A sustainable energy future for NZ (without all the hot air)

This is a guest post by Phil Scadden, a regular commenter at Hot Topic (bio at the end of the post). Phil’s interested in energy issues, and has spent a considerable amount of his personal time developing an overview of New Zealand’s energy issues, inspired by the approach used by Cambridge physicist David MacKay in his recent book Sustainable Energy – without all the hot air. I’m very pleased to say that Phil is making his work available via Hot Topic (PDF here), because the perspective he brings provides a starting point for the strategic energy debate we need to be having. Over to Phil:

Sustainable Energy – without all the hot air by Cambridge physicist David MacKay is an excellent and highly readable book of numbers about the questions associated with sustainable energy (available as a free download at www.withouthotair.com). As an advocate of sustainable energy, he describes himself as “pro-arithmetic” rather than a campaigner for one type of energy production over another, which is surely what informed debate needs. Rather than dealing with daunting numbers, he reduces energy calculations to units of kWh/person/day. 1kWh is the unit we pay for in our electricity bills — the energy used by one bar heater switched on for one hour. If you want to prioritise savings then you need to read this book. Turning off a cell phone charger when not in use for a year saves the energy found in one hot bath. “If everyone does a little, then we will achieve only a little”.

The majority of MacKay’s calculations are done for the UK, and I was interested in a New Zealand perspective. To this end, I have used a similar approach to look at two questions.

  • Can New Zealand maintain its current per capita energy consumption without fossil fuels and, in particular, can we live on renewable energy sources alone?
  • How can we achieve a BIG reduction in our personal and national energy consumption, in order to reduce our power requirements?

The detailed document (about 20 pages) can be downloaded here, but this is a quick overview.

Currently 30% of NZ’s energy comes from renewable generation. My calculations (based mainly on 2007 data) show that NZ has the potential to increase this to nearly 100% over the next few decades, thus eliminating fossil fuel use, while still maintaining our current per capita energy consumption (assuming no significant population growth). We could do this initially with new hydro, geothermal and wind generation, while large-scale solar and marine technologies are promising options for the future. Biofuels are feasible but only at the expense of considerable agricultural intensification.

NZ is energy-rich, but every option using renewable sources has its own problems. If we don’t like the environmental and other consequences of the available generation options, the only alternative is to reduce our power requirements. Vehicle fuel is NZ’s largest energy use (about a third of our total) so savings in this area have the potential for greatest significance. Optimistically, we might be able to reduce our energy needs by up to 25% by 2030, by savings and improved technology (especially electrification of transport).

I have also constructed an example plan that could be reasonably executed by 2025, incorporating both generation and conservation measures. This plan includes a huge number of windmills (10,000+), the 8 highest priority hydro schemes (including Lower Waitaki and Clutha), all geothermal schemes which could be consented within current resource management law, solar hot water and solar photovoltaic panels for half the homes in NZ, completion of home insulation, and large-scale adoption of electric cars. These combined measures could potentially allow NZ to operate on all-renewable energy, at an estimated cost of $91-174B. (Compare this with NZ’s GDP of $177B, or Sustainable Energy R&D of $0.032B).

Note that, if we want to live on renewable energy, we don’t have to say yes to every wind and hydro proposal but we have to say yes to a great many of them. And if we want power to be affordable for everyone, we have to say yes to proposals in places where it is cost-effective to generate power.

Living on renewables is relatively easy for our current population of 4 million. Doing the calculations for 14 million would be more difficult. To maintain the country in even close to its current state, we need to constrain population growth as a priority.

In addition to energy sourced in NZ, New Zealanders also contribute to overseas energy use, with opportunities for considerable savings. This applies particularly to air travel and imported “stuff” (eg the embodied energy in our imports from China).

Phil Scadden is a Dunedin-based geoscientist/number-cruncher working from GNS Science Ltd. While professionally involved in the thermal modelling and hydrocarbon geochemistry of sedimentary basins, he is also keenly interested in energy and leads a GNS project investigating thermal power efficiency from the perspective of fundamental thermodynamics. The investigation here is a private work.

