All posts by Matt Drew

Crescendo of activity in alternative fuel energy sector

If you’ll pardon the pun, activity is really heating up in the alternative fuel combustion market as a number of projects are commissioned this year. For Saxlund it’s a busy time and we are on schedule to deliver more than 13 alternative fuel handling solutions, supporting a variety of combustion and gasification projects in the UK alone. Most of these are now either waiting to be commissioned or already undergoing production trials.

Galliford Try Infrastructure, for example, appointed us back in 2016 to design and deliver the bulk fuel reception and handling technology for three waste wood gasification facilities in Barry, Boston and Hull, for the renewable energy company Biomass UK. All three projects are at an advanced stage, pending dry or wet commissioning, with project completion expected in the second half of 2017.

Galliford Try Barry Infrastructure Push floors
Galliford Try, Barry, Infrastructure Push floors

Other sites include the Tansterne Advanced Biomass Project in Hull for HRS Energy where the first of two fuel streams is already commissioned; fuel handling solutions for Bouygues Energies & Services at two waste-to-energy gasification plants, one at  Hoddesdon in Hertfordshire and the second in Belfast; a fuel reception and delivery solution for a pioneering green gas generation plant at Marston Gate in Swindon for Go Gree Fuels; three projects with Babcock & Wilcox Vølund A/S, for biomass powerplants at Templeborough in Sheffield, Margam in South Wales and in Teesside; and a fuel handling solution for M+W Group the lead contractor for the Surrey County Council SUEZ operated Eco Park,  at Charlton Lane in Shepperton.

Tansterne Advanced Biomass Project
Tansterne Advanced Biomass Project


Customers appointing Saxlund expect several things, but fundamentally they are looking for high availability, low maintenance solutions to ensure the plant achieves the projected output in terms of energy production, and in tandem with this the financial returns that shareholders are anticipating, without whom many of these projects would not be achievable. 

Engineers who have worked with biomass and other alternative fuels will appreciate the challenges and will, no doubt, have experienced some of the issues that these fundamentally difficult fuels can present.


Mouldering and stagnated fuel heaps and constant recourse to air lances and the like to remove obstructions and restore flow have plagued many sites over the years, with constant stoppages and downtime. As an engineering design house, we frequently find ourselves troubleshooting systems that aren’t delivering, either where the original design has been defective in some way, or where the finances haven’t allowed a sufficiently robust solution in the first place.

Maintenance, or more particularly planned preventative maintenance, is another area that sometimes doesn’t receive enough upfront consideration. While it might be tempting to push machinery fractionally beyond its operating window, unplanned maintenance shutdowns due to breakdowns are likely to be costlier to rectify with consequences to downstream processes and supply chain deliveries.

Tansterne Advanced Biomass Project in Hull Push Floor discharge conveyor

Fuel characteristics

Biomass and alternative fuels such as Refuse Derived Fuel (RDF), now on the increase in the UK, and Solid Recovered Fuel (SRF), share similar characteristics. They are typically non-free flowing, wet and liable to compact and will happily form bridges in silos and chutes. So the potential to disrupt downstream processes shouldn’t be underestimated.

Material characteristics can change too, delivery to delivery, and we frequently see over-optimistic expectations when it comes to feedstock quality and consistency.  Even a reasonably consistent input material like waste wood can throw-up surprises. One in ten truckloads for example may be largely or completely composed of fine dust. Others may be black and compacted having been stored too long.

RDF with mixed organic residues can be even more challenging. These factors may be outside your control and will test the capabilities of installed handling systems if the design is defective, resulting in poor or erratic material flow, stagnant product and costly periods of outage.

Future proofing

Over the lifetime of a plant, twenty-five years or more, its quite conceivable that fuel specifications will change too, or that you need to switch to a different fuel, say from biomass to RDF.  Planning for this at the design phase is also essential.

Returning to the fuel storage and handling projects in Barry, Boston and Hull for Galliford Try Infrastructure, future proofing the design specifically for this reason has been a key design focus from the outset.

