Preliminary investigation of greenhouse gas emissions from the environmental sector in Taiwan.

ABSTRACT

The United Nations Framework Conventions on Climate Change (UNFCCC) asks their Parties to submit a National Inventory Report (NIR) for greenhouse gas (GHG) emissions on an annual basis. However, when many countries are quickly growing their economy, resulting in substantial GHG emissions, their inventory reporting systems either have not been established or been able to be linked to planning of mitigation measures at national administration levels. The present research was aimed to quantify the GHG emissions from an environmental sector in Taiwan and also to establish a linkage between the developed inventories and development of mitigation plans. The "environmental sector" consists of public service under jurisdiction of the Taiwan Environmental Protection Administration: landfilling, composting, waste transportation, wastewater treatment, night soil treatment, and solid waste incineration. The preliminary results were compared with that of the United States, Germany, Japan, United Kingdom, and Korea, considering the gaps in the scopes of the sectors. The GHG emissions from the Taiwanese environmental sector were mostly estimated by following the default methodology in the Intergovernmental Panel on Climate Change guideline, except that of night soil treatment and waste transportation that were modified or newly developed. The GHG emissions from the environmental sectors in 2004 were 10,225 kilotons of C[O.sub.2] equivalent (kt C[O.sub.2] Eq.). Landfilling (48.86%), solid waste incineration (27%), and wastewater treatment (21.5%) were the major contributors. Methane was the most significant GHG (70.6%), followed by carbon dioxide (27.8%) and nitrous oxide (1.6%). In summary, the GHG emissions estimated for the environmental sector in Taiwan provided reasonable preliminary results that were consistent and comparable with the existing authorized data. On the basis of the inventory results and the comparisons with the other countries, recommendations of mitigation plans were made, including wastewater and solid waste recycling, methane recovery for energy, and waste reduction/sorting.

INTRODUCTION

Although the Republic of China (Taiwan) was not one of those Parties that ratified the Kyoto Protocol, it has still spent the highest efforts to comply with the international framework to confront the global climate change. Since 1992, Executive Yuan, the highest administration authority in Taiwan, has started to coordinate activities related to United Nations Framework Convention on Climate Change (UNFCCC) and other global environmental issues. In the meantime, the Taiwan Environmental Protection Administration (TEPA) has been continuously establishing greenhouse gas (GHG) mitigation policies. In particular, the sectors of Industry, Transportation, and Residential/Commercial were chosen by the TEPA for GHG inventorying, registration, validation, and methodology establishment. (1-3)

In Taiwan, the sources of GHG emission are closely related to the use of energy. (4) Despite abundant precipitation on an annual basis, most of the precipitations occur in the rainy season associated with typhoons. In addition, the rivers are very short, making them difficult to use for hydropower production. Producing almost no energy resources on its own, Taiwan relied on the supply of imported coal and petroleum for approximately 80% of its energy in 1998. Under this situation, the annual carbon dioxide (C[O.sub.2]) emissions per capita have increased at an annual rate of 5.8% from 1990 to 2000, to 5.57 t and 9.83 t, respectively. According to the statistics issued by TEPA, (5) the C[O.sub.2] emissions in 2003 increased by 121% from the level in 1990. The C[O.sub.2] emission estimation for 1990 ranked Taiwan 27th of 159 United Nations member countries, and Taiwan contributed approximately 0.5% to the global total. (6)

According to the Kyoto Protocol, adopted in 1997 at the Third Conference of the Parties to the UNFCCC and enforced on February 16, 2005, the Annex I countries must reduce their overall GHG emissions by at least 5% below 1990 levels in the commitment period 2008-2012. The anticipated balance between economic growth and GHG mitigation became a considerable challenge in Taiwan.

If Taiwan were one of the Annex I countries of the UNFCCC, the corresponding GHG emissions would have to be reduced by 227% of the projected value for 2010. (4) The amount to be reduced would be more than 10-20 times that of many developed countries, (7) which would have tremendous impact on an economy that has seen high growth in recent years through export-oriented industrialization. For this reason, TEPA considers Taiwan to be categorized as one of the Newly Industrialized Countries. Although the economic performance has surpassed those of many developing countries, Taiwan is not yet mature enough for making a sustainable commitment following the Annex I countries.

