Like it or not: our current society is heavily dependent on fossil oil.

Together we use the staggering amount of around 100 million barrels per day. Next to increasing global warming by the combustion of oil to CO2, fossil oil has other detrimental environmental effects.

Inevitable losses and spills occur in the production, refining and transport of oil. The most notorious spill of recent time is the Deepwater Horizon oil spill. Following an explosion on the Deepwater Horizon platform, an estimated five million barrels leaked directly from the oil well into the Gulf of Mexico. We all know the pictures of birds covered in black crude, and the harmful effects of oil spills on ecosystems requires little argument.

Does this oil stay forever in an eco-system after a spill? No, because some tiny lifeforms happily degrade this oil in nature.

To understand this, we need some basic biology. Humans, animals and any other living organisms need energy and building blocks to survive. If we eat a tasty tomato, the sugars, lipids and other carbon-rich compounds in the tomato are digested to supply us with energy and building blocks. The same holds true for bacteria, fungi and other microbial life: they all need carbon-rich food to stay happy. There is an enormous microbial diversity on Earth, and the preferred choice of food differs from microbe to microbe. Most like sugar, some thrive on lipids and a few can’t resist a meal of fossil oil.

In lab-scale experiments some species of bacteria effectively degrade fossil oil. And in oil-spill areas, such as the seawater around the Deepwater Horizon well, considerable numbers of oil-degrading bacteria are detected.

Does Nature thereby clean up the mess we created?

Not entirely, unfortunately. This is because bacteria need more than just food to live a happy life. Bacteria need a suitable temperature, other nutrients like nitrogen and phosphate, and some need oxygen. Only when this criteria are fulfilled, bacteria can consume and degrade oil effectively. In laboratory-experiments optimal conditions can easily be met, and oil-degrading bacteria perform very well under these circumstances. Creating optimal conditions for bacterial oil degradation at, for example, the bottom of the Gulf of Mexico is however practically impossible. The consequence is that oil is degraded, but at a much slower rate than theoretically possible.

In the very, very long term Nature will indeed clean up the oil we spilled, but it’s not fast enough for the people living in the area. They are affected in their everyday life, and the remarkable ability of Nature to clean up our mess should not slow down our efforts in creating renewable forms of energy.

Our planet might be patient, but can we wait that long?

By Peter Mooij, written under personal title

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