Mar 2008

Oil Companies and Climate Change Redux

A while ago I received an email from a friend asking whether or not I had a number for the amount of CO2 emitted by a barrel of oil. I searched for a while but couldn’t turn up anything definitive. So, given I know a little bit about the subject, I decided to work it out myself. The calculations can be found here: Oil Companies and Climate Change. After a few conversions, it turns out that the amount of CO2 produced by the liquid fuel products of an average barrel of crude oil is 317kg.

That’s simple enough and is pretty uncontroversial, I believe. The calculations themselves are not difficult, and anyone who paid attention in high-school chemistry should be more than capable of them. The only thing that made my calculations in any way noteworthy is the fact that I appear to be the first person to have published them in an easily accessible (via google) place. Nothing more.

I then took that 317kg (which was the primary goal of my work, as it’s a useful reference figure) and applied it to a specific real-world project. In this case, the Peterhead / Miller Field carbon capture scheme proposed by BP. According to the BP press release:

Injecting the carbon dioxide into the Miller Field reservoir more than three kilometers under the seabed could extend the life of the field by about 20 years and enable additional production of about 40 million barrels of oil that are not currently recoverable.

And in the following paragraph:

The project would also permanently store 1.3 million tonnes of carbon dioxide, the equivalent of removing 300,000 cars from the roads.

Based upon these figures, provided by BP, it is clear that the 40 million barrels of oil will generate (multiply by 317kg) approximately 12.68 million tonnes of CO2. Which clearly dwarfs the 1.3 million tonnes that BP claims will be stored.

My calculations were cited by George Monbiot in a recent Guardian article, as a demonstration that the claims being made for carbon capture are somewhat dubious.

However, in a response to Monbiot’s piece (via Tim Worstall) comes this:

In 2005 BP proposed to build a new gas-fired power station at Peterhead, capture the carbon dioxide produced and use it for enhanced oil recovery in the Miller field below the North Sea; this innovative project could have been up and running in 2009. Monbiot is wrong to suggest that the plan would have led to more carbon emissions than savings: between 1.8m and 2m tonnes of carbon dioxide would be injected each year over 20 years, producing an additional 40m-60m barrels of oil. Taking the higher numbers, 40m tonnes of carbon dioxide remains underground, while burning the oil produces approximately 20m tonnes; twice as much carbon dioxide is stored than emitted.

The abandonment of the Miller scheme due to lack of government support means a loss of $6bn in oil revenues and a missed opportunity to take a lead in reducing carbon emissions.

Professor Martin Blunt
Department of earth science and engineering,
Imperial College London

The important piece to note here is: “between 1.8m and 2m tonnes of carbon dioxide would be injected each year over 20 years”. While this doesn’t affect my “carbon-per-barrel” number, if true, then clearly it radically alters the figures for the BP project under discussion.

I’ve spent the morning on the phone to various people in BP (you would not believe how difficult it is to track down someone who knows what they’re talking about, let alone someone who has even heard of the project in question) and was eventually informed that contrary to the statement in their press release, the 1.3 million tonnes is indeed a per annum figure (they don’t know where the 1.8 to 2 million figure came from, but they do claim 1.3 million per annum).

This — if true — invalidates my claim that the project would produce far more CO2 than is captured. Worse, far worse, it undercuts Mr. Monbiot’s article and I feel completely sick about that. In my defence, I was carrying out my calculations based upon figures published by BP, and I’m not sure I should have expected them to grossly underestimate the amount of CO2 being captured by their own scheme. But all the same, I’m afraid I must apologise to all concerned, particularly George Monbiot. There’s few things worse than being responsible for errors in someone else’s work. Really makes you feel like crap.

Posted in: Opinion