The analysis, carried out by the Center for Air Pollution Impact, Trends and Analysis (CAPITA), also shows that coal consumption overwhelmingly accounts for the highest contributions to sulphur emissions worldwide. Other activities taken into account in the analysis were metal smelting and oil consumption.
The survey shows that China is using its massive reserves of dirty soft coal to fuel its booming industrialisation programme (See related story). “We’ve begun to see more acid rain complaints in Indochina, Japan and Korea, mostly from Chinese sulphur emissions,” says Rudolf Husar, professor of mechanical engineering and CAPITA director. “So, in the broad sense, as we begin a new century, that big problem of the ’70s and ’80s has now shifted more toward the East.”
The survey shows the stabilisation of US sulphur emissions was caused in part by the country’s switch from high- to low-sulphur coals and tighter environmental controls. In the former Soviet Union, there has been a greater reliance on natural gas, which is abundant in Russia.
Alternative fuels such as natural gas and nuclear power have made an impact on emission levels in both China and the US. In the US, the shift from a smokestack economy to a service-oriented economy has also made a difference, as have the use of scrubbers and desulphurisation techniques in coal-driven power plants, the survey shows.
The United States, the former Soviet Union and China have easily lead the world in sulphur production over the last 50 years, accounting for 53 percent of global sulphur emissions during the latter part of the study. The next highest emitters of sulphur over the same period were the European Community, followed by Japan.
The sulphur survey, conducted by Professor Husar looked at emission levels from 1850-1990, encompassing the Industrial Revolution, two world wars and complex economical and policy changes of the latter part of the century.
The study is the only sulphur emissions study to examine annual sulphur emissions by each country over a long timespan. Husar says that global fuel consumption over the past 50 years actually has gone up, yet emissions have stabilised in most parts of the world because of cleaner fuels and cleaner consumption methods.
“One of the reasons that emissions haven’t really gone up exponentially over the past 100 years in the United States is because of the fact that now perhaps two-thirds of the energy is supplied by relatively clean fuels,” he says. “Also, particularly in the past 40 years or so, pollution controls have reduced the amount of emissions released into the atmosphere. If not for cleaner fuels and emissions controls, the amount of sulphur emissions today would easily be three or four times what they are now.”
Husar estimates that global sulphur emissions in 1850 were 1.2 million tonnes, just 1.7 percent of his 1990 estimate of 71.5 million tonnes. Beginning in 1913, there was a levelling off and then a decline during World War I. The early years of the Great Depression saw a marked decrease in emissions, but that soon changed with World War II. There was a continuous increase in the post-war years, with a drop in 1981-83, corresponding to declining oil demand during the global recession.
Since 1970, US emissions show a general decline. No coincidence, according to Husar, who notes the passage of the Clean Air Act in 1977 and the subsequent Clean Air Act of 1990, which requires that all power plants not exceed a certain amount of emissions.
As the 1990s began, the United States and Canada were emitting a combined estimated 15 million tonnes of sulphur, compared with approximately 22 million tonnes by China. “The data clearly show that while North American and in some cases, European, emissions have been levelling off, rapid increases are occurring in China,” Husar says.
“Fuel consumption was the key piece of data,” Husar says. “And it is relatively easy to get because most countries have kept track of their consumption.” Husar and his colleagues relied on a vast network to get their fuel and metal smelting data. Nineteenth-century data were found in literature and in occasional obscure publications. The 20th Century data was mostly based on League of Nations – later United Nations – publications, mineral yearbooks of the US Bureau of Mines, and Her Majesty’s Stationary Office in London. The researchers also used fuel consumption data from 1950 to 1990, which previously had been compiled by the US Department of Energy, Oak Ridge National Laboratory.
In all, estimates were derived for 234 countries. The researchers estimated yearly emissions per country based on net fuel production – production plus imports minus exports. Sulphur content and sulphur retention information based on the individual country’s activities also figured in the estimates.