Hot answers tagged

20

General principles The important thing here is to realise what these heaters heat. Radiative heaters radiate infra-red light which strikes objects and heats them directly, heating the intervening air less. Fan heaters primarily heat the air in the room by forced convection. Oil filled radiators, work like ordinary central heating radiators, primarily ...


17

TLDR; don't use them for lighting. Given that you could keep your incandescent bulbs for when your current energy-efficient (I will assume CCFL) bulbs need replacing, your choice boils down to: buy a new CCFL; or use an incandescent that has already been manufactured. This helpful analysis gives the embodied energy in a CCFL as 1.7 kWh. Let's assume that ...


15

I'll take a slightly different line to Mark Booth's excellent answer. fan heater: If you've got a lot of still air, and / or if you only want the heater on for short bursts, then the fan heater is probably best, because it will get the warm air circulating in the room, and it will respond quickly to being turned on and off. However, dust can settle on the ...


14

TLDR; cadmium telluride panels have the highest EROI of the mentioned PV panels (around 34.2) EROI estimates vary widely. This is because of differences in the method of calculation, scope of the study, installation location, assumed lifespan of a panel, etc. This also makes it relatively easy to manipulate EROI calculations. Pessimistic The most ...


13

i signed up just so i could make this comment. THelper♦ provided a good link to a DOE report on this topic, which i was researching because my roommate is skeptical about the advantages of efficient bulbs. the report THelper♦ cited has the following bar graph that pretty much answers the question:


12

No. With nothing plugged in there is no circuit, so no current can flow. An exception to this is if the socket or the switch has an indicator light - usually a neon one - that is illuminated when the switch is on. In that case the light will use a (very small) amount of power.


11

I use them in garden/indoor. Something like this... (source : google search)


11

I live off-grid, so I did a lot of study on this topic. All used coffee grounds make good fertilizer. Drip machines seem to use a lot of energy, and they seem to use it for a lot of time. They also use disposable filters. Drip machines are kind of on the off-grid "blacklist". Percolators waste a lot of energy because they have to keep the water boiling ...


10

If you have the property, and resources, make sure your house is tight. Then, dig a four foot trench that zigzags across a suitable part of your yard, taking care to call Mis Dig for location of underwater electrical, water, and gas lines. Lay PVC pipe into the trench, making sure it's water tight. Bring one end up from the ground, above the maximum snow ...


10

Water loss is not the issue, because you need a lot of water to make it work at all. Even if your dams lose 30% of their water every year, that's about 0.1% per day. System losses in the best large-scale systems are about 20%. In other words, 70-80% efficiency of large scale systems (wikipedia). The big issue, though, is likely to be making it work at all. ...


10

No, you cannot get more energy out than you put in. No, you cannot invent a perpetual motion machine.


9

The answer you are looking for would be contained in a Life Cycle Assessment (LCA). For an LCA you first want to determine the boundaries that are important to your question. Are you considering cradle to grave (disposal)? Cradle to cradle (recycling after use)? What are the boundaries for recycled source materials if used to make the light bulbs? The ...


9

Well, I'm by no means an expert on giving this answer, and yet I'll take a go at providing something reasonable. Assuming a 1ha biodiverse, properly hydrated, young stage forest with optimal leaf coverage that gives us a solar catchment area of 10,000 square metres. Subtract say 20% to account for immature trees amongst the larger growth, another 20% for ...


9

Air is much more energy intensive. Gucwa and Schaefer looked at the impact of scale on energy intensity in freight transportation, and the chart below is taken from that paper. They looked at varying loads, across four modes - the line in the lower left is trucks, the cluster above it is air, the long spread-out light grey dots in the bottom-right is ships, ...


9

I disagree with the answers that say not to use it. It may in fact be an excellent idea to use it if: you live somewhere that requires your home to be heated in the winter you currently heat with electricity or with something less efficient than electricity The "wasted" energy from an incandescent bulb is wasted as heat. In the summer, this is really bad ...


9

Sort of. Consider the pay back time. high efficiency lights are expensive. Expense is, at least in part, a measure of the resources used to make it.* Replacing the fixtures in the kitchen where the lights are on 8-10 hours a day is probably a good idea. Replacing the lights in the hall closet that runs 20 minutes a week is not. Example: Our kitchen has ...


