Is bioenergy really sustainable?

Words by Patricia Thornley, SUPERGEN Hub Director

The use of wood for electricity generation has grown rapidly in recent years and this has led to concerns being raised about the sustainability and carbon savings associated with bioenergy, particularly imported pellets manufactured from U.S. forest residues. Firstly, this needs to be understood in context: only 2.4% of harvested wood in the south east U.S. was used for pellet production in 2014. That is largely because forestry is a commercial enterprise and the highest value product is the saw-log. Where possible foresters will sell this to high value markets to maximize profit and only the lower grade (cheaper) material will be used for bioenergy. It is possible that the bioenergy market could drive higher harvesting rates, but historically even when prices increased by 100% only a 3% harvest increase was observed.  It is possible that there could be further increases when new power plants are built, but the UK governments’ renewables obligation incentive has already implemented precautions to curb expansion.

The international accounting frameworks for greenhouse gases were developed in order to deliver national autonomy and responsibility: countries are assessed on the emission levels that are within their control/jurisdiction. This makes a lot of sense in terms of placing responsibility with the parties most able to deal with it, but is effectively usurped by the role of global trade.  This isn’t just an issue with biomass: every time the UK imports goods from overseas (food, electronics, plastics etc.) we are incentivizing carbon emissions in the producer country.

Bioenergy is not “carbon-neutral”. No currently available energy source is! However, sustainably sourced biomass can provide low carbon energy, which is valuable in reducing UK carbon emissions.  Bioenergy is actually the only UK energy source subject to protocols to calculate the actual carbon footprint of the energy being delivered.  Many of us carry out these calculations regularly and there is wide diversity, with some systems giving huge reductions compared to fossil fuels and others performing at a level that could be worse than fossil fuels.  The important thing is not to throw the baby out with the bath water and to continue to support sustainable bioenergy systems that are delivering real and much-needed GHG reductions today.

Sustainability criteria can ensure that only biomass with the lowest impact on the climate are used. It is important that such calculations take a comprehensive view of the supply chain and changes in forest carbon stock should be taken into account. It is relatively straightforward to carry out carbon balance assessments of supply chains and account for transport, processing and other emissions, but accounting for changes in forest carbon stock is complex. It requires modelling of forest management and growth, apportionment of the carbon stock change to different forest products and an understanding of the drivers of forest management.  It is also the case that the fastest carbon sequestration periods are actually in the earlier growth stages of a forest.  So once maturity is reached we have a large standing, sequestered carbon stock; but the amount of additional carbon being sequestered annually will have reduced significantly.  So it may make sense to fell the forest, use the prime products for applications that lock up the carbon sequestered and that frees up the land for re-afforestation, increasing the annual rate of CO­ sequestration again. It must also be remembered that forests are not generally established with the prime objective of sequestering carbon: they do this alongside delivering other important ecosystem and socio-economic objectives.  So it may not always make sense to manage for maximize carbon stock, since this might reduce biodiversity, recreational value or economic return and the reality is that forest carbon is not valued in any way that rewards management to maximize carbon.

It is right that we should focus on bioenergy systems with legislation and incentives to maximize greenhouse gas reductions, but we must also remember that over 90% of global biomass use is inefficient use of fuel wood in developing countries.  As populations and industrialisation in those countries increase there is a risk that deforestation may be driven by unsustainable fuel wood use.  Investing UK expertise to switch away from those inefficient systems would have much greater global impact than focusing on the relatively small proportion of global biomass that supports first world energy systems.

The Supergen bioenergy comic which you can download on this website, provides a general introduction to biomass sustainability and carbon balances, but for those who would like more detail, check out the other blogs from 3 leading UK researchers who explain the issues associated with:

  • the carbon balance of bioenergy systems
  • the international emission accounting framework and
  • the wider sustainability issues associated with biomass

I hope that these will clarify things for readers, but if you have any further questions please let me know.


Patricia Thornley

Seeing the wood for the trees: Forest bioenergy and greenhouse gas emissions

Words by Carly Whittaker, Rothamsted Research

There are a number of key points of concern that are raised by Chatham House that surround the calculation of net GHG emissions from the combustion of bioenergy from forest resources:

  • They state that the GHG emissions from providing a unit of energy from solid biomass are higher than those from the equivalent energy from fossil fuels.
  • They suggest that the demand for bioenergy will cause damage to future carbon stock sequestration potential of forests by changing shorter lengths, or higher extraction of wood or residues, leading to a loss in the carbon stock of forests. These changes may not be accounted for if exporting countries do not report under the second commitment period of the Kyoto protocol.

This article is an attempt to find common ground with these concerns and provide some context to the arguments. Please note that the ‘forests’ mentioned here refer to are existing plantation forests, rather than converting old-growth forests to plantations. It is widely acknowledged that old growth forests, and all forests, are highly valuable carbon stocks. If they are managed badly then significant losses of carbon can occur. This does not rule out all forest biomass as an important and abundant bioenergy resource that can make significant contributions towards mitigating climate change.