Each site is similar with twin Saxlund Push Floor storage bunkers discharging waste wood into a conveying and screening system. This incorporates oversize material and ferrous metal removal and weighing systems before feeding fuel to twin gasifiers. At each site one of the Push Floors is designed to accept straightforward modifications to handle RDF, extending the operator’s fuel flexibly if supply pressures occur.   

Each system will provide on-site storage for approximately 600m3 of waste wood and is designed to discharge some 100,000 tonnes of fuel per annum.

Galliford Try Infrastructure, Boston, screening tower

Good design

Good design is clearly essential if you want a fuel feed solution that works from day one and is also reliable. The temptation to select cheaper ‘equivalent’ solutions will be attractive if CAPEX expenditure can be reduced, but it makes no sense if the result is higher operational costs to resolve fuel feed issues, with expensive manual interventions and costly fixes.

Design direction to provide sufficient fuel storage, plus reclaim and conveying systems, will also be dictated by site constraints and available space, factors that are sometimes overlooked at the early stages of project development.

Permitted vehicle movements for example including delivery hours and weekend working will also determine storage requirements and truck reception systems, and there may be environmental factors at play, including noise, dust and water run-off to consider.

Whether you are processing fuel onsite or relying on shipments from third parties, fuel cleanliness will also be important with a requirement for oversize and undersize screening and metal removal. Weighing and sampling might also be required to monitor quality and deliver fuel at precise rates to the combustion process. Together with reception systems, storage systems and reclaim conveyors, these are elements that need to work together seamlessly, and for the life of the facility. 

For Saxlund engineers key technologies for handling and storage revolve around activated surfaces and ‘first in, first out’ principles. This limits the opportunity for fuel to degrade and for most materials some form of Sliding-Frame or Push-Floor system is advisable. These make for dynamic rather than static storage and ensure that easily-compacted materials are kept on the move.

In general terms, a system design that favours vertical rather than inclined surfaces, broad rather than narrow channels and positive handling options such as screw-feeders and chain conveyors will minimise problems.

For most projects delivering the energy output required to make the plant viable will always be a major focus, but this shouldn’t ignore the fuel feed and handling aspects of a project. One is very much dependent on the other. Design features to overcome difficult fuel characteristics and to ensure full availability are clearly important.

Early engagement to allow a holistic approach is also beneficial and planning for changing fuel specifications, which may be outside your control, together with appropriate maintenance, must all be factored into the solution you choose. These are some of the reasons why clients select Saxlund International and with more than 60 years’ experience, we can ensure that bulk fuel handling solutions aren’t a weak link in your energy project too.

Is your fuel handling plagued by excessive manual intervention?

  • Biomass fuel feed – Avoiding failure

If you are currently operating or developing a biomass energy plant or gasification facility, then you’ll appreciate the importance of a reliable fuel feed and reception solution, to ensure long term plant viability and performance.

The same is true whether you are burning refuse derived fuels such as SRF, favoured in the cement sector, or RDF, and any number of alternative fuels from Municipal Solid Waste to Distiller’s Dried Spent Grain.

That said, the industry is littered with plant failures and facilities that simply haven’t achieved predicted energy outputs precisely because of fuel handling and storage issues. Why?

  • repeated interruptions in the fuel feed prevent the plant reaching peak efficiency or
  • excessive cost of unplanned manual intervention and troubleshooting, required to rectify issues, destroys the financial foundations and investment opportunity for the project.

Not only is this hugely costly but some plants may never reach their full potential or overrun extensively in time and cost just to get them operating at all.

The fuels we are talking about all have similar characteristics. They tend to be sticky, abrasive and cohesive with a tendency to compact and bridge. ‘Buyer Beware’ should be at the forefront of your thinking when considering a solution for your project as these properties can easily disrupt storage and conveying systems if the design is defective, resulting in poor or erratic material flow, with stagnant product and periods of prolonged outage.

Reception systems, storage and discharge, screening, reclaim conveyors, plus weighing and dosing systems, are all elements that need to work together seamlessly and for the life of the facility, twenty to twenty five years is typical.

