What does the capacity factor of wind mean?

Posted by – 2014/09/29

Harald Pettersen/Statoil, NHD-INFO [CC-BY-2.0]

Sheringham Shoal offshore wind farm, photo by Harald Pettersen/Statoil, NHD-INFO [CC-BY-2.0]

The capacity factor is the average power generated, divided by the rated peak power. Let’s take a five-megawatt wind turbine. If it produces power at an average of two megawatts, then its capacity factor is 40%: two divided by five is 0.40 which is equivalent to 40%.

To calculate the average power generated, just divide the total electricity generated, by the number of hours.

You could do an equivalent calculation for a car. Let’s say your car’s top speed is Read more…

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Capacity factors at Danish offshore wind farms

Posted by – 2014/09/23

Thanks to the wonderful statisticians and data managers at ENS and Energinet.DK, we have a large amount of detailed data from Danish onshore and offshore wind farms. Here’s one quick cut of it: the average capacity factors, to date of every Danish offshore wind farm, newly updated to include data to the end of August 2014. The Anholt 1 windfarm, which only opened in 2013, hit an average capacity factor of 51.1% for the last 12 months.
Read more…

Watching the ships (part 3): Humber Gateway and Westermost Rough offshore wind farms

Posted by – 2014/08/27

There are two windfarms being built right now near the mouth of the Humber Estuary: Humber Gateway and Westermost Rough.

Here’s a map of the ships serving the windfarms.
Read more…

Decarbonising the Irish grid

Posted by – 2014/01/01

Following on from this question on the Sustainability Stack Exchange about decarbonisation in Eire, and a discussion on the Claverton Energy Group about the British and Irish grids, I took a quick look at the data on carbon intensity and wind generation in the Irish grid. This uses all the available data at time of writing — 38 months, from November 2008 to the end of December 2013.

Here’s the impact that its wind generation has on the carbon intensity of the grid: each MW of wind power that’s generating, reduces the carbon intensity of electricity by 0.138 gCO2/kWh: 1GW of generation reduces the carbon intensity by 138 gCO2/kWh. For context, average demand is about 2.9 GW, and peak demand is about 5 GW.

Scatter graph of wind generation and carbon intensity in Eire
I’ve used Robust regression, as there are some reporting errors in there (further cleaning has refined the estimate to 0.136 from 0.138).

The y-axis is baselined at 200 gCO2/kWh, because there’s very little real data below that line at present.

I note that Eirgrid has heat-curves for every thermal plant on the grid (which is how they calculate the carbon intensity). Does National Grid have anything like that for GB? Do you? Would you like to share them with me?

And re the data-cleaning — just in case anyone else downloads the wind forecast and generation data, note that every year on the last Sunday in October, the wind data for each of the four quarter-hours when the clocks go back is duplicated.

The UK is the Saudi Arabia of wind energy

Posted by – 2012/08/11

An article by Zoe Williams in The Guardian, towards the end of July 2012, began:

The UK is the Saudi Arabia of wind

Dale Vince of Ecotricity said the same thing back in 2011:

Mr. Vince continued by saying that the UK is the ‘Saudi Arabia’ of wind energy, which makes Britain a potential to become an independent producer of energy.

And back in October 2009, I said the same thing at the Claverton Energy Conference. Anyway, enough of the source of this: let’s look at the numbers.

2011 was something of a boom year for Saudi Arabian energy production. The Arab Spring uprisings resulted in reduced output from other countries, meaning Saudi Arabia could significantly boost production without trashing the oil price. So let’s use its 2011 production as our benchmark. From the OPEC Annual Statistical Bulletin 2012, and converting from millions of barrels of oil per year into gigawatts, and from millions of cubic feet of gas per day into gigawatts, we see that Saudi Arabia’s annual rate of energy production was just under 800GW. By comparison, in 2011, UK average final electricity demand was 36GW and total final energy demand (including all gas for heating, and all transport fuels) was 183GW.

So, as the chart above shows, the UK’s annual average offshore wind resource is somewhere between 1.5 times larger, and 11 times larger, than 2011 Saudi Arabian energy production. And the great thing is that the wind won’t run out. It will vary, at all scales from seconds to decades, but it won’t run out as long as the sun keeps shining.

My own earlier estimate (shown above as Smith 2011) of over two terawatts as the UK offshore wind resource is documented on the Claverton Energy website. Using the same method as described there, and considering all UK waters, the resource is given above as Smith (2012).

Stuart Gatley, in his Masters of Engineering thesis at the University of Nottingham, models a range of potential future scenarios both for turbine density and turbine technology. His Scenario A-T1, assuming current technologies, is given as Gatley 1 above; whereas Gatley 2 is his Scenario C-T5, which assumes advances in turbine technology and the opening up of all UK sea depths as accessible to wind.

Giorgio Dalvit, in his Masters thesis “UK Offshore Wind Source”, produced a set of estimates, for different constraints. His estimate for the resource at less than 200 metres depth, and within 200km of shore, is given above as Dalvit 1; his all-area resource is Dalvit 2.