The ‘debt’ is in the detail

An issue which is central to the carbon sustainability of bioenergy is the difference between the emissions of carbon at the point of combustion and the removal of atmospheric carbon through the past growth and assumed future growth associated with the supply chain for the feedstock [2]. Biomass combustion is certainly not carbon neutral. It is also true that the GHG emissions from burning biomass to provide a unit of energy are higher than is it for fossil fuels- however these facts are often used against biomass but are taken entirely out of context.

When harvesting operations take place in a forest, changes occurs both in terms of a loss of stored carbon in the standing trees, and from disturbance of soil [3]. As the Chatham House report states, it takes around 10-20 years for soil carbon to ‘recover’ from the disturbance in the following forest rotation. The replenishment of the stock of timber in trees depends on the rotation of that particular forest, and the following rotation. In plantation forestry this can range between 30 and 150 years, though it is worth noting that for the longer (mainly hardwood) rotation forests the majority of stem wood would be highly sought after for structural timber. It is important to note that, upon harvesting, the carbon contained in the standing trees is converted to a combination of timber products (sawn timber, pulp, even chemicals) and harvesting residues [4]. The key message here is that ‘biomass’ for energy is not the sole product of forest systems, and when examining the full life cycle assessment of bioenergy systems, the role of carbon storage in timber products is important and long-lasting. This is even more so considering modern high rates of wood recovery, reuse and recycling. Timber harvested today can have a long life as structural timber (60 years) which can then be reincarnated as chipboard or panel board and last another 50 years [3]. When accounting for this stored carbon, the ‘emissions per GJ’ statement is obviously taken out of context.

Can’t see the wood for the trees

In practice, forests consist of multiple stands that are not all felled at the same time [3]. It is broadly acknowledged that analysing carbon flows on a single-stand level is restrictive and not suitable for policy recommendations  [4]. Taking a spatial rather than single-stand approach to the calculations has large implications on the estimated ‘carbon payback’ period [5,6,7]. At the scale of a whole forest or landscape, losses of carbon stocks due to harvesting may be counterbalanced by sequestration in the remaining stands which are still growing [8]. This is where stored carbon in the landscape also becomes an important sink of carbon, despite when harvesting for timber or fuel is occurring in one compartment of the forest. This factor again contributes towards the net GHG emission balance of the forest, even if the combustion of biomass occurs.

Changing stocks

Remember that biomass is not the only product from forests; and fibre price is the most significant cost in pellet production, therefore it can only afford the lowest value forest products [9]. There is a concern, however, that increased demand for this lower value material will see more of it leaving the forest that would otherwise have occurred. If this leads to increased thinning rates, or shorter rotations then there will be a net loss in carbon stock in standing trees, litter and soil. This is when bioenergy strays into the ‘carbon debt’ zone, as this stock has to be compensated for by some other activity, such as afforestation. This needs to be considered and is important, especially considering that this practice all falls under the banner of ‘sustainable forest management’ but can still lead to lower carbon stocks. But is this actually happening? This could become a complicated story, as the main reason people thin is to improve the remaining trees, not necessarily because they want to sell the smaller stem material. So is it realistic to assume that bioenergy prices alone will increase thinning rates? Evidence shows that the financial return from pellets alone is not sufficient to drive increased harvests either in Canada or Southeast USA [9], as there is general insensitivity in lower value pulpwood due to changes in value. In fact, an expanding wood pellet industry could potentially encourage more positive management of forests, by providing a market for the lower value materials (Dale et al., in press).


Despite conventional thought, money does indeed grow on trees. There is a general acceptance across the forest industry that where economic value can be derived from the forest, the forest will be more likely to be preserved as forested land. The Chatham House report does not present any new concepts or challenge to the biomass industry. It is accepted that the sector must be able to demonstrate that it is delivering GHG reductions in a sustainable way [2], though many of the methods employed assume carbon neutrality. Mechanisms for detecting changes in production, or accounting for changes in forest carbon stock still need to be refined, even if the evidence suggest that this is not an issue at present. Thankfully, from areas like North America and Europe we have sufficient data in which to base our analyses and observe changes, therefore a policy recommendation would be to focus on biomass originating from countries with less transparency on details regarding land use and forest management. Information gathering from industry and landowners will be key to understanding where decisions about forest removals are made. It is important to note that, on the academic-side, studies generally agree that bioenergy can play an important role in climate change mitigation and there is a risk of failing to meet long-term goals without it.

Bioenergy – A Low Carbon Renewable Energy Pathway

Words by Andrew Welfle, University of Manchester

The UK’s greenhouse gas (GHG) emission reduction and renewable energy generation targets have led to increased focus on low carbon renewable energy technologies to decarbonise the energy sector. Bioenergy is energy pathway that provides a major contribution to the UK’s current renewable energy mix and increased generation is targeted. UK Government energy statistics for 2015 (BEIS, 2016) showed that renewable energy contributed 22.3% of total UK power generation (bioenergy reflecting 13.7% of total power generation); 5.6% of total UK heat generation (bioenergy reflecting 5.3% of total heat generation); and 4.2% of total UK non-air transport fuel energy (all from biofuels). Large power stations fuelled by woody based materials from the forestry sector are the predominant contributor of bioenergy generated in the UK. The biomass fuel demand for these power stations is large and already far beyond the availability of woody biomass available from UK forests (Welfle et al., 2014). As a result the UK has a growing network of international supply chains importing biomass fuels such as pellets sourced from North American forests. The UK bioenergy sector currently consumes about 25% of global forest-based wood pellet production, making it the largest consumer worldwide. Over 90% of these wood pellets are imported making the UK the largest importer of wood pellets, reflecting over 40% of the globally traded feedstock (FAO, 2016).