16 thoughts on “A sustainable energy future for NZ (without all the hot air)”

  1. Good work. A couple of quick comments. EDF 2009 has been freely available since July, and should cover 2008, but I haven’t checked

    Personal transport in cars is inefficient because both the SI and CI engines aren’t amenable to congestion and cities. Whilst reducing the vehicle mass helps greatly ( 1500 kg to transport 100 kg person ), the recent permission for 50 tonne trucks means other road users in 500kg vehicles are going to feel like ants walking with elephants.

    Biological cellulosic materials usually have >50% water, so either combustion is less than optimal or a drying step is required. I wouldn’t rush to buy those algae fuel shares just yet. Biofuels are likely to be useful locally, rather than for transport.

    1. Yes, but when I started work on this I only had 2007 EDF and I dont feel like redoing it all for the 2008. I am not expecting a lot of change.

      On biofuel, I am using the MacKay number for best production from temperate plants and the algal range is from published figures on net yield. It still seem like a good use for steel mill (and maybe cement emissions) and sewage pond fuel would be useful if not the solution. You have to have something to power those big trucks.

  2. “You have to have something to power those big trucks.”

    Electric rail for line haul, electric trucks for short haul, with hybrids in the transition period.

    In this current political environment these are just nice dreams however. Most of the National caucus would rather jump of a cliff than institute MEPS for televisions and lightbulbs. How are we going to change the economy if we can’t change lightbulbs? Labour are very very weak on this issue (partly you can’t blame them). They like to talk nice about sustainability but they have no commitment to it.

    I can’t see New Zealand being green before 2030.

  3. “In addition to energy sourced in NZ, New Zealanders also contribute to overseas energy use, with opportunities for considerable savings.”

    Hmmm it would be good if the same logic was used when dealing with emissions. More than 50% of NZ’s emissions are associated with exports.

  4. As in coal is accounted for where it is burned not where it is mined whereas farm products are accounted for where they are produced not where they are eaten? Frankly I am glad I am not an accountant. These are political footballs rather than science but someone has to deal with them.

  5. Actually R2D2, when I look at emissions are always counted at the point where emissions are made. It would seem to be the most effective way of doing so in terms of looking for mitigation measures.

    It also seems to me that are suggesting by queries on emissions counting, that the AGW would be a lot more acceptable to you if the personal costs of mitigation (as a NZ citizen) were lower. Now this might be a totally unfair allegation but if true, it would be intellectually dishonest. Finding truth has to be different from finding what is personally convenient.

    1. “emissions are always counted at the point where emissions are made”

      Yeah exactly right. I do not question the motives, its by far easier to calculate emissions where they occur, and if every nation had an all gases all sectors ETS it would be most efficient to count them where they occur. Trade needs to be remembered however when:

      Comparing emissions per capita of nations

      & comparing emissions reductions of nations

      Ie. Britain has a lower emissions production per capita than New Zealand but a higher emissions production per capita. New Zealand has grown emissions since 1990 but due to in part growth in exports (the majority of emissions growth has still come from transport and electricity generations however)


      And also because the majority of producers do not face ETS costs, the costs are not past onto consumers, so the decision to change consumption habits does not occur. As a result no emissions reduction occurs but rather production shifts location. If the costs were at the point of consumption at least the price signal would be sent to consumers (but this is fine in theory but considerably harder in practice).

      Note on another post (as your field is energy), can nuclear be cost effective in NZ? ie scale

      1. R2: for good info on next-gen nuclear (integrated fast reactors), check Barry Brook’s Brave New Climate (link in blogroll – also good on other energy issues). There was a good discussion on nuclear on Monday night on RNZ National’s Bryan Crump show: well worth digging out the podcast.
        As far as NZ is concerned, my understanding is that nuclear is good at baseload – but we have lots of that already (hydro, geothermal). Only if nuclear comes in smaller chunks than at present will it make sense here, to cover baseload growth. (Phil, correct me if I’m wrong…)

  6. To make the changes needed, we’ll need a major rethink of the design of our cities*, the need to commute and to move produce & products large distances. While NZ is energy rich, we’ll be dependent on global resources for exploiting that energy at a time when cheap oil & other resources are failing fast and widespread economic & political unrest is kneecapping our ability to change. Not looking good….
    (Ah well, we’ll probably have to rebuild them anyway is the oceans continue to rise.)

