Biomass energy (biofuels and waste) is currently the largest renewable energy source and the fourth largest primary energy supply in the world (International Energy Agency, 2019b). Defined by the Renewable Energy Development Act (Executive Yuan, 2019) in Taiwan, biomass energy (or bio-energy) is the energy produced by direct utilization or treatment of the agricultural and forest plants, biogas, and domestic organic wastes. In the Act, classified as the renewable energy, general wastes and general industrial wastes can also be regarded as a kind of biomass energy.
Biomass energy (generated from biomass and waste) is now the fourth largest renewable energy installed capacity in Taiwan, but it is the second largest renewable energy power generation supply. By the end of 2019, an installed capacity of 708.53 MW for power generation has been achieved through biomass energy utilization, which is primarily based on 25 municipal solid waste (MSW) incineration power generation systems (631.93 MW), biogas power systems (5.93 MW) and solid biomass (70.67 MW) power systems, with a total power generation supply of 343.82 GWh (Bureau of Energy, 2020). However, the growth rate of the biomass energy installed capacity has been almost zero over the past 15 years. On the other hand, solar PV installed capacity has grown by around 30 times, while the wind power installed capacity has grown by around 60% over the last decade.
FEED-IN TARIFFS ISSUE
Why has biomass power generation installed capacity not grown over the years in Taiwan? The major reason is that the feed-in tariffs (FITs) in Taiwan for biomass without biogas equipment and wastes are too low, compared with solar PV and wind power. Currently, FITs for the biomass power system with/without biogas equipment and waste are US¢ 17.06 (exchange rate: USD 1 = NTD 30), 8.96, and 13.16, respectively (Ministry of Economic Affairs, 2020). On the other hand, the electricity price for households was US¢ 8.41 in 2018 (International Energy Agency, 2019a). It can be seen that the FIT rate for the biomass power system without biogas equipment is almost the same as the electricity price for households.
Unlike solar PV or wind power generation systems, where free sunlight or wind is used, the solid biomass feedstock used by the thermochemical biomass power system must bear the costs of collection and transportation even if the feedstock is free. Here collection and transportation costs are considered the external costs and they are always ignored during the calculation of FITs. The FIT subsidy is only focused on power generation equipment. It cannot truly reflect the costs of installing and operating a thermochemical biomass power system, such as biomass combustors or gasifiers. Unfortunately, the costs of collection and transportation are quite high in Taiwan due to unstable supply and scattered distribution of biomass feedstock. Therefore, it is difficult to install a thermochemical biomass power generation plant without profit in Taiwan.
Moreover, biodegradable waste is a kind of biomass. According to the regulation (Ministry of Economic Affairs, 2019) to reach the higher FITs for employing general wastes or general industry wastes, the power generation efficiency must be higher than 25% for installing a waste power generation system. However, the power generation efficiencies for most existing large MSW incinerators (up to 48 MW) in Taiwan were not more than 20%. The efficiency set at 25% required by the regulation (Ministry of Economic Affairs, 2019) is to prevent the existing MSW incinerators from adapting the regulation to receive more incentives, because the existing MSW incinerators have already received the equipment subsidies. Currently, the average price for purchasing surplus electricity by Taipower Co. from 25 co-generation MSW incinerators was US¢ 6.20 in 2019 (Environmental Protection Administration, 2020), lower than that of biomass power system without biogas equipment (US¢ 8.96).
It is suggested that FIT regulations should exclude the large MSW incinerators to encourage installing small thermochemical biomass power plants. The FITs for thermochemical biomass power plants should be increased significantly as soon as possible. It can also be seen that while the biogas FIT increased, the biogas industry was booming, and the amount of installed capacity of biogas was also increased since 2017. Moreover, compared to massive FITs for solar PV and off-shore wind power installations (Ministry of Economic Affairs, 2020), more subsidies to thermochemical biomass power plants would not cost too much according to national finance.
BIOMASS CO-FIRING INCENTIVE
Another important policy that most countries have already implemented for enhancing solid biomass utilization is to apply co-firing of biomass in existing coal-fired boilers. The advantages of co-firing of biomass in existing coal-fired boilers include conducting retrofit on a short-term basis, low capital and operating cost, reducing emissions (CO2, SOx, NOx, etc.), and avoiding disposal of residues (Koppejan, 2004). Especially while biomass resource is limited, at least coal-fired boilers reduce coal consumption as much as they could. In the past two decades, however, there were no policies legislation, and incentive measures for biomass co-firing with coal in Taiwan, although some industries did co-fire biomass in their coal-fired cogeneration boilers, such as paper mill factories (Tsai et al., 2002).
