Category Archives: Biomass Energy

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:

How to deliver low cost energy to cities and municipalities

Delivering low cost energy

Energy security and rising electricity costs are big issues for cities and municipalities across Europe, especially for those that rely substantially on large energy producers and imported fossil fuels for their power generation. Recent falls in the cost of fossil fuels, on the back of declining oil prices, have given some temporary respite but already energy costs are rising.

Matt Drew, MD of Saxlund International says: “Renewables, driven in part by government and EU targets, are helping and as a consequence wind energy in particular has been growing in importance at both a local and national level. This has allowed some municipalities to take back an element of control. However renewables are only a small part of the solution and they aren’t right for everyone. Moreover, large subsidies frequently hide the true cost of the energy produced, nor are they a base load solution – if the wind doesn’t blow and the sun doesn’t shine you still need conventional solutions for generating power consistently.”

So what’s the solution for delivering low cost energy?

Well clearly there isn’t one single answer. But part of the jigsaw and one which is especially relevant to dense urban areas, where there is a high demand for both heating and electricity, is locally generated Combined Heat and Power (CHP). Sometimes referred to as co-generation, CHP integrates the production of electricity together with useable heat in one single, highly efficient process. Capturing waste heat in this way and deploying it for use in district heating and other processes makes CHP up to 80% more efficient than conventional power generation. It means energy costs can be reduced by as much as 20%.

That’s a significant reduction. If you combine CHP with biomass fuels, in particular sustainable timber and waste wood from forest harvesting, then the gains are doubly attractive. Fuel costs are significantly lower and it’s better for the environment. There’s the potential to cut CO2 emissions by some 90% compared to gas.

For parts of Northern & Eastern Europe where forestry is plentiful, the opportunity hasn’t gone unrecognised and local biomass energy solutions in the 2 to 5MW range providing Combined Heat and Power are starting to play an important role in delivering secure, affordable, green energy.

With two year’s successful operation behind them, a new CHP plant in Falköping municipality, Sweden, commissioned by Falbygdens Energi from Saxlund International, is a typical example. The plant supplies district heating and electricity, producing 2.4 MW of electricity and 10 MW of district heating, from locally sourced and sustainable forestry including bark and other forest residues as well as virgin timber.

Kaunas Municipality in Lithuania and the city of Tallin in Estonia will also benefit when new biomass CHP plants come on stream in 2016. Both make use of local renewable timber and follow a strategic partnership between Saxlund International and Axis Industries to deliver state-of-the-art biomass combustion solutions. The 5MW electric CHP plant for Danpower Baltic in Lithuania will be entirely fuelled by renewable timber, while the larger 21.4 MW electric solution in Tallin for energy company Utilitas will burn woodchip combined with 30% peat to deliver 20% of the municipality’s heat demand.

Small-scale biomass fired CHP solutions

There are a number of other reasons why small-scale biomass fired CHP solutions makes sense. They are easier to fund, with considerably less risk than much larger power stations, and quicker to design and build. Importantly the technology is robust and technically proven with dozens of examples especially in Scandinavia. At the scales we are talking about, between 5 and 10 MW electric, local fuel sources are easily managed without the supply chain issues and security of supply that much bigger plants will face.

Waste wood collection and processing

Moreover, the potential to use waste wood and Solid Recovered Fuel (SRF) means urban centres away from forested areas can also benefit, ticking the waste to energy boxes and diverting material from landfill. A typical CHP plant will convert for example between 6,000 to 80,000 tonnes of waste wood diverted from landfill and other low quality waste wood into 170,000MWhr of renewable thermal energy, each year. Importantly this isn’t diverting prime timber resources and it is also helping to create employment opportunities across Europe for waste wood collection and processing.

Saving waste from landfill in the UK

In the UK for example, the construction of a 3.4MW biomass CHP plant at Twinwoods Heat & Power in Bedfordshire, a privately operated power company, is nearing completion. Designed to produce over 27,000 MW hr of electricity and 8000 MW hr of district heating annually, the plant will burn approximately 40,000 tonnes of waste wood from commercial and domestic recycling centres each year, a fuel source that would otherwise be sent to landfill or exported.

Matt Drew says: “Selecting the right technology partner is crucial. The good news is that Saxlund has over 60 years’ experience and can supply everything required to deliver successful energy projects from the biomass combustion furnace, fuel handling solutions through to advanced flue gas treatment and heat recovery.”

To learn more please contact Saxlund International today on +44 (0) 2380 636330 or send your name and contact details to, to discuss how we can provide the right solution for your energy requirements.

A Swedish lesson for successful CHP – can you benefit?

Small-scale biomass fired CHP offers a real opportunity for UK Energy needs and other parts of Europe too. Especially when it comes to using waste wood, forest residues and other solid recovered fuels.

One year in a new CHP plant in Sweden, operated by energy company Falbygdens Energi, shows what can be successfully achieved in the sub 5MW energy range. Performance testing has been extremely positive with some 80 GWh of heating and 16 GWh of electricity in the first year alone.  And it’s extremely efficient.

Plants at this size are also quick to realise – just 18 months from drawing board to commissioning – making projects at this scale significantly attractive to investors.

Interestingly the plant uses hot oil Organic Rankine Cycle (ORC) technology for electricity production, rather than high pressure steam, which means engineering costs can also be reduced – another benefit.

For on-site industrial heat centres as well as some energy producers we believe CHP at this scale has significant potential. The technology is tried and tested too. For more on experiences at Falbygdens Energi read on…