With more companies looking to hit the magic net zero target by 2030, Fulton’s Leigh Bryan asks what options there are for those businesses with processing facilities that are off grid and having to rely on sometimes ageing heat transfer solutions using high-carbon, oil-based fuels for firing.

According to official statistics for England and Wales, there are over 1.6 million non-domestic buildings, with nearly 300,000 of those located in areas not linked to the gas grid and many using fossil-based fuels for various heating purposes. Why? Because their location makes connection to the grid too expensive or, in some case, not even possible.

So, with heat transfer solutions in mind, what are the options for those operating a business that is situated off-grid and facing the challenge of sourcing a reliable and efficient source of energy?


Liquid Petroleum Gas (LPG)

When it comes to off grid, LPG is considered the cleanest, most efficient and effective fuel compared to traditional fuel types, including coal, oil and electricity. It emits almost no particulate matter, with oil emitting 10x the value and coal a massive 100x. Additionally, LPG emits 35% less carbon than coal and 12% less than oil; and, for those struggling to meet current MCPD regulations LPG can, utilising the correct burner equipment, also significantly reduces NOx emissions compared to traditional off-grid fuels, with oil seeing 50% more emissions.

Aside from the environmental benefits of LPG there’s also cost benefits to consider, with the UK government scrapping fuel duty on Class D Red Diesel from April 2022, which could see fuel costs for those operating oil-fired heat transfer solutions rise by as much as 50%.

For a recent installation at leading British condiments maker Tracklements, production capacity has been boosted and the company’s environmental credentials enhanced by replacing its existing oil-fired steam boilers with modern, efficient liquid gas-fired Fulton VSRT vertical steam boilers.

With a relationship exceeding 40 years, Tracklements approached Fulton when specify a cutting-edge system that would help minimise its environmental impact. With a requirement for an off-grid solution, Fulton initially suggested a packaged system comprising of its Europack electric steam boilers but, following a site audit, it was realised that the infrastructure wasn’t in place to support a solution. So the company instead specified its award-winning VSRT steam boilers with LPG burners and recommended Flogas as the liquid gas supplier.

By modernising their steam raising equipment and changing their fuel type to liquid gas, Tracklements can expect an impressive 21% financial saving and a near 25% reduction in carbon emissions, with the cost savings being based on current oil prices before the planned withdrawal of tax relief on red diesel in April 2022 so, looking forward, they are actually far more favourable.

These savings, along with improved carbon emissions, can be improved further by up to 30% when combined with the potential steam system efficiency savings by running the latest fully-modulating, high-turndown boilers – each genuinely capable of a 10:1 turndown – resulting in the production of high-quality steam at up to 99.75% dryness. What’s more, our liquid gas-fired VSRTs will help minimise other pollutants, with NOx levels at commissioning reduced by 75% compared to the previous oil-fired steam boilers.

Based on the current cost of 32 second oil combined with the planned increase in production and efficiency of the VSRT steam boilers, the customer expects a return on investment within 18 months. However, if the planned duty increases on fuel are factored in, that period will be significantly shorter.

The installation at Tracklements is also supported by both service and water treatment contracts from Fulton, who have also provided certified boiler operator training for several employees at the facility.

However, changing fuel type doesn’t always mean a completely new boiler. Following a site survey and steam load distribution analysis by Fulton and Weishaupt at a brewery in the South West in 2020, the steam boiler and burner specialists identified opportunities to reduce carbon emissions at the site and save money on fuel by upgrading the burner on a Fulton RBC2500 horizontal steam boiler that was installed in 2007.

Tracklements – Guy Tullberg (11th November 2010)

The boiler was originally fitted with a high/low, conventional control box oil-fired burner, which was achieving a turndown ratio of less than 2:1. Partnering with Weishaupt, a micro-modulating LPG burner with integrated digital burner management system – air and gas servo motors accurate to within 0.1° – was specified and installed, with Fulton also specifying optional burner motor variable speed drive to reduce electrical power consumption and oxygen trim to maximise combustion efficiency. Additionally, with NOx levels reduced thanks to the upgrade, the RBC2500 is now also fully MCPD compliant.

The result of the partnership between Fulton, Weishaupt and Flogas (as the off-grid LPG supplier) is an upgraded steam boiler with turndown improved to at least 7:1 which, combined with the added burner options, is predicted to save the brewery in excess of 20% in fuel consumption alone. Impressive reductions in carbon emissions by changing to a cleaner, lower-carbon fuel like liquid gas will also be achieved and add to the efficiency savings.

“The cost savings predicted for the upgrade project at the brewery are expected to deliver a payback period of between nine and ten months and will go a long way in assisting the company’s Road to Net Zero efforts.” says Fulton’s Leigh Bryan.


