his calculation is wrong), we really need to know.
> By Mackay's account TS is potentially a resource comparable even
> with wind. Mackay still seems to see a huge gap unfillable by
> renewables in total, however. Lets hope he has underestimated the
> build out for wind and our capacity for structural adjustment.
>
>
>
>
>

[admin]

Mark,
Could you indicate what you mean by "smallish", and the manufacturers of commercially-available, smallish, biomass CHP plant you have in mind?
And the types of applications where they would be used?
We are perpetually looking for both, and in our experience, viable instances are rare as hen's teeth.
Also, could you show the calculations you used to reach the conclusion that transport energy costs are large unless local biomass is used?
We tried it for the case that was most relevant to us (pellets from Enniskillen to Retford, Notts. via Stranraer) and the transport-energy costs as a proportion of the energy content of the fuel were de minimis
- around 2%.
And that's more road-travel than would be normal. You would normally aim to do as much as possible by boat (e.g. pellets from Scandinavia and the Baltics), arriving at the nearest dock to the customer-base, which would further reduce the energy cost.
When you add in to that the fact that the larger, more remote pellet plants use biomass CHP very efficiently, whereas small-scale local biomass production tends to involve a fair amount of fossil-fuels (in the chipper and/or pellet plant), it seems highly debatable to me whether local biomass has a lower carbon footprint than some types of remote biomass.
And in any case, the fossil-footprint of local and remote biomass is a tiny fraction compared to fossil-fuels (which people tend to forget also has to be imported), heat pumps and micro-gas-CHP. It seems to me that you are letting best be the enemy of the good if you argue against use of remote biomass (much of which does not have a practical use in its original location), and thereby prolong the use of the fossil fuels which it would otherwise displace.
Cheers,
Bruno

[admin]

Bruno


· Economies of scale. Large CHP plant more efficient, cheaper per kW, and lower emitters. Attached suggests you want more than 25 MW for these economies.

· Diseconomies of scale. The larger the CHP plant the greater the transport distance, maybe approx as square root of TWhe/h production as biomass catchment area goes as square of radius. Obviously transport energy, cost and emissions depends on mode (road/rail/boat...), fuel type (fossil/bio/elec?), etc.

How the optimum between these factors changes I know not. That's why I used mealy mouthed words like smallish and said " though optimum scaling/location will vary"! So I basically agree with you, but don't have your knowledge to quantify optima. For a UK strategy, we need data on heat loads (now and future), biomass distribution (and other uses), technology scaling parameters transport options. I suspect there are many optima depending on these ‘local’ factors. It would be an interesting study – "The optimum use of biomass"...

Concerning manufacturers, again profound ignorance, though I would have thought there is some experience, e.g. attached.

Best wishes

Mark
Bruno


· Economies of scale. Large CHP plant more efficient, cheaper per kW, and lower emitters. Attached suggests you want more than 25 MW for these economies.

· Diseconomies of scale. The larger the CHP plant the greater the transport distance, maybe approx as square root of TWhe/h production as biomass catchment area goes as square of radius. Obviously transport energy, cost and emissions depends on mode (road/rail/boat...), fuel type (fossil/bio/elec?), etc.

How the optimum between these factors changes I know not. That's why I used mealy mouthed words like smallish and said " though optimum scaling/location will vary"! So I basically agree with you, but don't have your knowledge to quantify optima. For a UK strategy, we need data on heat loads (now and future), biomass distribution (and other uses), technology scaling parameters transport options. I suspect there are many optima depending on these ‘local’ factors. It would be an interesting study – "The optimum use of biomass"...

Concerning manufacturers, again profound ignorance, though I would have thought there is some experience, e.g. attached.

Best wishes

Mark

[admin]

Optimum size is far larger than the typical size even for methane digesters.
Why anyone would burn wood (0.33 kg/k/kWh) and not sequester it I do not know. Gas emits 0.195 kg/kWh and can be burned 1.1-2x more efficiently.
D.

[admin]

Dear David
----- Original Message -----

Subject: Re: [Claverton-Group] Biomass RE: Where is all this primaryenergy...

