Abstract
Biofuels are still too costly to compete in the energy market and it has been suggested that low-value feedstocks could provide an opportunity for the production of low-cost biofuels; however, the lower quality of these feedstocks requires the introduction of a conditioning step in the biorefinery process. The aim of this study was to evaluate whether feedstock savings cover the cost of conditioning in the case of animal bedding. The BioSTEAM software was used to simulate a wheat straw biorefinery and an animal bedding biorefinery, whose economic performance was compared. The wheat straw biorefinery could deliver ethanol at a minimum selling price of USD 0.61 per liter, which is similar to prices in the literature. The cost of producing ethanol in the animal bedding biorefinery without water recycling was almost 40% higher, increasing the minimum selling price to USD 1.1 per liter of ethanol. After introducing water recycling in the conditioning step, the animal bedding biorefinery could deliver ethanol at a minimum selling price of USD 0.38 per liter, which is 40% lower than in the case of the wheat straw biorefinery. This demonstrates that low-value feedstocks can be used to reduce the biofuel price, as feedstock savings easily cover the additional conditioning cost.
Highlights
In order to limit the global temperature increase to 2 ◦ C, almost three-quarters of the global energy supply mix would need to be based on low-carbon technologies such as wind, solar or bioenergy, by 2050 [1]
A plant size of 2000 dry ton/day of feedstock was assumed in the economic estimations, simulations based on a plant size of 1000 dry kg/h of feedstock were performed in order to facilitate the interpretation of the results, comparison with the results of previous studies, and to confirm the validity of the models
The results presented and discussed in the two following sections are based on a plant capacity of 1000 dry kg/h, whereas the economic data presented in the final section are based on a plant capacity of 2000 dry ton/day
Summary
In order to limit the global temperature increase to 2 ◦ C, almost three-quarters of the global energy supply mix would need to be based on low-carbon technologies such as wind, solar or bioenergy, by 2050 [1]. The supply of bioenergy would be especially important in the transport sector, where the use of biofuels would need to triple by 2030, with advanced biofuels accounting for two thirds of this increase [2]. The production cost of biofuels is still too high for them to be commercially competitive with fossil fuels in the energy market [3]. Zero- or negative-value waste could provide early market opportunities for the production of low-cost biofuels, the most significant potential for cost reduction lies in reducing the capital cost through experience gained in deploying demonstration and early commercial plants [4]. Biofuel researchers have started to investigate wastes that currently have no commercial use or value, such as municipal solid waste, food waste, slaughterhouse waste and industrial waste [5,6,7,8]
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