For bioenergy to be a viable low carbon renewable energy option and replace fossil fuel generation, it is fundamental that the energy generated provides genuine reductions in GHG emissions. As a result there has been much discussion about the accuracy of GHG accounting systems and applied methodologies for forest-based bioenergy. As the scale of traded biomass has increased and international supply chains have become more complex, the scrutiny of the GHG impact of bioenergy has rightly also increased.

GHG Accounting Methodologies – Where Does Bioenergy Fit?

Bioenergy is an attractive renewable energy option for the nations like the UK as it can be easily transported and stored, is compatible with many elements of existing energy infrastructure and the important notion that it delivers carbon neutral energy – CO2 emitted through the combustion of the biomass, balances with the CO2 taken up by plants/ forests as they have grown. This concept of carbon neutrality has become the focus of much current debate; and therefore demonstrating that bioenergy pathways deliver energy with reduced GHG emissions compared fossil fuels is a barrier needing attention if bioenergy is to be truly regarded as a low carbon renewable energy.

The Intergovernmental Panel on Climate Change (IPCC) oversaw the development of the universally adopted methodologies and guidelines for accounting GHG emissions (IPCC, 2014, 2006). Within this framework nations are required to individually account all their emissions within a series of GHG inventories, including emissions from: Energy Generation; Industrial Processes & Product Use; Agriculture; Land-Use & Land-Use Change (LULUCF); and Wastes. Using a case study example of a bioenergy pathway where the UK generates bioenergy from pellets imported from Canada, within the IPCC’s accounting framework this bioenergy pathway will leave a different GHG footprint in both the UK and Canada, but also a different footprint across each GHG inventory within each country. Figure 1 has been developed to provide a stylised demonstration of how the GHG inventories of both the UK and Canada may be impacted through the UK generating bioenergy from imported Canadian forestry biomass.

Figure 1: Stylised Representation of the Life Cycle GHG Emissions Resulting from the Generation of UK Bioenergy from Resource Imported from Canada: Highlighting the Potential Emission Footprint as Attributed to UK & Canadian GHG Inventories under the IPCC GHG Reporting Framework

The bioenergy pathway documented in Figure 1 shows that overall Canada will benefit in GHG accounting terms as a consequence of producing biomass pellets for export. Within Canada’s LULUCF GHG Inventory the production of biomass for bioenergy can generate large-scale uptake of CO2 from the atmosphere. The biomass pellets (classified as wood products) represent a sink locking up carbon from the atmosphere, whilst the growth and regeneration of forests following successive harvest cycles provide a further mechanism for storing carbon. Any energy expended in Canada in producing, processing or transporting the biomass will generate GHG emissions accounted within Canada’s Energy GHG Inventory, and emissions released as a result of the degradation/ management of wastes will be accounted within Canada’s Waste GHG Inventory. The Canadian biomass pellets may then be exported where under the IPCC’s accounting framework any transport ‘bunker fuel’ emissions are accounted but not attributed to any national GHG inventories (UNFCCC, 2017).

Once landed in the UK any further energy expended transporting or processing the pellets will generate emissions allocated to the UK’s Energy GHG Inventory. Finally the pellets are combusted to generate bioenergy and in the process the stored carbon is released back to the atmosphere. Within the IPCC’s accounting framework non-CO2 bioenergy combustion emissions will be allocated to the UK’s Energy GHG Inventory, whilst released CO2 combustion emissions (assumed to balance those taken up during the growth of the biomass) are estimated but only recorded as a memo item within national GHG Inventory Reports (MacCarthy et al., 2015). Therefore in GHG accounting terms bioenergy provide an attractive alternative for the nation generating bioenergy in comparison to energy generated from high GHG emitting fossil fuels.

The IPPC’s accounting framework of allocating emissions to different national inventories, or not to any inventory can make bioenergy a highly attractive option for nations decarbonising their different GHG inventories – but the accounting framework doesn’t provide the true overall GHG performance of bioenergy. The reality is that in order to evaluate the GHG performance of a given bioenergy pathway, all emissions from the biomass supply chain, from the transportation steps, and from each bioenergy process need to be accounted collectively regardless to where they are geographically emitted.

