Yoshiaki Kimura, Seiichi Yasui, Takahisa Hinata, Toshiyuki Imai and Hideyuki Takenaka

Abstract Currently, the biogas produced by biogas plants at dairy farms in Japan is a carbon-neutral energy. However, utilization of biogas has thus far been restricted solely to the farms where it is produced because there is no effective method of transporting unused biogas. Thus, there is a need to establish practical methods for biogas refinement and transport from operating systems. In this study, a biogas refining-compressing-filling facility using a gas membrane that would allow the use of surplus biogas produced by privately owned biogas plants was manufactured. Furthermore, field tests of biogas utilization systems (BGUS) made up of equipment that could use purified gas obtained from such a facility were performed. Finally, the possibility of a regional purified biogas system of Japan was validated in rural areas. The refining-compressing-filling facility was able to achieve a biogas Wobbe index of 49.2-53.8 and a combustion rate equivalent to 34-47 m/s. The total carbon load of the common portions of the BGUS was 102 t-CO2 eq. Compared with the carbon load of the common portion of the biogas plant before introduction of the BGUS and of the gas utilizing equipment inside and outside the farm production system (209 t-CO2 eq), a reduction of 107 t-CO2 eq was achieved. The area’s carbon dioxide emissions could be reduced through the standardization of biogas products through refinement; this would allow for the export of biogas outside of the system for use in common gas appliances. Currently, purified gas is locally produced and consumed as a source of carbon-neutral energy on dairy farms and adjacent residences. Packing the purified gas into tanks and supplying it to the town create the possibility of further reducing the carbon emissions of rural areas.

Keywords Biogas plant ■ Biogas purifier ■ Biogas utilization system (BGUS) ■

Gas membrane — Wobbe index

Y. Kimura (H) ■ T. Hinata ■ H. Takenaka

Hokkaido Central Agricultural Experiment Station, Hokkaido Naganuma, Japan e-mail: kimura-yoshiaki@hro. or. jp

S. Yasui

Zukosha. Co. Ltd, Hokkaido Obihiro, Japan

T. Imai

Green Plan. Co. Ltd, Hokkaido Sappro, Japan

Z. Fang (ed.), Pretreatment Techniques for Biofuels and Biorefineries,

Green Energy and Technology,

DOI 10.1007/978-3-642-32735-3_13, © Springer-Verlag Berlin Heidelberg 2013

13.1 Introduction

Anaerobic fermentative treatment of livestock waste by biogas plants is more effec­tive in lowering the environmental load than other methods. The biogas produced can be used as an energy source. Biogas from anaerobic digestion using livestock waste consists primarily of methane (typically 60 %) and carbon dioxide [1]. Other com­ponents can include oxygen and nitrogen, originating from air, sulfur compounds, particularly hydrogen sulfide, and water.

Approximately 80 biogas plants have been built in Japan as a means of effectively utilizing livestock waste. However, because many of the power generators installed in the plants to produce electricity—a representative method of utilizing biogas that has not been completely consumed by the facilities where it is produced—are foreign — made, repairing the generators when problems occur is difficult. Furthermore, the price of surplus electricity being sold is too low to recover the running cost. Use of biogas in Japan is premised on “consumption within the farm production system only used by farm management.” Because of this, a method of transporting biogas outside the farm production system is needed to capture the full potential of this agricultural biogas.

It was assumed that effective utilization of biogas outside the farm production sys­tem could be accomplished by simple application to general gas equipment. However, the amount of biogas produced and the concentration of methane fluctuates daily, its caloric value is not stable, and there is residual hydrogen sulfide; thus, domes­tic gas equipment manufacturers have shown reluctance to directly use general gas equipment for biogas. Also, as part of the IGF21 Plan, the Ministry of Economy, Trade and Industry, Japan has been advancing the integration of the highly caloric natural gases, for use as town gas [2, 3]. Thus, there is need for standardization of high-caloric biogas and stabilization of its caloric value.

A method of resolving this problem would necessarily involve the construction of a system that purifies biogas, fills storage cylinders at high pressure with the gas, and distributes it within the region. Purified biogas is used as transportation fuel in a number of countries but in Europe, it has reached a major breakthrough in Sweden [4-6] and German [7]. Thus, it is necessary to introduce a system of equipment that carries out in a single effort the basic technological sequence of biogas refining for Japanese rural areas, standardized high calorification of the gas, compression (high pressurization of the gas), and flow to storage cylinders [8]. There is also a need to extensively troubleshoot the problems that could occur in the actual use of this biogas purifier and clarify measures on how to solve these problems for rural areas in Japan.

In this chapter, a biogas refining-compressing-filling (RCF) facility that uses surplus biogas produced by privately owned biogas plants was devised and evaluated in terms of greenhouse gas (GHG) reduction, and field tests of biogas utilization systems made up of equipment that using purified gas obtained from the facilities were performed. Thus, the possibility of a regional purified biogas system of Japan was validated in rural areas.

Fig. 13.1 Gas membrane biogas refinement using membranes. (Hollow fiber separation)