A Sustainable Energy Future For NZ (without the hot air) – An Update

This is a guest post by Phil Scadden and Oliver Bruce (bios at the end of the post), who have updated to Phil’s 2009 paper Sustainable Energy Without the Hot Air – A New Zealand Perspective, which was published at Hot Topic. Inspired by the approach used by Cambridge physicist (and now chief climate change advisor to the UK government) David MacKay in his book of the same name, they bring a common sense perspective to the strategic energy debate we need to be having. Over to them:

Sustainable Energy – Without 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/day/person. 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 understand the which actions actually save energy (and which are just hype) 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. Phil was interested in a New Zealand perspective and so published the original paper at Hot Topic in 2009 (found here). Oliver read McKay’s book earlier this year, came across Phil’s work (thanks to John Peet at Phase2 for the referral) and with his help updated the figures for 2012.

To this end, we 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?

After completing the updated paper, we had a discussion with Gareth about the best way to publish the work and decided to run the report as a series of posts at Hot Topic. There are two reasons for this:

  1. Easier to get feedback issue-by-issue from the Hot Topic (and wider) community.
  2. It makes for a more palatable read than simply giving you folks a 22 page document.

This post today is a quick overview of the changes since the 2009 report, and serves as an introduction to the series which will appear at Hot Topic over the next couple of weeks.

For those that can’t wait, the full updated (2012) document can be downloaded here. Note it may end up being revised as your community finds errors in our work, so it might be better to wait till we’ve completed our series!


To begin, it might help to outline the things that haven’t changed since the 2009 report that Phil wrote. Based on our calculations NZ still has the potential to increase our energy generation to nearly 100% renewable 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 phasing in large-scale solar and marine technologies as they become more economically feasible in the future. Biofuels are feasible but only at the expense of considerable agricultural intensification, or on marginal agricultural land if the price of oil ranged around $200.

In short, New Zealand transitioning to 100% renewable energy in the next 20-30 years is very doable, but it will require some difficult decisions.

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). We’ve gone into a bit more depth on the electrification of electricity in this report given that a few factors have combined since the last report that indicate this is the most probable future. More on that in a later post.


The things that have changed since the last report is that our both our per capita energy consumption and costs of transitioning to a 100% renewable future have declined, while our renewable energy generation has increased.

We’ve been through a prolonged recession since 2007 (the year of figures available when Phil was writing the last report), and this has impacted on energy use like elsewhere in the developed world. According to the Energy Data Files from the Ministry of Economic Development, we’re using the equivalent of around 5 kWh/d/p less than we were in 2007. This reduction comes from a few different areas. The Tiwai aluminium smelter is using about 1kWh/d/p less energy now than it was in 2007, which is a pretty big chunk of energy. There is also a noticeable decline in transport fuels, which correlates with the news about Kiwi’s driving less on the back of the doubling of petrol prices. Finally, our population has increased by 6% in the five years since 2007, meaning there are more people to divide the energy consumption (kWh/d) across.

We’ve also seen an increase in the amount of energy coming from renewable energy sources. All the wind power that has come online since 2007 has added the equivalent of 1.6kWh/d/p to our energy generation total, while the new geothermal capacity has added around 1.4 kWh/d/p. While this is great, it should be noted that we use around 88 kWh/d/p, so these numbers don’t do anything substantial to change our energy mix. We’ll explore this when we get into our posts on geothermal and wind.

Finally, the costs of increasing our renewable energy capacity over the next 20-25 years to 100% using the same ‘energy plan’ model adopted by McKay has come down. In 2009, Phil calculated that these changes would cost anywhere from $81-163 billion dollars and involve new renewable energy capacity, the electrification of transport and some energy efficiency measures. Our revised calculations have this figure at around $70-75 billion by 2025, with lower costs for insulation and the electrification of transport than previously outlined.

This is a large figure, and it goes to show that this isn’t something that we can do for free. It will cost money, and it would require commitment from across the political spectrum to make it work. We’ll be cover the costs in one of our last posts after exploring all the options.