A Better Approach for Accounting Bioenergy GHG Performance

Life Cycle Assessment (LCA) is a well developed and widely implemented technique for analysing the whole life cycle emissions of bioenergy pathways, where the respective balance of emissions from all the processes and activities within a given bioenergy pathways are calculated and summed up to provide an indication overall GHG performance. Again using Figure 1 as a stylised demonstration of GHG emissions across a bioenergy pathway – the overall GHG performance of this pathway would equate to the sum of all emissions emitted to the atmosphere minus those taken up from the atmosphere during the growth of the plants/ forests. Using this logic it is clear that achieving desired levels of GHG performance from forestry bioenergy pathways will rely heavily on the forestry production processes providing a favourable balance of carbon being locked up from the atmosphere.

Examples of specific LCA research where this is demonstrated include the UK Government’s analysis of UK power bioenergy pathways using North American pellets (MacKay and Stephenson, 2014). This research has been much publicised and widely used to discredit the choice of bioenergy as a low carbon renewable energy option. What this research actually shows is that where pellets are produced for bioenergy using bad practice techniques such as the intensification of forestry harvests or where land-use change occurs resulting in the large releases GHG emissions from carbon sinks, the resulting bioenergy was found to reflect poor GHG performance – the results of these bad practice bioenergy pathways being much publicised. The research also highlights that where pellets are produced for bioenergy using good practice techniques the resulting bioenergy was found to reflect highly attractive GHG performances compared to fossil fuel generation. The true message from such research is not to stop bioenergy, but to develop policies, regulations and supply chain reporting that stamps out bad practice.


BEIS, 2016. Digest of United Kingdom Energy Statistics (DUKES) 2016. London.

FAO, 2016. 2015 Global Forest Products Facts and Figures. Rome.

IPCC, 2014. Revised Supplementary Methods and Good Practice Guidance Arising from the Kyoto Protocol. Geneva.

IPCC, 2006. Guidelines for National Greenhouse Gas Inventories, in: Agriculture, Forestry and Other Land Use. Intergovernmental Panel on Climate Change, Geneva, Japan.

MacCarthy, J., Broomfield, M., Brown, P., Buys, G., Cardenas, L., Murrells, T., Pang, Y., Passant, N., Thistlethwaite, G., Watterson, J., 2015. UK Greenhouse Gas Inventory 1990 to 2013. London.

MacKay, D., Stephenson, A., 2014. Life Cycle Impacts of Biomass Electricity in 2020. London.

UNFCCC, 2017. Emissions from Fuel used for International Aviation and Maritime Transport (international bunker fuels). New York.

Welfle, A., Gilbert, P., Thornley, P., 2014. Securing a Bioenergy Future without Imports. Energy Policy 68, 1–14. doi:10.1016/j.enpol.2013.11.079

Sustainability of forest bioenergy: Integrating bioenergy into forest value chains

Words by Mirjam Roeder, University of Manchester

The UK consumes about 25% of all globally produced forest-based wood pellets mainly to produce electricity in large-scale power stations that typically contribute 4% to the UK’s electricity supply. This makes the UK the largest consumer of wood pellets worldwide. Over 90% of these wood pellets are imported making the UK the largest global importer – reflecting over 40% of all wood pellets traded globally. Most of these wood pellets are sourced from North America where pellet production makes up less than 1% of the forest products by weight (Abiom 2016). These wood pellets are produced from forest residues (tree tops, branches, bark and low quality trees) and sawmill residues (sawdust and off-cuts). Available forest residues are predominantly not used for bioenergy, but are either left on the forest floor to decay or are burned at forest landing sites or sawmills.

As with all renewable energy technologies, for bioenergy to be a viable it needs to deliver energy with lower emissions compared to that generated from fossil fuels. The evaluation of associated emissions, climate change impacts and carbon balances of forest bioenergy has been done for various supply chains. Such assessments capture a snapshot of the emissions of the specific supply chain and carbon balance of a forest stand but are also subject to many uncertainties. If practices and processes change along the supply chain this has to be considered and possibly re-evaluated.

The other challenge is that there are many uncertainties, related to the different inputs, materials and technologies applied and varying practices at each stage within the supply chain (e.g. how wood is produced, how the forests are managed, how wood is processed and feedstock produced, and what energy conversion technology are applied). Each of these variations can be fairly easy assessed, reduced and controlled to improve the overall performance of the process. It becomes much more complicated to assess and assume impacts and related uncertainties considering natural variations within the system (e.g., how a forest grows, how seasons vary from year to year); social, economic and institutional conditions; and dynamics (e.g. how living conditions, perceptions, markets or policy develops); also how the potentially limited knowledge and/ or understanding of natural and behavioural processes.

Still, the common assessments analysing supply chain emissions and carbon balance can provide us with sufficient information to the evaluate systems and indicate possible outcomes and trends. Even regarding the uncertainties, which are less predictable we can get a comprehensive understanding of the scale of the range of potential impacts. Looking at forest bioenergy supply chains, we have a good knowledge and understanding of what is “good”, what is “bad” as well as what are the shades in between. Evaluating lifecycle emissions and carbon balances of such supply chains, even taking account of uncertainties, helps us to understand how we can reduce emissions to meet our emission targets. It also helps us to improve practices along the supply chain to maximise benefits, emission reductions and carbon savings. Whilst also helping us to identify where our knowledge is limited and where we need to do more research to understand these things.

