What if it was easy to compare energy from the food you eat, exercise you do, fossil fuels you burn and household electricity you use?
By Ted Mitchell
Published April 11, 2011
Does the concept of energy seem confusing to you? Can you envision a joule, calorie or kilowatt hour? What if it was easy to compare energy from the food you eat, exercise you do, fossil fuels you burn and household electricity you use?
Fortunately, there is such a human scale unit that makes intuitive sense. It assigns this unit as the amount of energy contained in the yearly food requirement for the average person. These "demotechnic units" were conceived by a local scientist, Dr. J.R. (Jack) Vallentyne.
Dr. Vallentyne was a limnologist, a scientist who studies fresh water lakes. In his career he promoted the ecosystem approach, lobbied for phosphate reduction and helped establish the experimental lakes in northern Ontario, famous for acid rain research. He even took his message to school children under the alter ego of Johnny Biosphere.
Unfortunately in 2007, Vallentyne was diagnosed with late stage cancer. Three days before he died, Jack signed a little book for my wife, who was briefly his physician, along with a scrawled cartoon Earth.
The book was called "Tragedy in Mouse Utopia". The title comes from a 1968 experiment that placed eight mice in an environment of perpetual plenty and watched them thrive until a peak population of 2200 was reached after a year and a half.
Even before the peak was reached, social dysfunction started building and soon was enough to doom the whole colony to extinction in less than 5 years. At the height of population, food was still being provided and 20% of the mouse apartments were still empty. It was not lack of resources or overcrowding, but the environment of plenty that led to social breakdown, essentially forgetting how to be mice.
The parallel is that the energy glut which fuelled the 20th century's human population, economic and technological explosion, could have a similar ending for humans.
A real nugget in the book is the term Vallentyne called Demotechnics, from Greek demos (population) and techne (technology). A demotechnic unit is the amount of food energy consumed by the average adult human in a year, something everyone can envision.
For the record, it is 2,333 kilocalories per day for a year, 3.56 gigajoules, or 990 kWh.
Demotechnic units, or D units are a very useful comparison tool for different types of energy. For example, 1 D unit is equivalent to a 113 W bulb burning all year, or 102 L of gasoline, or 210 kg of rice, or 95 kg of body fat (so those contestants on 'The Biggest Loser' start out carrying about a year's supply of energy).
Expending 1 D unit of energy will take you 60,690 km by bicycle, 2205 km with a Toyota Prius, 946 km with a Camry, or 500 km with a Sequoia (at Transport Canada rated city mileage minus 20%).
As a case study, let's look at this guy:
Greg Hill (Image Credit: Stayoutdoors.com)
This is an astoundingly energetic fellow from BC by the name of Greg Hill who just finished climbing and skiing a record 2 million vertical feet (610 km) in a year. This is like climbing the total height of the CN tower three times a day, every day, all year. In potential energy, that is 80 kg x 9.81 m/s2 x 609600 m = 478 megajoules. Human legs are about 20% efficient on stairs, and backcountry snow and variable slope probably cuts this in half again. Add 10% for skiing down, and you have 1.5 D units. So Greg has to eat 2.5 times normal intake, about 6000 Calories a day.
But Greg doesn't live on the base of the mountain in Revelstoke, and has scaled several other peaks as well as spending the summer in Chile. If he drives 30 km round trip to the base on average, 300 days a year, at the usual city mileage minus 20% with his Subaru, that's about 12.5 D units. A flight to Chile, 11,000 km from Revelstoke, racks up about 10 D units round trip, assuming airliners get 50 USMPG per passenger.
Greg Hill's 2 million vertical foot energy consumption
The cost of energy and food per D unit is interesting.
|Energy Type||Common unit||Cost (US$)||Energy (Joules)||US $ per D unit|
|Coal (lignite)||metric tonne||121.14||2.79E+10||15|
|Natural gas (henry hub)||thousand cubic meters||147||3.90E+10||13|
|Oil (west texas)||barrel||104.32||6.12E+09||61|
|Electricity (US ind. average)||kWh||0.099||3.60E+06||98|
|Electricity (US res. average)||kWh||0.11||3.60E+06||109|
|Electricity (Euro res. average)||kWh||0.17||3.60E+06||168|
|Actual food cost||day||5||9.77E+06||1824|
The cheapest food source is currently wheat, which is still about four times more expensive than non-renewable coal and natural gas. Record oil price was $147 in June 2008. Natural gas peaked at $456 also in June 2008, so it is capable of even greater price spikes than oil. Note that electricity produced from burning fossil fuels operates at about 40% efficiency, so that each unit so produced actually represents about 2.5 units of thermal energy.
