The Capstone C800 installation at Revico treatment plant for vinnasse waste from cognac distilleries.
Cognac production in France creates large volumes of a waste biomass product, vinasse, which has caused serious pollution problems. However, anaerobic digestion can break down the vinasse to create a biogas that now fires a microturbine installation to produce heat and power for use on-site and for export. Xavier Lombard reports.
Cognac, the celebrated brandy noted for its double-distillation process and social cachet, is only labelled ‘cognac’ if produced in the stunning Cognac region of France. For 300 years, producers of the fine spirit have boasted that the region’s stable climate, green hills, nearby ocean and meandering Charente River – described by Henri IV as ‘the loveliest in my kingdom’ – contribute to cognac’s exquisite taste.
While these astounding microclimate character-istics remain, distillation of this fine brandy produces millions of gallons of vinasse, a foul-smelling, sludge-like amber liquid rich in organic materials.
Until a few decades ago, the vinasse was simply spread across surrounding land, which harmed wildlife and contaminated nearby rivers. As concern about this pollution began to escalate, cognac producers in the region knew they had to take action to stem the flow of the effluent.
In 1971, several distilleries joined to create Revico, a wastewater treatment plant that collects the vinasse, removes harmful substances and releases clean water into nearby waterways. To dispose of the 300 million litres of vinasse produced each year by 140 distilleries, Revico installed four 5,000 m3 anaerobic digesters that break down the waste matter. Water is separated from the sludge, treated and released.
During the process to break down the vinasse sludge, bacteria in the digesters produce significant amounts of methane biogas. Rather than just flare the methane into the atmosphere, Revico captured the methane and used it to fuel three boilers that produced steam, which created electricity and heat to operate the digesters and to power the entire Revico facility.
Recently, Revico officials decided to update the facility’s on-site boiler system. They turned to Verdesis, a Capstone Turbine Corporation distributor in Europe. After several months of research and cost analysis, they decided to install a methane-fuelled C800 CHP Power Package.
The Power Package, which produces green electricity to run the entire plant and thermal energy to operate the four on-site digesters, and is extremely reliable and quiet while fitting easily into a small space.
In November 2009, the CHP Power Package was commissioned to serve as the powerhouse for the plant. In addition to the C800, the installation includes a Capstone-designed heat recovery module mounted inside the cabinet of the power package.
The C800 microturbine was selected because Capstone microturbines offer a low-maintenance solution that can help reduce energy costs while also providing the best technical fit with regard to Revico’s seasonal activity.
Today, Revico uses a single, methane-fuelled C800 to generate 3000 MWh of electricity per year and 4000 MWh of thermal energy per year that heats the four digesters used to breakdown the vinasse.
In addition, thermal energy warms a large nearby greenhouse that the city of Cognac uses to grow flowers for embellishing city streets. The cogeneration system’s efficiency exceeds 80%, while availability of the Capstone C800 nears an astonishing 97%.
MAKING MONEY WITH MICROTURBINES
The C800 also produces enough electricity on-site for Revico to sell power to Électricité de France (EDF), the country’s main utility, through a grid connection. Nicolas Pouillaude, Revico's manager, estimates this sale of electricity €400,000-€500,000 (US$500,000-$600,000) per year for a joint venture created between Revico and Verdesis.
The Capstone 800 installed at the Revico site
Revico is very satisfied with how quickly the plant was able to produce electricity from the C800 microturbine without a long testing period. The plant has had great success with its investment in the microturbine, said Revico’s Pouillaude.
For many years, Revico has been a pioneer in environmental protection in the region. With the C800, it continues to be first-in-class in protecting the region’s environment. In fact, French and European officials consider the innovative Capstone turbine system so environmentally friendly they offered Revico a significant subsidy to install the system.
The Capstone C800 operates nine months annually – from November to July during the distillation period – processing approximately 80 truckloads of vinasse each day during peak season.
During those busy nine months, Revico officials are confident about the microturbine’s availability. They’re familiar with its 99% reliability rate – a rate so high because it has just one moving part and is completely air cooled. A microturbine is void of a gas engine’s lubricant-hungry components, such as water pumps, oil pumps, oil filters, radiators, and fan belts.
In addition to regular monthly maintenance, most manufacturers of traditional gas engines also recommend 500-hour maintenance intervals that last a minimum of eight hours. Major overhauls can take several days or weeks.
By contrast, recommend-ed maintenance of a microturbine is a single shutdown once a year that lasts less than six hours. After 40,000 hours of operation at Revico, a major overhaul will occur where the engine will be exchanged. This interval will be accomplished by two technicians in less than six hours on average.
Back at Revico, the by-product of the digester system is combined with ‘green waste’ (branches, leaves and flowers) from the Cognac region and placed on surrounding land to compost and improve the soil quality.
Revico’s Pouillaude said the plant is very careful, not only with the production of Cognac but with the environment. ‘We’re very attentive to the way we make cognac. The greener we are, the better we are. Capstone’s C800 turbine and the company’s support have allowed us to produce an outstanding product in the best way possible.’
At a glance
Digester gas – methane
n One Capstone C800 Power Package used in CHP mode
n Capstone C800 cabinet and heat recovery module
n Four 5000 m3 anaerobic digesters.
n C800 CHP Power Package produces 3000 MWh of electricity and 4000 MWh of thermal energy
n Thermal energy heats four anaerobic digesters that break down the vinasse waste material
n Thermal energy also warms the city of Cognac’s large greenhouse
n Energy efficiency exceeds 80%
n Energy generated is sold to utility Électricité de France (EDF)
n Electricity sales to EDF generate €400,000-€500,000 (US$500,000-$600,000) per year.
More information: www.revico.fr
Xavier Lombard is the managing director of Verdesis, a Capstone distributor in Europe. Email: email@example.com
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