Biodiesel corrosion could cause leaks in fuel infrastructure
New findings show that microbes present in biodiesel cause reactions that weaken the steel in fuel storage tanks.
Wed, Jun 02 2010 at 12:38 AM
In the midst of the Gulf oil spill, the last thing anyone wants to hear is the potential for leaks in our fuel infrastructure. But according to new findings reported by Chemical & Engineering News, even eco-friendly biodiesel can develop highly corrosive qualities during transportation and storage, breaking down the steel tanks and pipelines that carry it.
Scientists now fear that steel weakened from reactions with biodiesel could leak fuel and other hazardous materials into the environment. It's a drawback that is sure to further complicate the ability of biofuel manufacturers to demonstrate to regulators the chemical compatibility of their product.
The problem is that "biodiesel is at least seven to eight times more biodegradable than traditional petrodiesel," according to Joseph Suflita, co-author of the biofuel study.
Biodiesel is not corrosive initially, but the fatty acid methyl esters it contains are readily hydrolyzed by microbes, which transform it into organic acids and highly corrosive hydrogen sulfide. Researchers found that organisms from a variety of environments (including some samples derived from seawater from Key West, Fla.) took less than a month to degrade the fuel.
To demonstrate how these chemical reactions can degrade steel, scientists immersed carbon steel samples into a soup of Key West seawater mixed with biodiesel. The steel emerged blackened and pitted, according to the report.
Biodiesel is recognized as more corrosive than traditional fuel, but these new findings suggest the problem could be even worse than previously suspected, especially as biodiesel is increasingly added to fuels at an elevated rate. "I suspect we will see an increase in biocorrosion in the materials used in biodiesel production and processing," said microbiologist Gill Geesey.
One possible solution to the problem could be to replace the steel piping and infrastructure with plastic, or by manufacturing pipes and tanks using polymer linings — but manufacturing plastic components isn't an eco-friendly solution. Furthermore, redesigning the whole fuel infrastructure could come with a heavy price tag.
"What we do in the guise of being environmentally green might not really be that green after all," noted Suflita, concerned about many of the problems that complicate biodiesel use. Even so, he believes there is reason to be optimistic. He thinks that companies have avenues to chemically alter fuels to resist biodegradation without making them more hazardous.
"As a society we need to strike a balance and I think that we can," he said.
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