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Tag Archives: bioenergy

BREXIT impacts and implications

By Dave Elliott

The overall context for UK energy policy and the prospects for renewables have taken something of a hit following the narrow referendum vote to leave the EU, with the climate for new investment looking uncertain. In what may become a familiar pattern, leading German engineering company Siemens has put new wind power investment plans in the UK on hold, and more may follow if the economy continues to falter. It certainly looks grim:  and


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Biomass and renewable gas

By Dave Elliott

Not everyone backs biomass, given the emission/biodiversity/land-use issues, but  biomass does offer a range of flexible green fuel options, biogas especially.  The World Bioenergy Association (WBA) says bioenergy already contributes over 14% to the global energy mix, and its use is bound to expand.  So what are the options? (more…)

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Biomass burning impacts: the debate continues

By Dave Elliott
The seemingly endless debate on the impacts of burning biomass continues. At one extreme there are those who see almost all use of biomass as suspect. More specifically there are objections to using whole trees or stem wood, especially if imported so that the source is less sure. One claim is that this can produce more carbon emissions net than would be produced from burning coal, and depletes biogenic carbon stores.

It’s actually a complex issue, since forests are managed for a variety of purposes. As a new EU report on ‘Biogenic Carbon and Forest Bioenergy’ from Forest Research notes:
‘Typically, forest bioenergy is produced as a complementary co-product of wood material/fibre products. It is unusual for forest bioenergy to be the sole product from harvested wood’. However it says EU forest bioenergy is likely to increase significantly, so that ‘it will be necessary to intensify management of EU forests in order to increase removals of primary wood and/or import more wood into the EU and/or mobilise the availability of sources of other woody biomass.’ But it claims ‘A requirement to produce forest bioenergy seems unlikely to become the principal driver of forest management unless demand for forest bioenergy becomes very intense’. In particular is suggest that ‘demand for forest bioenergy seems likely to be met through increased extraction of harvest residues including poor-quality stemwood and trees, the use of sawmill co-products and recovered waste wood. Some small roundwood may be used as a source of bioenergy. It is less likely that forest bioenergy will involve consumption of wood suitable for high value applications, such as sawlogs typically used for the manufacture of sawn timber’.

Having set the scene it notes that, given this complex and changing pattern of sourcing, ‘Biogenic carbon can make a very variable contribution to the GHG emissions associated with forest bioenergy. Consequent GHG emissions can vary from negligible levels to very significant levels (similar to or greater than GHG emissions of fossil energy sources)’, although ‘in some specific cases, forest bioenergy use may be associated with net carbon sequestration’ e.g. when the replanting or rotation rate is high.

Nevertheless ‘There is widespread recognition in the research literature that increasing the levels of wood harvesting in existing forest areas will, in most cases, lead to reductions in the overall levels of forest carbon stocks compared with the carbon stocks in the forests under previous levels of harvesting. Where the additional harvesting is used to supply bioenergy as the sole product, then such forest bioenergy will typically involve high associated GHG emissions (i.e. compared with fossil energy sources) for many decades.’

It is this that groups like Friends of the Earth (FoE) and Biofuelwatch focus on, claiming that this is now what is happening- to feed giant biomass combustion plants like Drax with wood pellets from North America, some of which are allegedly made from stemwood. Even so that doesn’t necessarily mean they are against the use of all biomass. For example FoE’s new report ‘Felled for Fuel’ focuses on, and objects to, ‘burning trees for electricity’. Instead it wants the government to ‘refocus support for bioenergy on the use of feedstocks such as agricultural and forestry wastes and biogas from sewage, food waste and other organic wastes’ and also to limit the use of the available sustainable biomass ‘to modern combined heat and power (CHP) plants which would ensure the most efficient use of these limited feedstocks, making use of the energy for heat as well as generating electricity’.

FoE does see overall biomass use as being constrained though by more careful assessment of sources and their bio-impacts. It calls for ‘the government’s ambitions for bioenergy to be scaled down and capped at a level that ensures supplies can be
sourced sustainably and domestically’. That raises many issues. Some see bio-conversion of big old coal plants as a useful stop gap, but if that’s not on, then others look to specially grown energy crops as a viable new source, in addition to wastes. And to the use of wood for heat production at the local level. It’s a broad ranging debate.

