The waste-to-energy framework for integrated multi-waste utilization: Waste cooking oil, waste lubricating oil, and waste plastics

The waste-to-energy framework for integrated multi-waste utilization: Waste

cooking oil, waste lubricating oil, and waste plastics

Ampaitepin Singhabhandhu*, Tetsuo Tezuka

Energy Economics Laboratory, Department of Socio-Environmental Energy Science, Graduate School of Energy Science, Kyoto University, Yoshida-honmachi,

Sakyo-ku, Kyoto 606-8501, Japan

article info

Article history:

Received 7 July 2009

Received in revised form

1 March 2010

Accepted 1 March 2010

Available online 2 April 2010

Keywords:

Waste cooking oil

Waste lubricating oil

Waste plastics

Pyrolysis

Waste utilization

abstract

Energy generation by wastes is considered one method of waste management that has the benefit of

energy recovery. From the waste-to-energy point of view, waste cooking oil, waste lubricating oil, and

waste plastics have been considered good candidates for feedstocks for energy conversion due to their

high heating values. Compared to the independent management of these three wastes, the idea of co￾processing them in integration is expected to gain more benefit. The economies of scale and the synergy

of co-processing these wastes results in higher quality and higher yield of the end products. In this study,

we use cost-benefit analysis to evaluate the integrated management scenario of collecting the three

wastes and converting them to energy. We report the total heat of combustion of pyrolytic oil at the

maximum and minimum conversion rates, and conduct a sensitivity analysis in which the parameters of

an increase of the electricity cost for operating the process and increase of the feedstock transportation

cost are tested. We evaluate the effects of economy of scale in the case of integrated waste management.

We compare four cases of waste-to-energy conversion with the business as usual (BAU) scenario, and our

results show that the integrated co-processing of waste cooking oil, waste lubricating oil, and waste

plastics is the most profitable from the viewpoints of energy yield and economics.

2010 Elsevier Ltd. All rights reserved.

1. Introduction

Industrial and household wastes are produced on a daily basis

and are managed in many ways, depending on their type. According

to their combustibility, wastes are basically categorized as either

burnable or unburnable. The burnable wastes are normally treated

by combustion with or without heat production, while the

unburnable wastes are treated by recycling, re-use, or landfilling,

depending on the material. Municipal and industrial wastes that

contain high heat value, such as waste plastics (WP), waste cooking

oil (WCO), and waste lubricating oil (WLO) are considered efficient

feedstocks for energy production in a Waste-to-Energy regimen.

Although these three wastes are usually separately managed, in

some countries and some specific regions of Japan there have been

efforts to collect WCO separately to produce biodiesel through

transesterification. However, the normal practice is to collect WCO

together with burnable garbage and combust it with or without

heat utilization, or even manage it by the inefficient method of

discharging it into a sewer system. WLO is mainly managed by

recycling it to produce heavy oil or lower-graded fuel, and through

a combustion process for energy purposes. Plastic wastes are

divided into two categories: those that can be efficiently managed,

such as by material recycling, solid fuel production, being the

feedstocks for energy production through liquefaction/gasification

and by blast furnace, and heat production by incineration; and

those that are inefficiently managed, such as by landfilling and

simple burning without any heat utilization.

Due to their continual availability, these three wastes cause

environmental disposal problems when they are inefficiently

managed. Landfilling often brings about undesirable reactions from

the nearby communities, and in some countries, there is the

problem of land limitation. Incineration generally emits airborne

particles and toxic gases that cause serious air pollution problems

when incomplete combustion occurs in the process [1,2].

Energy production from wastes such as WP, WCO, and WLO to

produce diesel-like oil is not only a solution to the waste disposal

problem but is also a means to recover the valuable energy content.

The idea of integrated co-processing of WCO, WLO, and WP takes

advantage of the synergistic quality of WLO, the reactivity of which

makes it a good solvent for WP when they are co-processed, results

in higher quality oil [3]. It has been reported that the integrated co￾processing of these three wastes, under appropriate conditions, can

bring about efficiencies that generate a high yield of oil production

[4]. Moreover, the integrated management of these three wastes is

expected to benefit from economies of scale in terms of reduction of

* Corresponding author.

E-mail address: [email protected] (A. Singhabhandhu).

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Energy

journal homepage: www.elsevier.com/locate/energy

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2010 Elsevier Ltd. All rights reserved.

doi:10.1016/j.energy.2010.03.001

Energy 35 (2010) 2544e2551