All subjects
Heat & Power

In good spirit – a tasteful repurposing of heritage

An iconic brand of quintessentially English spirit has settled into its new award-winning refurbishment. The former paper-mill, a dilapidated Victorian-Georgian era property of industrial heritage and building significance, was acquired in 2008 by international drinks major Bacardi. It was meticulously refurbished and repurposed it as a flagship distillery. Complete with a 999 kW biomass-fuelled boiler, Laverstoke Mill is now brand home for Bombay Sapphire gin.

A striking feature of Bacardi’s award-winning Laverstoke Mill refurbishment in the UK is its two botanical greenhouses. Both are heated using residual heat from the distillery process in turn supplied by a biomass boiler. The fuel is a blend of woodchips and spent botanicals.
A striking feature of Bacardi’s award-winning Laverstoke Mill refurbishment in the UK is its two botanical greenhouses. Both are heated using residual heat from the distillery process in turn supplied by a biomass boiler. The fuel is a blend of woodchips and spent botanicals. A striking feature of Bacardi’s award-winning Laverstoke Mill refurbishment in the UK is its two botanical greenhouses. Both are heated using residual heat from the distillery process in turn supplied by a biomass boiler. The fuel is a blend of woodchips and spent botanicals.

Tucked away in the picturesque Hampshire countryside, an iconic brand of quintessentially English spirit has settled into its new award-winning refurbishment. The Victorian-Georgian era buildings of Laverstoke Mill once housed a paper-mill that in its heyday supplied watermarked banknote paper to the British Empire. The dilapidated property was acquired in 2008 by international drinks major Bacardi, that meticulously refurbished and repurposed it as a gin distillery. Recently acclaimed as “a model of industrial sustainability”, now running with a 999 kW thermal biomass-fuelled boiler, Laverstoke Mill is a flagship distillery and brand home for Bombay Sapphire gin.

Bacardi-owned Bombay Sapphire is widely accredited by industry peers as having blazed the trail in the revival of UK produced gin. Launched by Bombay Spirits Company (BSC) in 1987 it was produced under contract by G&J Greenall at its distillery and bottling facility in Warrington although the two Dakin Carterhead vapour infusion stills, used to produce the gin, were owned by BSC. The brand came onto the market at a time when consumer interest had long since given way to other premium tastes.

Today, according to current brand owners Bermuda-based Bacardi, Bombay Sapphire is the number one premium brand by value. According to 2014 production figures published by trade publication the drinks business it is ranked number two by volume, having reached the 3 million case mark, up 7 percent from 2013. Undoubtedly the widely publicised move from Warrington to the new dedicated distillery at Laverstoke Mill where all production takes place has helped.

Formidable project

Having produced and supplied watermarked banknote paper for currencies within the British Empire as well as housing one of the first hydro-electric generating units in the country, the 2 ha former paper mill had very specific and important heritage that needed to be safeguarded for future generations.

– Every effort was made to salvage materials like bricks, windows and fixtures, to ensure that the renovation remained historically conscious and conservation-minded. At the same time the challenge was also to make the site fit for its new dual purpose, a state-of-the-art, resource efficient, eco-conscious gin distillery and visitor heritage centre, said Nik Fordham, Master Distiller, Bombay Sapphire as he gave a guided tour around the distillery.

An additional challenge to the project is that the entire property, including the River Test that runs right through it, is designated a Site of Special Scientific Interest (SSSI).

Biomass boiler

Currently there are four production stills installed at Laverstoke, the two refurbished Carterhead stills relocated from Warrington and two newly commissioned stills. A 999 kW thermal rated Uniconfort biomass-fired boiler provides the process steam needed to heat the stills and, by using a clever heat recovery system in the distilling process, the residual heat is used to heat the buildings as well as the two greenhouses.

