Potential production capacity far overrated
The Office of Metropolitan Architecture (OMA) headquartered in Rotterdam and headed up by the Dutch architect Rem Koolhaas, has developed a master plan for large-scale wind energy production in the North Sea. The operative adjective here is large-scale. The plan projects a potential annual production of 13,400 TWh by 2050.
The principal idea is to develop a huge ring of wind farms on offshore marine sites in the Exclusive Economic Zones of Denmark, Germany, the Netherlands, Norway, and the UK and to connect them by a power cable super ring. Such a ring would enable fewer connections with the coast, avoiding the necessity of connecting every wind farm with the grid separately.
The plan sounds good and looks brilliant. The trouble is that it appallingly neglects some basic technical aspects of wind energy. A quick verification of the annual production figure leads one to suspect that OMA simply "forgot" to take a capacity factor into account...
In many ways this integrated plan for wind energy generation in the North Sea resembles the ambitious scale of DESERTEC, a plan for developing large solar power plants in the Sahara desert and connecting them to Europe via HVDC lines.
According to the Antwerp architect Bob Van Reeth, who supports the OMA plan, 'The EU member states are currently only focussed on their own little projects. There is a need for cross-border initiatives and joint investment projects.' Instead of restricting international cooperation within the EU to defining rules and targets, cross-border investment projects could open up a whole new potential for renewable energy development.
The idea of cross border cooperation is actually the most valuable aspect of the OMA plan. The plan itself is, unfortunately, fatally flawed. David Mac Kay demands in his book (Sustainable Energy / Without the hot air) an energy debate with clear, traceable, and comparable figures. This is exactly what the OMA plan lacks. Let’s look at a few aspects of the plan in more detail.
OMA calculates the potential annual electricity production to be 13,400 TWh. This figure is compared with the annual energy production capacity of the Gulf States, namely 11,300 TWh. But is that last figure oil production alone, or oil and natural gas combined? Is it crude oil, or end use products? These essential facts are totally unclear. A more useful figure for comparison would be the total energy demand of the EU, which is approximately 22,000 TWh.
To calculate the annual production capacity, the project started by calculating the surface where the North Sea is less than 50 metres deep and at least twelve nautical miles away from the coast. From this surface, 15% was subtracted for commercial and military sea routes and other activities. The remaining surface of 193,000 m2 is supposed to be completely filled by wind farms, making use of 5 MW turbines that are spread according to a standard wind turbine distribution pattern. The report does not mention a total installed capacity, or an average capacity factor, but blithely concludes that this huge North Sea wind farm would result in an annual electricity production of 13,400 TWh.
Let’s compare the figure of OMA with the figures of David Mac Kay (Sustainable energy / Without the hot air) for the physical off-shore wind potential of the UK. The total surface of shallow waters in the UK Exclusive Economic Zone is 40,000 m2.First of all, Mac Kay subtracts 70% of this surface for sea routes, instead of 15%. But let us make abstraction of this widely differing assumption, and remake the calculations of Mac Kay subtracting only 15% of the surface instead of 70%. According to these assumptions, 40,000 m2 would yield 893 TWh per year, meaning that 193,000 m2 would yield 4308 TWh per year.
This is about one third of the figure of OMA. How strange: one third is exactly the capacity factor! Did the OMA simply forget to take the capacity factor into account in their calculations?
If one takes the more realistic assumptions of David Mac Kay into account, the North Sea could produce a maximum of 1400 TWh per year, about one tenth of the prediction of OMA and one fifteenth of the European energy demand. That is still huge, but far from making Europe energy independent, as OMA claims.
Even more disconcerting in the OMA plan is the inconsistency of the capacity calculation with the drawings contained in the report. Instead of one huge wind farm in the shallow parts of the North Sea, those drawings show a ring of numerous wind farms that stretches far into the northern, deeper parts of the sea. Nowhere in the report is this inconsistency explained. Neither is it illustrated how those wind turbines in the deep sea will be constructed – will they be floating turbines?
Nowhere does the report mention anything about maintenance of the wind turbines. How much maintenance effort would this North Sea ring require? What will be the annual cost? And how will the current maintenance problems with off-shore wind turbines be overcome?
The report does not address the availability and reliability of the electricity production either. I suppose that it assumes that in the North Sea, the wind will always blow somewhere. Will this claim still hold on the day that a large and stable summer anticyclone happens to settle right above the North Sea?
The plan couples the ring of wind farms with the creation of a massive sea reserve around those farms. In this way, the ring could be a solution for the recovery of the marine fauna in the North Sea. This is a great idea. But how will the fishing industry react? Even if fishermen can find new jobs in the wind industry, will they calmly watch the North Sea fishing industry disappear?
The plan also includes a huge research station for off-shore activities. This station is located in the middle of the ring, at the intersection of the borders of the Dutch, British, Norwegian, Danish and German territories. Why, except for symbolic, political reasons, should such a research station be built as far from the mainland as possible? And why should it be so incredibly huge? The drawing on the map shows an area of no less than 5,000 m2...
A valuable idea to be further developed
In brief, the OMA plan leaves far too many questions open or even unaddressed and its potential energy production is outrageously overrated. However, let’s not throw the baby out with the bath water. Hopefully one day some wind energy experts will get the assignment to discover what if any parts of this plan has merit or potential, and will be assigned to work this plan out in a more realistic and down-to-earth (or should I say down-to-the-sea-floor?) manner.Log in to post comments