Advances in Biorefineries

In the future, many consumer products presently derived from fossil fuel resources such as oil, coal and gas, are likely to be derived from renewable and sustainably produced biomass resources. In addition to the production of liquid and gaseous biofuels used for transport, structural composite materials, reinforced plastics using wood fibres, pharmaceuticals, health promoting products and food sweeteners, bio-products from indus­trial waste gases, innovative packaging and filtration materials, green biodegradable chemicals including polymers and resins, fine chemicals for paints and adhesives, and many other products are being researched and developed using rapidly advancing biotechnologies. It seems highly likely that these products will make a major contribution through both niche and mainstream markets in the bio-economy of tomorrow.

Very small markets are possible for high value specialty biopharmaceuticals up to $100,000 per kg and biochemicals with a market price up to $1,000 per kg, down to relatively low value, bulk, commodity products such as biofuels at around $1 per litre. So the aim of a biorefinery business should be to extract as much value as possible from the biomass feedstocks by achieving the optimum product mix. Focusing on high volume, low value commodities is usually not the most viable strategy, but neither is concentrating on low volume, high value products. The potential process options are being evaluated through international collaborations such as in the IEA Bioenergy’s Task 42, Co-production of Fuels, Chemicals, Fuels and Materials from Biomass (www. ieabioenergy. com/Task. aspx? id=4) that was established in 2007.

The concept of a ‘biorefinery’ varies between a single feedstock converted into a single product (such as sugarcane to ethanol), single feedstock and multi-products (such as oilseed rape to biodiesel, high-protein animal feed, and heat and power generation from the straw), and multi-feedstocks to multi-products. This is analogous to an oil refinery processing a range of petroleum products and base chemicals. During the last century, the number of oil products marketed has grown from a few fuels and lubricants produced by the simple process of distillation to over 2,000 products today using complex thermal and catalytic cracking as well as reforming processes. Many of the lessons learned by process and chemical engineers can be applied to modern biorefineries and hence shorten the experience of learning-by-doing to add value to the bioenergy industry.

But biorefineries are not new. In the 1700s, the forest industry produced pitch, tar and resins, turpentine and rosin used in ship-building and the sailing of them, with some of these still being produced. The modern biorefinery concept has also existed for some decades as exemplified by the Norwegian company Borregaard, which has long used woody biomass from spruce to produce a range of biochemicals, biomaterials and bioethanol. Ethanol is only a minor, relatively low value product of their processing activities, along with the world market domination of some high value, specialist chemicals. The mix of products can be modified as markets dictate.

A strong economic business case can be made for integrating the production of conventional biomass products with new ‘bio-products’. This can provide new employment opportunities, and benefit the local and global environment by the recycling of biomaterials or significantly reducing greenhouse gas emissions to reach a very low carbon footprint. Moving towards a future green bioeconomy that the world requires will enable heat, power, biofuels and materials resulting from the traditional use of biomass feedstocks to be complemented by adding value through the new and emerging bio-product technologies.

Biorefineries can be designed to create intermediate products for processing into end-products in facilities elsewhere, or derive products ready for market directly on-site. Where an available feedstock is seasonal, multi-feedstocks may be needed to keep the biorefinery operating all year round. This can add to the complexity and cost of the front-end of the plant. Minimizing the costs of collection, transport and storage of the feedstock is another challenge that cannot be ignored when determining the optimum scale of processing plant.

The biorefinery concept, even in its simplest form, provides a more complete utilisation of the biomass feedstock than bioenergy alone. This book provides an excellent overview of the numerous opportunities for commercial viability as a result of the science being applied to the engineering concepts of biorefining. New pilot-scale and demonstration plants that produce biofuels and plastic composites from woody biomass have already been established in Finland, Canada and elsewhere, with many others planned using a range of feedstocks. Development of biorefineries usually requires a supportive government policy framework, as well as research and development support in order to overcome the existing technological, social and environmental barriers. For example, recently in

New Zealand, my own country, an international forest paper pulp company has received government support to build a demonstration biorefinery with the aim to utilise plantation forest residues as the main feedstock, and formed a partnership with an oil company and the forest Crown Research organisation.

The biorefinery model enables the agricultural and forest sectors to diversify their traditional markets and products, to become more energy self-sufficient, and to displace fossil fuel-based products with low carbon and renewable alternatives. In a future carbon-constrained global economy, the use of fossil fuels will be constrained and there will be increased demand for renewable and sustainable products arising from biomass resources. Consequently, biorefineries and their bio-products will play an increasingly important economic role. The world-acclaimed editor and authors of this book have helped advance the knowledge needed to achieve that goal and provided a vision for the global green, bioeconomy of the future.

Ralph E. H. Sims, Professor of Sustainable Energy, Massey University, New Zealand

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