DECC’s new, long awaited, Bio-carbon Calculator may help clear the air a bit in relation to large scale biomass conversion plants. DECC uses it to assess a range of scenarios for the net carbon balance that would be associated with North American biomass used in the UK, with different land use changes assumed. It concludes that ‘in 2020 it may be possible to meet the UK’s demand for solid biomass for electricity using biomass feedstocks from North America that result in electricity with GHG intensities lower than 200 kg CO2e/MWh, when fully accounting for changes in land carbon stock changes. However, there are other bioenergy scenarios that could lead to high GHG intensities (e.g. greater than electricity from coal, when analysed over 40 or 100 years) but would be found to have GHG intensities less than 200 kg CO2e/MWh by the Renewable Energy Directive LCA methodology’.

So it can produce more emissions than coal, but also, done right, with proper choice and regulation of sources, it can be fine. The Renewable Energy Association agreed: ‘Anyone using biomass in accordance with the guidelines set out by the UK government would be lower-carbon than other fuels.’

However DECC says the energy input requirement of biomass electricity generated from North American wood used by the UK could be significantly greater than other electricity generating technologies, such as coal, natural gas, nuclear and wind. That may limit its use. But DECC says Energy Input Requirements can be cut e.g. by reducing transport distances and the moisture content of the biomass. So overall it sees some projects as viable.

Will that end the debate? Unlikely! FoE said it was vital to have tougher regulation and clearly it’s not convinced that stem wood isn’t being used. But at least the various stakeholders are almost now on the same analytical page, or ought to be, in relation to biomass conversion! How they then decide to respond in terms of strategic development priorities is another matter. Interestingly, DECC won an appeal against a Judicial Review ruling that required it to reinstate a large DRAX biomass conversion project which it had turned down. So it won’t now happen. And DECC has also said, in its allocation statement for future CfD rounds (limiting them to £205m p.a.), that it was‘ not at present intending to release a further budget for biomass conversion’, i.e. after the current ‘early’ CfD round. Clearly biomass conversion is something of a hot potato!

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Bio-energy in the UK

By Dave Elliott

There is a lot going on in the bioenergy field in the UK, with the government keen on biomass conversion of large old coal fired plants like the 4GW Drax plant in Yorkshire. That’s based on importing wood pellets from North America, something most greens are opposed too (see my last post), especially if it uses whole trees, as some allege:


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Imported wood combustion? Some say it’s fine..others disagree

By Dave Elliott

Many environmentalists are not keen on using imported wood pellets in old inefficient converted fossil-fueled plants. They say there are better ways to use biomass and better sources- local anaerobic digestion of biomass wastes and residues, along with Combined Heat and Power (CHP). Large-scale biomass conversion, and even co-firing with coal, is sometimes portrayed as an interim option, getting biomass use established, but not everyone is convinced that this helps build up support for local sourcing of biomass. It’s just a way to keep old power plants going, so as to avoid having to write off some sunk costs.  There is also the wider debate about the extent to which large-scale combustion of grown biomass, especially from forests, is net low carbon, given that it takes time for new growths to absorb emitted CO2. It’s even been claimed that using wood from trees might lead to more emissions net than from using coal, depending on the source of the wood: 


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Talking renewables up – and down

by Dave Elliott

A meta-analysis by NREL staff, comparing the various quantitative scenarios that have emerged with very high penetrations of Renewable Energy in the power system for a range of countries and regions around the world, concludes that they show that renewables  ‘can supply, on an hourly basis, a majority of a country’s or region’s electricity demand.’


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Bioenergy is good

by Dave Elliott

In a new book ‘The Sleeping Giant Awakens-Bioenergy in the UK’ (Alba press), Stewart Boyle, a former green activist turned energy consultant and woodland owner, who has worked in the bioenergy sector for 12 years, sets out a strong critique of the current status of bioenergy in the UK. Controversially, he takes issue with the conclusions of some green pressure groups who have of late opposed reliance on biomass. ‘Having reviewed the science and the arguments, I feel that some of the NGOs have lost the plot on bio-energy and are using really bad science without thinking through their long term energy strategy.’  He claims the UK could get at least 10% and maybe over 20% of its energy frombioenergy in heat, transport, power and bio-chemicals.