According to the Intergovernmental Panel on Climate Change (IPCC) guideline, (8) disposal and treatment of industrial and municipal wastes can produce significant amount of GHG emissions. C[O.sub.2] is mainly produced by waste incineration, methane (C[H.sub.4]) could be observed from landfilling and waste transportation, and nitrous oxide ([N.sub.2]O) is produced from incineration and wastewater treatment. To illustrate, C[H.sub.4] produced as a byproduct of the anaerobic decomposition of waste can contribute approximately 5-20% of annual global anthropogenic GHGs released to the atmosphere. (8) Also, in the United States, it was claimed that landfills were the largest source of anthropogenic C[H.sub.4] emissions, which accounted for 24% of total U.S. C[H.sub.4] emissions. On the other hand, waste-related sectors usually do not release other kinds of GHGs, such as perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), and sulfur hexafluoride ([SF.sub.6]).

However, none of the emission inventories from the waste-related sectors had been developed in Taiwan. Therefore, the TEPA commissioned a research project to investigate the GHG emissions from a so-called "environmental sector," which is comprised of the waste treatment activities that are under its administration. The activities in the environmental sector include solid waste incineration, wastewater treatment, landfilling, composting, night soil treatment, and waste transportation. This paper summarizes the results from this project, in particular, the latest information on Taiwanese anthropogenic GHG emissions from the environmental sector in 1990, 1994, and 2000-2004, by undertaking a preliminary investigation. Socioeconomic data from nine of the 25 cities and counties in the Taiwan area were collected in a survey for references, but all of the GHG calculation was completed based on the activity data for the entire population. The nine cities and counties cover 47% of the Taiwanese population (2004). To ensure the inventories were comparable to other countries, the presented estimates were calculated mostly using methodologies consistent with those recommended in the IPCC guidelines, (8) but some methods were modified or newly developed. In addition, a comparison with five developed countries (United States, Germany, Japan, United Kingdom, and Korea) were conducted and discussed. Finally, mitigation plans were discussed based on the inventory results and comparison and recommendations were made. Although the UNFCCC asks its Annex I parties to submit GHG National Inventory Reports (NIRs) on an annual basis, not many populated countries have either established their GHG inventory systems or linked their inventory to planning of mitigation measures at national administration levels.

METHODOLOGIES

The IPCC 1996 revised guidelines (8) was primarily followed in the study to estimate the anthropogenic GHG emissions in the environmental sectors. However, because the environment sector does not belong to a formal IPCC source category, some methods followed the principle of the IPCC guideline but modified with consideration of local conditions. The overall calculations were conducted with the principle expressed in eq 1:

GHG emission [kg-C[O.sub.2] equivalent] = Activity Data [activity] x Emission Factor [kg-GHG/activity] x Global Warming Potential [kg-C[O.sub.2] equiv./kg-GHG] (1)

The global warming potential (GWP) values for each of the GHG were defined in the IPCC Third Assessment Report. Note that instead of using measurements with scientific instruments, the GHG emissions were estimated by socioeconomic data. Officially published data were collected to employ the IPCC Tier-1 (simple) method, so that a top-down estimation was completed in the preliminary investigation. For example, for quantifying emissions from solid waste incineration, the mass of solid waste incinerated was used; for waste transportation, fuel consumption was taken into account. The IPCC method excludes C[O.sub.2] emissions from biomass (crops and forests) combustion, and definitively states, "The present atmospheric C[O.sub.2] increase is caused by anthropogenic C[O.sub.2] emissions." (10) However, the exclusion of biomass was not carried out in the present study because of lack of data for biomass content in the municipal solid waste (MSW) incineration. The biomass delivered to the MSW treatments was difficult to quantify during the study year because the MSW sorting policy enforced since 2006, in which food waste was subject to sorting from general waste as well as other recyclable materials, has changed the composition and amount of biomass delivered to the waste incineration. The best available data were carbon content and heat values, which were utilized in the GHG calculation.