Geotech looks at the world of biogas with focus through two case studies
Methane makes money. It generates energy revenues, carbon credits and is part of bio-treatment sludge processing. In most of the world it has only just begun. Measuring what we are doing and being responsible with this potentially damaging greenhouse gas makes good sense.
With gas production for revenue, measurement is essential. While landfill gas analysis has been required for compliance with national authorities, biogas analysis has different drivers. It can help optimise digester or fermenter operation and maximise methane production. Biogas analysis assists process control, which in turn can help protect CHP or other engines from H2S and moisture damage. It can also ensure newly installed biogas plant is operating to design specification.
When methane is in production, analysis is achieved either with hand- held portable instruments or static, unmanned and automated equipment. The need for data may dictate the equipment specified.
For carbon credit trading, automatic data logging every 15 minutes and data transfer to a secure server with password-protected Internet access is becoming the norm. That equipment can also monitor digester performance and alert operators if intervention is required. To run power-producing plant on methane, possibly from an array of sources, less frequent measurement may be needed and hand-held, portable ‘manned’ equipment may be totally adequate. That means finding the project-dependant balance between the man-hour cost of using portable equipment and the capital outlay of automated equipment. In tightening markets, manpower, time and money matter.
Case Study: Germany
Germany is one of the leaders with some useful experience for other countries now developing their own biogas production. Nowadays German landfills do not accept untreated municipal waste. It is generally separated into its principal constituents. The biodegradable part is fermented or digested and the residual waste is incinerated.
For a transition period of thirty years landfill gas extraction and energy recovery will continue. The biogas market has just started based on renewable vegetable raw materials. It is driven by high prices paid for ‘bio-current’ and government investment subsidies. In countless farm- sized biogas plants many farmers use portable biogas gas analysers as do numerous organisations and companies involved in the industry. According to Dr Robert Befurt at Ansyco – Analytische Systeme und Componenten GmbH, Karlsruhe in Germany, “We have supplied hundreds of portable gas analysers over the years to landfill sites.
Our customers now are farmers, farm cooperatives, research centres, universities and manufacturers’ commissioning and maintenance teams. Here, product value, quality, durability and technical accuracy are important. Our customers work with our analysers manufactured by Geotech for years without any problems.” Dr Befurt anticipates further German development with biogas digesters and fermenters in future.
Case Study: UK
For researchers at Greenfinch, biogas specialists in Shropshire, UK, measurement of the percentage methane within biogas provides an excellent indicator of the health of a digester. This in turn allows methane producers to be much more in control and able to manage gas production quality. If a digester is producing low quality gas its management can be altered to produce methane-rich gas. Gas analysis during a production run is very important to achieve the valuable high-percent methane gas output necessary to justify the investment in a digester and associated equipment and the work of loading and running one.
At Greenfinch, researchers trialled the new portable Geotech biogas analyser on laboratory and full-scale anaerobic digesters. “Our trials concluded the analyser is straightforward and very simple to use, whilst also producing robust and reliable results,” commented Greenfinch’s Becky Arnold.
Over half of the UK’s food goes to waste. That includes waste from food processing and packing, ideal for processing through digesters and making methane. In Asia, notably China and Thailand, farm animal waste in lagoons is causing problems with watercourse pollution and so digester treatment with biogas plant production is set to grow. The treated animal waste can then be used as a bio-fertiliser, replacing manufactured chemical fertiliser, reducing its energy costs and the CO2 generated in chemical fertilizer production.
Anaerobic digesters at a UK municipal site, Courtesy of Permastore Ltd. Glass-Fused-to-Steel Tanks & Silos – www.permastore.co.uk
Similar bacterial cycles occur in a digester as in landfill gas production. Like landfill gas, biogas is dirty and wet. It may contain hydrogen sulphide (H2S), trace elements and have higher methane concentrations at c.60 percent than landfill gas at c.50 percent. Biogas analysers need filters for gas-borne solids and particulates. Where used in environments classed as explosive, ATEX certification becomes an obvious requirement for safety and risk management, as are reliable dependable and robust instruments. Laboratory gas-analysis instruments are not suitable.
In this harsh gas analysis environment a primary requirement is an infrared bench to measure the CH4. Flame ionisation detectors (FID) and catalytic bead sensors need an oxygen supply and so are not suitable. Ideally components used in biogas analysers should be in frequent daily use in demanding conditions on sites around the world.
Case Study: Manufacturer
Landfill technicians are very experienced with gas analysis instruments. Not so, the new breed of biogas producers, typically farmers anywhere from Brazil to Bavaria to Beijing. For them, these precisely accurate, robust, heavy-duty biogas analysers must be simple to use. One key Geotech design standard, in the world of the ‘iPod-generation’, was that, ‘Anyone can pick up one of our biogas analysers and use it in any one of six languages without opening the manual’. They can and they do, globally.
Published: 10th Jan 2007 in AWE International