So, from here on out, we’ll be posting regularly on our various options starting tomorrow when we get into Post 1: The Renewable Energy Challenge. We hope you follow along and provide your thoughts and questions.

Oliver and Phil

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.

Oliver Bruce is a young Kiwi based in Doha, Qatar where he works in industrial business development. He graduated from College of the Atlantic in the USA, where he studied politics, ecology and business. He has long had an interest in renewable energy and climate change, and was part of the youth delegation to the Copenhagen Climate Summit. He credits Phil with doing the intellectual heavy lifting in this work– he just did some number crunching.

38 thoughts on “A Sustainable Energy Future For NZ (without the hot air) – An Update”

  1. Funny you don’t write more about (chargeable) hybrids. They remove range anxiety while delivering most of the advantages of electric cars already today. i would expect the long-term transition to electric to go through hybrids… if it ever runs to completion. Batteries delivering the same range as internal combustion are a tall order.

  2. Hey,

    Fair point. We’ll get into this when we post about electric cars, but in short, we wanted to see what the overall costs would be to transition the whole of the fleet off liquid fuels and over to electric. Plugins are great, but they’re actually still pretty darn expensive because they have to carry two types of motors, petrol and batteries (what’s the price touted in NZ?). Been reading the reviews of the Chevy Volt though and completely agree with your points about them being essentially electric cars without the range anxiety. Thanks for your comments – hope you check in when we get to transport.


    1. The Volt is slated for $85k, the Prius is about $65, so both pretty expensive. If we had a government that was even remotely concerned about climate change, these would be attracting a $5k to $10k subsidy,

      I think we will see a two-phase move to electric – first through PHEV, then to all electric. With a mean fleet age of around 15 years, this will take 30-40 years to happen, which is way too long.

  3. GM has to some extent placed the Volt as a prestige vehicle. Ford’s C-MAX Engeri PHEV is perhaps targeted more at the ‘average’ car buyer.

    I would like to point out that for the first 20 years or so of its existence the auto-mobile was as a plaything for the rich.

  4. ‘We’ve gone into a bit more depth on the electrification of electricity in this report ‘
    I don’t think you meant that. 🙂

    But this looks good. I liked MacKay’s book and have talked to him when he spoke at Stanford, a lively speaker.

    Chevy Volt:
    New technologies often appear at premium price points, then propagate downward with volume and learning curve. I.e., consider computer history.

    I’ve heard one of the engineering managers for Chevy Volt speak at Stanford CARS, where Sebastian Thrun led the groups doing robot cars for DARPA challenges, and then has been off at Google with their driverless cars. GM plans a whole range of applications of the technologies at various price and feature points, and their whole approach was impressively system-engineering oriented, working with utilities and others.

    Now, Silicon Valley is not particularly representative of the world, but people here are rapidly installing charging stations, parking areas are covered with solar panels, people are looking hard at smart grid with vehicles that decide whether they want to get charged or give some juice back to the grid. People are sorting out applicability of PHEV vs BEV, etc. Many of the big car companies finally have little R&D labs here and there are many efforts that meld cars and computing in various ways to make transport safer and more efficient. For urban transport, see GM EN-V, which they also showed along with the Volt talk. People got rides in them.

  5. John you are exactly right the price of vehicular li-ion batteries is declining all the time. Still expensive but the trajectory is good.

    The thing with PHEVs is if they have sufficient electric range most daily trips can be completed on the electric cycle. The Volt can do this with 50km AER most NZers would only need the petrol engine on the weekend. The C-MAX has a 30km range and this would be enough for me but not many others. Unfortunately the Prius PHEV only has a 20km AER which I think is not quite enough, but that is the problem with adapting the existing HEV vehicle.

  6. Hi Phil and Oliver,

    You pointed out that you are looking at what’s physically possible, but do you have at least some estimates on how that reduces when taking the full life-cycle of energy infrastructure into account?


    1. Clearly you see a problem which i dont. Perhaps you could be more specific about what you mean about full life-cycle. There are myths about energy cost of building windmills, solar that are debunked in MacKay’s book.