So a full understanding of the handling and flow characteristics of the material involved becomes important, with a direct bearing on the engineering solution and long term plant reliability. Important considerations are:

  • Particle size
  • mass flow properties
  • density variations
  • moisture content
  • compressibility
  • engineering partner

Specialised in bulk material handling for more than 60 years Saxlund’s design approach focusses on activated surfaces and ‘first in, first out’ design principles. This limits the opportunity for fuel to degrade in the system, ensuring a continuous uninterrupted flow of product 24/7.

Today solutions are deployed across hundreds of sites in Northern Europe. Of the twenty or so biomass energy projects currently under construction in the UK, 13 have specified Saxlund fuel handling solutions incorporating either Saxlund Push Floor or Sliding Frame silos for fuel storage and discharge.

Bouygues Energies & Services, the company responsible for the engineering and construction of the UK’s largest waste-to-energy gasification plant currently underway at Hoddesdon in Hertfordshire, is just one example.

Plant longevity is another key factor. Slough Heat & Power, now owned and operated by SSE, and one of the UK’s largest dedicated biomass fired Combined Heat and Power (CHP) plants, for example has been operating since 2003 with Saxlund Push Floors feeding waste wood and recently installed a third Saxlund Push Floor fuel handling solution to feed additional combustion capacity with a 720m3 fuel reception area with live storage.

With over three years successful operation already completed RWE’s Markinch biomass power station in Fife is one of the largest of its type in the UK, burning over 450,000 tonnes of sustainable waste wood each year. Again the fuel storage and handling solution, developed by Saxlund, is a crucial element, designed to ensure uninterrupted operation 24/7. Read the full case study here.

As with all these projects the efficiency of the combustion process and energy conversion is clearly where much of the industry’s science and engineering is currently focussed, and rightly so. But a consistent uninterrupted fuel feed, when the material is typically sticky and difficult to handle, is just as crucial. Choosing the right engineering partner, plus a clear understanding of the material characteristics you are working with, will help to deliver maximum plant uptime, better reliability and improved confidence for all stakeholders.

You can find out more by visiting us online or visit us at RWM stand no 4D80. Why not call or email to book an appointment.

Why By-Products Are a Valuable Resource for The Food And Drinks Industry

 – Biomass handling in the food and drinks sector

Across Europe food and drink manufacturers have been piling into the bioenergy sector for some time, turning waste and production by-products into energy. Some are successfully producing sufficient energy – both heat and power – for their own needs, with surplus energy feeding back to the grid.

AD processes producing biogas from liquefied waste tend to dominate, but in some sectors dried production residues are also being used to fuel combustion plants, including fluidised bed boilers and gasification solutions.

Food waste is a valuable resource that should never end up in landfill

In the UK, we throw away some 14.8 million tonnes of food every year throughout the supply chain. This accounts for over 20 million tonnes of greenhouse gas emissions and 6.2 billion litres of water.

Around 40% of this food waste ends up in landfill where it produces harmful methane that has a Global Warming Potential (GWP) 21 times greater than carbon dioxide.

A significant change in the waste industry over the past few years has been the shift in mindset from waste to resource. Central to this shift is the waste hierarchy and landfill tax, which push waste materials higher up the value chain by increasing the cost of landfill and placing a greater importance on the principles of reduce, re-use, recycle and recover.

This is what the UK could look like in 2020 if we achieve zero food waste to landfill

  • Over 1.1 terawatt-hours of energy produced
  • Greenhouse gas emissions reduced by 27 million tonnes
  • £3.7 billion potential savings in the public sector
  • £12 billion saved by UK householders
  • £2 billion saved by UK PLC (retailers, manufacturers and caterers)

Coffee & Grain by-products are a perfect biofuel with a high calorific content

Coffee, or more correctly spent coffee grounds, are produced in vast quantities as a by-product of instant coffee manufacture. All those coffee pods and capsules that have brought new convenience to that morning coffee, once destined for landfill, is a perfect biofuel with a high calorific content.

