GISPRI No. 14, 1996

"Recycling and Environmental Problems"

from the 22nd Conference on Global Environmental Issue.

The 22nd Conference on Global Environmental Issues was held on July 26, 1995. The following is a summary of the lecture given there by Dr. Masanobu Ishikawa, an associate professor at Tokyo University of Fisheries.

1. Introduction

With popular interest in environmental problems high in recent years, considerable research is being done on saving energy and decreasing carbon dioxide (CO₂) emissions. At the same time environmental problems are being taken up everywhere at grass roots level. Packaging or wrapping materials, whose role is finished the moment they reach consumers, often seem burdensome, inconvenient and wasteful to consumers. If the packaging or wrapping paper is attractive, consumers tend to feel these are too good to throw away, leading to movements, backed by popular sentiment, to save 'waribashi' (disposable wooden chopsticks) or recycle milk cartons, for example. When the environmental impact of such grass-roots recycling movements is comprehensively and quantitatively investigated, however, it is not clear whether such well-motivated activities really have much positive effect. In this lecture, I will attempt to describe the position we should give recycling as a response to environmental problems, and how materials and consumer goods can be best recycled.

2. Responses to Environmental Problems, and Recycling

Let us consider measures to deal with environmental problems by dividing them into three aspects (Fig. 1): demand (consumers), supply (manufacturers), and the social system. Recycling as a means of dealing with environmental problems can be classified into two aspects: recycling of consumer goods, which straddles the boundary between demand and the social system, and recycling of basic materials, which straddles the boundary between supply and the social system.

3. Recycling Basic Material

As an example of recycling a basic material, let us look at steel, which is energy-intensive to produce. Two steel production methods are used in Japan. In the blast furnace - converter method, iron ore is reduced and smelted into pig iron in a coke-fueled blast furnace, then made into crude steel by adjusting its constituents in the oxygen converter. The crude steel produced is then rolled into steel products. At the stage of reducing the iron ore, much energy is consumed and a large amount of CO₂ is discharged. On the other hand, in the alternative electric furnace method, scrap iron is melted into crude steel in an electric furnace and then rolled into steel products. Since already reduced scrap iron is used as the raw material, the amounts of both energy consumed and CO₂ discharged are smaller than in the case of the blast furnace - converter method. However, as the quality of electric furnace steel is inferior to converter furnace steel, this method is used mainly for making construction steel.

Looking at the changes in steel industry energy consumption rate by factor (Fig. 2), in the past energy savings were mainly achieved by technical improvements to the blast furnace - converter method, which uses iron ore as its raw material. Recently, a new method, the blast furnace - converter (scrap) method has been developed in which energy-saving scrap is fed to the converter to produce high-quality steel. But because the electric furnace and the blast furnace - converter (scrap) methods both depend on scrap, they are in competition for this limited resource. Therefore, as the share of the blast furnace - converter (scrap) method rises, the share of the electric furnace method must fall. The steel industry cannot simultaneously expand the use of both methods at once as it seeks to save energy.

Next, classifying energy-saving factors in the steel industry into technology and recycling factors (Fig. 3), we can see that technological factors predominated in energy saving until 1985 but have been stagnant since, and that recycling factors have been steadily improving energy efficiency since 1975.

Using multivariate analysis, we applied a model to the analysis of scrap iron prices in an attempt to shed light on the quantity of domestic scrap iron available (assumed to be proportional to the quantity of steel stocks) and the quantity of imported scrap (Fig. 4). The model matched the reality closely. According to this model, the price of scrap iron is in inverse proportion to the supply. Since the supply of scrap iron is in proportion to the domestic steel stock and the latter is increasing year by year, in the long run, scrap iron will fall in price provided there are no major changes in the present social and economic structure. This will help make electric furnaces relatively more profitable, while it is feared that scrap collection may no longer be viable in the future.

4. Recycling Consumer Good

As an example of recycling consumer goods, let us look at milk carton recycling. First, let us compare the energy consumption rate required to produce paper from virgin pulp with the energy consumption rate required to produce paper from recycled paper in Japan. Certainly, more energy is needed to manufacture paper from virgin pulp, but an almost equal amount of energy is collected from the black liquor at the pulping stage, and that energy is utilized in the downstream papermaking and processing stages. Although the energy required to treat recycled or waste paper is less than to produce virgin pulp (as there is no black liquor to collect from waste paper), the fossil fuels required to recycle waste paper is greater than to make paper from virgin pulp. In other words, if paper products now manufactured from virgin pulp were to be manufactured from waste paper, energy would be saved in the pulp manufacturing processes (waste paper treating processes), but extra energy would be required in the later processes, since energy was not recovered at the earlier stage. The result is a net increase in fossil fuels equating to the treatment of waste paper. That is to say, less energy is required to make paper from virgin pulp than to recycle waste paper.

How relate this to society as a whole? To grasp the environmental implications as comprehensively as possible, let us apply the Life Cycle Assessment (LCA) method to the scenario of recycling milk cartons as paper (resource recycling) and to the scenario of burning them and recovering the heat (thermal recycling) (Fig. 5). The parts of the life-cycle common to each scenario are omitted, and only the different parts are analyzed. In the first scenario of using pulp from the cartons, the milk cartons are washed and disassembled by each household, collected as a resource, and made into recycled pulp. In the second scenario of burning the cartons and using the heat, the milk cartons are thrown out as refuse, collected by a public refuse collection service, and burned to recover the heat. Here, we take the pulped milk cartons and compare the energy required to manufacture the same amount of pulp from wood. Analysis (Fig. 6) shows that burning the milk cartons and recovering the heat consumes less fossil fuel (net energy consumption is converted to fossil fuel equivalents), water, labor, and costs than recycling the cartons. However, recycling produces less CO₂, nitrogen oxides (NOx), and sulfur oxides (SOx), and requires less land. In the LCA of most other products, the consumption of fossil fuels and emissions of CO₂ show a similar pattern, and there is a similar correlation between the resource and thermal recycling scenarios. In paper products, however, results of evaluation by fossil fuel consumption are completely opposite to results of evaluation by CO₂ emission because so much energy is recovered from the black liquor.

If we examine the impact of recycling on the environment (Fig. 7), it becomes clear that the focus of the impact differs according to the terms of the evaluation. It is particularly remarkable that the impact by household treatment is large in many respects. Because tap water and heated water are used in washing cartons, households' labor, consumption of fossil fuels and water, and emissions of CO₂ and NOx are large. Since carton washing was a significant process, a questionnaire survey was undertaken to closely investigate how much cold or hot water was used to wash a carton and how the carton was washed (Fig. 8). Results showed that more than half of the respondents used hot water to wash cartons and many left the tap water running while washing. This greatly increased the impact resulting from household treatment. There appears to be much room for improvement in households' treatment of cartons. In the case of burning cartons and using the heat, transportation contributed considerably to consumption of fossil fuels, and to emissions of NOx and SOx because most of the wood chips were imported.

5. Conclusion

The recycling of basic materials has great potential to protect the environment. However, if some social policy would have to be introduced, it will be difficult to advance the recycle by self-controlled market system. Recycling consumer goods is not very efficient in some cases because consumers have no information with which to judge the rationality in terms of energy of how they dispose of things. Also, unlike the activities of a company, consumers do not necessarily base their behavior only on rationality. Therefore, it will be important to provide consumers with the information they require by analyzing profiles of environmental problems and indicating the points that can be improved.