This book brings together recent research from across the world on enriched methane, and examines the production, distribution and use of this resource in internal combustion engines and gas turbines. It aims to provide readers with an extensive account of potential technological breakthroughs which have the capacity to revolutionize energy systems. Enriched methane, a gas mixture composed by methane and hydrogen (10-30%vol), constitutes the first realistic step towards the application of hydrogen as an energy vector. It provides strong benefits in terms of emissions reduction, that is -11% of CO2, eq emission with the combustion of a 30%vol H2 mixture, if hydrogen is produced from renewable energy sources. Enriched methane offers the following advantages:• it can be produced at competitive costs; • it can be distributed by means of the medium pressure natural gas grid;• it can be stored in traditional natural gas storage systems; • it can feed natural gas internal combustion engine, improving conversion efficiency. /divdivThis book is intended for academics in chemical engineering and energy production, distribution and storage. It is also intended for energy producers, engineering companies and R&D organizations./divdivbr

This research investigated new approaches to control anaerobic methane oxidation coupled to sulfate reduction (AOM-SR) and enrich anaerobic methanotrophs (ANME) and sulfate reducing bacteria (SRB) with the purpose of designing a suitable bioreactor for AOM-SR at ambient pressure and temperature. The current knowledge about AOM and the microorganisms involved in AOM are discussed. The effect of different substrates and pressures was investigated on the ANME and SRB community adapted to the shallow marine Lake Grevelingen, the Netherlands. Further, microorganisms from the Alpha Mound (Spain) deep sediment were enriched with methane gas as substrate in biotrickling filters (BTF) at ambient conditions for 147-230 days of operation. The effect of alternative sulfur compounds (sulfate, thiosulfate and elemental sulfur) were studied and the microbial community was characterized. The highest AOM and sulfate reduction rates were obtained in the BTF fed with thiosulfate as the electron acceptor (~0.4 mmol l-1 day-1), but the highest number of ANME was visualized in the sulfate fed BTF (ANME-2 43% of the total visualized archaea). A BTF was proposed as a suitable bioreactor for the enrichment of ANME and SRB at ambient pressure and temperature which could be potentially used for future biotechnological applications.

Methane plays many important roles in the earth's environment. It is a potent "greenhouse gas" that warms the earth; controls the oxidizing capacity of the atmosphere (OH) indirectly affecting the cycles and abundances of many atmospheric trace gases; provides water vapor to the stratosphere; scavenges chlorine atoms from the stratosphere, terminating the catalytic ozone destruction by chlorine atoms, including the chlorine released from the man-made chlorofluorocarbons; produces ozone, CO, and CO2 in the troposphere; and it is an index of life on earth and so is present in greater quantities during warm interglacial epochs and dwindles to low levels during the cold of ice ages. By all measures, methane is the second only to CO2 in causing future global warming. The book presents a comprehensive account of the current understanding of atmospheric methane, and it is an end point for summarizing more than a decade of intensive research on the global sources, sinks, concentrations, and environmental role of methane.

Anaerobic oxidation of methane (AOM) coupled to sulfate reduction (AOM-SR) is a biological process mediated by anaerobic methanotrophs (ANME) and sulfate reducing bacteria. It has scientifi c and societal relevance in regulating the global carbon cycle and biotechnological application for treating sulfate-rich wastewater. This research aimed to enhance the recent knowledge on ANME distribution and its enrichment in different bioreactor confi gurations, i.e. membrane bioreactor (MBR), biotrickling fi lter (BTF) and high pressure bioreactor (HPB). Marine sediment from Ginsburg mud volcano, Gulf of Cadiz was used as inoculum in the BTF and MBR. The BTF operation showed the enrichment of ANME in the biofi lm, especially ANME-1 (40%) and ANME-2 (10%). Whereas, the dominancy of ANME-2 and Desulfosarcina aggregates was observed in the MBR. Moreover, HPB study was performed by using highly enriched ANME-2 community from Captain Arutyunov mud volcano. During the study of HPB at different temperature and pressure conditions, the incubation at 10 MPa pressure and 15 ̊C was observed to be the most suitable condition for the studied AOM-SR community. Furthermore, AOM-SR activity in the coastal sediments from marine Lake Grevelingen (the Netherlands) was explored and the microbial community was characterised which was dominated by ANME-3 among known ANME types.