Keeping the Lights on – Even with Intermittent Nuclear and Fossil Fuel Power Plants

October 21, 2014

The line you hear about renewable energy, over and over again, is that “renewables like solar and wind are intermittent” and therefore need a back up.
All sources of energy are intermittent, and all need a back up, – that’s why you have a grid.

Above, retired Austin Energy exec Michael Osborne was instrumental in negotiating the lowest price for utility scale solar ever.
He describes how Austin Energy, the municipal utility in Texas’ capital city, keeps the lights on with multiple sources of energy, including “intermittent” nuclear power.
One difference between renewables and traditional power sources is that you can lose a whole lot of power, unexpectedly, when something goes wrong with a large centralized power plant, like when a nuclear power plant trips offline, or as happened recently with a fire in a UK gas generator.
Carbon Brief:

What happens when a major gas power station catches on fire? Well, it certainly looks spectacular. But it appears the short term impact on the UK’s power generation is pretty minimal.

Energy company RWE npower had to unexpectedly shut down one of the Dicot B power station’s 700 megawatt units last night after a fire broke out in one of the cooling towers.

Didcot’s shutdown is the latest in a series of unexpected outages which National Grid has had to cope with in recent months. This has led to a spate of headlines questioning whether National Grid will have enough power stations available to cope with high demand over the winter months.

We take a look at how National Grid copes with such unexpected events, and why it remains confident the UK will have enough power this winter.

Where does the UK’s power come from?

National Grid is legally required to make sure there’s always enough power to meet demand. The UK’s peak demand – at around 6pm on weekdays – is currently around 45 gigawatts. This is expected to rise to about 55 gigawatts over the winter, as people spend more time indoors and use more electricity.

Big coal, gas, and nuclear power stations are responsible for meeting most of this demand. The government’s latest statistics show 30 per cent of the UK’s electricity comes from gas, with 28 per cent coming from coal. Nuclear power provides about 20 per cent.

When one of these power stations has to be taken offline, it’s big news. Earlier this year, the Heysham 1 and Hartlepool nuclear reactors with a total capacity of 2.3 gigawatts shut down after engineers discovered cracks in their boiler casings. Both power stations are due to come back online before Christmas, although they will only be operating at 70 to 80 per cent of their normal output, the Telegraph reports.

Two coal power plants – at Ferrybridge and Ironbridge – also caught fire over the summer, meaning National Grid has had to do without their combined 1.4 gigawatts of capacity in recent months.


The real challenge came this morning, when everyone got out of bed and made a cup of tea – and demand spiked.

So what filled the gap?

Last week’s electricity demand was fairly similar to this week’s. Using this time last week as a reference point, we can roughly estimate how much coal, gas, nuclear and renewables National Grid would have expected to call on this morning if Didcot B hadn’t closed.

If Didcot B’s outage had a major affect on the UK’s gas power supply, you’d expect to see gas providing much less of the UK’s demand this morning than on Monday morning last week. The graph below shows that wasn’t really the case.

The graph shows the percentage change in the proportion of demand each energy source accounted for last night and this morning, compared to the same time a week ago:

It shows National Grid was able to call on other fossil fuelled power plants to fill the gap left by Didcot B’s shutdown. The fact that most of the energy sources only provided a couple of per cent more or less power to the grid this morning shows the impact of Didcot B closing was very short term.

The main thing driving National Grid’s technology choices seems today is the fact there was less wind available this morning than the same time last week, rather than Didcot B’s outage.

When Didcot B was shut yesterday, National Grid called on a whole range of energy sources to make up the difference.

Within a couple of hours, gas generation had been ramped up to the extent that it was providing for about the same share of the UK’s electricity demand as last week. National Grid also called on companies to ramp up coal power generation, as you can see from the rising light blue line.

The UK also imported slightly more electricity (the dark blue line), and National Grid used some stored power to balance the grid (the purple line).

