Thursday, April 29, 2010

Beyond the environmental Kuznets curve: Diffusion of sulfur-emissions-abating technology

A group of students in Sweden sent me some questions about my paper:

Stern D. I. (2005) Beyond the environmental Kuznets curve: Diffusion of sulfur-emissions-abating technology, Journal of Environment and Development 14(1), 101-124.

The paper is fairly technical and so I thought it might be useful to post my responses here.

What would you say is the main question in the framework of dematerialization in your paper?

The focus of my paper is on the reduction in sulfur emissions. I don't think the paper is mainly about dematerialization as I understand it, in particular. Within my focus on sulfur emissions I am mainly interested in changes in sulfur emissions when we hold many other things that are going on constant - what economists like to call "ceteris paribus". Now those things I am holding constant are the shift of the economy from manufacturing to services or from agriculture to industry etc. and also the shift in the mix of fuels say from coal to natural gas or from oil to electricity. Those changes will affect sulfur emissions. All of these moves may involve "dematerialization". The effects of these variables are displayed in Table 2 "Frontier parameter estimates".

What is left after controlling for those factors are the trends in Figure 2 "Emissions technology trends". Over time there has been a reduction in sulfur emissions holding all the table 2 factors constant in most countries. This results in less sulfur being emitted into the environment as sulfur dioxide but doesn't probably result in dematerialization.

What is your reasoning on how to realize this dematerialization of sulphur emissions?

One of the leading methods of sulfur abatement is flue gas desulfurization (see picture above) which reacts the gas with limestone to form calcium sulfate. This requires mining limestone, building the machinery that removes the pollutant and then disposing of the waste. And desulfurization consumes energy. In some cases the waste has been used in the building industry and so there hasn't been a big increase in material and energy used. Other approaches are using low sulfur coal and "washing coal" to remove sulfur prior to burning.

What are your personal opinions on the outcome of the paper?

The most interesting result for me was how the countries ended up grouping into two groups by 2000 - a low pollution group of Germanic/Scandinavian countries and Japan and a high pollution group of Mediterranean and Anglo Saxon countries. I didn't really expect to find that quite so clearly. Recently I realised that this seems to be related to the idea of "legal origin". French and English legal origin countries have higher pollution, ceteris paribus, and German and Scandinavian legal origin countries lower pollution. Japan's legal system is based on the German system. I also found that countries with higher per capita income, higher population density, and higher potential pollution if nothing was done about it had lower pollution ceteris paribus.

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