Regulatory Promotion and Benefit Analysis of Biogas-Power and Biogas-Digestate from Anaerobic Digestion in Taiwan’s Livestock Industry

Wen-Tien Tsai

doi:10.3390/fermentation4030057

Abstract

The objectives of this paper were to summarize the status of the livestock (pig and cattle) industry and its waste management in Taiwan. The Water Pollution Control Act authorized the reuse of liquor and digestate from anaerobic digestion (AD) as fertilizers for agricultural lands on 24 November 2015. A large number of official databases and literature have been surveyed and analyzed to address the characterization of the biogas (AD-based) digestate and the potential benefits of biogas-to-power in Taiwan. On the promulgation of the Act, the central ministries have jointly managed the applications of livestock farms for reusing the AD-based liquor and digestate as fertilizers for farmlands. The survey findings revealed that the biogas digestate from a pig farm in Taiwan contained significant amounts of nitrogen, phosphorus, and other soil nutrients such as calcium and magnesium. However, it is necessary to control zinc present in the biogas digestate from pig-raising farms. A preliminary analysis based on 123 large-scale pig farms with a total of 1,223,674 heads showed the annual benefits of methane reduction of 6.1 Gg, electricity generation of 3.7 × 107 kW-h, equivalent electricity charge saving of 4.0 × 106 US$, and equivalent carbon dioxide mitigation of 152.5 thousand tons (Gg). Obviously, the integration of AD and biogas-to-power for treating animal manure is a win-win option for livestock farms to gain environmental, energy, and economic benefits.

Highlights

Taiwan is a small island country, posing a maritime climate with high humidity and warm temperatures due to its geographical location in tropical/subtropical zones
This trend should be mostly attributed to Taiwan entering the World Trade Organization (WTO) on 1 January 2002
The Taiwanese government was preparing for the WTO accession, assisting medium-scaled or uncompetitive pig farms in business transformation

Summary

Introduction

Taiwan is a small island country, posing a maritime climate with high humidity and warm temperatures due to its geographical location in tropical/subtropical zones. Over the past few years, livestock (e.g., pigs and cattle) waste (i.e., excrement and manure), due to its high levels of biodegradable matters and inorganic nutrients [1], has caused adverse impacts on environmental quality when they are discharged into surface water bodies or agricultural soils without adequate treatment, such biological treatment [2]. In this regard, the livestock sector contributes a significant share to anthropogenic greenhouse gas (GHG) emissions, especially in Fermentation 2018, 4, 57; doi:10.3390/fermentation4030057 www.mdpi.com/journal/fermentation

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