Posts Tagged ‘electricity’
South Australia and electricity revisited
Canto: So what’s the latest on SA’s statewide blackout of September 28 last year, who’s to blame, who’s blaming who, and what solutions are in the offing, if any?
Jacinta: Well the preliminary report on the NEM, which we’ve been reading and writing about, has a few things to say about this, and they’re based on the findings of the Australian Energy Market Operator (AEMO) in its own preliminary report.
Canto: He said she said.
Jacinta: Well maybe sort of. So the SA blackout is presented as a case study. Here in SA we have a very high proportion of VRE (variable renewable energy) generation – one of the highest in the world. Our peak demand as a region is 3300 MW, and our supply capacity is almost 2900 MW of gas, almost 1600 MW of wind, and 700 MW of installed solar. We’re connected to the rest of the NEM by two interconnectors, an AC connector with a capacity of 600-650 MW, and a DC connector with a capacity of 220 MW. With electricity demand here declining, or at least not growing, synchronous generation and supply have reduced, with a resultant reduction in system inertia.
Canto: I presume by system inertia you mean the tendency for a machine, a vehicle, or a generator, whatever, a system to keep going once the power’s switched off. Like the QE2 has a lot of system inertia.
Jacinta: Right, but it’s a particularly important term in reference to power generation. There are some neat explanations of this online, but I’ll give a summary here. Coal-fired power stations work through the burning of coal which generates steam to turn a turbine, putting energy into the grid, and being massive, it has a lot of spinning inertia. Slow to fire up, slow to wind down. Solar, though, doesn’t work that way. It has no spinning or even moving parts. When the sun’s off, it’s off, but when it’s on it’s on. There’s really no inertia at all in a conventional solar PV system.
Canto: And wind? That’s the principal renewable energy here.
Jacinta: Yes that has inertia, certainly, but it’s variable and not as significant as perhaps it could be. So anyway on the morning of the blackout weather forecasts were grim, but not enough for AEMO to put out alerts for a ‘credible contingency event’. As it turned out there were at least seven tornadoes in the north of the state that day, as well as numerous lightning strikes and high winds which caused structural damage to transmission lines. At blackout time electricity demand in the state was a little over 1800 MW, with nearly half of it being supplied by wind farms, and of the rest about a third came from gas-fired generators, and the other 600 or so megawatts came through the interconnectors from Victoria. The main Heywood connector was approaching its operating limit. Short circuits to the transmission lines, caused by lightning, were the probable proximal cause of the blackout. Thirteen wind farms were in operation at the time, and eleven of them experienced ‘voltage dips’. What happens in these circumstances is that ‘fault ride-though’ responses are invoked. However, nine of the eleven farms had a lower pre-set limit for the ride-through response to proceed, and after a number of dips those nine wind farms cut their connection. The other two had higher pre-set limits and continued operation.
Canto: Ahh, so those preset limits were set too low?
Jacinta: Maybe – that’s one for further investigation. So the lack of generation from the wind farms caused an overload on the Heywood interconnector, and it was disconnected as per protection systems, resulting in frequency failure on the grid, and blackness fell upon all the land.
Canto: Right, so how did things get restarted? What’s the normal procedure?
Jacinta: Well, there’s this contracted service, called the System Restart Ancillary Service, which in SA is contracted to two major electricity generators (unnamed in the report), who can supposedly restart regardless of the grid situation, and provide power to the transmission network, but these servers failed for unexplained reasons, and power was finally restored through the Heywood interconnector together with the Torrens Island power station.
Canto: Okay, so now the fallout. How could things have been done differently?
Jacinta: Some near-term fixes have been implemented already. Firstly, having to do with frequency rates which I won’t go into here, and secondly in relation to wind farms. Five of them have made changes to their fault ride-through settings, and AEMO is looking at this issue for wind farms across the NEM. The Australian Energy Regulator, another bureaucratic body, will have completed a full analysis of the blackout by early next year to determine if there were any breaches of regulations. Obviously it’ll be looking at the conduct of AEMO throughout, as well as that of the transmission operator, ElectaNet. It’ll also look at these fault ride-though settings of wind farms and the failures of the System Restart Ancillary Service. It all sounds as if everything’s being done that can be done, but the major problem is that grid security as it stands can only be provided by large generators. The report again mentions gas-fired generators as the best solution, at least in the short to medium term.