      1. Don’t know why it’s clear that I see a problem. I don’t. But I like to have the full picture.
        For instance, MacKay says that the energy yield for solar panels with a 20 year life span is between 4 and 7 (Europe, Australia). That’s not a fundamental argument against solar power, but makes a difference to the numbers. Call it nitpicking if you like.


          1. Except non-linear change is a bit like a warming Arctic, its a bit hard to imagine the rate of change from one’s ‘reality-base’. This makes it hard to see projections or scenarios of rapid change as ‘reality-based’.

        1. D

          There will always be uncertainty in LCA results because these studies are very sensitive to the assumptions used. Key ones are what are the boundaries of the study (in theory everything in the economy and environment could be taken into account). The expected life of the products, the values given to the inputs (which are also from LCAs studies), and the fate of the waste products.

          I have seen LCA results, both in terms of net energy and GHG emissions, for the same biofuel that range from way in the negative to reasonably good positive result.

          The fact that the results you quote both have the same sign and are reasonable consistent is either reassuring or concerning depending on the quality of the sources.

          Even given the limitations of LCA it is still a useful tool but the results do need to be assessed in context.

        2. Okay, I follow your point. In short term geothermal and wind ( factor 80) are the likely replacement. We have not factored in building costs for renewables into the energy equation. Certainly something to look at though the increase in energy would have to be done by comparing fossil fuel to sustainable energy requirements.

  7. Umm … I have a range/loadcarrying vehicle already. Afording to use it is another matter. Locally my longest trip (bi-monthly) is about 40km there and back, an occasional trip of 14 km and most less than 10 km there and back. My biggest savings would be effected by an electric shopping trolley!

    I saw a highly decorated weather proofed 2 seater electric shopping trolley a few days back.

    Yesterday while walking to the nearest supermarket I saw two large leggy jet black dogs loping along towing a man in a wheelchair at serious bicycle speed. I was impressed but can see problems with dog transport in crowded places. 🙂

    I had to step off the footpath for the dogs but not for the shopping trolley.


    1. Depending on your physical ability and load carrying requirements have you thought of an electric assisted bicycle?

      A Wisper will set you back about $2,700 new but then it is very cheap to run.

        1. First, you are being unnecessarily flippant.

          Second, I was not suggesting that such an option was suitable for everybody.

          Third, EABs are a great alternative for those that might want a cheap form of transport, but do not want the level of exertion that might result if they live in hilly terrain, or windy climates.

          Fourth, donkeys are a very efficient form load bearing transport in certain situations.

          1. It’s all very well for those living in urban environments, but not so good for rural dwellers.

            Furthermore, if you live somewhere with snow and rough roads, I don’t think electric vehicles are quite there yet.

            1. Horses for courses! Most people don’t live somewhere with snow and rough roads and no public transport. Most vehicle trips can easily be covered within the range of current EVs. many of these probably don’t even need a private car!

            2. Most people don’t live somewhere with snow and rough roads

              Yes, but I do, hence my interest or concern in any “one size fits all” policy.

              The fact is, there is no immediate sign of replacing the good old “Crumpy” diesel ute in backcountry NZ anytime soon.

            3. Andy,

              We fully concur with you – can’t see a Mitsi Miev out on the farm any day soon (or towing a boat for that matter).

              We propose two scenarios in the paper:
              1) There’s plenty of marginal agricultural land that could be used for energy forestry to generate biodiesel that can fuel this part of the fleet.
              2) We can see there being electric utes/SUV’s, and that they’ll be four wheel drive, and have great torque to replace diesel engined applications. The tech/low costs aren’t there yet, but I’d propose they’re not too far away either.


            4. Andy, even though I live in a rural environment my daily driving needs are well within 40Km. And some of my friends living in Auckland drive triple the daily Km that I do at half the average speed….. You seem to be – as always – commenting from what you think rather than what is actually happening. There are very few rural people who live so far in the bush AND commute often that this is an issue on a national scale. We can afford to leave them with their ‘biodiesel’ cars for as long as we need to.
              The traveling salesperson will not be served with an EV for a long time… but we can afford to give them petrol cars as a nation until we figure the long range EV strategy out properly.