Although simply assessing emissions and carbon balances is not sufficient on its own. We also need to understand what the forest bioenergy system is compared to, as this determines the context and trade-off of such systems. So we need to ask the questions of what we want to achieve by introducing bioenergy into the current system – is it simply to generate low carbon energy, or is it to specifically replace another fuel, to create an income for stakeholders, to create jobs, to support environmental benefits, to improve energy security, or to support a specific population group or industry. We therefore have to understand how forestry products are currently used, what are the dynamics of the current system, what are the impacts or benefits, who currently uses the products, what is replaced or substituted, how does it affect other product supply chains, who makes the decisions about access and utilisation – who benefits?

Especially when looking at forest bioenergy this picture becomes very complex. Sourcing bioenergy feedstocks from forests is just a small piece of a big mosaic. Forests are diverse and provide many different products and services for many different markets and end uses – bioenergy currently playing only a minor role in terms of revenue and amount of material. Nevertheless, forest value chains offer the integration of conventional forest products like sawn-timber, pulp and panel and bioenergy through the utilisation of forest residues such as tops, branches and bark of trees or trees and fibre of marginal quality, like trees affected by fires, pests and disease.

There are various sustainability measures in place setting standards for forest management. In addition many European nations such as the UK have regulatory and incentive schemes that aim to ensure that only biomass compliant with specific standards are eligible for subsidies. This is to ensure that bioenergy delivers significant emission reductions compared to fossil fuel derived energy and at the same time is not sourced in a non-sustainable manner.

Forest-based bioenergy can offer a great potential by both providing renewable low carbon energy as well as sequestering atmospheric carbon. This could be supported by the proposed Renewable Energy Directive of the EU, which aims to include that biomass is only sourced from countries that have ratified the Paris Agreement and are reporting their emissions and sequestration from forestry and land-use. This means that these measures are stricter than certification scheme for non-energy wood uses (e.g. sawn-timber, pulp, panel), which are currently not linked to emissions and carbon balances from wood product use.

Nevertheless, such sustainability and emission standards only capture a specific supply chain and cannot provide a guarantee that these criteria are met on a level beyond this specific supply chain and forest stand. To understand the full picture of forest management, supply chain emissions and carbon balance we need to consider the forest landscape, which is the sum of the different forest stands in a forest. In other words, sustainability schemes cannot necessarily capture how a specific forest stand is managed outside a specific time scale (e.g. outside one rotation from forest establishment to harvest) in the long-term (repeating rotations) and across all stands part of the forest landscape and how the rest of the forest is managed. Moreover, the way the forest stand is managed for this one rotation can then have an impact on how the forest stand grows in the  following rotation.

It is important that such standards consider both ends and all involved actors of the supply chain – the supplier and consumer as well as related sectors and stakeholders along the supply chain. E.g., while the UK and EU incentivise forest bioenergy systems according to a specific emission threshold, the forest producers and managers in the producer nations are not necessarily driven by that but follow their standards of producing wood in a sustainable manner to be eligible for the main product markets, which usually is a wood product. This again shows that forest bioenergy cannot be seen outside the context of the forest sector. If policy makers and industrial sectors want to achieve high sustainability standards they need to consider and understand the different drivers and trade-offs for the various actors along the forest value chains. These might be very different depending on type of forest, management methods, main product markets and target groups for the forest products, hence we need to look beyond carbon and climate change impact, too.

Simply placing bioenergy into the energy sector will fail to ensure sustainable forest management and potentially forest carbon management. To ensure that bioenergy provides the required emission reductions and forestry maximises carbon benefits we need holistic and long-term approach to understand fully the impacts of forest management with integrated forest bioenergy; and not just forest bioenergy on its own. For this, assessments as well as sustainability standards and incentives need to consider why forests are grown, what for are the grown and who are the direct and indirect stakeholders and their trade-off of such value chains. Moreover, we need to consider what the drivers and benefits are for forest owners and managers and why they integrate or do not integrate bioenergy into their system. Hence, to understand the impacts of forest bioenergy we need context specific assessments, as environmental, climatic, economic, political and social conditions are various.

There is a robust scientific knowledge of the benefits and impacts of forest bioenergy and various research has shown that forest bioenergy can provide significant emission reductions and carbon stock benefits. Nevertheless, these are often subject to high uncertainties. Forest grow over many decades and therefore time of carbon sequestration and emission release from supply chain related activities and carbon release form burning forest biomass happen at a very different point in time. For this, we need long-term data to build reliable models to evaluate the impact of forest bioenergy integration and potential changes in management practices and with this on forest production and carbon stocks.

To ensure sustainability of and maximise carbon benefits from forest supply chains, context specific and transparent assessments based on real life date are required to make decisions on which value chains should be supported and which should not. This will help us to identify biomass sourcing and supply chain practices likely to have minimum impacts in line with climate change targets and sustainability standards.