Canto: So, as the grid, and the general provision of electricity, undergo these transformations, we’ll no doubt experience a few more of these hopefully minor setbacks, which we can learn from as we develop security for a more diverse but more integrated system…
Jacinta: Greater integration might require less squabbling about the future of energy. I can’t see that happening in the near future, unfortunately.
on the preliminary report into the future of the NEM – part 1
Australia’s Chief Scientist, Alan Finkel, who also happens to be a regular columnist for Cosmos, Australia’s premier science magazine, of which I’m a regular reader, has released his panel’s preliminary report on our national electricity market (NEM), and it has naturally received criticism from within the ranks of Australia’s conservative government, which is under pressure from its most conservative elements, led by Tony Abbott amongst others, who are implacably opposed to renewable energy.
The report confirms that the NEM is experiencing declining demand due to a range of factors, such as the development of new technologies, improved energy efficiency and a decline in industrial energy consumption. It makes a fairly reasonable assumption, but one unwelcome to many conservatives, that our electricity market is experiencing an unprecedented and irreversible phase of transition, and that this transition should be managed appropriately.
The NEM has been in operation for over 20 years, and the recent blackout here in South Australia (late September 2016) was its first real crisis. The issue as identified in the report is that variable renewable energy (VRE) sources are entering and complicating the market, which heretofore has been based on the synchronous generation of AC electricity at a standard system frequency. VRE generation is multiform and intermittent, and as such doesn’t sit well with the traditional system.
There are a number of other complicating issues. Improvements in building design and greater public awareness regarding emissions reduction have led to a decrease in overall energy consumption, while high peak demand on occasion remains a problem. Also the cost of electricity for the consumer has risen sharply in recent years, largely due to network investment (poles and wires). It’s expected that prices will continue to climb due to the closure of coal-fired power stations and the rising cost of gas. Interestingly, the report promotes gas as a vital energy source for this transitional period. It expresses concern about our overseas sales of gas, our low exploration rates, and negative attitudes to the fuel from certain states and territories. Rooftop solar systems, numbering more than 1.5 million, have further complicated the market, as the Australian Energy Market Operator (AEMO) understandably finds it difficult to measure their impact. System integration, which takes solar and wind energy system contributions into account, is clearly key to a successful NEM into the future.
The report also stresses Australia’s commitment to emissions reductions of 26-28% by 2030. It points out that business investors are turning away from fossil fuels, or what they call ’emission intensive power stations’, and financial institutions are also reluctant to back such investments. Given these clear signals, the report argues that a nationally integrated approach to a system which encourages and plans for a market for renewables is essential. This is clearly not what a backward-looking conservative government wants to hear.
So the report describes an ‘energy trilemma’: provision of high level energy security and reliability; affordable energy services for all; reduced emissions. More succinctly – security, affordability and the environment.
In its first chapter, the report looks at new technology. The costs of zero-emission wind turbines and solar PVs are falling, and this will maintain their appeal at least in the short term. Other such technologies, e.g. ‘concentrated solar thermal, geothermal, ocean, wave and tidal, and low emission electricity generation technologies such as biomass combustion and coal or gas-fired generation with carbon capture and storage’ (p13), are mentioned as likely technologies of the future, but the report largely focuses on wind and solar PV in terms of VRE generation. The effect of this technology, especially in the case of rooftop solar, is that consumers are engaging with the market in new ways. The penetration of rooftop solar in Australia is already the highest in the world, though most of our PV systems have low capacity. Battery storage systems, a developing technology which is seeing cost decreases, will surely be an attractive proposition for future solar PV purchasers. Electric vehicles haven’t really taken off yet in Australia, but they are making an impact in Europe, and the AEMO has projected that 10% of cars will be electric by 2030, presenting another challenge to an electricity system based largely on the fossil fuels such vehicles are designed to do without.