Distillers Dried Spent Grain (DDSG) is another. It too is produced in huge quantities by an industry that produces millions of litres of spirits each year in the UK alone and is finding new uses as a biofuel in the drive for energy self-sufficiency. 

Resolving Sticky & cohesive material handling and storage problems

But these and other food and agricultural residues, such as palm kernels, make up a group of biomass products all with similar characteristics. The material is sticky, cohesive and non-free flowing with a tendency to compact and bridge.

For energy plant operators and developers, these properties can easily disrupt storage and conveying systems if plant design is defective, resulting in poor or erratic material flow, and periods of prolonged outage.  Excessive manual intervention and troubleshooting may be required especially at transfer points to remove blockages. This can be hugely costly and some plants may never reach their full potential.

Saxlund’s experience is ideally suited to resolving these material handling and storage problems. While the majority of bioenergy fuel handling projects we work on involve waste wood as the fuel – we are currently involved in 13 projects in the UK – we are also seeing an increase in projects within the food and drink sectors.

The ability to work with variations in the material composition

At one site in the UK for a major distillery business, a new fuel handling solution to feed Distillers Dried Spent Grain into an adjacent bio-energy plant is completing trials and testing. The system is based on the principles of activated and wiped surfaces, removing the opportunity for material to stick and build up in the system and restrict the flow.

The design involves a series of transport screws and elevating chain conveyors to transfer biomass cake 40 metres up and into an adjacent combustion plant. The standalone design ensures reliable 24/7 operation during production phases and is rated up to 30 tonnes per hour while ensuring additional handling system capacity for future expansion.

For this project Saxlund provided detailed consultancy with a number of design options, including live site trials for a section of the main elevating chain conveyor, to deliver proof of concept and project confidence.  The ability to work with variations in the material composition, including changes in moisture content, was a further design requirement.

Experienced solutions for the coffee drinks sector

Saxlund also has experience of handling coffee grain discharge solutions at a number of international coffee processing facilities. In the UK, for example, we recently completed the design and installation of a 150m3 capacity storage and discharge solution for handling spent coffee grounds used to fuel a fluidized-bed boiler.

Incorporating a welded stainless steel flat bottom silo, in place of conventional conical designs, with Saxlund Sliding Frame technology [click for more information here] at its base, the solution has been designed to provide an efficient and reliable storage and discharge system, with capacity to handle peaks in supply from freeze and spray dried production processes.

Measuring 12 metres high and four metres in diameter the silo sits on a base frame to allow vehicle access beneath the structure.  Pressed coffee grounds are pneumatically transferred to the top of the silo via separate blow lines while the reciprocating action of the Sliding Frame at the base of the silo continuously sweeps the material into a central trough which incorporates two separate screw conveyors to achieve the desired discharge option.

Unlike conical silos which rely entirely on gravity, the reciprocating action of the Saxlund sliding frame creates a ‘live base’ of material at the bottom of the silo to provide an entirely reliable and consistent discharge solution.

With both these projects, a full understanding of the flow characteristics of the material involved becomes important with a direct bearing on the engineering solution and long-term plant reliability. Particle size, mass flow properties, density variations, moisture content and compressibility are all important considerations. The composition of the biomass (or its source) may also change over time, and this needs to be factored into the system design to ensure a robust, enduring solution which can deliver an uninterrupted and consistent flow of material to ensure plant reliability.

As well as activated and wiped surfaces, Saxlund solutions also favour ‘first in, first out’ design principles, important where the calorific value of the material can degrade and for products that are likely to compact.

For more information on how we can help you optimise your existing biomass handling and storage systems or for turnkey engineering / visit … etc


Tel: +44(0) 2380 636330

Fax: +44(0) 2380 636343



UK data references:

The Secret Recipe for Efficient Energy From Waste Delivery

Challenging the status quo of conventional fossil fuel power stations.