Uncovering the mystery of the wood chip

Gina Castell investigates mysterious disappearances, talking to Ian Shield about research uncovering the mystery of the wood chip

‘Streamlining the Supply Chain’ project is focused on how a crop grows and how you maximise that crop. The energy crops are grown from scratch, but the project also deals with material straight out the forest. However, things got a bit complicated when a certain discovery was made.
It was discovered that a lot of crop yield suddenly disappeared through the rest of the supply chain. A supply chain maps out each stage, step-by-step, in getting a biomass material. A supply chain is how you harvest, store, prepare and deliver the material. Whilst streamlining looks at the losses at each of those stages.
If we know what the losses are, by measuring them, we can try to minimise them. We need to educate people, to spread knowledge saying ‘don’t do this! Be careful! You’re spoiling the life-cycle!’ Spoiling here refers to higher energy costs and harmful greenhouse gas emissions.
Material taken from the forest is low value but decent quality. They’re the ones that didn’t make it into the mainstream, the left overs like branches, brash and round wood. Some mixed woodland too, like conifers and broadleaf.
The biggest losses happen in storage. Wood material for energy is never going to be fresh, like fresh vegetables plucked out of the field. Because the wood is low value, people don’t put as much care into storing them. A lot of the wood is chipped, so these huge heaps of wood chips are left outdoors to dry out. They are dried-out by microorganisms in nature, carrying out microbial activity. Because of this drying, the wood chip loses weight and energy. Energy is lost as carbon dioxide and, the far more dangerous, methane.
Around 20% of the weight is lost. 20% sounds horrendous. However, although it’s not ideal, the practice is still sustainable. The main message is to not deliberately squash the wood chip heaps, as more methane could be released, the more powerful greenhouse gas. Instead, load it with a long reach (those dinosaur looking cranes) so the only squashing is from its own weight. Although work has been done across North America and Northern Europe, things could be quite different in tropical wet conditions, with potentially higher losses.
So remember, using chips is ok.
Just don’t deliberately squash them. It’s a climate killer.
Words by Gina Castellheim

Capturing the Invisible

Gina Castell investigates Research Encompassing Both Old and New Power through discussions with Professor Mohamed Pourkashanian

Reducing CO2. One of the big climate change challenges.
Most CO2 in the air comes from power plants and transport. A way of reducing this CO2 has now been discovered and is being developed for the commercial stage, where we capture and store it, using carbon capture technology. When we use Biomass Energy with Carbon Capture and Storage (BECCS or bio-CCS), the CO2 level emissions from power generation actually fall to net negative emissions. This just means that we’re capturing more CO2 than we’re releasing to the atmosphere.  When fossil fuels are burnt, carbon capture technologies are able to capture around 90% of the CO2 produced. This figure changes however when we consider emissions from mining and transporting the fuel. So this all adds up to produce higher CO2 emissions.
When we use sustainably produced biomass, the CO2 levels balance out between what is produced and what is captured – and so it can become ‘neutral’ or near zero. CO2 is absorbed by plants when they grow, so when we capture the CO2 produced from their combustion, we can achieve net negative CO2 emissions: Basically emitting lower CO2 than we produced in the first place – and removing CO2 from the atmosphere.
Last year, COP21 (the UN Climate Change Conference in Paris) set targets to tackle climate change. Every government committed to prevent a temperature increase of 2 degrees in the next 20 years. If the COP21 targets are to be met, then using ‘carbon capture technology and storage enabling technologies’ is essential. There’s no other technology out there that’s ready to be used globally. Carbon capture is the only way.
What the project is trying to do is to look at biomass to generate power. In other words, if we burn biomass, there is much less CO2. So using carbon capture technology with this makes generating power much more sustainable. This technology acts as a bridge between the two types of power, between conventional power and sustainable power, like wind and solar.
Biomass allows us to keep using conventional fuels in the future, but without the CO2 emissions. Countries can continue to rely on fossil fuels, as well as on a mixture of other power sources. So carbon capture makes things more flexible and increases national energy security.
A lot of work has been done on carbon capture from coal, but not so much from biomass. Researchers need to look at the problems we’ll encounter, so there’s a close relationship between industry and academics to see what the issues are.
The biggest obstacle is cost. Carbon capture means electricity costs will increase. Are customers happy to pay extra to mitigate climate change? Do people decide to reduce CO2 emissions? Or do we simply forget about climate change? These are just a few of the questions that pop up, not just with carbon capture, but with all renewable energy technologies.
At the moment, many companies are working on carbon capture from fossil fuels, but have been slow to embrace BECCS. It’s a large international community, involving the UK, US, China, India, South Africa, Mexico and more. In the future, the project hopes to broaden the biomass – from the more typical forestry residue, like branches, to include recycled material, like wood planks and other material which otherwise would have to be landfilled.
In a nutshell, the project is trying to ‘keep the lights on’ using biomass rather than coal, and capture the CO2.
Carbon Capture Technology is the bridge between old and new power.  So let’s march across the bridge! and make our way towards that COP21 target.
Words by Gina Castellheim.