Some controversies made it difficult to initiate the incentives for biomass co-firing in Taiwan over the past two decades. It seems that the exact amount of biomass consumption for co-firing was very difficult to be audited by governmental authorities. The authorities always worried that the industries may lie about burning biomass, but actually burned coal, in order to obtain more subsidies. Therefore, it is suggested that the government should employ an impartial and trustworthy third party, e.g., professional associations, to perform the audit. The subsidies can be based on proportion of co-firing biomass.
POTENTIAL AGRICULTURAL AND FORESTRY FEEDSTOCK
In addition to policy, measures, and instruments, the sufficient supply of biomass feedstock is the key to the success of biomass power deployment. According to the survey, Taiwanese potential agricultural and forestry surplus materials including straw and rice husks, miscellaneous crops, pruned fruit trees, surplus from timber logging site, bamboo, and driftwood, were estimated at about 1,275,777 tonnes per year. A total energy potential could reach 15,042 TJ (Chyang, 2011), which can generate about 4 billion kWh (TWh) of electricity. Although the amount of above biomass feedstock was not so much, the environmental hazards may be caused if it was arbitrarily disposed of. In addition, the above survey did not include spent mushroom cultivation bases which contained woody biomass, corn stalk, etc. Based on the latest data in 2013, the annual amount of spent mushroom cultivation bases (SMCBs) in Taiwan was up to 560 million small container bags (Lin et al., 2015), which was equivalent to 550,000 tons of agricultural wastes, i.e., biomass feedstock. Now the SMCBs have caused serious environmental pollution (Unite Daily News, 2018). Thus, it will be a win-win situation for energy and the environmental protection, if we make good use of SMCBs.
EXPLORING MORE DOMESTIC BIOMASS FEEDSTOCK
Exploring more domestic biomass feedstock resources is a priority task to expand the biomass power generation. According to the results of the fourth forest resource survey, Taiwan man-made forest area consists of about 440,000 hectares, and productive forest plantation is about 270,000 hectares (Lin, 2017). If 5 m3/yr timbers grow per hectare, there will be 1.35 million m3/yr timber production (Public Television Service, 2018). Given sustainable management and appropriate utilization of timbers, the primary residues after logging (i.e., forest residues, such as unusable branches and leaves) and the secondary residues, i.e., industrial residues (leftover wood chips or sawdust) after timber processing from factories (such as furniture, etc.) was initially estimated to be up to 320,000 tonnes of surplus woody biomass. If the above woody biomass is converted into power generation, it is conservatively estimated at around 1.3 billion kWh (1.3 TWh) of electricity production per year. The total potential of biomass energy in Taiwan produced from MSW, biodegradable industrial waste, biogas, agricultural and forestry residues, etc. can reach 8.5 billion KWh (8.5 TWh), which is around twice the current target biomass power generation in 2025 (Liao, 2019), and will exceed the total power generation of hydropower (6.6 TWh).
“Biomass is essential in the energy transition.” This quotation was shown in a board by Energy Research Centre of the Netherlands (ECN) at 27th European Biomass Conference & Exhibition (EUBCE 2019) in Lisbon, Portugal on 27-30 May, 2019. Indeed, it can be seen that the capacity factor of biomass energy is up to 84%, compared to the solar PV (16%) and wind power (28%) (Strauss, 2017). Consequently, biomass energy can be the ideal renewable base load power to reduce fossil fuel consumption and lower greenhouse gas emissions. Therefore, promotion of biomass power in Taiwan is an important task to readily increase the utilization of renewable energy.
Biomass energy is in line with the concept of sustainable development, in terms of waste disposal and energy utilization, thereby protecting the environment and reducing the CO2 emissions. It is suggested that under moderate promotion by the government, the thermochemical biomass power plants can be invested and operated by the private sector to form a complete bioenergy industry system. The conversion of biomass resources into bioenergy can increase domestic power generation capacity, which will significantly assist Taiwan in reducing heavily imported energy and also establish a good foundation for its sustainable development in the future.
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