Optimum size is far larger than the typical size even for methane digesters.
Why anyone would burn wood (0.33 kg/k/kWh) and not sequester it I do not
know. Gas emits 0.195 kg/kWh and can be burned 1.1-2x more efficiently.
* Let me tell you why it is sensible to burn wood rather than fossil fuel. Further, let me tell you how wood can be used as a fuel that is literally Carbon Negative.
* What you are doing is considering the CO2 that is liberated to the atmosphere, for a given energy release. This narrow view supports your statement. The important thing is the fact that C from fossil fuels, such as natural gas is "new carbon to the biosphere", while carbon from wood combustion makes no addition of carbon to the biosphere. The carbon in the wood is already in teh biosphere, and its combustion makes no addition to the carbon in teh biosphere. Wood is thus a "Carbon Neutral Fuel" while Natural Gas is a "Carbon Negative Fuel". Thus, using Natural Gas as fuel liberates an infinitely greater quantity of carbon to teh biosphere than does combustion of wood, for a given energy release.
* Now, if wood is Carbon Neutral, how can it be Carbon Negative?
* Simple. Convert it to charcoal, use the pyrolysis gases as fuel, and sequester the charcoal.
* Charcoal can be used as a beneficial agricultural supplement, and has been used in this manner for more than 3,000 years. The estimated half life of charcoal when used in agriculture by mixing with the soil is in excess of 1,000 years.
* 1 kG of wood has about 18 MJ of energy. By pyrolyzing the wood, about 50% of the energy goes off in the pyrolysis gases, and about 50% remains in the residual charcoal. The weight of the residual charcoal is about 1/3 of the starting wood weight. Thus, if we sequester the charcoal, we are removing carbon from the biosphere, and thus wood as a fuel is "Carbon Negative, is handled in this manner.
* So, in terms of the impact that fuels have on the CO2 mass in the Biosphere:
1: Any Fossil Fuel is BAD (Carbon Positive)
2: Wood is good (Carbon Neutral)
3: Pyrolyzed wood is best. (Carbon Negative.)
* "Sequestering wood" is not a long term solution.
* Kevin Chisholm

[admin]

Sequestering as charcoal loses energy in the sequestering process (pyrolysis, burying etc.) and in the buried charcoal.

The question is, what is the carbon release of the energy that will replace that lost (biomass) energy at the margin If renewable replacement, then net reduction of atmospheric carbon; if fossil (as will generally be the situation for several decades) then net change in atmospheric carbon depends on whether gas/oil/coal.

I think the calculation is as follows.

Bio energy sequestered Ebio(Seq) = Ebio * (1- sequester effic)

Bio carbon sequestered Cbio(seq) = Ebio(seq) * (carbon per GJ) * (1 –% loss of carbon from soil; over what period?))

Useful energy to replace Ubio = Ebio(Seq) * (effic of biomass use e.g. boiler)

Carbon from replacement Crep = (Ubio / (effic replacement energy e.g. boiler)) * (carbon per GJ) * (emission factor = 1 unless CCS)

So for Cbio > Crep depends on several factors. In many countries and globally coal is at the margin, and gas R/P life is ~50 years, coal 150 years. But plainly when renewables are at margin, bio sequestration probably good.

In addition:
· What is cost of sequestering?
· What are the environmental gains and losses?
· The half life of charcoal in soil is not well known– I ‘ve seen quotes 100-1000 yrs - and it’s probably very variable depending on soil conditions. What if we are wrong (as we have been about biodfuels, nuclear waste etc.) and it’s 50 years? (And I can’t quite believe there aren’t some bacteria that exploit this energy source as they do most others. And if such evolved....?)


So place your bets – my money (1 Euro) is still on biomass CHP without CCS.

Best wishes

Mark

Dr Mark Barrett, Principal RCUK Academic Research Fellow
Bartlett School of Graduate Studies, University College London

[clivehinchcliffe]

Dear All, whilst everyone continues to look at how much of a given energy supply can be produced to meet expected demand the problems will remain.

We must must must reduce our energy requirement, introduce micro generation even if that means placing mini wind turbines or solar heat and or electric panels on all buildings World wide.

A change in transport modes and in some cases a reduction in speeds such as the movement of goods by air.

So the answer is not just generation of Gas or other energy but reduction in demand.