Small-scale biorefineries, while at an early stage, hold enormous potential for the EU bioeconomy, particularly for rural and coastal diversification and regeneration
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In 2012, the European Union published its ‘Bioeconomy Strategy’, highlighting the benefits of establishing a bioeconomy in Europe and recognising its potential to meet future challenges, including climate mitigation, fossil displacement and food for a growing population.

The bioeconomy will play a key role in maintaining and creating economic growth and jobs in rural, coastal and industrial regions, while improving the economic and environmental sustainability of primary production. Rural regions, in particular, stand to benefit greatly from the emerging bioeconomy.

700,000 jobs expected to be created within the EU bioeconomy by 2030


Of the 700,000 jobs expected to be created within the EU bioeconomy by 2030, 80 per cent of these will be in rural regions. The Star-Colibri 2030 Biorefinery Roadmap emphasises specific opportunities for farmers in a bio-based economy, including development of new business models and jobs in rural areas; creation of new markets and a wider variety of products; capturing more value on farms by providing semi-finished goods for biorefineries; supplying raw materials to biorefineries; and improving levels of valuable components in crop varieties through genetic modification.

The bioeconomy strategy further highlights the role that the bioeconomy can play in the development of rural areas by promoting biomass supply and demand actions with regional dimension, supporting the creation of supply chains for bio-based industries, and the establishment of a network of small-scale local biorefineries.

Key enabler of a circular bioeconomy


Biorefineries are a key enabler of a circular bioeconomy, providing significant opportunities to ‘do more with less’ and to address many of our key challenges as outlined and implemented through the UN Sustainable Development Goals.

There are several definitions of a biorefinery and biorefining. Two widely used definitions come from the International Energy Agency and the National Renewable Energy Laboratory respectively: “Biorefining is the sustainable processing of biomass into a spectrum of marketable products and energy”; and “A biorefinery is a facility that integrates biomass conversion processes and equipment to produce fuels, power, and chemicals from biomass”.

Biorefinery is no longer a niche area. A recent study by the Biobased Industries Consortium (BIC) and Nova-Institut reported that, across Europe, there are 224 biorefineries where biomass is transformed into a large variety of chemicals and materials.

These include ‘Sugar-/starch based biorefineries’, producing bioethanol and other chemicals (63), ‘Oil-/fat-based biorefineries – biodiesel’ (64) and ‘Oil-/fat-based biorefineries – oleochemistry’ (54), ‘Wood-based biorefineries’ (25) excluding those that produce pulp for paper only, ‘Lignocellulose other than wood’ (5) and finally ‘Biowaste-based biorefineries’ (13).

There are a number of classification systems used to describe biorefineries. Norden identifies five main biorefinery concepts, primarily based on feedstock used. On this basis, a biorefinery taxonomy with colour-coding is established as follows:
• Yellow borefinery, processing recalcitrant yellow biomass, straw, stover and wood
• Green biorefinery, processing green grass and other fresh/green plant materials
• Grey biorefineries processing agro-industrial waste
• Blue biorefinery processing marine biomass, from fish waste and discard, and macroalgae
• Brown biorefinery, processing sludge from wastewater treatment.

This classification, however, excludes a number of potential feedstock possibilities, including sugar (e.g. beet, cane) and oil crops (e.g. rape seed, used vegetable oil). Another classification system for biorefineries has been elaborated by IEA Task 42, with a focus on four main features: feedstocks, processes, platforms and products. Feedstock is the renewable raw material (biomass) that is converted into marketable products in a biorefinery.

Fig 1: IEA Task 42 biorefinery classification system

Processes are the mechanism by which feedstocks are transformed into final products and energy and are usually divided into four subgroups: mechanical/physical, biochemical, chemical and thermochemical.

Cascade use principle


Platforms are intermediates which link feedstocks and final products. The platform concept is similar to that used in the petrochemical industry, where the crude oil is fractionated into a large number of intermediates that are further processed to final energy and chemical products. Products can include both energetic and non-energetic products.

Fig 2: Biomass value pyramid

In the 2015 Circular Economy Package, the European Commission encourages the cascading use of biomass, recognising its innovative potential for new materials, chemicals and processes.

The Biomass Value Pyramid demonstrates how biomass can be optimally cascaded firstly into high-value, low-volume products including products for the pharmaceutical and fine chemicals market; secondly, into relatively high-value and high-volume products including food, feed, proteins, functional chemicals and bio-based materials; and lastly, into high-volume, low-value energy products such as fuels and electricity.

In principle, a biorefinery can promote a cascading approach to biomass, by converting biomass and residues into food or feed, value-added products and energy in an integrated system.

Optimally, a biorefinery process will produce a profitable combination of value added products, while at the same time producing enough high-volume products which offer a much greater capacity to reduce CO2. The SOFIPROTEOL group, for example, has developed an integrated network of oil crop based biorefinery systems centred around the transformation of 4.1 million tons a year of oil seeds.