Sugar, Oh Honey Honey. You Are My Candy Girl…Or Should I Say Energy Girl?

Although The Archies were definitely talking about sweet treats, Gina Castell talks to Miriam Röder about hub research using the sweet stuff for its own purposes.

Sugarcane, a common plant in South Africa. It’s known as a cash crop, because people earn cash with it (if you hadn’t already guessed). Sugarcane is mainly used to make sugar, but also bioenergy. When people talk about sugarcane bioenergy, people think of the biofuels that are used to run cars, like bioethanol. However, discussions have raged over issues of food fuel, from how the land is used to whether the land should even be used for fuel over food.
But we’ve missed something here. A sharp, pointy something. People seem to have overlooked what’s left once the sugar is gone. The remains.
When all the sugar has been collected from the sugarcane, farmers burn the sugarcane fields to get rid of the residue. The residue is made up of long, spikey leaves. The great thing is we can actually use these leftover leaves, instead of just burning and creating pollution.
(Burning sugarcane field)
Most sugarcane in the world comes from Brazil. Brazil has been making bioethanol for decades, so bioenergy from sugarcane is not new. Brazil even has cars that run on 100% bioethanol, not a drop of fossil fuels! Countries like the US have been buying bioethanol for a long time. The residue on the other hand is new territory. When people talk about using sugarcane as bioenergy, they talk about the cane, not so much the leaf.
The idea is to grow sugarcane as normal, for sugar in South Africa, but to just start thinking about bioenergy as an add on to this. So tweaking what currently goes on to include the sugarcane leaf. This is what ‘bioenergy integration pathways’ is.
This is a science project, but very much a social one too. It will open new opportunities for sugarcane growers in South Africa. Most growers are poor and only grow sugarcane for sugar. But using the leaf to produce energy in the future could see their incomes rise. Handing the leaf to bioenergy operators or even owning their own bioenergy equipment, bringing energy to the local community, could bring in more money. The extra energy, which they didn’t have before, could also be sold on.
At the moment, the plan is to spread ideas about what can potentially be done. Just getting people on board and getting them to start thinking about other options is a milestone. It’s all about trying to overcome unsustainable processes in sugar production, but also empowering grower communities and improving their energy access.
The project faces many obstacles. When speaking to locals, the biggest challenge they face is irrigation (pumps watering plants) as the pumps are poorly maintained. Climate change doesn’t help, as droughts and heavy rainfall cause further damage to the pumps. Crime means pumps get stolen and people feel unsafe irrigating at night. So there are social obstacles to overcome in South Africa, not just technology and economics.
How this project evolves really depends on the future of the sugar market. The price of sugar continues to fall lower and lower, which makes growing sugar harder. It might be that our diets change, or that sugar mills no longer see the point in producing sugar, or maybe something completely new is done with sugar residue as making materials from bio-based stuff becomes more and more popular. Who knows? It’s hard to say. We’re pretty sure sugarcane doesn’t end with sugar though.
To the question of spreading research worldwide, Mirjam explains that you can try, but different communities work differently. For instance, there was the plan to bring Brazilian technology to Mozambique, Africa, but it failed because of political and social problems. The project knows that you need to be very sensitive, especially with poor communities, with how you introduce bioenergy.
There are many roads to take with sugarcane, to do something else aside from sugar, so lets branch out. If one thing’s for certain, its that sugarcane leaf is not waste and can be used for bioenergy.
After all, one mans trash is another mans treasure.
Words by Gina Castellheim

This Glasgow project turns your concept of control inside-out

Gina Castell explains why.

‘What goes up, must come down.’ – Isaac Newton.

The famous quote resonates with the project ‘Real Time Control of Gasifiers’, albeit with a few tweaks. The idea behind the project is what goes in, must come out: by controlling what we put into the gasifier, we can control what gas comes out of it. The project is about finely tuning the bioenergy apparatus, so it will run better and give off better quality gas, reducing harmful emissions once and for all.

Why so controlling?

Not all biomass is exactly the same, like how no two humans are exactly the same. Different biomass have a different make-up, so they create different products (varying gas, tar, ext.). Biomass is also seasonal. In one season you find one biomass, and in another season you find another, just like seasonal fruit and veg. To deal with this, it’s necessary to control the gasifier so it works with all the different types of raw material, come summer or winter.

A year since starting up, the project has looked at the need for temperature control. When temperature is controlled inside the gasifer, we control the product gas it creates. The project also looks at how balancing the air to fuel ratio helps give off better gas.

However, control is influenced by results from experimentation. The project mainly experiments with Miscanthus, a plant biomass, in the UK. There is also experimentation with control techniques, as we need something to measure, and the idea is to develop cheap ways to monitor tar. Two techniques being used are flame analysis and fluorescence. In flame analysis, if we put oil on a flame, it changes from blue to yellow. So we can see how much tar is in the gas simply by looking at the colour of the flame. However, fluorescence is not so easy. The gasifier is loaded with all sorts of things, all emitting different wavelengths. As a result, the researchers need to be selective with the wavelengths they decide to detect for tar.