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Biomass for energy debated

By Dave Elliott

The use of biomass to produce electricity need not cause significant land-use tensions and Government should look to support the development of this type of power generation with Carbon Capture and Storage (CCS), according to a new policy statement by the Institution of Mechanical Engineers.


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Biomass burning – worse than coal

By Dave Elliott

The Climate Change Committee’s report on bioenergy last year argued that, at best, the UK might only get 10% of its energy from bio sources by 2050. The subsequent DECC/DEFRA/DfT Bioenergy Strategy was a lot more positive, as was the parallel DECC Heat Strategy. It claimed that biomass could supply up to 21% of the UK’s energy by 2050:

Certainly it has attractions. Consultants Deloitte say “As the amount of intermittent generation technologies in the UK’s energy mix increases, flexible fuel sources that can provide stable and predictable electricity will become increasingly more valuable. Sustainably sourced biomass could provide this stability.”


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Biomass limits (Part 2)

Liquid biofuels for transport, but also other types of biomass production and use, have been promoted as away to reduce greenhouse gas emissions, boost rural development and ensure energy independence. However this approach has run up against major constraints, including land-use and biodiversity issues. Moving to second generation non-food biofuels, and also biomass wastes, may help, as may tighter regulation (see my previous Blog–1.html

But there may also be clever approaches that avoid some of the land-use limits of biomass.

Perhaps the most obvious is to use biomass differently. Biogas production via anaerobic digestion (AD), e.g. of bio wastes, is widely seen as a good idea – coupled with using the gas grid for delivery. You can then use it for heating. But you can also use biogas in car engines. For example, it’s been claimed that methane through AD requires only about a quarter of the land area ethanol requires, and is a far more efficient fuel than ethanol, easily used in cars and trucks. There are certainly enthusiasts for it in the UK and elsewhere:
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Another option is to produce hydrogen by thermo-chemical processing of biomass/wastes, as proposed by Karl-Heinz Tetzlaff, possibly combined with CCS.

The hydrogen can be used for heating, possibly admixed with methane and delivered via the gas main; in fuels cells; or as a vehicle fuel direct. Or it can be used to make syngas /ammonia.

There are however some efficiency penalties involved with these various conversions. A PhD thesis by Anna Suess from Eindhoven Technical University looks at biomass as a CO2 saving technology. She compared synthetic natural gas (SNG), methanol, Fischer-Tropsch fuels, hydrogen and bioelectricity. Although she concludes that the overall practical resource is limited, the best option evidently proved to be converting biomass into electricity and using that to power electric cars. ‘First of all, biomass can be converted efficiently into electricity. Electricity can also be generated in smaller plants, which reduces the need for transport. And finally, electricity is a clean and efficient energy source for vehicles’. That certainly fits with the current vogue for an all-electric green energy future with cars run of electricity from renewable sources, but whether bio-conversion is better than electrolysis (e.g. using wind generated electricity) is far from clear- although you can store biomass.

However there are also more radical approaches. For example , “Breaking the Biomass Bottleneck”, a report by Henrik Wenzel (from Concito, a green ‘think tank’ in Denmark), suggest that we could upgrade biomass by hydrogenation, using hydrogen produced by the electrolysis of water, powered by excess electricity from variable renewables like wind. The report claims that you can react biomass with hydrogen ‘to produce hydrocarbons of much higher energy content and energy density than the original biomass. Moreover, using the biomass and the biogenic carbon from hydrogenation in central applications like heat and power , it is possible to collect the CO2 from the biomass and further recover and recycle it in a process here called Carbon Capture and Recycling, CCR. This will further multiply the use of the biogenic carbon from the biomass. Overall, upgrading and recycling biogenic carbon by hydrogenation and CCR, can approximately five-double our biomass potential for providing storable and high-density fuels and carbon feedstock compared to the presently applied technologies for converting biomass to fuels and feedstock.’

