1 A smart water heater thermostatBryan Leyland MSc, FIEE(rtd), FIMechE, FIPENZ.
2 Ripple control Before the electricity reformsripple control managed peak demand huge savings to the consumer Then came the reforms that did not allow lines companies to recover the cost of ripple control… So most lines companies effectively abandoned peak load control and increased their profits… and cost the consumers more than a billion dollars all storage water heaters were ripple controlled the Power Boards managed the peak demand of their consumers on a peak demand day Power Board load and system load were held constant from 7 AM to 9 PM huge savings in generation, transmission and distribution
3 How it once worked
4 The current situation Distinct morning and afternoon peaks have returned Demand is ~500 MW higher than it needs to be North Island lines companies obviously abandoned ripple control The upper South Island continues to use it
5 The potential If every lines company in New Zealand followed the Upper South Island, New Zealand peak demand would be reduced by something like 500 MW. The consumer benefit would be hundreds of millions of dollars pa The electricity reforms have ripped off the consumers What can be done about it?
6 Other problems.. In an efficient market, when the demand goes up, the price goes up and demand backs off Wiggly prices is not an uncommon scene Why all these wiggles? Does the load respond? Perhaps our market is not efficient after all?
7 An even smarter relay Current ripple relays simply switch groups of water heaters off and on Can only be controlled by the lines companies A presentation at last year’s EEA conference spawned the idea of a truly smart hot water relay.. They cannot be controlled by the retailer or the consumer Some can respond to system frequency but little use has been made made of this facility
8 Smart hot water thermostatPlug-in replacement for the thermostat on a conventional electric water heater A version without temperature sensing could control other loads.
9 How it works A triac regulates the power inputIt monitors frequency, voltage and water temperature It has a Wi-Fi connection so it can be controlled by the consumer, the retailer, the lines company, and the system operator Installation consists of disconnecting the two wires to the thermostat, inserting the new thermostat, reconnecting the two wires and connecting to the Internet Voltage sensing would be by switching off the triac for a few cycles every few seconds. Frequency sensing would come from the residual voltage across the triac Its power supply would come from an ultra capacitor that was charged by switching off the heater for a few seconds
10 What it can do.. Manage demand as requiredReduce the need for peak load generation, transmission and distribution costing ~ $3000/kW Reduce the need for spinning reserve and active frequency management Reduce the need for under frequency load shedding Solve the over frequency problem Limit price spikes Limit constraint problems Help with line voltage problems The potential savings are enormous! Transpower and the lines co can manage their peak demands The retailer can reduce his load if the price is high The consumer can set his water heater to be on during the early hours of the morning Replace spinning reserve for managing small frequency disturbances and the fluctuating output of wind farms
11 Compared to ripple control it can...control a single relay or all relays or anything in between sense temperature and switch on if the water gets too cold eliminates fear of losing hot water sense and manage frequency and voltage Easier to install – could be installed by the home owner Can be made by a number of suppliers – compatibility is not a problem Does not require expensive and complex injection systems Cheaper and better!
12 Frequency management It could ramp water heater power over a range of to cycles The biggest load diversion governor in the world! ~800 MW of water heater load available Reduce the need for frequency management 200 MW of spinning reserve All for virtually no cost! 200 MW of spinning reserve would be virtually eliminated
13 Managing price spikes Sometimes we get brief price spikes that last a few minutes to a few hours It is much better to dump load rather than have to use expensive quick start reserve plant Benefits everyone but the generators!
14 Manage transmission constraintsWhen a constraint occurs, it would be easy to dump load in the affected area
15 Manage solar power A 2.5kW solar cell exports about 2 kW to the grid during the middle of the day Some lines companies are pushing batteries to store this electricity even though research shows that the cost of storage in batteries is about 60 cents/kWh A 250 L water heater can store something like 5 kWh for no cost at all! The smart thermostat could switch on the water heater when surplus power is available
16 Security The big risk is, of course, the internet connectionthe same applies to smart meters Hackers could use it to crash the system Security is important! Hackers could give everybody cold water or switch on all water heaters and crash the system Security will have to be foremost in the minds of the hardware and software engineers
17 Who benefits? The consumer Transpower System operatorThe lines companies Generators Retailers The consumer pays much less for power Transpower reduces expenditure on transmission lines better control of constraints System operator reduces costs of frequency management and spinning reserve The lines companies save on system reinforcement (not necessarily a benefit to them?) Generators reduce/eliminate expenditure on e.g. open cycle gas turbines to meet peak demands and wind fluctuations Retailers can manage consumer’s loads to reduce expenditure when the spot price is high
18 Industry benefits 500 MW reduction – or lack of increase – in peak demand at $3000/kW and 5% return, – $150 million per annum? Reduction in frequency management and spinning reserve – 50 million pa? Reduction in power price from reducing price spikes and constraints million per annum?
19 Will it fly? Under the present regime, there seems to be no way to make it fly even though the consumer benefit is huge To be really effective, they should be fitted to every water heater – and maybe other appliances It should be attractive to retailers, lines companies and generators if one of them promotes it, he will collect only a fraction of the total value I approached the Electricity Authority they could not see that there was anything that they needed to do! if one of them promotes it, he will collect only a fraction of the total value the rest will ignore it or free ride on it
20 What could we do? The Electricity Authority could take the leadit would be fair and equitable to finance it through a levy on all kWh Would need a regulation saying that if a load can be controlled without you noticing it must be it available for load control less Draconian than the current AUFLS regime Will it happen? The Electricity Authority cannot see that there is anything wrong with the rundown of the ripple system so why fix something that, according to them, is not broken? they have a blind belief that anything that the market does not provide is not needed it would be fair and equitable to finance it through a levy on all kWh it would benefit every consumer whether or not they have a relay installed a levy of 0.25 cents/kWh – $20 a year for a domestic consumer – would adequately fund a five-year installation program industry cost would be ~$100 million pa peanuts compared to the more than 1 billion spent on smart meters with little consumer benefit
21 What is the underlying problem?NZ electricity supply requires three commodities sufficient MWh at a reasonable price sufficient MW capacity to meet peak demands sufficient stored MWh to get us through a 1:20 dry year How about a market that pays for MW actually available over peak demand periods? and the same amount to generators held in reserve? How about a market that pays for MWh held in reserve for dry years? How about a peak demand charge that reflects the cost of an incremental MW? householders with smart meters can then be charged on peak demand Householders with smart meters can then be charged on the basis of their peak demand smart meters would finally pay their way and everyone would demand a smart thermostat!
22 The best solution? A single buyer marketIt would be blindingly obvious to the single buyer that the smart thermostat would be a major contributor to a “reliable and economic supply” so the Single Buyer is obliged get on and do it The consumers would be delighted it would have no significant effect on the profits of the other players.. But a single buyer is heresy of the worst sort! Not to be contemplated!
23 Conclusions The smart thermostat would bring huge benefits to the power system and save the consumers millions of dollars It has no chance of being adopted under the present regime Its value would be recognised if some relatively simple changes were made to the market and the regulations But only if the powers that be recognise that the present market is flawed The chances are that this will not happen until we have had serious shortages in a dry year Watch this space!
24 Questions…