By Robert McLachlan 01/07/2019 13


There’s an old joke set variously in Maine, in Scotland, and probably in any number of other places, about some city folks asking directions from an elderly local. After several lengthy, confusing false starts at directions, the local finally concludes, “You know, you really shouldn’t be starting from here.”

This, to me, is the central joke of climate change mitigation. If only we were starting from somewhere else, say from twenty years ago, or even ten years ago, or if our economic, social, and political systems were set up slightly differently, things would be so much easier.

The problem is particularly acute in New Zealand where we haven’t really begun the actual work of cutting emissions yet, and where the range of allowable strategies is unreasonably restricted. There are many actions that have been tried and tested in most other developed countries (such as solar incentives, electric vehicle incentives, and vehicle fuel efficiency standards) but which are very far from being acceptable in New Zealand.

However, the rash of climate protests and councils declaring climate emergencies is about to force the moment to its crisis.

One flashpoint is the election pledge of 100% renewable electricity by 2035. The Interim Climate Change Committee reported to the government on this target in April. The press are now reporting on a leaked copy of the report, resulting in an all too familiar media circus.

National’s climate change spokesman Todd Muller said the report exposed the “economic lunacy” of being fixated on greenhouse emissions from electricity generation, which formed only a small part of New Zealand’s overall emissions. “The report talked to the economic lunacy of seeking 100 per cent renewable energy in the first place,” Muller said, with New Zealand’s large generation from renewable giving a significant strategic advantage.

The issue has enough ingredients – a large industry that is complicated technically, economically, and politically; an election promise; obvious pollution by large companies; the price of an essential consumer item – to guarantee a classic stoush.

Setting aside Muller’s use of “renewable energy” when he means “renewable electricity” (“energy” includes things like petrol), does he have a point?

Unfortunately the ICCC report is not available yet. However, the ICCC website does host a report by the New Zealand Initiative, a libertarian think tank formed out of the Business Round Table, that comes to similar conclusions. That report, virtually a hatchet job on the whole idea of renewable energy, devotes a lot of space to criticising two of the more successful decarbonisation efforts underway worldwide, those of the UK and Germany.

For about a decade, the percentage of renewable electricity has been rising slowly, partly in response to the present target of 90% renewable (on average) by 2025:

Source: NZ Energy Quarterly, March 2019

It is now regularly over 80%, and the addition of more wind power is predicted to cut into the remaining fossil fuel baseload, cutting emissions further. Unfortunately, those emissions are still 5 million tonnes of CO2 a year. Is that really a small part of our overall emissions, as Muller claims?

The Huntly coal- and gas-fired power station before the Waikato River, a familiar sight from State Highway 1.

Here are a few different ways of looking at the significance of our electricity emissions.

  • As a proportion of our 85 million tonnes (Mt) of gross emissions, they are small but not that small.
  • On the other hand, 34 Mt of those emissions are biogenic methane, which has been set aside. That leaves 51 Mt.
  • But the important target is zero net emissions. Those are currently 24 Mt. Suddenly the 5 Mt from electricity is looking more significant.
  • In addition, some of our emissions such as aviation and shipping (6 Mt), trucking (8 Mt) and many industrial emissions (12 Mt), such as those arising from producing steel, aluminium, fertilizer, and paper, are hard to eliminate and/or protected as trade-exposed industries.
  • Some obvious uses of fossil fuels, like natural gas used to heat homes and workplaces, are possible to eliminate, but turn out to be quite small (1.6 Mt).

Taken together, we are left with only two sources that are large and possible to start eliminating right now: electricity (5 Mt) and cars (7 Mt). That requires tackling these two institutions head on.

So, to paraphrase the situation in terms of the old joke I started with: How can we get there, starting from here?


13 Responses to “100% renewable electricity: A classic kiwi stoush in the making”

  • A reader has written in to correct the emissions figures for land transport – in 2017 they were 9.4 Mt for cars, 3.5 Mt for light trucks, and 1.5 Mt for heavy trucks and buses, having risen a total of 0.85 Mt in one year.

  • The problem that those proponents of wind and solar won’t face, and this includes you Robert, is that of unreliability.; An electricity system cannot work on average GWh. It has to have power generated when it is needed. And it has to be predictable. The hydro systems are currently ramping up and down at near maximum levels (Waikato typically 800MW peak, 60 -100MW off peak) to meet the variability. That adds greatly to their running cost. The CCGTs and Rankines are two shifted, making their operating costs higher and increasing the cost of power. Then you have to have all the machines in backup or voltage support because of the asynchronous generators. That support is why power prices in places with very high wind or solar penetration is so high.
    Try telling everyone the price of power will go up 5 cents a unit to decarbonize (it will actually cost a lot more than that) and see how much support it gets.

