Just Joules -- Dedicated to Unifying Our Energy Terminology

Just Joules advocates for unifying our confusing and arcane language for energy units into a single measurement unit, joules, so that we can easily understand the relationships between different forms of energy and make better energy decisions based on clearer understanding.


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Just Joules!


The Problem: As the 21st century opens, we as a world are facing an uncertain energy future.  Where fossil fuel once seemed an inexhaustible resource, this is now known to be false.  And the harmful effects of fossil-fuel consumption are becoming more apparent by the year.  As we move to more and different energy alternatives, we will have even more chances to misunderstand and misinterpret their impact if we continue to use a mixture of energy units in our science, our commerce, our personal decisions, and in our national and global energy policies.

Just Joules!


The Confusion: We now deal with a plethora of energy units in the western, highly developed, and highly energy consuming world.   Among these are "btu", "therm", "kilowatt-hour", "calorie", "Calorie", "erg", and "joule".   In specialized fields, it is not difficult to find additional units which are attached to energy; for instance, "tons" or "kilotons" for explosives.  The mixture of terms for essentially one entity (energy) leads to confusion, especially among citizens who need to be aware, now more than ever, of energy consumption patterns.   It is difficult, without a calculator and a conversion chart for units, to weigh the energy usage of one modern convenience against another, one type of space heating or cooling against another, one type of transportation mode against another, and so on.  We can only make informed and correct energy decisions when energy is treated as a single quantity, with one single scientific unit.

Just Joules!


A Quick Analogy: Imagine if your local food store priced dairy produce in dollars, meat produce in euros, and grain produce in yen. Would you object? It seems that this would make comparative shopping for best value in protein foods very difficult. Your bill, itemized in these different currencies would seem strange indeed. The situation with energy units is somewhat similar in that it is difficult to do comparisons when we are presented quantities with different units.

Just Joules!


The Unifying Choice: The SI (Système Internationl in French) unit of energy is the joule.   Definition of the joule in more basic SI units can be found at, for instance, Wikipedia. This is the most logical choice around which to unify our confusing energy definitions.

Just Joules!


Why Joules: One need not even understand exactly what a joule means other than it is a measure of energy.  The fact that it is based on the fundamental SI units of kilogram, meter, and second makes it the preferred choice to measure energy.  The well-defined means provided by the metric system to handle much larger or smaller quantities than can be written easily with the base unit is also attractive.  Thus, we can use kilojoules (kJ), megajoules (MJ), and so forth; or on the downside, millijoules (mJ), microjoules (μJ), and so forth.

Just Joules!


The Benefits of Consistency: Having a consistent way of quantifying energy should begin to bring all our energy usage into clearer focus.   Energy can change forms (for example, thermal to mechanical or mechanical to potential) but it remains unchanged in quantity.  Whatever form it resides in, it makes sense to quantify it in a consistent manner.  Thereby the workings of different processes, physical or biological, all come under the same view.  The energy needed to sustain life (contained in food) can be readily compared to that which heats our house and that which moves our vehicle and so forth.

Just Joules!


A Related Issue -- Power Units: There is also a problem with units of power.  Power is the rate at which energy is provided.  It determines, for instance, how many light bulbs can be kept on at once, how fast a vehicle can accelerate, or how fast a chain saw can cut through a tree trunk.   Power is measured in SI units as "watts" which is the amount of joules per second.  There is really only one other widely used unit of power in the western countries -- horsepower, and it is not consistently defined.  Clearly an acceptable unit when the industrial revolution was taking over agrarian society, this is now an antiquated phrase which has relevance to nearly no one.  It simply makes sense to let "watt" be the universal unit for power.  Again, we take advantage of SI prefixes such as kilo, mega, giga, and so forth to easily describe large amounts of power (for example, a gigawatt power generating plant).

Just Joules!


Energy Storage: For a fuller discussion, go to Energy Storage, but the short message here is that our technology has developed many energy storage systems or devices (for example, batteries, fly wheels, fuel cells). These are not energy sources in the normal sense, as they only hold energy temporarily, waiting for it to be drawn out. Of course, the distinction grays in many ways. One can consider oil not as an energy source but as an energy storage medium because it has resulted ultimately from the action of the sun on living matter. Even the sun can be thought of as an energy storage device, an enormous one at that. It is not unreasonable to suggest that all energy storage entities should be rated in joules because quantities of energy are what they deliver.



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Last updated: 5/12/2007