            5. You seem to be – as always – commenting from what you think rather than what is actually happening

              My comment is from observing the rural community – farmers etc, who need Utes and fairly heavy duty trucks to get around the hilly country in the Mackenzie region.

              I personally hardly use a car at all. Maybe 10km a week during weekdays.

      1. I have thought upon electric bikes which could be very handy with a couple of saddlebags for the shopping. What I hate with a bike is having to put on the inadequate wet weather gear but well why not wait for the rain to stop?

        However there is also the phenomenon that can aflict the aged known as “Rocks in the Ears”, or “Top shelf syndrome”. Crystals jamming the balance mechanism can bring on a state easily confused with a stroke. Usually one side is affected more than the other and one tends to fall to one side in particular. Some simple excercises found on the net can set one up for about a year although I toss and turn so much at night I do the exercises by accident and can go several years before the next attack so not really a big issue with a bicycle. I know cyclists who suffer this – and do the exercises. I can be found up ladders, on the roof but would not dare if I felt close to such an event. It happened once while driving. A sudden application of the brakes dislodged the crystal and I was OK again. The trick is to exercise control as it happens.

        andyS – hills


  8. Nice work Phil and Oliver. In the age of mass customisation, why wait for the big guys to make your vehicles electric? We’ve got bikes, scooters, motorbikes and cars being made and converted right now, and we’re starting to make cars from scratch too. Here’s a great example of what’s possible – and remember, 5 years is a long time when change is not linear! for example the cost of going 100% renewable has dropped 50% in the last 5 years.


    Joe was planning to visit November, and there are teams starting work in NZ now. For a few Wellington examples of urban fabrication workshops look up Wellington Makerspace, FabLab and Ponoko.

  9. I converted on old Toyota Starlet to an EV four years ago. It has a range of 40Km max and my usual ride is more like 10K. I use it where this range fits my needs which is 80% of the time. Otherwise I use my old diesel car.
    So have the best of both worlds.

      1. Yes Li-ion would be great. I did a low budget conversion with Led Acid batts and 72V system with nominally 150AH @72V. But good old Peukert’s law (google it!) demolishes the Led Acids to about 40AH of effective energy useable @72V as drawing these batts down further will damage them. If I were to do it again I would go for a high voltage (low current) design and yes, Li-Ion once the cost comes down. But all I wanted was a short range small car handling those 80% of my driving needs for which it is ideal. To get it to do 90% or more of my needs would require to double or triple my investment, not a good return on the buck, for what essentially 80% of the time is sitting around as wasted potential of a drive I don’t undertake in that car. It was low hanging fruit sort of gamble and it worked out o.k. for me.

        1. Thomas at 40AH @72V that is about 3 kWh. So if you are getting up to 40 km you are doing about 75 Wh/km which is very good fuel economy for an EV. I suspect you are getting a few more AH out of those batteries than you think.

          1. My car is driven only in the vicinity of our rural town and within about 60Km/hr speeds or so. Its max speed is about 80Km/hr

            The 40AH are conservative as not to enter damage territory of the battery while the 40Km range is its max realistic range, not its usual range. The relationship of 150AH nominal works like this: the 150AH are based on a 20hr discharge time or 7.5A. But my current driving is about 100A say on average. At that current the effective capacity of the battery according to Peukert is about 75AH or 50%. Now in order to not damage the led acid battery you should stay within 50% of the effective (not the nominal) capacity. So that is about 40AH. In practice (with my AH meter) I often recharge after about 20AH of discharge due to the usage pattern of my car. This seems to maintain the batteries well.
            With LiFePo batteries the range would increase a lot as the Peukert effect is not applicable and the batteries can be discharged to about 20% or less of capacity.
            Once the $$/AH comes down…. 😉

Leave a Reply