Disposal of platforms at sea can be a sustainable activity, with platform remains being a potential enhancement to the seabed.
The fundamental aspects of sustainability are conserving the environment and natural resources, while generating wealth for economic growth.
To this end, emissions of solids, liquids and gases to land, sea and the atmosphere need to be managed. We must limit the scarring of the land and seascape and limit the number and size of the footprints we leave behind.
Care of the environment and natural resources is often seen as being in conflict with economic growth. Often they will be competing demands, but they need not always be. Above all, what is needed is balance. I would say: do not pursue economic growth to the exclusion of conserving the environment and natural resources, but equally do not pursue conservation to the point of diminishing returns and in ways that inhibit economic growth.
The disposal plans for Brent Spar led to public and political outcry in many parts of Europe. The debate has raged ever since.
There are a little over 100 platforms in the North Sea in water deeper than 75m, which under international agreements need only be partly removed. These are mammoth structures. Some are of concrete and others are steel lattice structures or `jackets’ piled to the seabed. They have to be cleared away down to 55m from the sea surface for safety or navigation reasons. This could be achieved by entire removal, by cutting off the top part, or by toppling.
Let me examine abandonment in terms of sustainability and in relation to other options. Leaving platforms in the sea raises the question of the level of toxicity that the sea environment can handle by natural means. Provided platforms are adequately cleaned it is generally accepted that there is no adverse environmental effect, despite what opponents say.
It is true that the opportunity to recycle is lost. No one pretends any longer that recycling of the concrete platforms is viable, but what about the steel platforms?
On the face of it, recycling is the right and honourable thing to do – until one looks closer. The problem is the energy consumed and the consequence for atmospheric emissions. The most detailed study of energy consumption for alternative options was completed recently by Energy Resource Technology and has been submitted to the international Ospar regulators.
It shows that bringing entire deep-water steel platforms ashore for recycling into useable steel consumes just as much energy as leaving parts of platforms on the seabed and mining and smelting new iron ore to replace the steel not recovered. In fact, recycling the whole platform results in a higher consumption of energy. The main reasons are the extensive offshore operations of removal and transport to shore, so much greater for entire removal than partial removal.
The more energy consumed the greater the emissions of gases to the atmosphere. This includes carbon dioxide, a greenhouse gas.
What we can conclude so far then is that, from atmospheric emission considerations as well as from considerations of emissions to the sea, there is no incentive to remove all deepwater platforms to shore.
Whatever people do, they leave a footprint. Recycling plants make footprints, but let us accept that by toppling offshore platforms or by leaving the lower parts in place on the seabed we leave larger footprints than bringing them completely ashore. But a moderate amount of benign material, carefully controlled and strictly regulated, could be an asset in the protection of fishstock.
So there is no compelling argument for either bringing platforms ashore or leaving them at sea. That leaves us with the economics. What is the best use of an investment when it comes to sustainability? We are talking of chunky amounts of money, about $20bn for removing all the platforms in the North Sea.
Complete removal can cost two or two-and-a-half times the cost of toppling in situ, a differential of, say, $50m for a typical platform. Is it justifiable to commit so much extra cash to the option of complete removal to shore for such questionable benefit?
To those who disagree I would ask: is there really no better way to invest in sustainable development? Are there not worthier uses in terms of benefiting the global environment? It could probably be done if it had to be, but the cost is enormous, not just for oil companies, but for society too.
Dr Mike Cloughley is executive secretary of the Oil Industry International Exploration & Production Forum. This is an edited version of his speech at the Institution of Civil Engineers this month supporting the motion `In the search for sustainability, abandoned oil platforms are an enhancement to the sea bed’.