This sound wonderful- something for nothing, although, not really, since it can’t invalidate the laws of thermodynamics. But, the report notes, even with electrolysis losses, 1 Joule of wind can save 1 Joule of biomass, by upgrading it. However, the report adds ‘The total energy content of the biomass and the hydrogen is, of course, greater than that of the fuels on the output side. If, therefore, hydrogen is sufficiently good for the demanded energy services in question, there is no sense in taking a detour of producing the carbon based fuels from the hydrogen. The conversion from hydrogen to carbon fuels as energy carrier is only justified by the inherent differences in the properties and qualities of the two’.

So it’s end-use utility that matters, especially as it costs more, given the efficiency loses. But even so, the report claims that it makes sense. Not only go you get a valuable green fuel, you can also store it easily and help balance variable wind and other renewables, while using less biomass and less land. Moreover, if the biomass used is replaced consistently and sustainably, and you capture the CO2 produced when the fuel is burnt, then you have an overall net carbon negative system- although the report says that transport uses are less attractive, since then you can’t capture the CO2.

There are also versions of this idea which just use hydrogen produced from wind derived electricity and carbon dioxide from the atmosphere, to generate methane, methanol or some other synfuel. See for example

It would in effect create a carbon neutral fuel from the movement of and COs in the air, and it could be carbon negative if the CO2 was collected after combustion. Moreover, it avoids biomass land-use issues entirely. However air capture of CO2 still remains very expensive, so biomass looks a more likely carbon feedstock for the moment.

All in all though, there’s some clever green chemistry emerging. For more see:]

Another very ambitious approach involves using algae, or other biomass, grown in desert areas, possibly coupled with CCS. It’s been argued that, if algae is grown at the yields that the IEA Task Force bio-energy says is credible, then a land area the size of 24 % of Australia (in practice spread around Earth’s deserts) would produce 90,000 TWh/y which nearly equivalent to the current global final energy demand of 98,000 TWh/y. Moreover if some of that algae /biomass is used in CCS schemes then we would have a powerful carbon-negative energy technology: BECCS – bio-energy with CCS.

The Global CCS Institute has just produced a report which concludes: ‘there is a widespread unawareness of BECCS amongst policy makers, and also a lack of research and demonstration programs directed at the BECCS segment of climate mitigation measures. The insufficient efforts in research and deployment of BECCS are detrimental not only for the biomass industries, but for climate mitigation policies in general. Studies show that billions and trillions of Euros could be saved by including BECCS in mitigation portfolios. There are also large benefits to be gained in developing joint transportation and storage systems for fossil fuel CCS and BECCS, as this would increase economies of scale and lower the costs’.

One way to do this might be by growing algae in a Seawater Greenhouse As I’ve noted before, the first commercial SG scheme is up and running in Australia and more are planned around the world, possibly in conjunction with CSP technologies, to desalinate water. See

For food or algae production, as well as energy and water, you have to provide nutrients. One way to do this might be to stir up the sea-bed near the water entry point and suck in the sediment, then filter and dry it. Of course there are many uncertainties in relation to, for example, costs and impacts on fragile desert and marine ecosystems. However, the Dutch routinely use ocean sediment, allowing the saline content to drain back to the sea. Clearly, if this is to be done on any scale, we will need some detailed Life Cycle Assessments first.

Certainly many ‘greens’ are worried about the use of biofuels to keep the cars (and planes) going for a range of reasons.. See for example:

Moreover, in terms of electricity and heat production, many would see conventional flow renewables, like solar, wind, wave and tidal power, as a better bet, with fewer eco impacts: e.g. see Mark Delucchi’s biomass LCA studies: Ann. N.Y. Acad. Sci. 1195 (2010) 28-45 and Biomass and Bioenergy (2010), doi:10.1016/j.biombioe.2010.11.028

The debate continues, with the latest input being a fairly critical report from the RSPB: ‘Bioenergy: A Burning Issue’, which says the rush to build new power stations in the UK will mean that imports of the wood needed will have to rise from 13% to 68%- three times higher than the UK’s total current wood production. [

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