Cleveland, Ohio based quasar energy group has begun construction of its first integrated Anaerobic Digestion (AD) system, utilising a patent-pending iADs system to increase the types of waste that can be converted to biogas for energy and fuel uses.

The company said that the technology has been developed by the Ohio Agricultural Research and Development Center (OARDC) - a part of the Ohio State University - and couples quasar's liquid AD technology with solid-state AD to increase energy outputs, expand the feedstock base, and broaden the market application for the system. .

According to the university, the integrated system is currently under construction next to quasar's Zanesville, Ohio, biodigester - which annually processes close to 30,000 tons (27,300 tonnes) of agricultural and food waste and can produce 7800 MWh of electricity each year.

The OARDC said that the system allows for the production of additional biogas from a number of organic materials with high solids content (such as yard trimmings, crop residue, corn silage and lignocellulosic food waste) that are not suitable to existing AD systems.

The integration of technologies at the heart of iADs is the brainchild of Yebo Li, an OARDC biosystems engineer who specialises in bioenergy and bio-products.

Li explained that the new system has the potential to increase the amount of feedstock available for AD within a specific area, thus reducing transportation costs. It can also boost the amount of biogas generated at a biodigester.

"Current liquid-phase anaerobic digesters used in the United States can only process up to 14% solids content. My system has been successfully tested with 20-35% solids content, substantially increasing biogas production efficiency compared to existing systems," said Li.

The university claimed that because of the higher amount of solids that iADs can process, this system also generates a compost-like solid residue that can be used as fertiliser.

The iADs technology received a $2 million grant from the state of Ohio's Third Frontier Advanced Energy Program in 2009. Funding has also been provided by the Ohio Department of Development's American Recovery and Reinvestment Act (ARRA) State Energy Program.

The funding enabled the development of a demonstration scale facility is located adjacent to quasar's operational digester at 6400 Maysvile Pike. Construction of the new facility is scheduled to be completed by late April 2012.

" iADs will allow quasar to accept and process a wider range of high-solids feedstocks, including high-volume off-spec and major market recall material" concluded quasar president, Mel Kurtz.