Sustainable Energy NZ #2 – How much dam energy is there anyway?!

Welcome to the second post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. Today we’ll be crunching the numbers on hydroelectricity potential in New Zealand. For the background to the work and an explanation of the methodology, please visit our last post here. Remember that we are looking for around 55 kWh/d/p from renewable sources to replace what we currently use today. So, with that, today’s post!:

At the moment, ~15kWh/d/p of New Zealand’s energy comes from hydroelectric generation. How much more is feasible? For the United Kingdom, MacKay simply does back-of-the-envelope calculations, but because of widespread hydro-electrical use in New Zealand, there are reports that allow us to make a more complete assessment of hydroelectric potential. [8k8vf25] and [9nvw27h]. Firstly, I discount any scheme that would be in a National park, or protected by a strong Water Conservation Order (e.g. Motu), or extremely remote. Some 34 schemes of >20MW capacity have already been identified as economically and technically feasible (e.g. Mokihinui River). These deliver a potential of 10kWh/d/p. on top of the 15.4kWh/d/p already commissioned. 26% of that is from North Bank Tunnel project in the Lower Waitaki and a further 22% comes from four possible schemes on the Clutha River.

Continue reading “Sustainable Energy NZ #2 – How much dam energy is there anyway?!”

Sustainable energy NZ #1 – can we live on renewables only?

Welcome to the first post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. Today we’ll be going through the figures of our current energy use. This helps us get a baseline of consumption to aim towards, and lets us explore the difficulties in calculating per capita energy use. For the background to the work, please visit yesterday’s post here.

Before we begin, we should note the following:

We follow MacKay’s example in presenting all energy data in kWh/day/person. McKay’s motivation for this was that kilowatt hours are energy consumption units that most of us are familiar with from our monthly electricity invoices. To give you an understanding of the numbers, one 40W lightbulb consumes 40W per hour, or ~1000W hours (1kWh) a day. Most toasters are rated to 1kW, so running one of these for an hour will take 1kWh of power. A petrol car driving 100km will use, on average, 7 to 9 litres of petrol, which is the equivalent of 70-90 kWh of energy (one litre contains ~10 kWh). If interested, read McKay’s chapter on his reasoning and methodology here: [8z7lwjg]
All of the reference links (like the one above) are tinyURL codes. Eg the EECA library will be [ydtzb5v]). We’ve done this to maintain the same format as McKay. Most are hyperlinked but if not, type in the code).

The sources that we’ve used are noted at the end of this post, as well as our contact details and a link to the spreadsheet that we’ve used for all of our calculations. OK! With that housekeeping out of the way, lets get into it!

The big question that is continually asked about renewable energy is: Can NZ live with renewable energy only?

Continue reading “Sustainable energy NZ #1 – can we live on renewables only?”

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 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!

Continue reading “A Sustainable Energy Future For NZ (without the hot air) – An Update”