Biodiesel Stability: New findings show that biodiesel corrodes the carbon steel

[djh]

I don't know anything about the subject but I thought this might interest some ...

http://pubs.acs.org/cen/news/88/i22/8822news1.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+cen_latestnews+%28Chemical+%26+Engineering+News%3A+Latest+News%29

Readily made from vegetable oil, biodiesel has become a popular fuel, with worldwide production now exceeding 10 million tons per year. Yet like all energy sources, biodiesel has its share of drawbacks. New research shows that it can accelerate corrosion of the carbon steel used to manufacture pipelines, storage tanks, and other components of the fuel infrastructure (Energy Fuels, 2010, 24, 2924).

Co-author and microbiologist Joseph Suflita, of the University of Oklahoma, Norman, says that steel weakened from biodiesel interactions could leak fuel and other hazardous materials to the environment.

"What we do in the guise of being environmentally green might not really be that green after all," he says.

Biodiesel, a mix of fatty acid methyl esters, doesn't start out corrosive. Instead, bacteria and other microbes hydrolyze it in reactions that ultimately generate hydrogen sulfide and organic acids, Suflita's research shows. These compounds eat into steel and degrade it, he explains. Manufacturers already have to demonstrate biodiesel's chemical compatibility with the fuel infrastructure. But the fuel's biological stability during transport and storage generally isn't considered, he adds.

... Continues ...

[Iain]

Hi
We get "FAME" imported into Plymouth by Greenergy. I heard that they are just installing an additive tank to dose the fuel as it comes ashore to stop corrosion in the pipework and storage tanks. Seems to tie in
Iain

[Amy]

Looks like plastic tanks are a must have item

[guydewdney]

use plastic / copper pipes?

[Justme]

use plastic / copper pipes?

& plastic high pressure pumps, fuel lines & injectors too?

[wookey]

It corrodes copper too - Cambridge Ethical Fuels found the copper bits in their pump system went all manky after a while.

[Countrypaul]

Bacteria in Bio is a well known problem, often refered to as "Biobug", "Dieselbug" etc. I believe that the problem can also occur with dino diesel and is more common in boats especially those left unused over winter. There are several additives available, one iirc is called Alklear.

Just like many other sensitive substances, keep the bio in the cold and dark in containers that are almost completely full thereby excluding as much air as possible.

I believe that some bio is washed with dilute sulphuric acid to remove any remaining soap, this process will convert the soap back to FFA which will like most acids begin to attack many metals.

[mespilus]

Its not the biodiesel corroding the stainless steel,
it is the sulphurophilic bacteria, oxidising sulphur to sulphuric acid
that is doing the damage.

In the early days of North Sea Oil, there was disbelief as steel components exhibited much reduced lifetimes.

The problem was found to be that those
sulphur dependent bacterial life forms
that are often shown in nature programs
existing at great depths where volcanic gases vent into the sea,
are present nearly everywhere,
at very low population levels,
but given the opportunity,
food source,
somewhere to live,
they can multiply like any other bacteria.

The ones in the North Sea showed an ability to secrete a tough outer layer that protected them from
many basic disinfectants.
The resultant 'bio-film' was best mechanically removed.

What I find surprising, is that there is any sulphur in the biodiesel.

The EN for biodiesel does have a (very low) upper limit for sulphur content,
consistent with EU regulations to reduce SO₂ emissions,
but I have yet to read of any consistent source of sulphur in biodiesel.

Possibly in the US, where oil refiners have been very reluctant to fit sulphur
removing equipment, there are colonies of sulphur oxidising bacteria endemic,
and shared pipework id leading to some cross contamination of biodiesel.