Tag: David MacKay

Grand final: Sustainable Energy NZ #16 – counting up the dollars and sense

Welcome to the sixteenth and final post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series.

To recap, we started with a bit of energy accounting and worked out that Kiwi’s use around 88 kWh/d/p (methodology for what the kWh/d/p means is here), and that of this, about 33kWh/d/p came from sustainable sources or we couldn’t substitute. As a result, we’ve been looking for how to shift the remaining 55kWh/d/p of our current energy use to renewable energy sources. We approached this in two ways:

How much could we increase our energy generation capacity in renewable sources?

Here, we looked at hydro power, geothermal and wind (and a summary on the big three), solar, biofuels, marine and waste energy and did some basic calculations on the overall potential of these sources. Then:

How much could we achieve a BIG reduction in our personal and national energy consumption, and where those savings would come from.

We went through the areas of energy use for Kiwis, including road, air transport, home energy use and general consumption before doing some calculations on the overall reductions we think we could make.

What might it cost to achieve an all-renewable energy economy?

Today, we’re looking at how this might translate into action at a national level. This post contains both some costing, and suggestions for action that might effectively be channeled into effective change.

Continue reading “Grand final: Sustainable Energy NZ #16 – counting up the dollars and sense”

Sustainable Energy NZ #14 – how much energy hides in food and ‘stuff’

Welcome to the fourteenth post in the Sustainable Energy without the Hot Air – A New Zealand Perspective series. After our previous posts on hydro power, geothermal and wind (and a summary on the big three), solar, biofuels, marine and waste energy, we’re now looking at answering the question:

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

Remember, as before, 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’ve been looking to replace around 55 kWh/d/p of energy currently generated by fossil fuels.

Food

Farming and food processing cost about 8kWh/d/p of the NZ energy bill, much of which is of course exported. This is only energy consumed in food production – a great deal more energy is directly incorporated into our food from the sun. When looking at land for either biofuel or solar production, energy production competes directly with food. We could grow a lot more biofuel if we produced a lot less milk, for instance. For the purposes of national energy supply, we doubt much can be gained in terms of energy efficiency to support current production.

New Zealanders eat more beef than the UK population, but we eat next to no grain-fed beef and barning is rare. Overall, the 15kWh/d/p for a UK person is probably pretty similar here. Reduce that to 10 for vegans, but remember that crops cannot be grown on much of the land that we graze (especially not continuously).

Continue reading “Sustainable Energy NZ #14 – how much energy hides in food and ‘stuff’”

Sustainable Energy NZ #12 – do Kiwis have to be flightless?

Welcome to the twelfth 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.

A few notes before we begin: as before, 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.

Planes

The 2.6kWh/d/p spend on aviation fuel, from the Energy Data File, is a very poor indicator of what New Zealanders actually spend on planes, because of airline fuelling regimes. For example, the return flight from London is included in the UK statistics. Data from the UN [o96d7t] and the International Civil Aviation Authority [8cc3859] gives an estimate of NZ passenger kilometres in 2004.  Dividing by 2004 population converts to 18kWh/d/p using MacKay’s estimate for fuel use. This includes energy spent overseas, and is a better indicator of New Zealanders’ actual energy use on air travel.

Continue reading “Sustainable Energy NZ #12 – do Kiwis have to be flightless?”

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.

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

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.