The four crucial factors governing success for Energy from Waste (EFW) and biomass combustion projects continue to revolve around:

  • location
  • technology
  • fuel supply
  • investment

Ground Breaking Technology Will Win the Smart Money

Despite the challenge of what can be ground breaking technology, at least in its application to residual waste, the ever increasing interest in EFW projects appears undaunted.

This is because the environmental and financial returns stack up extremely well and it’s an excellent alternative to other intermittent renewable energy sources such as wind or solar.

Waste wood biomass and residual waste from domestic and commercial sources are certainly plentiful in the UK and  there is a trend to move away from large mass-incineration to smaller, more sustainable plants fueled by local recycling operations. There are a consistently growing number of EFW  projects in the pipeline and under construction, and smaller Combined Heat and Power (CHP) schemes. Saxlund, for example, is involved with a number of projects in the UK including Margam in Port Talbot, Templeborough in Sheffield and Port Clarence in Teesside. [Link to press releases]

Fixing Weak Links Can Be Costly and Time Consuming

Attention is starting to shift to less common Advanced Thermal Treatments (ATT) such as gasification or pyrolysis. While this technology has been around for many years, its application to municipal / residual waste as a feedstock is somewhat more challenging. You only have to look at one of UK’s largest advanced plasma gasification projects in the Tees Valley, known as TV1, which has been struggling recently with technical difficulties. At this scale, 1,000 tonnes per day, you would expect some initial teething issues as it’s the first of its size and type in the country. However there are a number of smaller, simpler ATT projects under construction in the UK based on previously proven technology.

Four Steps to Clean Energy at The Grid

Whatever the technology involved, the basic process remains the same:

    • A reception system to receive the fuel whether biomass, RDF, or another waste derived fuel, and then feed it to the combustion process. This may include systems including weighing, screening for oversize and ferrous and non-ferrous metal removal.
  • The selected thermal treatment, to release the energy from the fuel, the most challenging aspect (especially with gasification)
  • Conversion of the energy to produce electricity, heat and derived fuels
  • Emissions clean up

Enabling Optimum Plant Performance

While significant project attention is focused on the technicalities of the selected thermal process and the energy conversion technology to which it is linked, there is a real danger if front end systems for fuel handling aren’t as robust as the end point technology.

It’s understandable given the focus is on ensuring the chosen thermal process will deliver the efficiencies and energy output required to make the plant viable. However, if the design process fails to identify material handling efficiency it will have a direct bearing on whether the plant reaches its full potential.

Reducing Human Intervention in The Feed Process

Waste derived fuels and biomass are non-free-flowing with a tendency to bridge and compact. It means the flow can easily clog and block, disrupting dependent processes often with far reaching consequences, up and down the supply chain. Indeed, some plants may never reach their full performance or overrun extensively in time and cost just to get them operating at all.

Disruption or poor consistency in the fuel delivery will inevitably lead to costly plant shut downs, so it is important that the material handling aspects are treated as part of the whole project and not a separate add on once everything else has been decided. Automated ‘first in first out’ storage principles are also vital, an area where Saxlund continues to lead the industry.

Proven Technology with Efficient Results

Saxlund has been engineering successful material handling solutions for biomass combustion and EfW over many years.  Our goal is to deliver the lowest cost of ownership for the lifetime of the plant and to design out premature failure. To ensure bulk material handling isn’t the weak link in your energy project, read my article in Materials Recycling World [link to MRW article] or contact us for further information.

How Water Companies Save Up to £17,000K P/M

Increasing demands on water companies to meet environmental targets, reduce costly overheads and streamline operations have opened up further debate on alternative ways to be more profitable.

The UK Government and the Environmental Agency produced an evidence document in 2009 “transforming wastewater treatment to reduce carbon emissions”. The WFD (Water Framework Directive) set targets that good chemical status needs to be achieved by 2015.

So in 2016, today’s innovative water companies are shifting their focus from sewage disposal to energy generation.

Generating gas from sludge at large water treatment sites using anaerobic digestion and thermal hydrolysis infrastructures is a key part of the solution.