8

tl;dr: Yes, lowering the room thermostat at night will generally help save energy, assuming we are in the heating season (winter), rather than the cooling season (summer). Let's take two points in time, one before the night, one after it. Let's choose them so that the dwelling has the same amount of heat energy contained within it at each point, so all the ...


8

Electronically they're the same and will waste as much energy as a conventional adaptor. Depending on your electrical regulations they may be forced to be at the good end of adaptor efficiency, or they may be at the very cheap end. This will be a matter of safety regulations, but the cheapest designs fall down on safety and efficiency. I hunted for one ...


8

It is common knowledge that hot air rises and cold air sinks. Inside a fridge the coldest air will be in the bottom of the fridge. As soon as the fridge door is opened cold air from the bottom of the fridge drops out onto the floor of the room where the fridge is located. This air is replaced by room temperature air entering the top of the fridge space. ...


8

To determine the power used when the computer is in sleep mode you can acquire a power meter that plugs into a power outlet & measures the electricity used by devices that are connected to the power meter. This has been done by one person who posted the results online. The summary states: The standby mode power consumption is just a bit more than ...


8

tl;dr: No, shipping plastic waste to China for recycling does not offset the benefits, as it reduces the net energy savings by 3% or less. Polyethylene, The most common plastic According to Wikipedia, polyethylene is the most common type of plastic. There are three main categories of polyethylene (also from Wikipedia): PET (polyethylene terephthalate), ...


7

You will probably lose less energy from a very short burst of high-rate ventilation, than slow ventilation over a long period. That's because you'll probably lose more hot air in a long, slow ventilation: it will take some time to notice that the air really is fresh now, whereas with all the windows open for a few seconds, you'll notice the fresher air ...


7

Beware that chart - it is from 2004, and hence is very out of date! In particular, photovoltaics ("solar panels") have become cheaper much faster than anybody expected a decade ago, and wave and tidal power have proved more difficult and costly than some had projected. Here's some more up to date info on costs: http://www.eia.gov/forecasts/aeo/...


7

According to the REN21 Renewables Global Status Report 2014, China had 91.4 GW of installed wind capacity by the end of 2013, more than any other country in the world, of which 75.5 GW was in commercial operation. The USA had 61.6 GW of installed wind capacity. In terms of actual generation from wind, the USA was world leader in 2013, with 19.4 GW mean ...


7

The best analogy for this is the use of daylight savings time, where in effect people wake up one hour early than they usually do. A study by the US Department of Transport in 1975 (see page 4 of the website), showed that Daylight Saving Time trims the entire country's electricity usage by a small but significant amount, about one percent each day, ...


7

There is no one reason for why humans are using non-renewable resources like fossil fuels and nuclear fuels to generate energy. I'll write what I know about and others can do the same and from all the answers you'll be able to see complexity of the situation. To begin with humankind has been burning things for energy for millennia. It's something we know a ...


7

It sounds like the Kill A Watt wireless might be what you are after. For more alternatives keep reading. There is another product line called the Watts-Up that has USB connections to computers on some models, and a built in web server on the high end one. The high end one can be made to work over wireless with an adapter. The USB only versions could be used ...


7

It depends. It is possible to farm wood sustainably, or unsustainably. Both ways happen now. It is possible to use wood pellets for energy while trapping particulate matter and other non-GHG pollutants. This sometimes happens, and sometimes it doesn't. It is possible to dispose of the resulting post-combustion products in a way that returns the nutrients ...


7

Your grinder may be less efficient than a commercial unit, and shipping beans rather than ground coffee may affect the bulk for shipping. If you use extra (hot) water in washing a permanent filter you may be better off using unbleached paper filters and composting them along with the grounds. I find that you can't put lots of coffee grounds through a ...


7

Well, if you are really into it and quite handy, you could turn it into activated charcoal, and then add it to your soil! Grind it into small bits, heat it anaerobically, then introduce high-pressure steam. The result will be charcoal with many fissures and cracks, which is ideal for gardening purposes. Then, before introducing it to your garden, pee on it ...


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