Author: Oliver Bruce

Sustainable Energy NZ #6 – our place in the sun – doing the math on solar power

Welcome to the sixth post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. Today we’re crunching the numbers on solar potential in New Zealand. For the background to the work please our introductory post here. Also check out our earlier posts on the potential of hydro power,  geothermal and wind, and yesterday’s summary. Note: the units are in kWh/day/person – ie. if you ran a 40W lightbulb for 24 hours, it’d take ~1 kWh over the space of a day. We then divide it by person to give you a sense of the scale of the resource proportionate to the size of the population. Be sure to check out the methodology. For reference – we’re looking to replace around 55 kWh/d/p of energy currently generated by fossil fuels. 

So, solar! We’ve got a lot of it, or do we? Our lower latitude means that New Zealand’s solar potential is certainly rather better than that of the UK and the current world leaders Germany. A roof inclined at the optimal angle in NZ gets on average 181W/m2 in Northland, 178 in Auckland, 195 in central Otago, 185 in Canterbury. (This is based on averaging all available NIWA hourly radiation data at suitable measurement sites). This is impressive compared to the UK average of 110W/m2 and 130W/m2  in Germany.

There are 4 ways to harness solar energy:

Continue reading “Sustainable Energy NZ #6 – our place in the sun – doing the math on solar power”

Sustainable Energy NZ #5 – Summing up the Big Three – hydro, geothermal and wind

Welcome to the fifth post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. Today we’re summarising the numbers on wind, hydro and geothermal potential in New Zealand (and finding they’re pretty big!). For the background to the work please our introductory post here. Also check out our earlier posts on the potential of hydro power,  geothermal and wind. Note: the units are in kWh/day/person – ie. if you ran a 40W lightbulb for 24 hours, it’d take ~1 kWh over the space of a day. We then divide it by person to give you a sense of the scale of the resource proportionate to the size of the population. Be sure to check out the methodology.

So, after going through the numbers for hydro, geothermal and wind, we find that we have a total realistic extra potential generation of 59.4kWh/d/p (hydro 23, geothermal 4.4, and wind 32kWh/d/p), without considering offshore wind. So, if we don’t mind parts of the country covered with windmills, multiple new hydro schemes, including all those proposed for the Clutha and Waitaki Rivers, and new geothermal schemes, we can readily get more than our required 55kWh/d/p from hydro, geothermal and wind alone.

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.

In other words, it’s a feasible possibility.

The important point to make here is that much of the energy we’ll be generating will be in different forms to those we will be replacing – i.e. we’ll be generating a lot more electricity, but moving away from energy in liquid fuels. It’s worth noting that even if we manage to find a significant resource of oil in our offshore drilling efforts, this will be sold on the international market. Also, because they’re finite won’t change the long term requirement of having to transition towards renewable energy sources.

Aside from these options, there are other possible sources of power that will become more important over time. We’ll be having a look at them in our next post.

Summary: We could meet of our energy requirements (note: not including our air travel, diesel fuel used for shipping or the embodied energy in imported products) almost exclusively on a hydropower, wind and geothermal. It would mean saying yes to schemes that are in places where it’s cost effective to generate power.

Up next: We crunch the numbers on solar for New Zealand and find it’s a pretty massive resource.

Sustainable Energy New Zealand #4 – Thar’ She Blows! Wind potential in New Zealand

Welcome to the fourth post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. Today we’ll be crunching the numbers on wind potential in New Zealand. For the background to the work please our introductory post here. Also check out our earlier posts on the potential of hydro power and geothermal. Note: the units are in kWh/day/person – ie. if you ran a 40W lightbulb for 24 hours, it’d take ~1 kWh over the space of a day. We then divide it by person to give you a sense of the scale of the resource proportionate to the size of the population. Be sure to check out the methodology.

New Zealand has significant wind resources with much of the country having average wind speeds in excess of 6m/s. Even with the amount of development since the last report in 2009, we’ve only added around 0.64 kWh/day/person.

Another 1000 turbines (around 2 times the existing capacity) could deliver 4kWh/d/p while a reasonable upper limit (avoiding national parks, settlements, structures, waterways, steep slopes, low wind areas and assuming 50% willingness by landowners) has been calculated at 83kWh/d/p [cntnmby], with 32kWh/d/p available at competitive pricing. 33kWh/d/p would see windmills on 0.6% of total NZ land area, that is, if clustered, an area the size of Stewart Island.

Continue reading “Sustainable Energy New Zealand #4 – Thar’ She Blows! Wind potential in New Zealand”

Sustainable Energy NZ #3 – When having a Hot Earth is Desirable – Crunching the numbers on Geothermal.

This is the third post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. Today we’ll be crunching the numbers on geothermal potential in New Zealand. For the background to the work and an explanation of the methodology, please visit this post. Also check out the last post on the potential of hydro power.

Unlike the UK, New Zealand has significant geothermal resources which currently contribute to national energy requirements. Geothermal energy has the advantage of being always available at full capacity, and unaffected by weather. Currently about 5.2kWh/d/p is available (3.6kWh/d/p of electricity is produced plus 1.6kWh/d/p in direct heating) but it is estimated that there is potential for a total of 12kWh/d/p at an admittedly higher price than gas generated electricity [dbpz7n]. Environmental and regulatory constraints further limit development. The Electricity Authority foresees generation rising by a further 4.4kWh/d/p by 2025 [9v5c9my] but little growth beyond that. Geothermal energy is low quality, producing lots of hot water for disposal. Ideally, better use of this hot water in co-located industry would improve overall efficiency.

Summary: There’s definitely potential here – but remember that even if we built every geothermal plant in the pipeline it’ll only ever make up about 8-9% of our overall energy supply.

Further Reading:

UCSD Professor Tom Murphy of Do The Math does the numbers on global geothermal potential.  

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?!”