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Water Heater Confusion

February 23, 2016
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During a recent radio interview where I was discussing PV rooftop solar electricity, a caller said he had saved money by using the sun to heat the water used in his home, rather than using an electric or gas fired hot water heater.

Using the sun to heat water for household use, or to keep the swimming pool warm, can be, and often is, a good decision, but using the sun to generate electricity is probably a bad economic decision in the United States.

Rooftop solar water heating with water piping. Photo by D. Dears

Rooftop solar water heating with water piping. Photo by D. Dears


PV rooftop solar with electrical connection. Photo by D. Dears

PV rooftop solar with electrical connection. Photo by D. Dears

A recent article in PowerMagazine lauded the use of electric water heaters for demand response, and touted a report by the Brattle Group, “The Hidden Battery: Opportunities in Electric Water Heating

It also touted a program by the Great River Energy (GRE), electric cooperative, for incorporating electric water heaters in its demand response program

It should be made clear however, that for the most part, this is nothing new.

Demand response has historically been used by electric cooperatives, such as the GRE, and utilities in general, to dump load during peak periods of demand. It used to be called “load shedding” but “demand response” (DR) is more glamorous in this day and age of fear of climate change and CO2.

The only feature that is new in the Brattle Group’s report, is the use of electric water heaters for frequency correction.

While it’s a fairly simple matter to incorporate demand response with electric water heaters, using them for frequency correction requires new water heaters or new controls, which increases costs for the utility and homeowner, unless new water heaters and controls are subsidized.

Calling electric water heaters a “Hidden Battery” is another eye catching phrase, but is obviously a distortion of the facts. It will confuse people who will jump to the conclusion that something new has been invented and added to the arsenal to fight climate change.

In fact, virtually nothing has changed except the rhetoric.

Water heaters are not batteries and cannot produce electricity.

They store thermal energy, which can be manipulated by timing when the electricity is used to heat the water.

Unfortunately, in their quest to promote CO2 as the cause of climate change, Power Magazine, and the proponents of the Brattle Group report, are willing to distort the facts by calling electric water heaters “Hidden Batteries.

Whether using electric water heaters to control frequency is the least costly or best method for frequency correction is another question. There are other methods, such as flywheels.

However, there wouldn’t be the need for new frequency correction methods if unreliable wind and solar weren’t being added to the grid … at tax taxpayer expense, with subsidies.

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Nothing to Fear explains why CO2 isn’t to be feared, why politicians are harming Americans by pushing the CO2 agenda, and that mankind has benefited from using fossil fuels and can continue to do so, perhaps for 1,000 years.

Nothing to Fear is available from Amazon and some independent book sellers.
Link to Amazon:


Book Cover, Nothing to Fear

Book Cover, Nothing to Fear

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3 Comments leave one →
  1. Bryan Leyland permalink
    February 23, 2016 3:15 pm

    Dear Don,

    A few comments.

    In the 1920s, we had storage water heaters and a switch over the stove labelled “stove” and “water heater”. So you couldn’t cook and heat water at the same time. This made issue difference to domestic peak demand.

    From the 1950s onwards every home in New Zealand had a ripple control relay that controlled water heaters from a centralised system. This managed water heater load – then about 16% of the total New Zealand load – so system peak demand was steady from 8 AM until 9 PM. The reforms associated with the new electricity “market” killed this system. New Zealand peak demand is now several hundred MW higher than should be. The consumers pay.

    Recent research showed that the most effective use of solar PV is to connect the output direct to the water heater element. It seems that it is even cheaper than putting solar water heater systems on the roof.

    Did I tell you about my smart water heater thermostat? I hope to present a paper on it at the next conference. Abstract attached.

    I hope your book is selling well. It deserves to.

    Kind regards,

    Bryan Leyland

    Phone +64 9 940 7047 Mobile +64 21 978 996 A smart water heater thermostat

    Bryan Leyland MSc, FIEE(rtd), FIMechE, FIPENZ. Bryan Leyland Consulting Engineer

    EEA Conference & Exhibition 2016, 22 -24 June, Wellington

    Abstract Before the electricity reforms and market, New Zealand had the best demand side management system in the world: ripple control of domestic water heaters. The electricity reforms prevented the lines companies from making any return on the costs of extending, operating and maintaining it so most lines companies effectively abandoned ripple control.

    Ripple control avoided expenditure on generating plant, transmission lines and distribution systems. Had it continued, New Zealand’s peak demand would be 300 – 400 MW less than is now. In all probability, the $950 million 400 kV line would not have been built. More would have been saved by avoiding reinforcement of other transmission and distribution systems.

    Modern technology makes it easy and cheap to manufacture and install hot water thermostats that would bring back all the benefits of ripple control – and many more.

    The smart thermostat would sense water temperature and regulate the power input to the water heater as required. It would also be sensitive to system frequency and would ramp down the power to the water heater if frequently dropped to, for instance, 49.9 Hz. But if the water temperature dropped by more than say, 10°, it would restore power so that no one would be short of hot water. If the water heater was off and the frequency was high, it would inject additional power into the water heater for the few minutes needed to manage the frequency excursion.

    It would be connected to the Internet via Wi-Fi so it could be controlled by the System Operator if the system was in serious trouble or if a constraint occurred in a certain area. The lines companies could regulate the demand on Transpower, the retailers could reduce demand during price spikes and the consumers could minimise expenditure on electricity.

    The paper will show that the fragmented nature of the industry and the shortcomings of the electricity market makes it impossible for any one entity to aggregate all the benefits and so justify the expenditure on the new devices.

    Smart meters have been more or less forced on consumers and have cost them many millions of dollars without bringing them any significant benefits. The smart water heater thermostat would cost much less and bring enormous benefits. But, unless the Electricity Authority and others make the changes necessary to allow this smart device – and maybe others – to realise their potential benefits, nothing will happen.


    • February 25, 2016 3:08 pm

      Thanks. I was away for a day without access, so your comment was delayed a day.
      Great information.
      Nothing to Do is ding very well. I’ve had 12 radio interviews so far. More scheduled for next week.


  1. Weekly Climate and Energy News Roundup #216 | Watts Up With That?

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