Anticipating blackouts has become a new national sport in the UK. I can recall blackouts as a child. I’m guessing this was during the first 1974 oil shock when OPEC first flexed its muscles and Britain had a lot more oil fired power generation then than it does now. But a quick check shows that Britain was also in disarray because of strikes, especially striking coal miners. Blackouts were a time of excitement where whole towns went black, citizens reached for their candles and crooks reached for their crowbars.
Things have moved on in the intervening 40 years with a much more complex society today dependent upon electronic communications, a myriad electronic devices and economic growth that is founded on reliable supplies of electricity.
Figure 1 “100 crowbars were nicked during the last blackout”
So why does the UK find itself on the threshold of blackouts? Or does it?
The difference between power cuts and blackouts
A good starting point is to understand the difference between a power cut and a blackout. Power cuts tend to be localised and caused by local technical problems such as a power line brought down by a tree or a local transformer fault. A Blackout is larger scale, affecting a whole grid segment. It may also be caused by a larger scale failure, such as a power station tripping out. But what we will be mainly talking about here is intentional blackouts where National Grid pulls the plug owing to a shortage of generating capacity.
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Power demand pattern in the UK
UK demand for electricity and gas follows a very specific pattern. Electricity I have covered a number of times before. The main point is that electricity demand follows three cycles – daily, weekly and annual. In 2009, peak demand was 58.9 GW at 6pm on a Tuesday in January and the minimum demand was 22.3 GW at 6 am on a Sunday morning in July. Peak demand is 2.64 times greater than the minimum demand and the electricity delivery system requires the flexibility and controllability to match supply with demand exactly at all times (Figure 2).
Figure 2 UK electricity demand follows a very specific and predictable pattern.
Peak electricity demand is always going to be on a weekday in January or February at around 6 pm and especially when the weather is cold. This is when the grid will be at it most vulnerable to failure.
Demand for natural gas also follows an annual cycle (Figure 3) with peaks in December and January each year. A point I will emphasise below is that it will be the UK’s ability to source sufficient gas in mid-winter to power its large fleet of combined cycle gas turbines that will determine its ability to keep the lights on. But the picture is a bit more complicated since the UK (and Europe) does have and depends upon gas storage to meet peak demand. Storage is normally full going into winter and may be used to meet the December and January peaks. Supply problems are more likely in February and March if there is a late cold snap and storage runs dry which almost happened a couple of years ago.
Figure 3 UK demand for natural gas also follows a very specific annual cycle.
Sharp eyes will notice that demand for gas dropped significantly in 2012. This is linked to the Fukushima Daiichi nuclear accident in Japan. Japan shut down all its nuclear plants and has ever since been sucking in more than its fair share of global liquefied natural gas supply. So what is the UK now using instead?
Figure 4 UK electricity generated according to fuel type.
Figure 4 shows that the significant decline in the use of gas in the UK for electricity generation in 2012 and 2013 was met by increased coal, increased wind and solar, increased bio-mass and a decline in overall demand. This is a fairly chaotic and toxic mix that is a story for another day. At some point Ed Davey may find it regrettable that the UK has shut down about 7 GW of coal fired plant since 2012 (next chart).
Capacity Margins
The capacity margin is that surplus generating capacity a country has over and above that required to meet peak demand. The margin is required to cover for unscheduled outage of generating plant, for example the UK has two nuclear power plants out of business at the moment. Capacity margin is also required to maintain competitiveness.
Figure 5 Installed electricity generating capacity in the UK.
Figure 5 shows that despite recent coal and nuclear plant closures the UK retains a vast capacity margin of about 20 GW, over 30% of peak demand. So where is the problem? The problem lies in the large slice of total capacity that is gas fired and that brings us back to the question of whether or not we can source sufficient gas this winter to keep us warm and to keep the turbines spinning? This is not a simple question to answer. And a significant chunk of the capacity margin is wind, that may or may not be available.
Renewables to the Rescue
Wind and renewables opponents always hate this part. But it is a fact that if it is a windy winter, wind will generate a significant amount of electricity allowing the UK and Europe to save on natural gas that is cycled down or off when the wind blows*. This eases competition for gas on the international markets and saves gas in storage for use later in the winter when the risk of storage running dry increases. In this regard, wind power may enhance energy security, but only if the wind blows which is leaving our security to chance.
Of course it would have been better to have that extra 7 GW of coal fired power and a gigantic pile of coal sitting by the Humber in reserve.
Related: UK Renewables May Be Turning The Tide
[* note added 11:45 7th November in response to an email. Over the last 5 years wind and solar has amounted to 1.9% of UK electricity generated. 4.2% in 2013. In 2013, wind and solar amounted to one third of gas. "Significance" is in the eye of the beholder.]
Grid instability
There has been much speculation that a blackout in northern Scotland earlier this year was caused by strong gusting winds feeding irregular wind power on to the grid. There was no evidence that this was the actual cause. But it does seem possible that in future, as the dependable dispatchable component of power generation is replaced by intermittent wind, grid stability will become increasingly difficult to maintain in blustery, stormy conditions.
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Weather
The winter weather plays a large role in determining grid resilience to power cuts in two ways. The first is that a prolonged cold spell runs down natural gas supplies in storage making a country more vulnerable to gas shortages late in the heating season. And second, extreme cold weather pushes up demand for electricity raising the peak load that has to be met. And so, in the UK this winter if it is mild and windy there should be no problem with the grid coping and the same will apply throughout most of northern Europe. But if we get a prolonged cold winter that runs down gas in storage with very cold and calm days in February and March then a country like the UK may struggle to meet peak electricity demand.
The Official View
The official view from the UK National Grid Winter Outlook is typically robust (Figures 6 and 7). National grid presents a picture of a well-supplied gas market with supply capacity well in excess of demand, even in the coldest of winters. Russia is too far away to worry the UK. If all this is true, then the UK will have ample gas to fuel its vast fleet of CCGTs and will come nowhere close to blackouts this winter. This is I imagine what Ed Davey has been told.
Figure 6 The summary prognosis for gas supplies to the UK this winter from National Grid.
Figure 7 A cynic might take the view that National Grid have simply adjusted the gas capacity figures to match anticipated demand. Capacity is a hugely flexible variable while actual gas supply is not.
What might go wrong?
Figure 7 shows where National Grid expects UK gas to come from this winter split roughly into 4 equal parts: 1) UK North Sea production; 2) Norway; 3) LNG imports and 4) pipeline imports from the continent. UK gas storage provides the margin of security. Not so long ago, UK North Sea production covered all of our gas needs.
It is beyond the scope of this post to go into the details of European gas security (I may go into that in a week or two). But suffice it to say that if the winter is cold, and / or if Ukraine once again disrupts supplies from Russia, then that will set the whole of Europe scurrying for alternative sources of supply. Europe will look first to Norway and then to LNG. The UK will find itself in competition with the whole of Europe for gas traded on international markets that have in the past proven to be only just enough to keep everyone’s lights on. And that was before the UK took the wrecking ball to 7 GW of coal fired power generating capacity at the behest of our masters in Europe.
By Euan Mearns
Source - http://euanmearns.com
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