  • Did some fag packet numbers shown below giving the most favourable costs for replacing thermal with wind. The elephant in the room is resource consents which would be a decade long very expensive process with no guarantee of success. I disregarded solar as that cannot provide useful power in winter when needed.
    To replace all of NZs thermal generation by wind with pumped storage to back it up.
    Average thermal generation about 1000MW Transpower counts on thermal plant having 98%
    availability over the winter months 24GWh/ day
    For wind to do this needs 1000/0.4 load factor = 2500MW new wind
    To allow for calm periods need pumped storage for 5 days wind generation from full to
    empty 100GWh (Taupo is 410GWh full range). NZ uses about 105GWh/d. Pumped hydro
    storage only viable battery storage system. To fill these pumped storage lakes at 80%
    efficiency (90% fill, 90% generate) from “surplus” wind needs additional 700MW wind
    So wind needs 3200MW total new build.
    At 5MW each generator, needs 640 turbines $3M/MW
    $9.6B
    These turbines have 150m dia rotors, 135m tower. 10D clear air and valleys means say 1 per
    2km2, assume 16 windfarms, each 200MW and 80km2 land area spread throughout NI
    Each wind turbine needs double width road access >150m radius bends, less than 5% slope
    and no significant changes in gradient all made into hilly terrain
    For pumped storage, Rotoaira, 15.8km2 is 8GWh /m for 200m head so:5GWh/ 10km2/ m
    range/ 200m head
    5 pumped storage sites needed, each 500MW, 20GWh storage at each plus there would need
    to be an additional 2 sites to cover for the existing windfarms as these can’t be covered by
    non-existent thermal.
    10m working range, ave 200m head, twin 4km2 lakes. That is each of the 14 lakes about ½
    size of Lake Karapiro or Lake Whakamaru. No recreation use because of working range.
    They need to be spread throughout country to support grid. Cost $10M/MW $35B
    Single circuit 220kV power lines $3.5M/km, Double circuit for pumped storage $5M/km
    undergrounding 10X that so not done
    Power lines to pumped storage, ave 50km, wind farms ave 100km (no 220kV on East Coast
    except at Napier. With additional switchyards, filters, protection, transmission upgrades etc,
    say cost $10B
    Total Capital Cost $55B plus consents, Assume $200M pa O&M
    Pay off over 25 years (life of wind turbines 20y, hydro 50y) 5% cost of capital
    Need extra $5B year from consumers – at most $0.5B fuel saving
    so cost to consumers $4.5B
    Additional power cost ~extra 9c unit plus margin (doubling the wholesale cost)
    And all of this assumes resource consents will be granted speedily at little or no cost. And
    there is no growth in electricity demand.

  • Chris, thank you very much for such an interesting analysis. You seem to know enough to perhaps be able and willing to give me an informed answer to a couple of questions.
    Apart from the enormous $$ cost of putting in a pumped hydro storage system to enable wind generation to fully replace all our thermal generation I do wonder if it is even remotely possible to find sites where the nominal 14 new dams, lakes, and power stations might reasonably be placed. (or whatever other combination of sizes and heads might be possible?)
    However might there be another option to do the same thing? (maybe at least partly?) Along with the nominal 16 wind farms, could new generators and pumps plus nearby bottom-side lakes be installed alongside the existing hydro generators at the existing stations (or maybe at only some of them) in sufficient amount to take up on the required occasions what thermal generation does now? (ie. pumping back up to the lake where the water recently came down from) Of course this would result in the storage lake levels often dropping more rapidly than now, but in this suggested scheme these lake levels might then be restored quickly enough by having the wind generators kick in again in a sufficiently timely fashion. Could the total storage capacity, through their working ranges, of our lakes (those which might be augmented as above) cope with your nominal 5 days of zero wind generation in this suggested scheme? How might the relative $$ cost look?

  • Further to Ron’s question Chris, and again on the back of your fag packet, what COMBINATION of reduced consumption per capita through insulation, energy-efficient applinaces; micro-generation and/or domestic storage; local area distributed networks; transmission system upgrades would be required to get to a point where carbon-fuelled generation support was at an “acceptable” level – say, 8% and reducing?

    Always assuming that some of these options will be driven by pricing signals ie, nationally distributed electricity becomes expensive enough that consumers seek out and apply conservation or alternative generation methods.

  • Ron – I don’t profess to be an expert but being in generation for 40 years, you pick up a lot and I listened to what guys in System Control told me. I also retained all the NZE and CEGB training manuals. . I had dinner with an old flatmate who has had even longer in the transmission side of the business the other night, and he agreed that things are now so complex that there is probably no-one around who understands the lot. But if it is a simple solution, it is definitely wrong and not worth considering.
    I haven’t got the numbers handy but the storage on the NI river hydro lakes is only a few GWh each – some less than 1GWh. Some of them only hold a few hours storage at full load. If you take it from a practical sense, if you pump water from Karapiro back up into Arapuni, where would the water to continue past Karapiro come from? It would rapidly dewater the Waikato. You also have to store the water for periods of weeks to months to counter the wind variability, which was the basis of my calcs. That would mean the hydros couldn’t help do the daily ramp up ramp down of 3000MW.

    I don’t think there are the lake sites – there may be the opportunity to build bigger ones somewhere (Karapiro sized and 1000MW) but the fewer there are, the bigger the security risk. They almost certainly would not get resource consents without a lot of objections as many would have to be built on Conservation land.