The demotechnic index (DI) is the ratio of a country's total technological energy consumption per capita to the D unit of physiological (food) consumption. Hunter gatherer humans have a DI of 0, that is, they consume only enough to feed themselves and harness no other energy source. Pre-industrial societies could enlarge that energy use by including the work of water and wind power and beasts of burden, but we're still talking single digits.
Canada in 1990 had a DI of 118, which is an astounding amount of energy that we clearly take for granted.
The DI has grown rapidly in the last century for industrialized countries.
|Rank||Country||Demotechnic Index||Population (000)||Demotechnic Population (000)|
|11||German Dem Rep||64.5||16,249||1,064,310|
|19||Germany, Fed Rep||49.8||61,324||3,112,193|
|20||Trinidad & Tobago||47.0||1,281||61,526|
From: Consumption: The Other Side of Population Paper prepared for the International Conference on Population and Development Francisco J. Mata, Earth Council Larry J. Onisto, Ontario Hydro. J. R. Vallentyne, Canada Centre for Island Waters.
Note: countries of similar economic standing vary widely in energy consumption, for example Germany has twice Canada's population but similar standard of living and the same total energy use. Since this data is out of date, I ran some ballpark numbers and it appears that Canada hasn't changed much, although China and India are now much bigger contributors.
Consumption adjusted population cartogram resizing each nation by the ecological load they exert on the planet through their population multiplied by the effects of consumption.
From: Consumption: The Other Side of Population for Development (May 2010 draft update, unpublished)
There are several other scales such as the carbon footprint, and human development index, and all of them have their advantages. None of them really put a hard number to the kind of use, or waste, that the DI does.
Another way of looking at this is the unofficial (but very useful) statistic Gross Domestic Product per Barrel of oil equivalent, which can be used to rank the 'dollar energy efficiency' of a country's economy.
Not surprisingly, Canada ranks high on the DI (undesirable) and low on GDP/BOE (undesirable), in fact is the worst of the large first world economies on both of these scales.
If energy prices are low, being energy wasteful can actually be good for the economy, as most economic activity requires or is at least leveraged by energy use. But if prices continue to rise relative to the rest of the economy and Canada cannot make rapid improvements in efficiency, non energy producing sectors (and regions) could be out-competed by every country on the above list.
Canada could end up demoted to a second class economy. Indeed, with Canadians increasingly embracing regressive leaders like Rob Ford, we are making our beds to do just that. Will we end up like the oil producer nations of Saudi, Venezuela, and Nigeria that have energy wealth but little else? If we keep the status quo, the future is fairly predictable: Alberta's oil patch and other energy producing areas flourish, and the rest of Canada slowly rusts into irrelevance, especially outside of the larger cities.
I really think the key to turning this ship around is getting serious about a carbon tax.
I have a pet theory, likely inherited from my father, that there is an optimal level for just about everything. Energy is extremely useful for enhancing our lifestyle, but is it too cheap and too easy to burn away? Based on our behaviour for the last half century, I'd say absolutely yes.
We always have choices: Cycle or drive, apartment or mansion, urban or suburban, local or imported, Canadian or exotic vacation, kayak or seadoo, ski or snowmobile, rake or leafblower. For every lifestyle choice comparison, I tend to favour the lower energy choice, not because it makes me feel conscientious but because it is almost always more fun or at least better for the body and soul.
I think Jack would agree.
Vallentyne, J.R.: Tragedy in Mouse Utopia http://www.trafford.com/Bookstore/BookDetail.aspx?Book=181860
Consumption: The Other Side of Population, Paper prepared for the International Conference on Population and Development 1994, Francisco J. Mata, Earth Council, Larry J. Onisto, Ontario Hydro. J. R. Vallentyne, Canada Centre for Island Waters.
Personal communication: Thanks to Doyle Crosswhite and Larry Onisto for making this article and a 2010 draft update available respectively http://www.sci.sdsu.edu/salton/MataConsumption.html (the link to the above article is dead)
Note: Energy price data is current as of April 4, 2011 or the most recent available month
Dollar cost of energy calculations are available on request
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