Hot answers tagged

25

I disagree that dishwashers, compared to hand washing, will not save energy. First of all, as with almost anything, it depends how it's done. If you run your dishwasher half full, that's going to be bad for energy and water use. Similarly, if you hand wash, with the hot water running the whole time, that's bad. So, either technique requires tuning the ...


20

Take a look at a passive solar heat collector. They work on the principle of thermosiphoning. The design in the link and the picture below has an additional top vent exposed to the outside so you can close the top interior vent and draw air out of the building during the summer. I've seen more advanced designs that include doors that automatically close at ...


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 ...


18

Efficiency The inefficiency you're referring to is probably not the efficiency with which the gas is burned (a separate issue), but instead is likely to be because the air heated by an oven does not mix well with air in the room, so convection causes it to rise straight to the ceiling. This doesn't tend to make a cold house feel much warmer (especially if ...


18

Water takes energy to pump, filter and treat (and the treatment chemicals require energy to make), so it's likely a substantial part of the water cost goes to energy anyway. Given that in your case you can save a massive proportion of water for very little extra electricity, I'd go with the water saving. Secondly, it's often possible to run a lower ...


18

Perhaps this article is what you are looking for? It's a study by the US Department of Energy on the life-cycle environmental and resource costs in the manufacturing, transport, use, and disposal of light-emitting diode (LED) lighting products in relation to comparable traditional lighting technologies. There is a similar study done by manufacturer ...


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 ...


16

From http://www.treehugger.com/green-food/meat-eaters-guide-get-to-know-the-carbon-footprint-of-your-diet-lamb-beef-cheese-are-the-worst.html we have which I find pretty fascinating — certainly I would have put pork much closer to beef than either salmon or Turkey... really interesting stuff. I'd like to see as well the same graph but per calorie rather ...


16

Use the kettle if you have one, and if you're nearby, switch it off as soon as it boils. Here's some evidence to prove it's the best option: Method: Measure 252g of cold tap water into Frog Mug using electronic kitchen scales, being the amount I'd use to make a cup of tea. Temperature according to my thermometer is 18 degrees C. Plug microwave in through ...


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

Do “100% renewable” electricity plans increase renewable electricity production? Well, it will depend on how the specific scheme is implemented, what the renewable suppliers are, and what timescale you are considering. So, the answer could be yes, no or maybe. I don't know about your supplier's particular plan, and in order to keep this answer useful to as ...


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

Someone has done it. A majority of the electricity I buy comes from geothermal energy †. Of course, I live in the Pacific Northwest of North America, which puts me close to a tectonic plate boundary. This presents good conditions for extracting geothermal heat (since the earth's crust is thinner at such boundaries ... making shallower wells productive). ...


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

While such a project is technically possible, I have to wonder: why bother? There already exists a huge energy infrastructure, warehouses full of photovoltaic (PV) waiting to be bought, electricity transmission networks, mineral extraction and processing plants, and so on. Doing it all from scratch while ignoring available infrastructure looks like putting a ...


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

First, given that the heat has to go somewhere, I don't think you will get more heat transferred usefully to your house from opening the oven door. You may get less for the reason that the hot air may rise as a mass (rather than trickling out) and thus have less impact on the rest of the air. As some of the others have said the issue efficiency-wise will ...


9

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 ...


9

It's highly unlikely that within "our" lifetime we will completely run out of oil. What is likely to happen is that oil prices will continue to rise, until it gets to the point where it's economically advantageous to invest more significantly in alternatives. Why we're not going to run out of oil (soon)... When we talk about how much oil is "left", we're ...


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

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

A few things to keep in mind. Food safety for unrefridgerated food is a very complex thing and the answer very much is "it depends." Factors include temperature, time in the so-called danger zone (40-140F), pH, other bacterial activity, salt content, and much, much more. In general a few guidelines: If your food stays between 32F and 40F you can treat it ...


8

Generally, no they're not. For a combination of several reasons the tracking system itself has a high capital cost. static PV systems are extremely low maintenance. Tracking PV systems are not. adding a tracker means bigger spacing between groups of panels, so that they don't shadow each other The net additional energy yield isn't that high: for PV, ...


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