The Power of Transformity

I recently understood the elegance of H.T. Odum’s concept of transformity.

The transformity table presented at the link above shows that electricity has a transformity of 300,000 seJ/J, where seJ stands for solar-equivalent joule. It’s a weird unit, so I tried to digest it as follows: to produce electricity requires 300,000 solar-equivalent joules per joule. By contrast, sunlight is by definition 1 seJ/J. The numerator is the emergy input to the energy source / carrier in question. (Brief aside about emergy: the reason that emergy is measured in “solar-equivalent” joules, as I understand it, is so that there is a common basis for embodied energy comparisons. One trap that’s easy to fall into when doing such calculations—one I’ve fallen into—is to do a calculation based upon different sorts of energy inputs, and then to combine them together as if they’re equal, like oil and electricity. By using solar energy as the root, this issue is mostly resolved.)

Back to transformity: the confusing part is the measurement of the denominator. The joule in the denominator can be thought of as the useful work you can extract from the energy source. To put it more concretely, since a joule is a bit ugly as a unit (I don’t like thinking in newtons), we can translate all the transformities into calories (i.e. solar-equivalent calories / calorie). So to heat a gram of water 1 degree using sunlight takes 1 solar-equivalent calorie. But to do the same thing with electricity takes 300,000 solar equivalent calories. That’s a massive difference. Heating water using sunlight is not just a bit more efficient than using electricity or fossil fuels—it’s multiple orders of magnitude more efficient.

It seems the main reason for electricity’s high transformity is that the fossil fuels used to produce that electricity have high transformity. That in turn is because of the quantity of biomass transformed through geologic time (i.e. that biomass’s emergy is large) to produce fossil fuels.

From a practical (shortsighted) standpoint we don’t really care that biomass and geologic forces went into making fossil fuels, as long as we ignore that we’re running out of them. So you could think of rescaling the transformity of electricity to a fake unit we could call a “nature-equivalent joule / joule” (neJ/J) and treat seJ/J as equivalent. (The idea being that as long as a joule came from “nature”, I don’t care if it’s from the sun or from a chunk of coal.) Then we could rescale electricity by the value of coal to something like 4.5 neJ/J, which tells us even in this case using solar to heat water is 4.5 times more efficient than using electricity to do the same task. (However, using neJ/J, using coal directly is by definition as efficient as solar.)

There are some interesting ideas in the post linked above, such as Odum’s conjecture about how solar PV might be inefficient because it is trying to leap too far in transformity. The open question there, in my thinking, is whether electricity is fundamentally of high transformity. It would be interesting to see the analysis done again for CdTe cells, for example, since they may have high EREOI.

The reason to repeat that analysis is another reason that transformity is a great concept. EROEI, along with most net energy variants, have the weakness of conflating different sorts of energy inputs, and also of ignoring the fossil fuel subsidy provided to all industrial processes. Even if CdTe photovoltaic cells have high EROEI, that doesn’t mean that they have low transformity. And post-fossil fuels, it’s tranformity that will matter.

Hemenway made a good case for the resilience of the food system post-peak oil, and he argues, I think with good reason, that we ought to be concerned about the sustainability / stability of the numerous high transformity systems we depend upon in industrial societies before we worry about the food system. The transformity of today’s food system is low compared to banking and the electric grid and so on—and that’s today’s food system, which is more complex than it ought to be or needs to be.

In any case, I’m reminded of a great saying, one that I now understand is backed up by the idea of transformity: “let light be light; let heat be heat; let food be food.”

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Responses to “The Power of Transformity”

  1. Everytime I talk to you I realize I need to add a figure. At the link, scroll to the bottom, Emergy Yield Ratios for different types of electricity.

    Notice the nuke EYR of 4.6 from the mid-80s in the US. What is the current emergy yield ratio of nukes in Japan?!?

    We need to get a lot smarter very quickly about the renewables we attempt.

  2. Mary -

    Definitely. I think nuclear is definitely an instance where conventional calculations of net energy / EROEI ignore the massive downside risk / energy cost / financial cost.

    I do wonder though about new solar cells and whether there is something fundamental about electricity being high transformity. That seems like the major open question to me that could, if anything, provide a reasonable semi-renewable electricity option.

  3. “…these [hardware PV cells] ignore the energy hierarchy law that requires many calories of available energy at one level to make a few calories at higher levels. . . Evaluations that claim net yield from solar cells leave out the huge empower required in the human services for manufacture, distribution, support, connections, operation, management, and maintenance. . . where a dilute renewable energy has to be concentrated to support society, either emergy is used to concentrate the energy spatially or time is allowed for the energy to accumulate in a broadly distributed storage. There is an emergy equivalence between accumulation of available energy over time and the work of concentrating energy in space. Self-organizing systems do both” (Odum, 2007, p. 209).

    So if we cover the earth in solar panels in order to use many times the resources that nature uses for photosynthesis and basic ecosystem support in order to supply 7 billion of us with electricity at the same time we have to go back to traditional agriculture and have to fall back on our ecosystem supports in many other ways as well . . . . how will that work?

  4. Mary -

    Though, just to play devil’s advocate, isn’t it the case that the combination of a) rapidly improving lower-emergy solar PV cells combined with b) vast regions of desert that aren’t being used for much in the way of agriculture (and have little plant life) are perfect to deploy PV? And rooftops, highways, and all the other wasted spaces in cities.

    Setting that aside, I guess it comes back to this question: what fundamentally about electricity requires it to be of high transformity? Might its currently-high transformity only be dependent upon the sources of energy we use today to produce it?

  5. barath wrote:
    “I guess it comes back to this question: what fundamentally about electricity requires it to be of high transformity? Might its currently-high transformity only be dependent upon the sources of energy we use today to produce it?”

    Exactly! You hit the nail on the head.
    Please check out the following scientific papers:
    - Raugei M., Fullana-i-Palmer P., Fthenakis V., 2012. The Energy Return on Energy Investment (EROI) of Photovoltaics: Methodology and Comparisons with Fossil Fuel Life Cycles. Energy Policy, DOI: 10.1016/j.enpol.2012.03.008

    - Brown M.T., Raugei M., Ulgiati S., 2012. On boundaries and ‘investments’ in Emergy Synthesis and LCA. A case study on thermal vs. photovoltaic electricity. Ecological Indicators 15:227-235