Biomass boilers: what are the boiling points?

The world is currently in a state of transition. Fossil fuels are becoming increasingly difficult to extract and burning them is a seriously criticised practice.

The process industries, however, are very energyintensive and still rely heavily on technology powered by fossil fuels.

For instance, boilers installed at process plants traditionally run off oil or gas, or a combination of fuels.

I think we will see more and more biofuels being used in steam plants and with hot water generation in the future

Fulton Boilers’ Doug Howarth

Essentially, industrial boilers are designed to generate steam or hot water for use in a vast number of industrial processes.

However, with fossil fuels looking to be on their last legs, boiler manufacturers and plant operators have to consider more environmentally-friendly alternatives.

Fortunately, there are a number of options. Biomass boilers burn sustainable fuel sources such as wood pellets and wood chips and can be installed to replace oil or gas-fuelled steam or hot water boilers.

If adequately supplemented with emissioncontrolling technology, biomass boilers can also fall into the government’s non-domestic Renewable Heat Incentive (RHI) which rewards companies that burn fuels with over 90% biomass content.

However, the installation of a biomass boiler, particularly within process operations, depends largely on the accessibility of specific fuel – hence why they are often installed at pulp and paper mills where biomass is readily available on-site, or else at plants where by-products can be readily burned as fuel.

Used as a fuel source, a pulp and paper mill’s by-products often feed directly into a biomass boiler - with minimal storage required and virtually non-existent transportation costs making the technology a particularly viable asset.

Similarly, food processing plants and large farms often turn to biomass boilers because of the commercial benefits.

In March last year, Bernard Matthews announced the installation of 170 biomass boilers at a number of its turkey farms in the UK – a project that was partly funded by the government’s Green Investment Bank (GIB) and fund management firm Equitix.

Fortunately for Bernard Matthews’ turkey farms, they have readily available and easily stored turkey litter that can be used to fuel the boilers.

For those plants that do not have on-site access to feedstocks or robust storage facilities, however, installing a biomass boiler and running it economically can become an issue.

“Quantity and logistics are a huge factor,” says Harry Forbes, research director at ARC Advisory Group.

“You can’t transport biomass fuel easily. You must have proximity to ensure fuel costs remain competitive,”Forbes says.

He also says it is unlikely that biomass boilers will be installed in the vast majority of process plants because of the issues surrounding access to fuel.

Capital costs are another major issue.

Especially if the system in question is under 1MW, says Matt Hale, international sales manager at HRS Heat Exchangers.

“A standard biomass boiler is not expensive, but when you have to purchase additional kit to make sure it is green, it becomes a far bigger expense,” Hale says.

“In theory, biomass boilers are a really great idea, and if installed under the right circumstance they become more viable,” he says.

“But for the majority of small and medium enterprises, the capital costs are currently far too high.”

Fulton Boilers, who has been manufacturing oil and gas-fired boilers in the UK since 1966, has chosen not to pursue biomass boilers because of the operational complexities currently associated with the technology.

“It would be pertinent for Fulton Boilers to stick to its core knowledge of oil and gas-fired steam and hot water boilers in the immediate future,” says Doug Howarth, the company’s sales and marketing manager.

For Howarth, one of the issues with an industrial biomass boiler is controlling combustion.

“If you think about it, there is a lot of inertia in the fuel when it is burning,” Howarth says.

“If you have a gas boiler, for instance, you can quite easily turn the flame down to stop the water boiling.”

“With a biomass boiler it’s a slower process,” he says.

“They aren’t as good at adapting to varying loads.”

What’s more, the market perception is that biomass boilers are often susceptible to maintenance issues, even when they are sold as ‘maintenance-free’ installations, Howarth says.

In reality, plant operators often need a higher frequency of maintenance engineer visits, he suggests.

“That is often because of the varying qualities of biomass fuel plant equipment & safety feature clogging the feed from the storage to the boiler,” Howarth says.

“For the process industries in particular, you need a consistent, reliable heat source at your plant because downtime results in a serious loss of money.”

To alleviate this issue, plants will often have a back-up boiler installed; as a single biomass boiler could potentially let a plant down, Howarth says.

Interestingly though, the ‘back-up’ boilers installed at process plants are not usually biomass boilers, Howarth says.

They are most commonly oil or gas boilers, or dual fuel boilers that require far less maintenance than their biomass equivalents, he says.

Remembering that oil and gas reserves are dwindling, however, industry must constantly look at more sustainable approaches.

For instance, Howarth says biogas produced from food waste once refined is essentially the same as any other natural gas and he claims it will burn in much the same way.

With biofuels such as food waste biogas, operators must ensure some preventative maintenance takes place before the biogas is used, and they must undertake preventative maintenance in terms of storage prior to the biogas’ delivery, Howarth says.

If those checks are completed, there are usually no issues at all with using the biogas in a normal boiler, he says.

“I think we will see more and more biofuels being used in steam plants and with hot water generation in the future,” Howarth says.