SOFIPROTEOL serve the needs of both food/food (LESIEUR), oleochemicals (NOVANCE, OLEON) and fuel markets. Bio-based products are developed from the co-production of biodiesel, which generates glycerine, rape and sunflower seed oil medium chain fatty acid methyl esters. In addition to food, feed and fuel products, value-added products are produced, including biopolymers, bio-lubricants, biosolvents and chemical intermediates serving a wide range of applications.

Different rules apply in a bio-based economy


In the bio-based economy, thus far, the emphasis within the EU has primarily been on large scale plants where economy of scale is seen to deliver cheaper products as in the chemical sector. This is reflected in the large number of flagships plants supported by the H2020 Bio-based Industries Joint Undertaking (BBI JU). This approach mimics the status quo of the petrochemical sector.

Lange has identified that due to the high heat requirements of reactions in petrochemical plants, the petrochemical sector benefits from economy of scale and large petrochemical plants, or even clusters of large plants, which facilitate heat transfer, are preferred. By comparison, many industrial biotechnologies do not have the same heat demands. Another factor impacting scale is the feedstock.

In the bio-based economy, large quantities of water (more than 80 per cent in some cases) are being transported long distances to large scale biorefinery facilities, incurring significant financial and environmental costs. In the Netherlands, for example, half of the variable costs of beet refining are associated with transportation of the nearly 80 per cent moisture, sugar beet. There are additional significant costs associated with the return of minerals back to fields, including concentration, storage and logistics.

Design rules for small-scale biorefineries


As noted by Richard, there is an obvious push-pull in the bio-based economy between economy of scale for conversion facilities and diseconomy of scale for feedstock supply chains. The comparison, therefore, with the petrochemical is much more complicated than it may seem, and new rules may apply in the bio-based economy, which could allow the scale of biorefineries to be reduced compared with fossil-based systems. Wageningen UR have identified a number of other design rules associated with small-scale biorefineries including:
• The right combination of small scale (pre)processing and additional centralised processing;
• Products for a local or domestic market;
• Use of modular, transportable units allowing the process to be applied at several locations;
• Minimising man-hours through automation and central support.

Small-scale biorefineries, while at an early stage, hold enormous potential for the EU bioeconomy, particularly for rural and coastal diversification and regeneration. Small-scale plants significantly reduce absolute capital investment requirements, as well as relative capital costs per unit product, a key barrier to uptake of bio-based technologies.

This should help to de-risk investment and improve the speed of innovation within the bioeconomy. As small-scale technologies can be less expensive and the costs of raw materials can be irrelevant, farmers can be both producers and processors, and rural employment can increase.

These technologies, therefore, represent a model through which farmers and foresters can become more central stakeholders in the bioeconomy. The large degree of automation being considered within small-scale prototypes will improve accessibility for farmers and contractors to become bio-based entrepreneurs, rather than simply biomass suppliers.

Opportunity for farmers to become equal players


There is, therefore, an opportunity for farmers to become equal players and secure a fairer share of the bioeconomy value chain. In small-scale biorefineries, biomass is broken down, or fractionated into molecular or structural components including fibres, proteins, amino acids, (fermentable) sugars, oil, nutrients and value-added materials (e.g. bioactive materials), which, when combined, can significantly increase the overall value of the biomass.

Grassa BV, for example, allows small-scale, local processing of high-moisture fresh grass, into protein juice, press cake fibres, value-added sugars and fertiliser. This mobile system has already been demonstrated with farmers in the Netherlands and Belgium, offering the opportunity to increase the value of grass by doubling the usable protein per hectare. Mulder et al (2016) has highlighted the need to find a durable protein supply for humans and animals in the future.

The role of biorefinery will be key in improving protein availability. The GRASSA BV unit separates the grass into a protein rich juice fraction suitable as a non-GMO soybean substitute for chickens and pigs, value-added sugars in the form of fructo-oligosaccharides, and fibres with resistant protein, the most optimal form of protein for cattle. The fibre when fed to cattle as an optimised feed, shows an improvement in milk yields compared with unrefined grass. By optimising grass to increase the protein produced, GRASSA is helping to alleviate one of the key challenges facing the world in the 21st century.

Through innovative and efficient technologies, the scale of traditional processes can be reduced in a bio-based economy. Solvay’s production of Epichlorohydrin, for example, represents a cost-competitive, eco-efficient production of a drop-in biochemical. This highly reactive building block, used in the manufacturing of plastics and epoxy resins, is traditionally produced from propylene in a three-step process.

Smart bio-based processing


An alternative two-step process starts from glycerol, a readily available byproduct from biodiesel production, which is produced through saponification of triglycerides from plants and animal sources. Glycerol is converted to dichloropropanol with hydrochloric acid in the presence of an acidic catalyst. This smart production route avoids the chlorination of propylene using toxic chlorine at 500 °C and yielding many other chlorinated byproducts.

According to de Jong and Jungmeier (2015), capital costs of producing chemical compounds can be greatly reduced by directly obtaining the required molecular structures from biomass. In such cases, the economic value of biomass feedstocks grossly exceeds the value associated with their caloric value.

