Reinterpreting Data: The wind turbine that produces 200 barrels of oil equivalent per day

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Here at Green Finance Guide we like to experiment with information relating to renewable energy and the communication of that information. By reframing information we hope that it can open up different perspectives and viewpoints. For example, enabling a direct comparison between things which are not often compared, such as, existing and new technology or methods of finance.

Offshore Oil and Gas vs Offshore Wind

The North Sea has been the cornerstone of the UK’s energy industry for the past 60 years. The output from UK offshore oil and gas platforms grew rapidly in the second half of the 20th century and peaked in the 1990s but is currently 40% below the highs of 1998 [1]. As the oil industry wanes the natural power of the North Sea is being harnessed and increasingly powerful wind turbines are being installed further out to sea generating an increasing amount of clean electricity.

Yet wind farms are rarely compared directly with offshore oil fields. They both occupy the same hostile environment and the energy they produce will increasingly be in competition with each other. That is, the main use for crude oil is petrol and diesel for internal combustion engines, but as electric vehicle adoption increases more and more electricity from wind farms will be used to charge EVs decreasing the demand for fossil fuels.

Barrels of Oil Equivalent vs Megawatt-hours (MWh)

Currently a prototype of the gigantic Haliade-X wind turbine is being commissioned in Rotterdam in the Netherlands. This wind turbine is being built by General Electric (GE) and is the largest wind turbine ever constructed. The blades are 107m long and once installed the tip of the blades will reach 260m above the sea below. Each turbine has 12MW maximum capacity and will generate enough electricity for 16,000 European homes per year (for more information on the Haliade-X and GE see our previous blog on the subject).

A few weeks ago GE secured an order for several hundred Haliade-X to be installed in the North Sea in at least 3 of the 4 Dogger Bank wind farms [2]. In total all four wind farms will have a maximum output power of 4.8GW and will supply 5% of the UK’s annual electricity needs. If all four wind farms were built with the Haliade-X then they would require 400 turbines in total (4,800MW/12MW).

The wind farms are being built 77 to 180 miles out to sea [3] and notably in the middle of the UK’s main oil and gas producing region. These vast arrays of offshore turbines are rarely (if ever) compared directly with a fossil fuel energy sources. Obviously, there are some differences in the way the energy sources behave, but it is still possible to compare their energy outputs. In order to do this we need to use the same set of units for energy, so in this case we will convert the annual power output of the 12MW Haliade-X to barrels of oil equivalent (boe), i.e. the energy content of a single barrel of oil (42 US Gallons).

Calculations:

67 GWh = Annual Power Production of GE Haliade-X Wind Turbine [4]

67GWh/365days = 183.5 MWh/day – Average daily production

183.5MWh/12 = 15.3 tonnes of oil equivalent per day [5] (12MWh in a tonne of crude oil)

15.3/0.1364 = 112.1 barrel oil of equivalent per day [5] (conversion factor between a tonne and a barrel of oil)

BUT the value of energy in a barrel of oil only refers to the total value of energy and not the usable energy. Petroleum based engines and machinery are nowhere near 100% efficient, meaning much of their energy is wasted. According to [6] they are between 20%-45% efficient (excluding the loss of energy converting it from crude oil to a usable form of energy, e.g. petrol or diesel), therefore the majority of energy in a barrel of oil is wasted as heat. Electrical items, however, have mush less wastage. Batteries and electric motors are much more efficient with the majority 70%-95% of energy being converted to useful energy. So if we want to compare like with like then we need to factor this into our calculations. Using a petroleum efficiency of 35% and an electrical efficiency of 70% (being conservative and including losses in transmission [7]) we can account for the differences in efficiency:

112.1*(70/35) = 224.2 barrel of oil equivalent per day (including efficiencies) per wind turbine

Therefore when averaged over a year the daily energy produced from single 12MW Haliade-X turbine is the equivalent of a 224 barrel per day offshore oil platform.

Scaled up in a wind farm

Recently the Dogger Bank collection of wind farms announced that they would use the Haliade X turbine. The four wind farms will have a combined capacity of 4.8GW between them from x400 12MW turbines. Therefore, their total energy output would approximately be:

400 x 220boe/day = 88,000 barrels of oil equivalent per day (averaged over the course of the year)

Context: How does that compare to an oil field

How much is 88,000 barrels of oil a day? According to the EIA [10] the UK’s total oil production is 1,000,000 barrels of oil per day, so the Doggerbank farms will be producing nearly one tenth of the UK’s oil output. In comparison, one of the largest oil fields in the North Sea is the Clair Oil Field in the West of Shetland zone [8] and, according to the field’s operator, had a peak output of 120,000 barrels per day [9]. But once the 640 million barrels of recoverable oil have been pumped out and released into the atmosphere that’ll be it, whereas Dogger Bank will keep on producing year after year after year. Furthermore, the recovery rate of an oil field quickly tails off after the first few years, so it will not sustain 120,000 barrels per day for long.

Therefore, the Dogger Bank wind farms will have a similar output to the peak oil output of the Clair Oil Field: 88,000 barrels of oil equivalent vs 120,000 barrels of oil.

There are plenty of nuances to this comparison, for example, intermittency of wind and varying efficiencies of fossil fuels. But wind farms and oil fields are rarely compared directly and as we move from a fossil fuel economy to a renewable economy it is important to be able to compare the two. As we can see from the numbers, the energy produced by a large wind farm is comparable to that of a large oil field, and that is an important conclusion, but this reinterpretation of the data could also be very useful in allowing people to understand new technologies within the context of existing technologies. It may assuage a nervous consumer that the UK can charge electric cars in a renewable way or convince an investor that renewables are to be taken seriously as a large scale form of energy.

Just as we have a revolution in the green energy sector, we need a revolution in the way we analyse that green energy data.

30th October 2019 (Updated: 16th December 2019)

References

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