Arundo Donax for Biogas Production

Biogas is produced from organic materials in anaerobic fermentation processes, in which microorganisms play a central role. Biogas is lighter than air and contains ca. 50–70% methane (CH4), 30–50% carbon dioxide (CO2) and 1-2% other gases (H2S, CO, N2). The main component for the energy use purpose is methane. Sewage sludge and slaughterhouse waste are of the best methane production sources to ca. 65-70% proportion, whereas methane from biomass reaches in best cases ca. 60-65% of the produced gas. The produced biogas needs to be refined in a final processing phase to bio-methane, which can be used for heating and as fuel or after combusting in gas engines, for electricity production. Bio-methane is therefore the most valuable component of biogas and can also directly be sourced into the public gas system or be temporarily stored. Biomass processed in thermochemical ways produces so-called synthesis gas (syngas), which has a methane share of only ca. 0-20%. This is used mainly in the chemical industry, for producing e.g. fertilisers or liquid fuel, respectively, for car fuel production (SNG -Synthetic Natural Gas).

The perspectives for biogas production are very promising worldwide, but especially are of high importance in the EU, where by 2014 nearly 15,000 biogas facilities were established. Out of these, over 9000 sites are located in Germany followed by Italy, having over 1300 production sites (Eurostat- 2014). Recently ca. 700-800 biogas sites were constructed every year in the EU due to mandated fuel and energy targets. Based on that, a production volume of ca. 20 million m3 bio-methane is envisioned in Europe by 2030 (EBA 2013).

Biogas sourcing from Arundo Donax in Europe is mainly established in Italy:
To illustrate results of arundo use for this purpose, the information of Arundo Italia Ltd. shall be used. This company has established over 500 hectares of arundo plantations across Italy by 2016 – to a large extent for biogas production purposes. Main figures from this experience are the following:

  • 80-100 metric tons of arundo silage production per hectare can be reached by intensive production technology, such as exercised in Italy.
  • The arundo sourced biogas has a methane share of over 60%, associated with minor costs of upgrading.
  • Production of biogas and bio-methane from arundo reaches up to 1.5 times the yield from corn of the same planting area.
    – Arundo Donax – total production on 1 ha = 16,000 m3 / ha (100 metric tons of silage / ha x 160 m3 of biogas / metric ton)
    – Corn – Total production on 1 ha = 11,000 m3 / ha
(50 metric tons of silage / ha x 220 m3 of biogas / metric ton)
    – Triticale – Total production on 1 ha = 4,800 m3 / ha
(30 metric tons of silage / ha x 30 m3 of biogas / metric ton).

In conclusion: 1 ha of Arundo Donax plantation produces about 50% more biogas than corn and almost 3 times more than triticale. This proves that Arundo is highly suitable for biogas production. However, this statement is subject to a high cultivation intensity and resultant high biomass yield.