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The following is just one of many articles form LP 4:
Superstitions about Energy
Where do ‘old wife’s tales’ originate from?
It seems very hard to tell; some may be based on reality, some may have originated from misunderstandings and just perpetuated, and some may have been spread deliberately either as a joke or by someone with a vested interest in the tale.
But what seems common to all of them: They are passed on from person to person; even from generation to generation, without anyone questioning their validity.
Many people believe that superstitions slowly died out during the 20th century. I would like to show you this is not the case. In fact the age of technology created less founded superstitions than anything ever heard before.
Most of the old fairy tales seem to contain some truth at least. E.g. the rule not to cut down all the hawthorn bushes: Whether one believes in fairies as little humanoid people or not, it is a very valid warning not to take the last bit out of nature.
In contrast, the newer technological ‘tales’ often miss the point altogether. My father told me a good one: Back in the 20s or 30s, he observed more than once how older tram passengers asked the conductor to switch on the lights in a thunderstorm. They honestly believed the lights would protect the tram from lightning strike. We may smile about this one, but the stories I picked up in the line of energy over the years, are not too far off either. Here is a selection:
| The Tale |
The Facts |
| It takes less energy to leave an appliance running than to switch it on and off |
Most appliances take a starting surge for less than 1 sec. Assuming starting power = 5 times running power, it pays switching them off for at least 5 seconds! |
| It takes less energy to leave a fluorescent lamp on than to switch it on and off. |
See above. Starting power of fluorescent lights is about twice the running power for 1-2 seconds. However, conventional fluorescent lights (which flicker at start) may ‘blacken’ from frequent switching. |
Electric showers are energy saving
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Any grid-electric heating wastes energy due to the low efficiency of steam power stations. Electric showers with their high momentary load also increase power line losses considerably. |
A boiler runs more efficient at high temperatures
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Output is higher at high temperatures, but fuel efficiency is highest at low water temperatures. At very low temperatures however, condensation can become a problem. A sensible compromise is 55-60o C water temperature. |
Radiators are more efficient at high temperatures
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Output is higher, but, as the ‘unused’ water always returns to the boiler, efficiency remains almost the same at all temperatures. |
Underfloor heating is bad for your feet
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??? (Are frozen feet healthier…?) |
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It’s better to run a car at high engine revs
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A petrol engine runs most efficient at medium revs, a Diesel engine at low to medium revs. Engines will last longer when warm, but forcing a cold engine into high revs wears them out even quicker. |
It’s better to buy new cars because they have fewer emissions
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Only if you change to a lighter car and/or smaller engine. However, poorly maintained engines can have higher fuel consumption and emissions.
It seems the most fuel-efficient cars have been sold during the 80s after the ‘second oil crisis’. |
Petrol engines have fewer emissions than Diesel engines
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Diesel engines are by no means ‘environment-friendly’ but they are, by their design, some 30% more energy-efficient than petrol engines and therefore emit less CO2 . Other emissions:
CO: much less on Diesel
NOx: more on Diesel
SO2: much more on Diesel, but largely avoidable by de-sulphurizing the fuel
CxHx (unburnt fuel): much less on Diesel
Only petrol engines with catalytic converters have fewer emissions than Diesel engines without. The fact that a petrol engine smells less doesn’t mean it’s healthy… |
By the way, most of the stories above are not confined to Ireland at all. In fact the one about fluorescent lights seems to be very international, and highly persistent! (Does this indicate good international communication, or rather the fact that electricity supply companies in all countries have similar interests? I still don’t know.)
Solar energy is no good in Irish weather
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Within the northern half of Europe (north of 50o latitude), Ireland gets slightly more solar radiation than most areas |
Solar energy needs a hot climate
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Solar energy works on light, not heat. Solar heating works slightly better when it is hot. Solar electricity (PV) works slightly better when it is cold. |
Solar energy can only pre-heat
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Depending on the weather, temperatures between 20 and 160 degrees are possible |
Solar energy is unreliable
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As to the technology: solar panels (both heating and PV) are some of the most reliable items one can buy. They have no moving parts and therefore require no maintenance.
As to the output: While solar radiation changes with weather and season, it is still much more predictable than other renewables, especially wind. |
PV modules need more energy in production than they produce during their lifetime.
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They re-produce the energy used in production within 1.5 - 3 years. Even if raw materials, transport, administration etc is taken into account, the balance will hardly be negative within their lifetime of 50+ years
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Wind turbines are noisy
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This depends on the turbine and wind speed. Most are hardly audible if over 200m away.
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There is good wind everywhere in Ireland
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There is a big variation in wind speed across the country with highest winds along the west and north coast, lowest in the eastern midlands. Also wind speed will vary a lot locally depending on how ‘open’ a site is.
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Wind has more potential than solar energy in Ireland
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Only in certain areas, see above. |
Hydro energy is bad for the environment
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The main environmental problem of hydropower is large dams changing the landscape and interfering with fish migration. Small run-of-the-river systems do not need a dam and are hardly visible.
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| Hydro energy is too expensive |
Cost depends on the site. Today, many sites work out slightly more expensive than (cheap) fossil fuels. Very small systems can be cost-efficient if they replace grid electricity at retail rather than wholesale prices (i.e. if used on site rather than sold). |
| All viable hydro sites have been developed already |
There are many small sites, many of which actually had hydro turbines installed before the ESB wired rural areas. |
| The cost of grid-connecting small systems is too high |
If power is produced at a consumer’s site in amounts similar to the average use, there is virtually no grid-connection cost. It can even save upgrading the grid if power demand rises in future. |
| The Irish electricity grid is unsuitable for connecting small generating systems |
It depends what is meant by ‘small’. The grid can be too weak for wind farms in remote locations (e.g. west coast) and may have to be reinforced to enable connection.
But any generator that is smaller than the nearest grid transformer can be connected without any alteration to the grid. This applies for instance to all PV, wind and small hydro systems with a maximum output of some 12 kW and in most cases even more. However, there is no straightforward metering procedure or incentive in place at present (such as ‘net metering’). |
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Superstitions about Energy 