    Ashton – Transpower and AEMO have a lot of documents on their sites – read them and do the maths yourself with whatever assumptions you want. However, if electric vehicles take off and decarbonization is to occur, the generation load will markedly increase . Electric cars will add about 3-5000GWh to the annual load. If that is all wind, then the grid will collapse.
    All the easy pickings on load reduction have gone unless high power using industries go offshore – the new domestic loads will increase – for example, changing log fires and gas heaters for heat pumps will put load up. Microgeneration and solar will make the problem worse, not better, as there will be a lack of voltage control management. Powerwalls are just virtue signaling as they are useless in winter at 7am when they are needed. Distributed grids and domestic load management other than ripple control has been promised for thirty years with it getting no closer.
    Making electricity dearer doesn’t give more generation options, just gives the very real problem of fuel poverty.

  • Ashton – though the thermal plant produces about 10,000GWh a year, the ancillary services they provide is often a lot more important than the MW. NZ needs Huntly running to give both inertia and voltage stability. Wind cannot provide that and hydro doesn’t do that good a job. That is why AEMO dispatches wind off to keep GTs running in South Australia.

    The domestic load in NZ is about 2M households, each consuming 8-9000kWh a year. A 10% reduction there would have no significant benefit in the big scheme of things. Even shutting down Tiwai would need $10B of transmission lines and new Cook Straight cables to get the power to North Island. It still couldn’t be used as it wouldn’t support the grid as it is asynchronous, the same category as wind. Getting the DC north at present is limited by the number of thermal units on. Cut back on those and the power north has to drop.

  • So could it be that nuclear fission energy is the only viable option which could enable NZ to decarbonise electric power generation in sufficient amount to reliably meet demand –taking on the majority of base load requirements and so freeing up hydro to come and go as needed?
    Or is there a remote possibility that geothermal could be adequate, safe enough, and not too polluting in this role?

    Regarding ‘nuclear-free NZ’ the regrettable reality is that we here are so badly served by such a generally scientifically illiterate group of journalists that the public, and consequently politicians, will probably need decades to come to see sense. As is the situation with genetic engineering.

  • Ron – There is only maybe another 300MW of geothermal available but undeveloped. There are a lot of fields but most of those like Waiotapu or Waiamangu have Conservation orders on. Geothermal is baseload power 24/7 at full load. Very hard and expensive for it to do anything else. Nuclear is the same. The problem with NZ is the very daily big peaks we have. This time of year, it is about 3500MW at 3:30, 6000MW at 8am, 5000M at noon and 6500MW at6:30pm then dropping again after 10pm. There has to be the generation mix to meet this. Here is the last 24 hours
    https://www.em6live.co.nz/Default.aspx
    At present, about two thirds is met buy ramping up and down all the available hydros. The rest is by ramping the CCGTS, Rankines and start/ stop on the OCGTs. Get rid of the thermal plant and it would be near impossible to use hydros to fill the gap – especially with any degree of system security. They need thermal plant running to bring the DC north.
    And that is without even worrying about the voltage control problems there would be from lack of generation north of Whakamaru if Huntly wasn’t there.
    They could all be “solved” but the cost would be eyewateringly high. Fuel poverty would be very real and no energy using industry for people to work at. And it would take decades because of the BANANAs (aka Greens) who would object to every consent, even though they caused the need for them.

  • Chris, thanks again. I appreciate learning from someone with experience and understanding, Taking the matter a bit further, might it still be useful in terms of physics and economics for NZ to put in some nuclear so as to take away most of the thermal requirements?
    Also in this regard I add the following.
    For each energy source, the average number of fatalities per Gigawatt-year of energy produced (counting accidents of 5 or more fatalities from 1969 to 2000) are:
    Coal (without China) = 0.60
    Coal (with China 1994 – 1999) = 6.1
    Oil = 0.90
    Natural gas = 0.11
    LPG = 14.9
    Hydro = 10.3
    Nuclear = 0.048
    Source: Nuclear Energy Agency. “Comparing Nuclear Accident Risks with Those from Other Energy Sources” (OECD, 2010)

  • Ron – The practical problem with nukes (disregarding all the political and people issues) is that the ones available as standard models are far too big for NZ. With our grid size, you don’t really want anything bigger than 400MW. The standard ones on the market now are 2-3 times that size. So anything built would need to be downsized. And that is not an easy thing to do as reactor physics is very size dependent. And that means we would have specials, with all the problems that causes. And they would still be base load, which isn’t really what we need.
    You would also need a lot of trained engineers, operators, technicians and the like, as well as setting up a massive infrastructure to support it and do things like fuel storage and nuclear island mtce. That means you need 3-4 reactors as a minimum to make the development worthwhile. NZ isn’t big enough to do that. If Australia built a lot of the right size, we could piggy back on them, but that is very unlikely.
    I am always wary of those tables giving things like fatality figures, especially as you don’t know what is behind them. Even if you take single events like Chernobyl explosion, the number of deaths that caused, depending on source, is anything from 100k down to 29.