The energy heart is a 999 kWth Uniconfort biomass boiler. A blend of spent botanicals from gin distillation and woodchips are used as fuel. From a small receiving hopper the material is screw augered into a storage silo.
The energy heart is a 999 kWth Uniconfort biomass boiler. A blend of spent botanicals from gin distillation and woodchips are used as fuel. From a small receiving hopper the material is screw augered into a storage silo. The energy heart is a 999 kWth Uniconfort biomass boiler. A blend of spent botanicals from gin distillation and woodchips are used as fuel. From a small receiving hopper the material is screw augered into a storage silo.

The boiler is capable of using wood pellets but uses a mixture of locally sourced clean woodchips supplied at around 20 percent moisture content and the spent botanicals used in the gin making process. Flue gases pass a bag house capturing fly ash and other fine particulates ensuring particulate matter (PM) emissions under the 60 mg/m3 threshold. A 2 MW gas-fired boiler is used for peak load and backup. In addition a 6 kW run-of-river hydro-electric turbine has been installed where the original turbine once sat as well as a photovoltaic (PV) array.

– So far under normal production conditions the biomass boiler seems to manage the heat load needed though we have only been in production with it a few months. Perhaps a prolonged cold spell would require supplemental heat from the gas boiler, said Nik pointing out that, as a rectifying distillery, much less energy is needed compared to a full distillery.

– A reason we choose to use a biomass boiler and pursue a heat recovery solution was that it enabled us to act upon our corporate operational efficiencies commitment. That is zero-waste to landfill by 2022, greenhouse gas (GHG) and water use reductions of 50 percent and 55 percent respectively by 2017, explained Nik adding that negotiations are underway to have a local woodchip supplier take the bottom-ash back for use as a soil improvement medium.

– This closes the fuel loop and provides an incentive for both parties to keep the biomass clean and within spec, commented Nik.

Vapour infusion distillation

In essence gin, the name being derived from Dutch jenever or French genièvre both of which mean “juniper”, is a predominately juniper-flavoured spirit with a minimum bottled strength, in the EU, of 37.5 percent alcohol by volume (ABV). Distilled gin and London (dry) gin are two additional categories. Bombay Sapphire is a London dry gin and the key differentiating feature at Laverstoke Mill distillery is the use of the so-called “vapour infusion” distillation process.

Juniper berries, a gin condenser with heat recovery and a jacket insulated infusion chamber and the end product.
Juniper berries, a gin condenser with heat recovery and a jacket insulated infusion chamber and the end product. Juniper berries, a gin condenser with heat recovery and a jacket insulated infusion chamber and the end product.

– Distilled gin can be produced by either boiling botanicals together with the base spirit and then separate out the unwanted solids or by infusing directly in the spirit. Whilst both methods are quicker and thus less costly than vapour infusion, neither get anywhere close to the level of process control, predictability and repeatability. To give you some perspective it takes about six hours to produce 10,000 litres of gin by boiling botanicals whereas our vapour infusion method takes longer to produce less than half that volume, commented Fordham.

The incoming base spirit, a triple distilled neutral wheat grain alcohol, is heated up in a special type of steam-jacketed still known as Dakin Carterhead vapour infusion stills. These historical pot stills of which there are only a few remaining in the world have a closed rectifying reflux column on top of the pot that originally purified lower quality spirits used to create gins before infusion.

Innovative heritage

Two of these refurbished Carterheads are located in the “Heritage Still House” at Laverstoke. In the “India Still House” are two new 12 000 litre modern interpretations of the classic Carterhead stills. These uniquely shaped stills are fitted with an innovative steam management system capable of applying large amounts of energy very gently as well as a reflux section that enables exceptional precision in the control of the distillation process. Furthermore all four stills have been completely insulated saving steam and eliminating the need for air-conditioning of the still houses.

All the distillation equipment, the two new stills “Henry” and “Victoria”, the two refurbished Carterheads along with condensers and allied equipment were designed and fabricated by Green Engineering, an Italian engineering procurement and construction (EPC) company specialising in industrial ethanol plants for beverages, biofuels, pharmaceuticals and the chemical industry.

– As the base spirit we use is already triple distilled, the original rectifying columns in the two Carterheads have been reconditioned and redesigned internally to control the flow of spirit vapour through the distillation process ensuring an energy efficient process, explained Nik.