In the bio-based economy, we see many technologies which operate at moderate conditions, for example, low temperature fermentation or the use of advanced membrane technologies instead of evaporation for concentration in downstream processing. Smart and efficient processing which avoid large heat and pressure demands, and harsh and corrosive conditions, can enable competitive production at potentially smaller scales.

Processing close to the farm


Limitations in optimal size for biorefineries are also determined by feedstock transportation needs, with larger plants demanding larger distances to fulfil feedstock requirements year round. Long transportation distances are especially harmful for feedstocks with high concentrations of water (transport of which is expensive but not effective), minerals, or organic components (required to maintain local soil quality).

Small-scale biorefineries tend, therefore, to favour feedstocks with high moisture content, such as sugar and grass. In the Prokris sugarbeet refining system, for example, an innovative and efficient solution is applied to reduce the large heat demands of traditional beet production and to avoid transportation costs. Through the addition of an anti-solvent, the solubility of sugar in water is reduced, allowing the crystallisation of sugar to occur at relatively high-water concentrations.

This replaces three processing steps of the traditional large scale sugar refinery with one efficient step, to allow competitive beet refining at a fraction of the scale17. Since the viscosity of the mixture is much lower than a sugar/water mixture, the sugar crystals can be harvested without the need for energy intensive centrifugation and the anti-solvent is recovered and recirculated in a closed loop system. The sugar can be sold locally, or transferred centrally with significantly reduced transportation costs. The smaller scale and localised supply chain means that unused nutrients can be much more easily returned to the farm.

Materials produced locally through small-scale units can be final products themselves or, alternatively, serve as intermediates in a decentralised system. In this case, the local unit is linked to a centralised processing facility where more intensive or sophisticated technologies can be applied at scale to upgrade these intermediates to value-added bio-based products (e.g. grass fibres could be blended with recycled plastic to produce a composite material).

Decentralised biorefineries


One example of a decentralised biorefinery model is the Zeafuels small-scale decentralised ethanol process. A demonstration factory is built in Lelystad (the Netherlands) for a 2000 m3/year capacity, 100 times smaller than maize to ethanol factories in the USA. The costs of heat exchange are reduced because concentration for the return of minerals and residual organic matter to the field is avoided. Distillation of the ethanol-water mixture is performed locally to a concentration of 70 per cent ethanol, which can be done with a simple low-cost short column, reducing transportation costs to a centralised plant.

At the central facility, removal of residual water from the ethanol-water mixture can take place at a facility in which the intermediate products of several small factories are combined. In this way, scale can be built in a gradual manner with the best environmental and societal benefits. Heat for the distillation process at Zeafuels small-scale plant is obtained using the waste heat that comes with converting biogas produced from the co-digestion of corn stover and animal manure into electricity.

Small-scale and decentralised models of biorefinery can act as an enabler of the circular economy within the agriculture sector and indeed within the broader bioeconomy. Not only does it promote the widespread and affordable use of agriculture waste streams to produce new bio-based products and energy, there is also the promotion of nutrient recycling, a key feature of the biological cycle within a circular economy.

In small-scale systems, only marketable products or intermediates leave the farm. The unused nutrients (especially N, P and K) that do not form part of the marketable produce can remain on the land and re-enter the nutrient cycle. In a centralised processing facility, the minerals, once removed from the farm, are rarely returned as doing so incurs significant costs on volume reduction and transportation. Additionally, in many cases a small-scale biorefinery can be combined with a biogas unit to use the residual stream as an energy source for the process or external heating.

Conclusion


As we transition from a linear economy to a circular economy, we can reflect that the rules which applied in the linear economy will need to be altered. Within the bioeconomy, small-scale bio-refinery offers a real opportunity to adapt circular principles while offering significant economic, societal and environmental advantages. Efficient small-scale processing can reduce energy required for transportation and heat, while keeping overall capital expenditure more affordable.

Processing locally and close to the farm using sustainable processing, helps to ensure circular agriculture principles, helping to maintain soil fertility and reducing overall greenhouse gas emissions. These technologies can also help to future-proof rural and coastal communities through diversification into new areas of the bioeconomy, resulting in the production of sustainable local produce, allowing farmers and foresters to play an equal role in the bioeconomy and see a greater share of the value chain.

Authors: James Gaffey is Biorefinery Specialist at the Institute of Technology, Tralee, working on the Horizon 2020 AgriForValor project and is Principal Investigator on Biobased Industries Joint Undertaking project ICT-BIOCHAIN. Johan Sanders is Emeritus Professor of Valorisation of Plant Production Chains at Wageningen University, Food and Biobased Research (FBR).

References


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http://www.engineersjournal.ie/wp-content/uploads/2018/05/a-bior1.pnghttp://www.engineersjournal.ie/wp-content/uploads/2018/05/a-bior1-300x300.pngDavid O'RiordanElecagriculture,biofuel,energy
In 2012, the European Union published its 'Bioeconomy Strategy', highlighting the benefits of establishing a bioeconomy in Europe and recognising its potential to meet future challenges, including climate mitigation, fossil displacement and food for a growing population. The bioeconomy will play a key role in maintaining and creating economic growth...