The management of these new and variable technologies and generators may involve the evolution of micro-grids as local resources become aggregated. Distributed, two-way energy systems are the likely way of the future, and an Electricity Network Transformation Roadmap has been developed by CSIRO and the Energy Networks Association to help anticipate and manage these changes.
In chapter 2 the report focuses on consumers, who are becoming increasingly active in the electricity market, which was formerly very much a one way system – you take your electricity from the national grid, you pay your quarterly bill. With distributed systems on the rise, consumers are becoming traders and investors in new forms of generation. The most obvious change is with rooftop PV. The national investment in these systems has amounted to several million dollars, with the expectation that individual households will be generating electricity more cleanly, more efficiently, and also more cheaply, notwithstanding the traditional electricity grid. Developments in battery storage and other technologies will inevitably lead to consumers moving off-grid, likely creating financial stress for those who remain. The possibilities for developing micro-grids to reduce costs will further complicate this evolving situation. Digital (smart) metering and new energy management software empower consumers to control usage. And while this is currently occurring mostly at the individual level, industrial consumers will also be keen to curb usage, creating added pressure for a more flexible and diverse two-way market. The report emphasises that the focus should shift more towards demand management in terms of grid security. One of the obvious problems from the point of view of consumers is that those on low incomes, or renters, who have little capacity to move off-grid (or desire in the case of passive users), may bear the burden of grid maintenance costs at increasing rates.
Chapter 3 deals with emissions. In reference to the Paris Agreement of 2015, which has been ratified by Australia, the report makes this comment which has been picked up by the media:
While the electricity sector must play an important role in reducing emissions, current policy settings do not provide a clear pathway to the level of reduction required to meet Australia’s Paris commitments.
The current Renewable Energy Target does not go beyond 2020 and national policy vis-à-vis emissions extends only to 2030, causing uncertainty for investors in an already volatile market. Clearly the report is being critical of government here as it has already argued for the primary role of government in developing policy settings to provide clarity for investment. The report also makes suggestions about shifting from coal to gas to reduce emissions at least in the short term. The report discussed three emissions reduction strategies assessed by AEMO and AEMC (Australian Energy Market Commission): an emissions intensity scheme, an extended large-scale renewable energy target, and the regulated closure of fossil-fuelled power stations. The first strategy is basically a carbon credits scheme, which was assessed as being the least costly and impactful, while an extended RET would provide greater policy stability for non-synchronous generation, so adding pressure to the existing grid system. Closure of coal-fired power stations would reduce low-cost supply in the short to medium term. Base load supply would be problematic in that scenario, so management of closures would be the key issue.
Chapter 4 looks at how VRE might be integrated into the system. It gets a bit technical here, but the issues are clear enough – VRE will be an increasing part of the energy mix, considerably so if Australia’s Large-scale renewable energy target is to be met, along with our international commitment vis-a-vis the Paris Agreement. However, VRE cannot provide spinning inertia or frequency control, according to the report. Basically this means that they cannot provide base load power, at a time when coal-fired power stations are closing down (nine have closed since 2012) and eastern states gas is being largely exported. The Hazelwood brown coal power station, Australia’s largest, and one of the most carbon intensive power stations in the world, will cease operation by April next year.
The difficulty with non-synchronous, distributed, intermittent and variable energy generation (e.g. wind and solar PV) is that these terms seem to be euphemisms for ‘not effing reliable’ in terms of base load, a problem currently being encountered in South Australia and likely to spread to other regions. The report identifies frequency control as a high priority challenge.
Frequency is a measure of the instantaneous balance of power supply and demand. To avoid damage to or failure of the power system the frequency may only deviate within a narrow range below or above 50 Hertz, as prescribed in the frequency operating standards for the NEM.
It’s likely that this narrow range of frequency proved a problem for South Australia when it suffered a blackout in September. I’ll look at what the report has to say about that blackout next time.
national electricity consumption – apparently on the rise again?