Electricity Grid

Some experts believe that electric steam boilers are superior to fuel-fired steam boilers in a few ways. They believe that using electric boilers may be less expensive than using a fuel-fired boiler in the long term, whilst also being more environmentally friendly.

Using Fulton’s portfolio of electric steam boilers as an example, less ancillary equipment is required than a traditional steam boiler, therefore helping to reduce the installation costs that come with a fuel-fired boiler. Electric boilers also generally have a smaller footprint and can therefore fit into smaller areas thanks to the way they are constructed and the lack of ancillaries that a fuel-fired boiler needs to operate. And thanks to their small footprints and the fact there are no flue requirements to consider, they can often be used for point-of-use steam requirements, making them a good choice for many smaller operations, including small-batch distillery, micro-brewery and autoclave applications.

Electric boilers are sometimes overlooked as a potential solution to steam generation due in part to the higher cost of electricity versus the cost of traditional fuels such as LPG, kerosene (gas oil), etc. However, with the UK government scrapping fuel duty in April 2022 and the cost of gas oil set to increase dramatically as a result, many companies are now turning to more sustainable methods of generating electricity, including solar or wind generation, with such schemes offsetting, or at least partially offsetting, the higher fuel costs.

Traditional fuel-fired steam boilers generally require multiple elements to operate successfully. In contrast, electric boilers are relatively simple devices. Additionally, because electric steam boilers do not use complicated forms of heat exchange, they do not contain many of the potential hazards that are commonly present in a fuel-fired boiler. Electric boilers are also generally easier to maintain because they don’t require tube replacements, burner maintenance or statutory non-destructive testing (NDT), all of which fuel-fired boilers often require.

Electric steam boilers are more efficient than fuel-fired boilers because they require less energy to be put into them for operation at capacity. This is because there is little energy lost when the transfer of heat from the heating element to the water occurs, unlike traditional fuel-fired boilers where there is a substantial amount of energy loss from the air flow required to supply oxygen to the flame.

Additionally, because electric steam boilers can be fitted, in some cases, with as many as 12 electrical elements (dependent on model), they have a high turndown – up to 12:1 in the case of Fulton’s electric steam boiler range – so are able to modulate efficiently to varying steam loads.

Electric boilers are, as already stated, more efficient and recognised as having smaller carbon footprints than their fuel-fired counterparts, but for large generating capacities are frequently impractical to install due to large supply cables and infrastructure requirements. However, with no burner service and no NDT inspection required every five years, the actual maintenance costs can be up to 50%* less than those of fuel-fired steam boilers. Generally, the only major parts that are periodically changed are the electric elements themselves, yet these are often replaced quickly and cost effectively. This balances lower life cycle costs against the high maintenance requirements of fuel-fired boilers, including refractory repair/replacement, 5-year NDT requirements, burner maintenance, flue maintenance, and the requirement for highly-skilled and often highly-paid plant operatives.


Blended Fuels

With the UK government scrapping fuel duty on Class D red diesel in April 2022, many companies unable to invest in upgrading existing or installing new plant are looking to equivalent blended fuels to fuel their steam boilers which, at present, are not subject to the implementation of the fuel duty scrappage.

The use of blended fuels requires little change to an existing boiler setup, with only minimal re-commissioning of the burner required. However, blended fuels burn at the same calorific value as Class D oil, there will also be minimal benefit from the reduction in carbon emissions or NOx levels achieved from switching to electric or LPG.

Compared to Class D oil, there is also a shortage of blended fuels in the marketplace. Additionally, like many other fuel types, there are winter and summer grades to be aware of. So, if you’re still running a summer-grade fuel in the winter, you need to be conscious of potential waxing of the fuel pipes, filters and other burner components.

Many blended fuels also required agitation to ensure the fuel mix remains consistent. This can be achieved with a simple two-pipe system that runs back to the tank to achieve circulation, but without this type of system, the installation of an in-tank agitator is recommended to ensure there is no stratification of the fuel.

Finally, there’s the residue found in boilers from blended fuels and their associated bio-components not burning as efficiently. Any residue will impact the overall efficiency of the boiler and we have seen cases where we estimate at least a 12% loss in efficiency due to the insulating properties of the residue in the boiler causing an increase in flue gas temperatures of around 90ºC.


What does the future hold?

We have of course only looked at three firing options for operating steam boilers off-grid in this article, but there are others. And what about the future?

At Fulton, we are already developing hybrid steam boiler solutions that combine a LPG-fired boiler with electric, where the base load of the process is picked up by the electric boiler and seasonal swings and high loads by the traditional boiler; all of which helps to dramatically reduce carbon emissions. We are also working with partners, such as Weishaupt, and looking at the future of hydrogen, although a move to 100% hydrogen-fired steam boilers is unlikely for off grid solutions.