Tar creates a sticky situation, clogging up pipes in the apparatus. The danger is that when this ‘unclean’ gas is used in gas turbines, the tar will get stuck to the turbine blades, reducing the effectiveness of aero-energy. To remove this danger, we simply optimise the temperature so less tar is produced.

In short, the goal is to reduce harmful emissions. A controlled system, one that is finely tuned to work with all sorts of biomass, will giveway to a new and improved gas. If we can get better quality gas, we can reduce emissions. Simple.

So we’re one step closer to a cleaner atmosphere.

Time to take control and embrace the wonder gas!

Words by Gina Castellheim

Searching for the new ‘fossil fuel’

Gina Castell collects bite-size version of innovate hub research going on at Newcastle. Find out how Professor Adam Harvey searches for the new ‘fossil fuel’ of the world.

The ‘Gasification Integration’ SuperGEN project at Newcastle is a trailblazer, paving the way with its innovative methods and shaping our bioenergy future. But already confused by the title? Here’s a quick low down of what’s going on in the lab.
Biomass is organic material that can be used for energy, from wood to plants to manure, even garbage!
Integrated gasification is when biomass is turned into a gas. This is done inside a gasifier, and the end result is cleaned product gas. Tar is a big issue here as it contaminates the product gas. Tar needs to be removed from the gas, so it is ‘clean’ and ready to generate power, to produce chemicals, hydrogen, gasoline and ammonia. Every step of this gasification takes place inside the equipment. So for the steps we have collection (of the organic stuff), pyrolysis (a fancy word for decomposition under high temp.) and gasification.
What’s the deal with integrated biomass gasification?
It’s an important step, not only in power generation, but also in turning biomass to products. The idea is to replace what currently happens, which is a chemical process that heavily relies on fossil fuels with biomass. It tackles the shortage of energy problem, which will inevitably happen. So it’s a pretty big deal. We currently use fossil fuels but they are quickly used up, like petroleum. So it’s a question of finding an organic energy source, so people use biomass and convert it into energy. Imagine a future where fossil fuels are no longer used, we can use biomass to sustainably supply the worlds’ energy, totally eclipsing the bygone fossil fuel age.
Gasification is a sustainable way of getting our energy, because a) low energy costs means it’s a money saver, and b) less energy is wasted. So what are we waiting for?
A big challenge with this is tar removal. Tar builds up inside the equipment and gets stuck inside the pipes. This creates a sticky situation, with the gas unable to be used until the tar is removed.
What has been discovered is a unique way of loosening the tar. Normally, tar is dealt with by using high heat and high pressure. However, the project has found that low energy plasma at room temp and atmospheric pressure does the trick. (Thunder is an example of plasma on Earth). The clean gas can then be used to make gasoline and generate power.
Right now, the knowledge is still new. But if we can industrialise this technology we can use it globally, not just in the UK. Some Asian countries already use biomass for heating, and it’s only a matter of time before biogas catches on all over the world, becoming the key sustainable energy source.
The message here is move over fossil fuels! There’s a new biogas sheriff in town.
By Gina Castellheim

Picking at the fine grains of the SUPERGEN Rice Straw Project, Southeast Asia.

Gina Castell in conversation with Prof. Patricia Thornley at Aston University, exposes the environmental issues, climate change benefits and social impacts.

The Rice Straw project in the Philippines is really about two things. Firstly, there is a really big problem with rice straw. Farmers only have a short amount of time before they need to grow the next crop. There isn’t enough time to let the straw degrade naturally so people take the shortcut and burn the rice straw instead, despite this being illegal. This leads to catastrophic pollution problems.

Rice straw burning happens all across Southeast Asia and India, not just the Philippines. A big part of what the project hopes to do is offer people alternatives, where waste rice straw can be quickly removed and the land freed for the next crop, without the massive pollution.

Energy access is also a big part of the project. At the moment, there are 1.2 billion people in the world with no access to clean energy. Although many have access to biomass material, most simply burn it for cooking fuel. If we can swap what goes on now for something much cleaner, then we can improve health and improve peoples lives.

Researchers believe that rice straw should be used as biomass for many purposes, including heat, light, cooking, manufacturing materials and transport fuel. Using biomass in this way leads to improved mobility, trade, educational opportunities and safer well-lit communities. This will transform rural areas and empower local people.

There is also the question of gender. Women in developing countries spend hours collecting firewood on a daily basis. But if rice straw were collected instead, the time spent and distance walked would be much less.

Expanding population in parts of the world comes as a warning. If people continue to collect firewood and use it inefficiently, deforestation will result. We are already struggling with deforestation, which is highly unsustainable for the planet. We’re not saying that all the rice straw could be used, but even if 20% could be harnessed, then we could get energy from that.

Prof. Thornley predicts that future global rice straw will occur in Vietnam and Southern India, particularly Punjab, where we see the biggest pollution problem from rice straw burning.

To sum up, the rice straw project is about resolving the environmental problem, whilst socially empowering developing countries through this new access to energy.

It’s an exciting time to be a rice farmer!


Words by Gina Castellheim