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), solarbiofuelsmarine 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.


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).


The remaining energy budget, 28kWh/d/p, disappears into concrete, steel, cement, and our industry, which we can describe as making stuff. Buying less stuff would obviously reduce energy demand, but it is hard to otherwise identify what saving can be made in this area in terms of efficiency. Energy cost is a significant factor in making stuff so economic factors usually work to maximise efficiency in the larger scale projects.

Not included in the 88kWh/d/p from the Energy Data File is the energy that we import as stuff. We are burning coal in China for every Chinese-made appliance or clothing item that we buy. MacKay estimates 48kWh/d/p at least. Looking over our list of “stuff”, we would have to conclude “at least” as well. It is hard not to conclude that a significant way to reduce energy use in China would be for us to buy less stuff, buy stuff that will last, and use it for a very long time. Tossing out a cellphone or laptop because the battery has run out is not good but product lifecycle data suggests that this is what many people do. The average lifetime of a cellphone is 18 months (or less if you buy a new iPhone every time it comes out!). This calculation of 48kWh/d/p though is tough and we have considerably less confidence in it compared to other calculations we have used.

We, like McKay, don’t have any concrete suggestions for how to reduce this other than to encourage less consumption of this ‘stuff’ and to buy things of higher quality that will last longer.

6 thoughts on “Sustainable Energy NZ #14 – how much energy hides in food and ‘stuff’”

  1. Anything to do with lime, like cement production can be done in such a way as to eliminate CO2 from the process and by selling the carbon monoxide, actually make … well read here:

    According to the researchers, the STEP process can be performed at a lower projected cost than the existing cement industry process. In fact, when accounting for the value of the carbon monoxide byproduct, the cost of the lime production is actually negative. The researchers’ rough analysis shows that the total cost of the limestone material, solar heat, and electricity is $173 per ton of lime and 0.786 tons of carbon monoxide (0.786 tons of carbon monoxide are produced for every ton of lime). The market value of carbon monoxide is $600 per ton, or $471 per 0.786 tons. So after selling the carbon monoxide, the cost of the lime production is $173 – $471 = -$298 per ton. For comparison, the cost to produce lime in the conventional way is about $70 per ton. The researchers emphasize that this analysis is not comprehensive, but it indicates the cost benefit of STEP cement, not even considering the value of eliminating CO2 emissions.

    The scientists add that the STEP process could be extended beyond cement production to other applications that convert limestone to lime, such as purifying iron and aluminum; producing glass, paper, sugar, and agriculture; cleaning smoke stacks; softening water; and removing phosphates from sewage.

    The process has still to be scaled to commercial production but the science is done. Full story here


  2. I recall that quite a few years ago there was such a noticeable change to vegetarianism that the UK government began to take this into account in planning. Cited then was the observation that vegetarians required only a third of the land for production that meat eaters do. I don’t know that that thinking came to anything. A distinction between vegetarian and vegan was not common then.

    Also from the past when states were always revaluing their currencies and a perception grew that it might stabilise prices if they were based on energy accounting. GHGs were not part of the valuation process and beyond a brief flurry of interest it did not go anywhere. Two papers amused me at the time, both by Americans. These were days of food-aid. One paper made an energy evaluation of food aid to Bangladesh. The sum was so high that he had no doubt that food-aid from US to Bangladesh was an impossibility. Perhaps, instead of considering the bulk quality of food-aid and the absence of US style packaging in Bangladesh he took his figures from the other paper on the energy content of American food which revealed packaging, and marketing as dominant components in American food pricing?

    Still this process of energy accounting we are following in this series appears to be a much maturer and useful kind of accounting to those first attempts which perhaps fizzled because they were too scary and what merchant wants an objective basis for pricing?


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