Category: Climate business

Sustainable Energy NZ #10 – How can we achieve a big reduction in our personal and national energy consumption?

Welcome to the tenth post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. We’ll be changing gears here from our previous posts on hydro power, geothermal and wind (and a summary on the big three), solar, biofuels, marine and waste energy. From here on out we’ll be attempting to answer the question:

How can we achieve a BIG reduction in our personal and national energy consumption?

It’s a very important topic – and one prone to greenwashing and hype. Like McKay, we want to have informed discussion about the options available to us here in NZ, so we’ll be going through topic by topic and looking at energy use in each sector of our lives: transport, residential energy, the things we buy, and so on. We hope that you find it interesting and informative.

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Sustainable Energy NZ #9 – Here Comes the Sum – what are renewables worth?

Welcome to the ninth post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. Today we’re summarising the numbers on the various renewable energy options in New Zealand (and finding they’re more than sufficient!). 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 the summary on the big three. More recently we’ve dealt with solar, biofuels, marine and waste energy. 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 we’ve gone through the various renewable energy options over the last week or so. So where does this leave us for increased generation potential among renewable options? The affordable, mature technologies are hydro, geothermal, wind, waste gas, solar heating and biofuel. Large-scale solar and marine technologies are really promising options for the future but cannot be realistically considered now.

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Rising Sea Levels

Of all the consequences of human-caused global warming, sea level rise has always held special alarm for me in its inexorability, its extension into the future, and the enormous disruption it threatens to centres of high population and essential infrastructure. Scientist Scott Mandia (blog) and writer Hunt Janin have teamed to produce for the general reader an explanation of what it will mean for the world in coming decades and beyond. Their book Rising Sea Levels: An Introduction to Cause and Impact is patient and restrained in its survey, but no less sobering for that. Their coverage leaves no doubt as to the magnitude and extent of the measures that will have to be taken to try to cope with the effects of sea level rise as it gathers momentum and extent.

The authors don’t expect much in the way of mitigation of climate change by international agreement to limit emissions. Indeed, they take it for granted that emissions  are going  to continue to rise and that international agreement will continue to founder on obdurate differences between political blocks which negotiators appear unable to resolve even in the face of such a threat as global warming. Presumably one day the common danger will become so overwhelming as to force international agreement, but the authors see no such early likelihood and certainly not in time to forestall metres of sea level rise. The book is not about preventing sea level rise but about preparing for it and adjusting to it.

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Sustainable Energy NZ #8 – The Tides They Are A-Changin’ – the marine and waste energy resource

Welcome to the eighth post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. Today we’re crunching the numbers on marine and waste incineration 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 the summary on the big three. More recently we’ve dealt with solar and biofuels. 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. 

The marine environment offers several possible renewable energy sources, notably wave and tidal energy. Wave energy systems have been studied by the Electricity Authority, and data here comes from their report [yeqtogu]. Feasible wave energy plants need wave energy greater than 20kW/m “close” (say 6km) to coast. New Zealand has 2000+ km of coast-line fulfilling these parameters, mostly on the west coast. Wave derived energies in the far south can be 60 to 80kW/m, which is impressive. That is approximately 86kWh/d/p for a 50% efficient wave generator covering half our available coastline. However, a reality check indicates that no such mechanism exists (so far wave generators have been built for survivability rather than efficiency) and many factors would constrain where wave generators could be built.

A fairly detailed analysis based on currently available technology has identified sites offering perhaps 2kWh/d/p and a maximum potential for perhaps 27kWh/d/p. While a number of prototype and early commercial plants have been deployed worldwide since 2009, this realistically still is best be described as an emerging technology with very substantial environmental and economic barriers to deployment.

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Sustainable Energy NZ #7 – Biofuel Bonanza? – NZ’s bio-energy potential

Welcome to the seventh post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. Today we’re crunching the numbers on the potential for biofuels 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 the summary on the big three. Yesterday we dealt with solar (and found it was pretty big!). Note: the units are in kWh/day/person – that is, 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. 


Energy problems are just one of the significant challenges facing our civilisation so we are reluctant to consider options that affect food production or contribute further to soil degradation. However, as we transition away from liquid fuel-based transportation, biofuels could play a role in keeping us mobile.

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