Like what you've read?

On Line Opinion is the only Australian site where you get all sides of the story. We don't
charge, but we need your support. Here�s how you can help.

  • Advertise

    We have a monthly audience of 70,000 and advertising packages from $200 a month.

  • Volunteer

    We always need commissioning editors and sub-editors.

  • Contribute

    Got something to say? Submit an essay.

 The National Forum   Donate   Your Account   On Line Opinion   Forum   Blogs   Polling   About   
On Line Opinion logo ON LINE OPINION - Australia's e-journal of social and political debate


On Line Opinion is a not-for-profit publication and relies on the generosity of its sponsors, editors and contributors. If you would like to help, contact us.


RSS 2.0

The implicatations of dispatchable versus intermittent electricity generation

By Charles Hemmings - posted Friday, 28 June 2024

Many have a strong opinion on where we should go with electricity generation. Opinion does not necessarily equate with fact. Surprisingly little focus is put on the economic and technological aspects of this important matter, considering its vital importance. To say " transition from fossil fuel generation" is easy, but its implementation is proving to be a massive challenge for the world with no immaculate solutions found to date. Anthropogenic greenhouse gas emissions are the cause of the need to transition. The so called 'renewables', (solar panels and wind turbines), have captured the hearts of many. The rich world has gone bonkers, on the mistaken idea that we can get to net zero by using only 'cheap renewables' for generating our electricity. Given the more than a decade that large scale subsidized experiments have been done, experience is clear that relying totally on 'renewables' alone is non-viable.

The Need for Transition

The world's energy consumption has increased by some 8.7 times between 1950 and 2021, an exponential growth of some 3% per annum. This has led to much greater anthropogenic emissions of greenhouse gases. As well as the increase in atmospheric carbon dioxide since the Industrial Revolution, satellite and spacecraft information show that there is a significant deviation in the Earth's outgoing longwave radiation (OLR) at around 15 microns, which corresponds to an absorption band of carbon dioxide. This is clear evidence of a surface-warming effect resulting from our emissions. Extreme weather events are suggestive but not proof of any substantial warming effect of our activities. There are factors, both known and unknown, which affect the climate also. To avoid panic about this, remember that the oceans have an enormous heat capacity compared to the atmosphere, that the energy intensity of the Earth's OLR varies as the fourth power of the absolute temperature and that climate modelling is very inexact. These mechanisms (not the modelling) slow down the rate of surface heating, that is, cause a lag. We need to transition, but we should best do it without a knee jerk reaction and with essentially global agreement on how to proceed. Also, best done on the basis of technology and economics, rather than on ignorant ideology or should that be idiotology?




Dispatchable generators are those that can quickly provide electricity when called upon and can vary with demand. These include fossil and nuclear fission.


Intermittent generators are those that produce electricity at irregular intervals, not continuous or steady, coming and going at intervals, sporadic. These include solar and wind.

Categorical Difference


Dispatchable and intermittent define the two categories of electricity generators in terms of their critical performance characteristics. Dispatchable generators include all fossil fuels and nuclear fission. Intermittent generators include solar panels and wind turbines. The critical, essential, significant difference between the performance characteristics of these two classes of electricity generators is, in general, either is not well-understood or is ignored. Society wants reliable, affordable electricity on demand, 24/7 and now carbon-free. Without the backup of dispatchable generators, 'renewable' generators are not fit for purpose. This has been world experience and can be deduced also from a technological and economic evaluation basis. Dispatchable generators are indispensable, whereas 'renewable' generators are not indispensable to an electricity utility.

Individual Generator Costs

Comparing dispatchable to intermittent generators is not possible by the method used in the past (Levelised Cost of Electricity) because intermittents only work when the weather obliges, also the redundancy. Consider a 10MW coal-fired power generator and a 10MW solar panel array. Given that the solar panels only work for about 6 hours a day on average, the 24 hour output of the solar array is 2.5 MW. This means the solar array is only useful for ¼ of a day, so comparing the 2 systems on the basis of 10MW capacity is invalid. Take note also that the capital cost of the solar array must be increased by four times to compare with that of the coal-fired generator. Similar considerations apply to wind turbines. 'Renewables' are cheaper to operate, costing essentially nothing, but when the capital costs are included, as good accountancy or reality dictates, the picture is not so rosy, even comparing generators in isolation. In addition, the 'renewables' cannot supply electricity needed on demand. Also to provide the 10MW for 24 hours the 'renewables' require expensive battery backup.

  1. Pages:
  2. Page 1
  3. 2
  4. All

Discuss in our Forums

See what other readers are saying about this article!

Click here to read & post comments.

45 posts so far.

Share this:
reddit this reddit thisbookmark with Del.icio.usdigg thisseed newsvineSeed NewsvineStumbleUpon StumbleUponsubmit to propellerkwoff it

About the Author

Charles Hemmings has a background in metallurgy, earth sciences and business. He is retired.

Other articles by this Author

All articles by Charles Hemmings

Creative Commons LicenseThis work is licensed under a Creative Commons License.

Photo of Charles Hemmings
Article Tools
Comment 45 comments
Print Printable version
Subscribe Subscribe
Email Email a friend

About Us Search Discuss Feedback Legals Privacy