In a recent article in “Water and Waste Treatment Magazine” I discuss an effective solution that reduces costly overheads, transport logistics and processing waste. The in-depth article titled “Getting to grips with… sludge cake optimisation” covers and answers important areas such as:

  • What issues do water companies face from building new advanced digestion facilities?
  • Why do water companies need to transfer sludge between sites?
  • What methods are available for transporting it?
  • Why is sludge dewatering important?
  • How important is the quality of your sludge to you?
  • Why is the choice of storage systems important?
  • Why change from a hook lift container storage system?
  • What factors should be borne in mind when designing the Reception facilities on site?
  • How can costs of the process be reduced?
  • What’s the “transport system” cost / benefit?

See the full article here

In an article titled Sludge Management Water UK said: The recycling or disposal of sludge in a sustainable manner is a major challenge to the water industry”.  In a further statement they have said: “Many water companies have decided to increase renewable energy generation to offset the impacts of increased energy prices, to use their resources (e.g. sludge) as efficiently as possible”

The solution of dewatering of slurry and processing into cake reduces load volume representing 4:1 reduction in volume and enables a quicker turnaround of trucks, reducing transport and storage costs. This means 1 truck could be used instead of 4, typically the saving is around £10,000 to £17000 per month for a 100m3 truck loading silo.

If you would like to know more about how to reduce your cake handling costs and generate energy, please contact me on +44(0) 2380 636330

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Biomass Solutions, WfE and Bulk Materials Handling – RWM 2015 – Stand 4B33

Saxlund International is exhibiting at RWM 2015 on September 15th to 17th in halls 4/5 stand 4B33.

RWM is one of the biggest European events for companies researching & actioning the best solutions for resource efficiency and waste management.

Saxlund is a leading specialist in biomass combustion, Energy-from-Waste, alternative fuel systems for cement works and bulk materials handling solutions. We will be outlining our European-wide capabilities and the latest technologies we have deployed across a range of current and new projects.

These include small to mid-scale biomass fired CHP plants in the UK, Sweden, Estonia and Lithuania, energy from waste solutions in the cement industry, as well as new bulk materials handling solutions such as the new 3 million Euro contract to provide a state-of-the-art biomass multi-fuel handling system for a 40 MW green energy project in Margam, Port Talbot for Babcock & Wilcox Vølund, which is due for commissioning in 2016.

Saxlund’s involvement covers the design, manufacturing, delivery and commissioning of two fully automatic fuel handling systems, providing 100% redundancy, including  fuel reception, conveyor feed systems, mixing and fuel storage.

Due to begin production shortly, Saxlund will also be discussing experiences at the new 3.4MWe waste wood biomass CHP power station based at Twinwoods Business Park in Bedfordshire. Key components of the project include proven Saxlund fuel handling and push floor technology, conveyors, biomass combustion boiler and associated equipment feeding a Siemens turbine.

Managing Director Matt Drew says:

“The Renewable Heat Incentive offers a real window of opportunity in the UK for the development of small-scale, waste wood biomass plants, and we are busy collaborating with a number of new partners who see the value of consistent green base-load energy. There is increased interest across the board from energy producers, large business consumers and district heating groups for onsite CHP biomass power solutions. Appropriate technology, realistic project outcomes and the right investment partners remain essential, but at Saxlund the combination of our project management skills, our Combustion Centre of Competence and 100% success rate, put us in a uniquely strong position.”

With 60 years’ experience in delivering BioEnergy projects across Europe, the company holds patents on key technologies to improve feed and combustion efficiency which in turn reduce fuel costs and carbon emissions.

The Southampton-based company is currently collaborating with consultants, contractors and investors, to deliver biomass combustion solutions for combined heat and power (CHP) plants, district heating, electrical production and process steam for manufacturing. Solutions are capable of converting from 6,000 to 80,000 tonnes of waste wood per annum to produce renewable energy and heat, a fuel source that would otherwise be sent to landfill or exported.

To book your free tickets or find out more about RWM 2015 click here –  RWM 2015

Contact Saxlund  International and book an appointment to discuss waste management solutions at RWM 2015 here – Email: