Joule in the Crown

By The Metric Maven

The creators of the television series Futurama had a question about money in the future. Would there be any? After deciding there probably would be, they speculated about what form the currency might take. An early suggestion for a currency basis was the joule, but in the end they opted for the dollar. The joule seemed like a much better idea to me, what is more important to the “modern” world than energy? Energy has made life luxuriant when compared with the life our forefathers (and foremothers) experienced. The joule is the unit of energy in the metric system and would be universally recognized—well except in one country.

Recently a fellow from the local energy company knocked on my door and announced he needed to work on the gas meter. Apparently in the mid-1990’s a wireless reader was installed so it could be read remotely. The battery was at the end of its life and so it was to be replaced. I watched as the technician unscrewed the existing meter module, which has its units in cubic feet. He then replaced it with an identical module, which in the year 2014 still reads out in cubic feet of gas.

My utility company sends me a bill for energy usage each month. The word energy is even in their corporate name. Below is a scan of a recent bill’s comparison information section:

Energy Bill -- Electricity usage assumed Kwh -- Gas usage assumed Therm (click to enlarge)

The gas and electric energy usage is offered in Kwh per month and in therms respectively. The Kwh stands for kilowatt-hours. A watt is a joule per second, so multiplying a value in watts by hours is pigfish talk. The recognized unit of time in SI is the second. For this bill, the first energy value given is 928 Kwh for the electrical energy used, but energy is internationally described in joules. When all the conversions are done, the electrical energy used for the month in SI is 3341 megajoules.

The natural gas usage is assumed to be in Therms. So what is a therm?  Well, in the US, it’s 100 000 BTU, and BTU are British Thermal Units, but not the British Thermal units used by the British, those are a bit different. These are American British Thermal Units—you know—the patriotic kind. Gas meters don’t directly measure the energy delivered, but instead the volume of gas delivered. According to Wikipedia:

Since (Natural Gas) meters measure volume and not energy content, a therm factor is used by (Natural) gas companies to convert the volume of gas used to its heat equivalent, and thus calculate the actual energy use. The therm factor is usually in the units therms/CCF. It will vary with the mix of hydrocarbons in the natural gas. Natural gas with a higher than average concentration of ethane, propane or butane will have a higher therm factor. Impurities, such as carbon dioxide or nitrogen, lower the therm factor.

The volume of the gas is calculated as if it was measured at standard temperature and pressure (STP). The heat content of natural gas is solely dependent on the composition of the gas, and is independent of temperature and pressure.

Therms “Explained” for Consumers.  It is noted that 10 therms is a decatherm (Dth) and not a dth as one might expect. This is very “metricy” sounding but clearly not metric. Therms are BTUs  (click to enlarge)

So we have to have a temperature correction, and apply a therm factor which is in therms/CCF. So what is a CCF?  Well, it’s centium cubic feet or 100 cubic feet. So  the first C is the roman numeral C and stands for 100. The second identical C stands for the word cubic and F is for foot. It is sometimes alternatively written as Ccf. MCF is also used for 1000 cubic feet. The M standing for the Roman numeral for 1000 The correction factor is used to calculate the value as if it were at STP (i.e. standard temperature and pressure). Obviously, accurate values for temperature are important in determining accurate values of natural gas usage. I assume that the average daily temperature has some relationship to this required correction factor. It does not have an obvious entry on my bill. Here is what my energy company states:

Therm Multiplier

Gas usage is defined in Therms, a measure of the heat, or energy content of natural gas in a billing period. One Therm equals 100,000 British Thermal Units (Btu). The energy content of gas changes depending on its source, the altitude and temperature at which it is delivered. After your meter measures your usage by volume (in hundreds of cubic feet and appearing on your bill as “Measured Usage”), this volume is multiplied by the Therm Multiplier to determine the units of energy consumed.

Kwh "Explained" for Consumers (click to enlarge)

The multiplier is not broken down any further and does not spell out the individual contributions. Apparently the temperature, altitude, energy content and such are all wrapped into the Therm Multiplier. The comparison section on my bill is strange, as it has natural gas printed on a line above electric as if the top line is gas, and the bottom is electric. What appears to be the case is that the Kwh value (yes I used a capital K) is the amount of electrical energy usage and the therm value is the natural gas energy usage. It is assumed the customer knows and understands this energy demarcation from the Account Summary they’ve presented.

The most straightforward way for both electric and gas usage to be described, would be in terms of energy usage with a single, simple, internationally recognized unit, but they choose not to do this. Instead, the company uses kilowatt-hours and therms. In the case of kilowatt-hours, it is a pigfish unit, which is metaphorically based on metric, but not the actual metric unit for energy, and for therms it is a semi-imperial system unit for energy. Neither of them use the internationally  accepted unit for energy—the joule.

The comparison section of my energy bill could have been written  in a  much, much clearer way, that anyone could understand, using the metric system and gigajoules:

Comparison Information

Metric Comparison (click to enlarge)

When the bill is written this way, one can immediately see the difference in direct energy cost per gigajoule between Electric and Gas. Electricity is 4.85 times more expensive per joule when compared with natural gas. One can assume that the electric usage is essentially for operating appliances and gas is used for heating, just by looking at the energy usage from this year to last. This year was sixteen degrees colder than last year, and the amount of gas usage in gigajoules was different by a factor of 2.6. The previous energy use was lower for the warmer average temperature as one would expect. One also notices what is missing in this table, the comparison cost per gigajoule from the previous year for electric and gas. This would be a very useful way to gauge the change in cost from year to year. The way the energy bill is originally written one could easily confuse the columns. When presented this way, it is clear.

The way the energy usage is presented in the actual/original bill does not allow a consumer to directly compare energy prices—which are offered by an “energy” company. This is because two non-metric proxy units are used, kilowatt-hours and therms, which have a conversion factor between them of approximately 29 (i.e. 1 therm = 29.307 kilowatt-hours).

One cannot be certain about the origins of the format of the bill I received, but I could not help but think about the word confusopoly, which was introduced in Scott Adams’ book The Dilbert Future. According to Wikipedia:

The word is a portmanteau of confusion and monopoly (or rather oligopoly), defining it as “a group of companies with similar products who intentionally confuse customers instead of competing on price”. Examples of industries in which confusopolies exist (according to Adams) include telephone service, insurance, mortgage loans, banking, and financial services.

I would like to add energy companies to the list.

Australian Gas Meter -- Photo by Peter Goodyear

Electricity and Gas are pretty basic, both are sold by energy content, so despite the view they are public utilities, one can only wonder if they are not following the confusopoly model when they present bills in Kilowatt-hours and Therms. My rework of my utility bill certainly looks simpler to understand than the one that uses “our traditional measurements.” When the metric system is implemented, people can readily see it’s a system.  When energy is discussed in any context using the metric system, it is always joules, so the energy content on food packages are in kilojoules, as is a person’s energy bill in gigajoules. The metric system allows for a more integrated and systematic understanding of the world by everyone. There will always be those who will try to use metric in a non-transparent manner, but it takes much more effort than when using the potpororri of “traditional” measures currently established in the US. The joule in the crown for energy description is the joule. No matter what energy is under discussion:

Australian Subway napkin with food energy in kilojoules (kJ). An average person burns (i.e. radiates as heat) about 169 000 kJ per month (169 MJ) (courtesy of Peter Goodyear -- click on image to enlarge)

US Subway Napkin with Calories (kilocalories) and grams of fat -- The word energy does not appear on the US napkin (click to enlarge)


On a side note, New Scientist on 2014-01-04 related that since the UK phased out incandescent light bulbs there has been a considerable drop in energy usage. They state:

The average amount of electricity needed annually to light a UK home fell from 720 kilowatt-hours in 1997 to 508 kWh in 2012, a drop of 29 percent.

So  the average energy use by a UK home in 1997 was 2592 megajoules/year  and in 2012 was 1829 megajoules/year

Unfortunately New Scientist can play fast and loose with energy quantities and power values. On 2014-03-08 in an article about using batteries for energy storage from wind power they state on page 20:

Last year California passed legislation requiring the state’s energy companies to create more than 1.3 gigawatts of energy storage between them by 2020.

One could blame this technical faux pas on scientifically illiterate California legislators, but one would expect New Scientist to note this mistake, and possibly comment on it. Energy storage is in joules, the amount of energy flow out of the batteries is watts (joule/second). It is like equating the amount of water behind a dam with the flow rate of water leaving it.