Arundo

Arundo Is Better than Switchgrass for Biomass Power Generation

While in the US some regulatory hurdles remain, Europe is already using this fast-growing plant to produce ethanol and electricity.  It is considered an invasive plant and requires procedures to prevent unwanted spreading

Arundo donax, Giant Cane, is a tall perennial cane growing in damp soils, either fresh or moderately saline. Other common names include Carrizo, Arundo, Spanish cane, Colorado River Reed, Wild cane, and Giant reed.   It’s seeds are generally sterile and propagation is by root cuttings.

Arundo donax is native to eastern and southern Asia, and probably also parts of Africa and southern Arabian Peninsula. It has been widely planted and naturalised in the mild temperate, subtropical and tropical regions of both hemispheres, especially in the Mediterranean, California, the western Pacific and the Caribbean.  It forms dense stands on disturbed sites, sand dunes, in wetlands and riparian habitats.

Arundo donax generally grows to 6 metres (20 ft), in ideal conditions it can exceed 10 metres (33 ft), with hollow stems 2 to 3 centimetres (0.79 to 1.2 in) diameter. The leaves are alternate, 30 to 60 centimetres (12 to 24 in) long and 2 to 6 centimetres (0.79 to 2.4 in) wide with a tapered tip, grey-green, and have a hairy tuft at the base. Overall, it resembles an outsize common reed or a bamboo.  Arundo donax flowers in late summer, bearing upright, feathery plumes 40 to 60 centimetres (16 to 24 in) long, but the seeds are rarely fertile. Instead, it mostly reproduces vegetatively, by underground rhizomes. The rhizomes are tough and fibrous and form knotty, spreading mats that penetrate deep into the soil up to 1 metre (3.3 ft) deep.

Arundo donax can produce 20 dry tons of biomass per acre.  That’s compared to Switchgrass, which only averages up to 8 tons an acre annually. It’s estimated that Arundo would produce about 10,000 Btu/lb compared to 8500 Btu/lb for coal operations.

Since late last year, Beta Renewables, whose partners are Chemtex, Novozymes and TPG, has been operating a 20-million gallon a year ethanol production facility in Crescintino, Italy using Arundo donax and wheat straw as feedstock. “In Italy, we use enzymatic hydrolysis fermentation,” said Delane Richardson, a chemical engineer at Chemtex in Medina, Ohio. “You extract the sugar from the biomass and the enzymes take the long chain sugars and cut them into digestible C5 and C6 sugars that are then exposed to a patented ethanologen microorganism to produce ethanol.”

Richardson says Chemtex would like to build a biomass to ethanol plant in Clinton, North Carolina that would operate on a combination of Arundo, Switchgrass, Fiber Sorghum, Miscanthus, and Rye at a delivered aggregate biomass feedstock cost of $50 or less per dry ton. However, the largest single component would be 100,000 tons of Arundo, which would account for 7 million gallons (or at least a third) of the Clinton facility’s annual ethanol production. If the plant’s local biomass supply chains were firmed up, Richardson says the North Carolina facility could be operational by mid-2015.