[For the large-print, easy-reading version of this post, click here.]
Besides the EROI (see previous post), another measure of the various energy options is ‘efficiency’. This is usually applied to mechanical systems and given as a percentage: a machine which turned all of its energy input into a useful output (without wasting any of it) would be ‘100% efficient’. In practice, of course, this never happens. ‘Zero waste’ may be a noble ideal when it comes to materials, but it is unattainable in the realm of energy usage – which of course is the realm inhabited by all living beings.
One of the basic laws of physics, namely the second law of thermodynamics, tells us that there is no way of using energy without wasting some of it by converting it unintentionally into useless forms. ‘Wasted’ or ‘lost’ energy is called entropy (which can also be mathematically described as randomness in contrast to order). Of course, the usefulness of anything is relative to who’s using it, and for what purpose. Many scientific sources refer to entropy as ‘heat’, because they have machines in mind, and heat is an unwanted byproduct of the work most machines are designed to do. But in another context – surviving a northern Ontario winter, for instance – heat can be very useful indeed. That’s why our four-legged neighbours have evolved ways to generate and conserve it (for instance fur).
Efficiency is a useful measure for comparing various devices which convert one specific form of energy into another. For instance, if you expose two solar cells to the same amount of sunlight, and Cell A generates more electrical energy than Cell B, then Cell A is more efficient. However, if it costs more in resources or energy to make Cell A, then its EROI – the ratio of energy output to the energy input required to generate that output – may not be higher. In other words EROI is the more comprehensive measure for use in making decisions about what technology to use.
The catch is that EROI may not be easy to calculate in practice, because the energy consumed by production and maintenance of any device or system may be difficult to measure. Like entropy (a.k.a. waste), guesswork can’t be entirely eliminated from the decision-making process, but we have to do the best we can if we hope to make the transition to a sustainable energy economy. And sometimes your guesswork has to rely on information you can only get from sources other than your own experience. How we can judge the reliability of a source is a problem i’ll take up in a future post.
Some of the decisions we face are related to the electrical grid. At the provincial level, it’s an obvious problem that a major part of the energy on the grid is generated from non-renewable (and polluting) sources such as coal. Current Ontario government policy is to reduce the amount of ‘dirty’ energy on the grid and bring more renewable sources online (hydroelectric, solar, wind). Some opponents of the latter option have argued that the grid itself is the problem, because it is inefficient: the greater the distance between energy source and user, the more is lost to heat. But this argument makes sense only if there is an alternative with a better EROI. I have yet to hear anyone suggest any such alternative, let alone compare its EROI with that of the existing grid.
Besides, the extended reach of the electrical grid also confers some advantages: not only economies of scale, but also the wide distribution of sources feeding into it – and this advantage increases as more renewable sources come online. The wind doesn’t blow all the time, but it does blow at night, and in the winter, when solar and some hydro sources are not producing much. And when the wind isn’t blowing, other sources may be able to make up the difference. The technology of matching demand with supply on electrical grids is already fairly advanced and customized to specific regions. One district in England has two reservoirs, one much higher than the other; so when they have surplus energy, they pump water from the lower one to the higher one, and when demand exceeds supply, they release the water through a turbine system that generates power as the water flows back down. Other innovative storage methods are always in development, and so is the ‘smart grid’ which can anticipate loads and direct energy where it’s needed.
Of course, there is one advantage to burning fuels as a way of generating energy: when demand increases, you can meet it by simply burning more. This advantage will be lost (along with all the disadvantages of fossil fuels) as we make the transition to renewable sources, and even the smartest grid won’t be able to supply everyone with energy on demand. Part of the transition, then, will be a change in our habits, as we learn to adjust our energy demands to the rhythm of our actual supply. Ontario Hydro is already pushing us in this direction by making energy more expensive at peak demand times. The loud complaints about this, and about rising energy prices generally, show how difficult it is for people to shift their consumption habits, once they’ve got used to having cheap energy on demand. But again, what alternative do we have in the long run?
If you are more ready than most to change your habits, you might consider getting off the grid as an alternative. Certainly it would force you to live within the limits of your household energy economy. But how viable that option is will depend on how much energy you are willing and able to do without. If you are off the grid, and your primary energy source is not producing (for instance solar panels on a long winter night or dark winter day), then what do you do? Go without energy until the sun reappears? If you value the usefulness of an energy supply, you will probably prefer to invest in an alternate source (such as a gasoline generator) or a system that stores enough energy to get you through the night (such as a bank of batteries). But even if you can afford all this, it seems unlikely that the EROI of your off-grid system is higher than the EROI of Ontario’s electrical grid. If anyone can show me that it is, using reliable estimates, i’ll be happy to eat those words. (Especially since we’ve already installed a solar-and-battery system here at gnusystems headquarters.)
Even if going off-grid is a viable option for you personally, that doesn’t make it viable as a provincial policy. At our place we heat with wood, but if everyone in the province did that, just think what effect it would have on Ontario’s carbon footprint and air quality, not to mention the forests … For the province as a whole, asking everyone to go off-grid is about as practical as asking everyone to burn wood. Whether it’s even practical for a typical Manitoulin household is no easy question. On the provincial level (and above), we are not likely to make the transition to sustainability by eliminating the grid. The more sensible course is to clean it up and diversify the sources feeding into it – and work out ways of dealing with whatever new problems accompany that shift. My next post will look at some of those.