Even diesel fuel itself was being reformulated to cut down on its sulfur content.

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The majority new oil being developed are heavy, sour crude oils which have a high sulfur content, high viscosity, and high density.

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The reactor, according to Petrobras, was built with technology to produce oil with low sulfur content, respecting the new environmental standards on fuel quality.

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Its ugly relative--heavy, sour crude--sells at a discount of 10% to 25%, depending on blend and location, because it takes more refining to break down its hydrocarbons and remove its higher sulfur content.

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What it does have (and must have, as a starting point for the diamonds) is lots of coal: dirty, high-sulfur-content coal, which feeds 75% of the country's primary energy requirements.

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Further, the coal is low on sulfur and fly ash content, which increases its attractiveness.

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