Biomethane: Production and Applications

By Sirichai Koonaphapdeelert, Pruk Aggarangsi and James Moran

This book discusses biomethane and the processes and applications downstream from biogas production. Biogas is a result of anaerobic digestion of agricultural or general household waste, such as manure, plants or food waste, and as such is considered a renewable energy source. Biomethane is a gas that results from any process that improves the quality of biogas by reducing the levels of carbon dioxide, hydrogen sulfide, moisture and other contaminant gases. Chemically, biomethane is the same as methane, and its name refers to the method of production rather than the content.

Biomethane plants are generally found in locations with a low population density that are close to farms or food processing plants. In situations where there is no natural gas pipeline nearby, biomethane downstream applications can include storage, transportation, home heating, industrial use and distribution through small-scale local gas grids. This book discusses each of these applications and lists some of the design criteria as well as various issues relating to them.

• Language: English
• Publisher: Springer
• Release date: Nov 6, 2019
• ISBN: 9789811383076

Book preview

© Springer Nature Singapore Pte Ltd. 2020

S. Koonaphapdeelert et al.Biomethane Green Energy and Technologyhttps://doi.org/10.1007/978-981-13-8307-6_1

1. Introduction to Biomethane

Sirichai Koonaphapdeelert¹  , Pruk Aggarangsi² and James Moran³

(1)

Department of Environmental Engineering, Chiang Mai University, Chiang Mai, Thailand

(2)

Department of Mechanical Engineering, Chiang Mai University, Chiang Mai, Thailand

(3)

Department of Mechanical Engineering, Chiang Mai University, Chiang Mai, Thailand

Sirichai Koonaphapdeelert

Email: [e-mail]

1.1 Background

In 1630, Jan Baptist van Helmont discovered that organic material in decomposition produced flammable gases. Some years later (1776), Alessandro Volta discovered methane by collecting gas emerging from Lake Maggiore in Italy. In 1804, John Dalton established the chemical composition of methane. Louis Pasteur reported that biogas could be used for heating and lighting. The concept of anaerobic digestion was introduced around 1870 with the development of the septic tank system by Jean-Louis Mouras.

In the modern era, within the next few decades, bioenergy from biogas and biomethane has the potential to become a significant global renewable energy source as an economical attractive alternative to fossil fuels. The future potential of biomethane will be aided from its broad variety of applications, such as the production of heat, steam, electricity, hydrogen, and for use in transportation. Biogas can be produced in small and large scales which allows for versatile production all over the world. The electricity capacity from biogas plants in different regions of the world is given in Fig. 1.1.

../images/469947_1_En_1_Chapter/469947_1_En_1_Fig1_HTML.png

Fig. 1.1

Global installed electricity from biogas

(Reprinted with permission from [14])

Biogas production is predicted to increase to 40.2 million tons by 2030. The world bioenergy association estimated that renewable energy contributed approximately 18.6% of the total global energy consumption in 2014, in which bioenergy accounted for nearly 14% (Fig. 1.2).

../images/469947_1_En_1_Chapter/469947_1_En_1_Fig2_HTML.png

Fig. 1.2

Gross global energy consumption by fuel in 2014

(Reprinted with permission from [4])

1.2 Biogas Composition

Biogas consists of two main components, methane ( $$\mathrm{CH}_{4}$$ ) and carbon dioxide ( $$\mathrm{CO}_{2}$$ ), which is a nonflammable gas. Other components include hydrogen sulfide ( $$\mathrm{H}_{2}\mathrm{S}$$ ), nitrogen ( $$\mathrm{N}_{2}$$ ) and oxygen ( $$\mathrm{O}_{2}$$ ). The general concentration of the gas is shown in Table 1.1.

Table 1.1

General composition of biogas

Biogas’s usefulness as a fuel comes primarily from its methane component. It exists in the gaseous state at normal temperature, $$0\,^{\circ }\mathrm{C}$$ ( $$273.15\,$$ K), and pressure, $$1\,$$ atm ( $$101.325\,$$ kPa). If biogas liquefaction is desired, a pressure of approximately $$20\,$$ MPa and temperatures of $$-161\,^{\circ }\mathrm{C}$$ are needed. Table 1.2 shows the heat output for different components and compositions of biogas. It has the ability to replace fossil fuels in transportation or for electricity generation [17].

Table 1.2

Selected gas properties at atmospheric pressure and a temperature of $$0\,^{\circ }\mathrm{C}$$

1.2.1 Biogas and Pollution Reduction

Biogas can be formed from the organic compounds commonly found in wastewater from industrial plants, such as tapioca factories, breweries, fruit processing plants, as well as wastewater from livestock farms. Without biogas production, this organic waste is usually discarded into a nearby water supply, especially in developing countries. This effluent competes with downstream organisms for oxygen. This oxygen demand can kill marine life downstream of the discharge area. A measure of water quality is a parameter called the chemical oxygen demand (COD) which measures the amount of oxygen in the water consumed by organic reactions. It is expressed in mass of oxygen consumed over water volume, milligrams per liter (mg/L). A COD test can be used to quantify the amount of organic matter in water. It is a useful test because it provides a metric to determine the effect organic waste will have on the waterway. If instead of directly discarding the waste, biogas is produced, this reduces the wastewater   chemical oxygen demand (COD) by over $$80\%$$ [13]. In other words, the waste output from biogas production causes substantially less damage to the natural environment than the raw waste. A rule of thumb is that every kilogram of COD removed from wastewater can