Biomass Handling Issues – What can Henry Ford teach us?

Biomass is probably the biggest growing area of processing in the last ten years, and set to continue into the future. The biggest growth in the business started with wood pellets, both for small scale heat and for large scale power generation, but nowadays most of the interesting potential is in making use of raw biomass materials and wastes, for use as both energy and feedstocks. 

Ford foresaw this revolution – in his 1926 book “My Life and Work”, he said “I believe the day will come when the resources we need for our factories and products will be grown in our fields, not dug from the ground” and this is a vision that is increasingly popular today. But he also said something more profound when it comes to the reality of biomass handling system procurement, as we’ll see later on.

Many investors have stepped up and put their money where their mouth is. Especially for small scale plants using things like wood chips, reclaimed wood, food waste, plastic wastes, animal waste, agricultural and forestry residues. And I have to say that with that growth has come an explosion in the number of troubleshooting projects that my team at The Wolfson Centre has been doing!

Why so many biomass handling troubleshooting projects?

Usually it starts with a ‘phone call which goes something along the lines of;

 “We’ve got this heat/CHP/pyrolysis/reclamation plant that we’ve bought from a supplier. The material keeps getting stuck in it/wearing it out/not flowing/catching fire and so we’re suffering a lot of downtime/repair costs/burnt out drives/high manning costs/poor productivity/environmental emissions leading to financial losses that are stacking up. The supplier has been struggling with it for months but things don’t seem to be getting any better so we’re considering getting some expert help/changing supplier/replacing certain pieces/taking them to court to move things forwards. Can you help us?” (Choose whichever applies from the lists in italics, but these are by no means exhaustive!)

There’s an immediate lesson here – often, getting the handling of the feedstock, the intermediates and residues right, usually turns out to be much harder and more expensive to get right then the conversion process (e.g. combustion or pyrolysis). But invariably, the handling has never been given the same level of attention or importance as the conversion process.

Usually, a site visit is a good start, though these have been difficult in recent months so we seem to do a lot using live WhatsApp video links, which is actually not too bad as a second choice.

In many cases the seat of the problem seems fairly obvious, although it’s not uncommon to find that there’s more than one difficulty when you look at the system. And when it comes to what do about it, often there’s no easy fix, significant outlay and time is usually required to remedy the problems.

In some cases we’ve seen some really badly-designed equipment that has clearly been put together by people with little or no previous experience in bulk solids handling. We’ve seen feed screws with drives that are underpowered by a factor of ten or more, storage vessels that appear to require the material to flow like water rather than bulk solids, and other things that look like they’ve been designed by people who have never even heard of the science of bulk solids handling.

More often, we find equipment that’s ok in its generic design, but just doesn’t suit the material being handled – a design that had been supplied before for a biomass that maybe had the same name, but doesn’t work with this particular biomass material. Wood chip over here is not necessarily the same as wood chip over there, and reclaimed wood is completely different again, from every different source.

This latter really highlights one of the main issues with biomass materials. It’s a problem across all bulk solids, that they behave very differently from one another. If you design equipment to store, handle and feed sand for example, it won’t work very well for cement or vice versa. But with biomass, the situation is much more severe. Any biomass with a certain name, can vary greatly according to where it comes from and the particular circumstances on the day it’s been made.

There’s another common problem with biomass and waste projects, which is – shall we say – cultural, for want of a better word. Often the feedstocks are low value, in some cases people will pay you to take them and there’s a perception that taking something “as cheap as chips” and turning into saleable energy, heat or product is a way to make “a quick buck”. “Where there’s muck, there’s brass” as they say in Yorkshire.

Dealing with waste was traditionally a shady business inhabited by suspect characters and dodgy practices. This often leads to the culture of a low-cost, corner-cutting approach, that drives project promoters to search hard for the lowest-cost supplier. However, it’s a truism that the lowest cost supplier of the plant will usually be somebody who hasn’t done this before, doesn’t know the pitfalls, and in many cases doesn’t have the financial muscle to support the costs of corrections when things do go wrong.

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Here’s what Henry Ford had to say about this –

“There’s always someone willing to do it cheaper – but at what cost?”

This “race to the bottom” on price of plant and equipment, is something that has caught out a lot of project promoters. It’s resulted in many “cheap plants” that actually cost their owners a colossal amount of money in retrofits, lost productivity, slow start-up and excessive manning. But we’ve seen it has also often caught out some more experienced suppliers as well, often in a situation where they felt the pressure to cut costs to be competitive, and made technical shortcuts as a result.

Apart from the “race to the bottom” on project price, another common source of trouble that has caught out many people is simply not giving enough care to understanding the behaviour of the particular biomass material that is going to be handled, and how this may vary. There are a number of techniques that can be used to undertake what we call “characterisation” of biomass materials for their handling properties, such as their potential to hang up in hoppers, their tendency to self-heat and so on.

Failure to do enough work on characterising the precise behaviour of the biomass to be handled, has turned out to be a very common cause of mis-design on equipment. Naturally, making sure you have meaningful samples to put through such characterisation tests is also critical; if the biomass samples around which the design is done, differ from the material that is loaded into the finished plant, trouble is guaranteed.

Against all this is the reality that the margins in the business of biomass and waste processing are low. So, buying cheap gear that costs a lot of money to fix up, takes a long time to get up to full output, and costs a lot to run, is a sure-fire way to make big losses.

So how about a few ground rules?

• Don’t make the mistake of thinking that biomass is a business to get into “on the cheap” just because you can secure a cheap supply of feedstock. You have to be prepared to invest a lot of time and money to get to a system that will have the efficiency to make a profit.
• Beware of low-cost feedstocks, they are likely to have the greatest difficulty in handling, the greatest variability and overall the most likely to cost you a lot of money to deal with.
• Don’t make the mistake that you can just rely in buying in the handling equipment from the cheapest supplier as an afterthought – getting the handling right usually requires much more time, care and money than the conversion process.
• Before even thinking about planning the plant, get many different samples of the feedstock from different possible sources, and get them characterised for their handling properties NOT just their chemistry and conversion properties.
• Don’t be tempted to use the price of the handling system tender to compare offerings. The cheapest offer is probably the one that will break you. Instead, take the technical details of the offers apart, analyse them carefully, take account of how much the supplier understands the importance of characterisation for flow, and preferably get expert advice from a specialist in biomass handling to make a judgement on the system. Work with the supplier to improve or test anything you think might be risky, even if this means increasing cost. Choose the system that has the best chance of working well, from the company that has the most extensive relevant experience – this may be the most expensive, but it will cost you less in the end.
• Don’t take anything the supplier says at face value. Get a second opinion, a peer review on every aspect large and small, from somebody who has done it before.
• Don’t be tempted to try to get the plant delivered in a tight timescale. Shortening the timescale to starting construction is a guaranteed way to create long delays in getting up to production.
• Instead, take a lot of time to review and refine the design, consider alternatives, undertake extensive feedstock sampling, flow testing and characterisation and use it to evaluate and refine the design. My rule is that every day spent on these things before breaking ground, will save you a month on getting the plant up to performance. Likewise, every pound invested in these activities will save you a thousand or more on retrofit and modification, and more still on lost productivity and down-time.

For more information on how to get biomass handling systems right, refer to the following resources:

The web site for The Wolfson Centre for Bulk Solids Handling Technology. www.bulksolids.com and go to “courses”.

The Solids Handling and Processing Association web site www.shapa.co.uk and go to “technical manual”

And finally remember Henry Ford –

“There’s always someone willing to do it cheaper – but at what price?”