  7. Nuclear offers lots of opportunities. I believe it to be a myth that it doesn’t come in chunks that we could use – you can buy plants around the 600MW, NZ has around 8GW of power generation, so we should be able to justify 1.2GW more / replacing coal or gas stations. http://www.kiwiblog.co.nz/2008/08/nationals_infrastructure_forum.html#comment-470480

    NZ is very hilly, so hydro storage could offer great surge capacity. Think about it this way – if we put many more turbines on our existing dams, we could turn hydro from baseload into surge capacity, and we could then use nuclear for baseload. We could also put some downstream storage on that hydro so we could pump back uphill if the dams get too low.

    Also, wikipedia (well known to be the source of all truth) claims that “It is often claimed that nuclear stations are inflexible in their output, implying that other, typically fossil stations would be used to meet peak demand. Whilst it may have been true for certain reactors, this is not longer true of at least some modern designs.[33] Nuclear plants are routinely used in load following mode on a large scale in France.” http://en.wikipedia.org/wiki/Nuclear_power#Flexibility_of_nuclear_power_plants

    The thorium fuel cycle also looks very interesting – could deal with most of the environmental concerns around nuclear. http://www.cosmosmagazine.com/features/print/348/new-age-nuclear?page=0%2C0

    1. I’ll happily defer to someone with more knowledge than I… But even if smallish nuclear plants could work in an NZ context, we would be starting from scratch — and that’s likely to be a lot more expensive than adding a station to an existing network. I was thinking more in terms of the sort of “nuclear battery” being built by Toshiba, which is a sort of “no user serviceable parts inside” device, replaced when the fuel runs out. They’re at town supply scale, IIRC.

      Also worth a look: Mr Rabett notes that the price for polysilicon is dropping fast, which suggests that solar PV could soon get down to fossil generation cost.

  8. I am no expert on nuclear either, but regarding the size issue I would note:
    All thermal stations are most effecient at peak load – they are designed that way. I am not really sure how relevant that it.

    The scale of nuclear is not just about size of your power station – you need an infrastructure to support fuel and waste management which is going to be lot more efficient if you have a lot of stations.

    Whether nuclear is goer for NZ I think is going to be settled on economic grounds. Its hard to find investors for nuclear and someone, somewhere else in the world, is going to need to have a working safe design that is economic compared to wind, hydro, geothermal and perhaps tide before you will see nuclear development. Lots of talk so far about new designs but not so much building of them.

    Again, I would strongly recommend reading the relevant sections in MacKay’s book. (He is often criticized by greenies for being pro-nuclear by the way).

  9. Phil,

    I’ve read MacKay’s book, and really enjoyed it. He did the numbers well without being too preachy.

    I agree with his premise that we’ll stop using fossil fuels soon – either because of warming, because they run out, or because other things become more cost effective/less polluting or some other reason.

    For much of the northern hemisphere, I think nuclear is probably the best answer.

    For the US, north Africa (and therefore south Europe if they can import), Australia, some of South America, I think solar is the best option. All those places have large land areas that are uninhabitable, have little conservation value (so we’re not talking about digging up national parks), and are very sunny. I also note that many places in those countries are water poor – and water poor is another way of saying energy poor (with enough energy, you can make water). I often wonder whether we can desalinate water as a byproduct of concentrating solar – say, if we used salt water as input in a once-through design (so when we condense the steam at the other end, we pipe it off elsewhere, and keep piping in new salt water instead). With the right setup of heat exchangers you could use the salt water to condense the steam and cool the fresh water. You’d lose some efficiency, but you’d produce boatloads of fresh water.

    For NZ, after reading your analysis, I’d agree that hydro is where we should start. I’ve often thought that already, but hadn’t seen the full numbers on it. Unfortunately nimby-ism still reigns. I have little faith in significant amounts of wind power, and I doubt that solar is going to work so well in NZ as it does elsewhere – most of our land has other uses.

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