Why are there such different forecasts for the UK offshore wind resource? Because each analysis uses different assumptions. And they each use a different estimation method. Though, notably, they all use the same underlying data set: the Renewables Atlas. A future paper (being written now, in Summer 2012), will set out the different assumptions for each figure, and propose a new protocol for such assessments.

2050 Calculator

Posted by – 2012/06/12

Introducing the EnergyNumbers 2050 Pathways calculator

The DECC 2050 calculator is a good start at producing a toy model to give some ideas of the trade-offs, and approximate orders of magnitude of costs involved in converting Britain’s energy systems into a low-carbon system.

But it has its flaws.

So I’ve revised some of the model’s weakest parts, and re-released it. Here’s the EnergyNumbers 2050 Pathways calculator

A summary of the changes (most recent, first)

  • Added a new option to change the amount of fossil-fuels (coal, gas, oil) extracted in the UK. This option exists in the DECC spreadsheet, but wasn’t previously available in the web interface.
  • Added a whole new section with performance against national and international targets. In the top-left corner of every page, you’ll find indicators showing progress against targets. Click on them to read an explanation of each target, and how well the selected pathway performs against each.
  • Change nuclear level 1 to phaseout by 2020; bumped all the other levels up by one (so old level 1 is new level 2; old level 3 is new level 4), and updated all the “expert” pathways accordingly. Old level 4 wasn’t plausible, wasn’t used in any of the “expert” pathways, and so has been removed
  • Added estimated damage costs for greeenhouse gases: low £70/tCO2e; medium £100/tCO2e; high £200/tCO2e
  • Added estimates of nuclear liability costs: low 0p/kWh; medium 11p/kWh; high 100p/kWh
  • The choice of car and van techology, between fuel cells and electric batteries, is a category scale (A,B,C,D), not ascending order of difficulty (1−4)
  • Ensure coal capacity has a floor of zero
  • Selecting biomass plant will not drive up coal use
  • Updated nuclear build costs: high £4.548/Wp rising to £5.072/Wp; medium £3.50/Wp; low £2.478/Wp
  • Onshore wind, level 4 upgraded to hit 50GWp by 2020 and stay steady
  • Offshore wind fixed-foundation, level 4, from 2020 onwards, upgraded to 10GWp annual installation rate


Live mapping of ships building the London Array

Posted by – 2012/04/13

The map below shows the live positions of ships working on the London Array offshore wind farm, Phase 1, off the coasts of Kent and Essex. It’s almost like sitting on the dock of the bay, watching the ships roll in and roll out again.Read more…

Why the Green Economy?

Posted by – 2011/11/15

A while ago, the French Chamber of Commerce in Great Britain invited me to write an article for their magazine’s (INFO) special edition on the Green Economy. Here’s the article, updated (Feb 2013) and with links added to further information

Why the Green Economy? Summary

Markets that exclude the impact on natural capital are distorted. Markets that exclude the costs of pollution are distorted. Markets that allow the Tragedy of the Commons are distorted. These distorted markets represent economic efficiency, and leave us all worse off.

The polluter-pays principle corrects the market distortion caused by unpriced pollution. Joint-stewardship agreements allow us to sustainably manage common resources, preventing the Tragedy of the Commons. Tracking changes to the value of our natural capital base is just as important as tracking transaction values: both represent changes to our wealth.

The Green Economy, in all those forms, is here because it fixes problems that have been accumulating for decades. Why the Green Economy? Because in the long run, the Green Economy leaves us better off, environmentally and economically.

Background to the Green Economy

The Green Economy is worth hundreds of billions of pounds (euro / dollars) each year; it spans many sectors including the most fundamental ones of energy, food and water supplies; and in the last fifty years, it’s gone from fringe to mainstream, growing in value and coverage each year. For example, in 2011, global investment in renewable energy was US$257bn; and there are electric cars on the market that can out-run a Porsche.

But the Green Economy has been around for quite some time, and its academic foundations, in the “polluter-pays principle” dates back to the early decades of the twentieth century. However, more recently, the problems have become global in scale, and the solutions have required international co-operation, for example in banning the industrial production of some of the worst ozone-depleting chemicals. The next wave of problems and solutions dwarfs what has gone before, requiring revolutionary changes to how we generate electricity, how we heat our homes and offices, how we power our transport systems, how we manage our livestock and fertilise our crops. The economic risks (and opportunities) are orders of magnitude greater than what has gone before.
Read more…

How Denmark manages its wind variability — paper launched today

Posted by – 2010/09/22

Today, at the 2010 BIEE conference, I’ll be presenting a paper on how Denmark manages its wind variability, and some of the implications for its target of delivering 50% of its electricity from wind by 2025.

Here’s the abstract of the paper:Read more…

Surpassing Matilda: record-breaking Danish wind turbines

Posted by – 2010/07/21

By 2008, Matilda was the world’s most productive wind turbine, having generated 61.4 GWh of energy by the end of its life.

But by the end of March 2010, this record had been broken four times over, Read more…