National Grid has spare capacity to draw on because many of the UK’s fossil fuelled power plants aren’t running at full capacity – gas plants are generally producing only about a third of the electricity they could provide.

Coal plants are currently only producing about two-thirds of the electricity they could. So when there’s a big outage, as there was yesterday, it’s relatively straightforward for National Grid to ask companies to increase the amount of electricity those power stations are producing.

One reason coal and gas plants are running at less than full-power is that the UK has been building lots of renewables. That allows energy companies to rely on renewable power, save money on fuel, and leave some power spare for when National Grid needs it.

131 Responses to “Keeping the Lights on – Even with Intermittent Nuclear and Fossil Fuel Power Plants”

  1. […] The line you hear about renewable energy, over and over again, is that "renewables like solar and wind are intermittent" and therefore need a back up. Hello? All sources of energy are intermittent,…  […]

  2. Replying to Arcus at

    You are a realist? OK. Provide your global plan for nuclear rollout to prevent GW. Give details. Show how it affects GNP, how many meltdowns, the whole thing.

    Oh, right.  You want me to give you a blow-by-blow plan for the world, when your idols Jacobson and Budischak have only done one for the USA… and a fraudulent one at that, with zero reality checks against the real-world examples like Denmark and Aruba and simulations over a couple of (likely cherry-picked) weeks in one year of weather and load data.  And you want me to do it for no pay.  Or are you going to give me a grant?  I’ll take half a mil to hire the graduate assistants and buy access to the required databases, half a year for the design, two years to crunch and a year to edit, how’s that?  Cut the check tomorrow and get back to me around April-May 2018.

    Why do I have to keep pointing you BACK to the examples of France and Belgium and Ontario, which rapidly de-carbonized large fractions of their electric supply with no muss, no fuss?  Those are not simulations or projections, they are established and proven historical fact.  Why are they not good enough to prove anything to you?  Why are they not “real”?

    Show how its feasible including all the political and other ramifications.

    Of course, you are enamored of the Jacobson scheme which is physically impossible.

    If the public ever gets worried enough to bulldoze the procedural roadblocks and let the technocrats do the dirigiste thing here, I have no doubt that we’ll de-carbonize our energy very quickly.  Things like the sodium leak and fire at Monju never presented a threat to the public.  One of those a year would not be a problem, except that would never happen; after the first one, inspections would be done and designs would be changed to make sure another was unlikely to happen for many years.  That’s how the FAA treats fixable aircraft defects, and how a functional nuclear regulator would treat faults in plants.  There is no role for “intervenors” or “public comments”.

    But it has to have concrete numbers, not just pie in the sky.

    Here’s some numbers:  The Fermi 2 plant in Monroe, MI has a net capacity of about 1100 MW(e).  Had the USA built 10 such units per year between 1980 and 2020, we would have 440 GW of capacity from them alone.  This is roughly equal to the average electric load of the USA.  The base load would be fully decarbonized, and the off-peak power would be sufficient to electrify a substantial fraction (perhaps 50%) of personal transportation and de-carbonize that as well.  Had that been done we would currently be at least halfway to a fully-decarbonized US economy.

    What could we do now?  I know what we have, I just don’t know how long it would take to get a full effort rolling at a pace we could maintain until the job is complete.  Then there are wildcards like NuScale and Terrestrial Energy and LEADIR.  If we get a certified reactor that can be put beneath a city parking structure to supply electricity and low-pressure steam for space heat, DHW and absorption air conditioning, whole cities could be de-carbonized all at once.

    Here’s another figure:  TRISO fuel (specified for reactors like LEADIR) costs about 2¢/kWh(e), or about 0.7¢/kWh(th).  Waste heat from such a reactor would cost about $2/million BTU, equivalent to natural gas at 20¢/therm.  Natural gas, from fracced wells or otherwise, could not compete.  Neither energy poverty nor carbon would be an issue if you could put a LEADIR under your city and use it to supply electricity and steam.

Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: