Low temperature BMP tests using fish waste from invasive Round goby of the Baltic Sea

A. Gruduls*, K. Balina, K. Ivanovs and F. Romagnoli

Riga Technical University, Institute of Energy Systems and Environment, Azenes street 12-K1, LV-1048 Riga, Latvia
*Correspondence: Arturs.Gruduls@rtu.lv

Abstract:

Round goby (Neogobius melanostomus) is an invasive fish species in the Baltic Sea. While meat can be used for human consumption, fish processing residues are considered as a waste. Within circular economy and bio-economy perspectives fish waste could be used as a valuable feedstock for biogas production. However, the research is mostly focused on evaluating biogas yield at mesophilic conditions (i.e. 37 °C). In this study the impact of low temperature on Biochemical Methane Potential (BMP) tests has been investigated. Round goby’s processing leftovers – heads, intestines and skin/bone mixture were tested in codigestion with sewage sludge. Anaerobic digestion (AD) was carried out in 100 mL batch tests at low temperature 23 °C and 37 °C conditions, over an incubation period of 31 days. The results show that AD at low temperature occurs twice as slowly as under 37 °C conditions. However, after 31 days the BMP values for 23 °C samples were only 2% lower than for high temperature samples. Heads and skins showed similar BMP values reaching on average 502 L CH₄ kgVS^-1 and 556 L CH₄ kgVS^-1 respectively. BMP for fish intestines was higher, reaching on average 870 L CH₄ kgVS^-1. Average BMP for mixes of fish heads, skins, intestines and bones was 660 L CH₄ kgVS^-1. Acquired BMPs were further compared with the theoretical BMPs from Buswell’s formula. Research results suggests that anaerobic digestion of fish waste under low temperature conditions could be feasible as the process still efficiently occurs, in fact opening a new opportunity to explore the overall sustainability of technologies based on these conversion processes.

Key words:

Model-based estimation of market potential for Bio-SNG in the German biomethane market until 2030 within a system dynamics approach

T. Horschig¹*, E. Billig² and D. Thrän¹,²

¹DBFZ – Deutsches BiomasseForschungszentrum gGmbH, Department of Bioenergysystems, Torgauer Straße 116, DE 04347 Leipzig, Germany
²UFZ – Helmholtz Centre for Environmental Research, Department of Bioenergysystems, Permoserstraße 15, DE 04347 Leipzig, Germany
*Correspondence: thomas.horschig@dbfz.de

Abstract:

One option for energy provision from renewables is the production and grid injection of synthetic natural gas from lignin-rich biomass like wood and straw. Bio-SNG (biological produced synthetic/substitute natural gas) is the product of the thermochemical production of methane via gasification and methanation of lignin-rich biomass. The first commercial bio-SNG plant went successfully into operation in the end of 2014, in Gothenburg (Sweden). Regarding the huge potential of lignin-rich biomass bio-SNG is expected to have a high potential for a sustainable and greenhouse gas reducing contribution in power, heat and fuel markets. Being a future technology with great advantages like storability and transportability within a gas grid but recently too high prices for market implementation, possible future market shares are uncertain because bio-SNG has to compete with anaerobic biomethane as well as fossil alternatives. With the combination of an extensive techno-economic evaluation for present and future costs of bio-SNG depending on the feedstock supply chain and economy of scale, Delphi-Survey and a quantitative market simulation we determined future market shares for biomethane and bio-SNG for Germany under varying scenarios like incentive schemes, economy of scale and feedstock prices. Results indicate that substantial governmental support in terms of either R&D effort to lower bio-SNG prices or direct subsidies for a further capacity development is necessary to achieve significant market shares for biogenic methane.

Key words:

bio-SNG, Bioenergy markets, biomethane, system dynamics.