The pure spirit vapour emerges from the top of the column via the lyne arm and into the bottom of the infusion chamber. Inside the infusion chamber perforated copper baskets contain the ten botanicals used. These are layered by species, according to a specific but undisclosed order and quantity. The hot vapour passes through extracting the aromatic oils that provide the unique taste without cooking or denaturing them. The infused vapour comes out the top of the chamber and is then condensed in a water-cooled condenser, turning it into high-strength gin that is collected and stored in a holding vat.

– During distillation, hot water is collected in a storage tank ready to be reused, the specially designed condensers recover the heat from gin condensation and this is used to pre-heat the incoming base spirit as well as the two greenhouses and space heating throughout the site which saves both time, energy and water all-round, explained Nik.

The distillation process is monitored and controlled by state-of-the-art systems and laboratory tests are carried out on samples taken from each cycle for quality control. The final decision though rests entirely on Master Distiller Nik Fordham’s sense of sight, smell and taste.
The distillation process is monitored and controlled by state-of-the-art systems and laboratory tests are carried out on samples taken from each cycle for quality control. The final decision though rests entirely on Master Distiller Nik Fordham’s sense of sight, smell and taste. The distillation process is monitored and controlled by state-of-the-art systems and laboratory tests are carried out on samples taken from each cycle for quality control. The final decision though rests entirely on Master Distiller Nik Fordham’s sense of sight, smell and taste.

Once the distillation cycle is completed, a new botanical charge is set for the next round, while the spent botanicals are gathered and transported over to the biomass boiler. The entire process is monitored using state-of-the-art PLC systems. Samples are taken from each cycle with various tests performed in the adjacent laboratory to ensure quality is maintained, though the final decision is entirely human sensory based — eye, nose and tongue.

– The technology enables precision in process control minimising the guesswork of some of the variables but the ultimate decision is subjective, said Nik.

As a single-shot distillation the ABV of the high-strength gin is reduced once with purified water to bottling strength. ABV reduction and bottling takes place at the Warrington plant.

International acclaim

– The redevelopment of Laverstoke Mill was no easy task and required a substantial upfront investment, but none of it was wasted. Bombay Sapphire will reap the rewards of equally substantial dividends in the form of long-term sustainability, and reduce waste and energy consumption for future generations to come, said Nik Fordham, without detailing what the final figure, for what must have been a multi-million pound project, actually was.

From an architectural viewpoint, Laverstoke Mill is spectacular example of how state-of-the-art design can be seamlessly integrated into a Victorian-Georgian context. The greenhouses were designed by the renowned UK architect Thomas Heatherwick.
From an architectural viewpoint, Laverstoke Mill is spectacular example of how state-of-the-art design can be seamlessly integrated into a Victorian-Georgian context. The greenhouses were designed by the renowned UK architect Thomas Heatherwick. From an architectural viewpoint, Laverstoke Mill is spectacular example of how state-of-the-art design can be seamlessly integrated into a Victorian-Georgian context. The greenhouses were designed by the renowned UK architect Thomas Heatherwick.

It is very hard to disagree, as the multi-faceted project is nothing short of spectacular no matter what aspect you choose to weigh in on. In fact, the Building Research Establishment Environmental Assessment Method (BREEAM), the world’s foremost environmental assessment method and rating system for buildings, dedicated the prestigious 2014 BREEAM Industrial Award to the distillery. BREEAM rated the Laverstoke Mill refurbishment project as “outstanding” — the first ever such project to be awarded such a rating anywhere in the world. Indeed BREEAM gave the renovation project the highest possible marks for the lowest possible environmental impact.

– We were of course delighted to achieve an outstanding rating. Fundamentally though we believe building such a sustainable distillery makes financial sense, increasing efficiency and long term operational energy and water use savings, ended Nik Fordham.

4846/AS

Most read on Bioenergy International

Get the latest news about Bioenergy

Subscribe for free to our newsletter
Sending request
I accept that Bioenergy International stores and handles my information.
Read more about our integritypolicy here