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11 votes

Getting power from an innovative new mechanism

No, you cannot get more energy out than you put in. No, you cannot invent a perpetual motion machine.
410 gone's user avatar
  • 14.7k
10 votes
Accepted

Can pumped water energy storage be combined with rainwater harvesting?

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-...
Ⴖuі's user avatar
  • 1,307
9 votes

Is leaving the fridge door open for, say, 10 seconds a "big deal"?

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 ...
Fred's user avatar
  • 3,517
9 votes

Should I replace existing inefficient light bulbs?

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 ...
Sherwood Botsford's user avatar
8 votes
Accepted

Laptop nights: shutdown or sleep?

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 ...
Fred's user avatar
  • 3,517
8 votes
Accepted

Does transporting plastic offset the benefits of recycling it?

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 ...
LShaver's user avatar
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8 votes

Saving energy in the dryer: short and hot, or long and low?

The generic and vague wording of the question seems deliberate, but unfortunately a meaningful answer can't be so simple. The primary factor that determines how long it will take a dryer to dry a load ...
Tim's user avatar
  • 2,844
7 votes

What to do with old, unused incandescent light bulbs

Please consider donating incandescent bulbs to a support group for diseases that can sensitize some people to light. One disease with fairly widespread support group chapters is Lupus. Lupus has ...
lemurmoon 's user avatar
7 votes

How can I determine whether roof top wind turbines would be beneficial in my area?

One approach is to look for studies in this area and decide whether the idea is even plausible. Is it "a bit more expensive but I like the technology" or is it "much more expensive and ...
Móż's user avatar
  • 3,935
7 votes

How much energy do wall outlets with USB waste when not actively charging?

In most countries, legislation limits the amount of power a device on standby, i.e. under power but not performing a function, are allowed to use. In Europe it's 0.5 Watts (see EC Regulation No. 1275/...
Gannet's user avatar
  • 161
7 votes

What should I do with coal that I have been given?

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 ...
Jan Steinman's user avatar
7 votes

Is oil actually a renewable and sustainable resource, but we just use much too much of it?

What does renewable mean? Wikipedia defines a renewable resource as (emphasis added): a natural resource which will replenish to replace the portion depleted by usage and consumption, either through ...
LShaver's user avatar
  • 11.9k
7 votes
Accepted

Gravity assist as energy source

Yes, you can. It is entirely possible to create tidal power plants, stealing energy from the Earth-Moon system. Eventually this source runs out of energy, but it would be a much longer duration than ...
juhist's user avatar
  • 5,114
6 votes

Anything similar to GravityLight that can be readily purchased?

The big advantage of GravityLight is that you can pull the weight once and then you have electricity for a relatively long period (I read somewhere it's 30 minutes). This is ideal when you need to ...
THelper's user avatar
  • 14.5k
6 votes

Is Tesla Powerwall a good investment?

No it is not. Your calculations of 13year ROI is based on the assumption that charging the power wall is free during the day time. It is not. Depending on your locale, either you need to factor in ...
Aron's user avatar
  • 380
5 votes

Is 3 phase electrical generation more efficient to utilize than single phase?

I'm going to assume you'e in the USA since you're using Imperial units. 1) Is 3 phase power more efficient to generate/use? In bulk, yes. Three phase (or sometimes 6 phase/3 phase 220V in low-...
Móż's user avatar
  • 3,935
5 votes

Being a sustainable Digital Nomad in a Van - First Steps

Three routes: A: Your van has all your worldly possessions. B: In addition you have a place you can store stuff. C: Use a car towable R.V. A: Everything is in your van. Consider removing the ...
Sherwood Botsford's user avatar
5 votes
Accepted

Cost benefit analysis of a PV array with racking to set optimal angle, vs a larger array

According to the New Zealand Ministry of Business, Innovation, and Employment (pdf), the average home in New Zealand uses 7,046 kWh per year, and pays a rate of $0.2879/kWh (NZD). I used this as a ...
LShaver's user avatar
  • 11.9k
5 votes

Why does wind just track the economy

It doesn't. Assuming you're referring to wind capacity additions, it most closely tracks the political winds in the U.S., in the form of the Production Tax Credit (PTC), a federal incentive program ...
LShaver's user avatar
  • 11.9k
5 votes
Accepted

What is the energy payback time of portable solar panels, in hours?

Given that static, thin-film photovoltaic panels, exposed to the sun all day every day, might pay themselves off in 3 years (according to NREL in 2004), there is an extremely high probability that a ...
Tim's user avatar
  • 2,844
5 votes
Accepted

Will a warmer climate reduce energy demand and increase solar PV production?

tl;dr -- For the west coast of the U.S., a 20% decrease in heating demand and 18% increase in cooling demand results in a 5% reduction in carbon emissions from electricity and natural gas usage Here'...
LShaver's user avatar
  • 11.9k
5 votes

Will a warmer climate reduce energy demand and increase solar PV production?

Wouldn't it therefore be better to have a small rise in global temperature? No. The radiative forcing by carbon dioxide does not increase solar radiation that can be captured by solar cells. The ...
juhist's user avatar
  • 5,114
5 votes
Accepted

What quantity of basalt would power NYC with power for a day?

Engineering Toolbox gives the specific heat capacity of rock as 0.84 kJ/kg.K. Let's work with 40 TJ = 4 × 1013 J = 4 × 1010 kJ. Let's say we could operate with rock starting at 600°C and ending at ...
Transistor's user avatar
4 votes

What is the least environmentally damaging way to start a fire?

I think Fire Pistons offer probably the best balance of features. Basically little more than a piston inside a cylinder which, when struck, compresses and heats the air inside the cylinder to such an ...
Tim's user avatar
  • 2,844
4 votes

How to log wind statistics data

Firstly, if it's rooftop wind you're asking about, then that's easy: it's not worth it - the air's too turbulent. But if it's a pole-mounted turbine that you're considering, then talk to a supplier ...
410 gone's user avatar
  • 14.7k
4 votes

What is the most sustainable way of making coffee?

TL;DR Get your coffee beans with rainforest alliance certification Drink it black or with non-dairy whiteners Full answer: I think the points you mention are relatively trivial compared to the big ...
Dave's user avatar
  • 348
4 votes

How can I find out what a reasonable rate for installed solar is?

As with many purchases, the most straightforward route is to get quotes from 3 completely separate suppliers. There isn't a simple rule for establishing what a reasonable rate is, because every ...
410 gone's user avatar
  • 14.7k
4 votes

Will customer preference drive adoption of energy storage the same way as EVs and solar power?

Customer preference has been crucial at the start of adoption. Early adopters are driven more by non-financial features than by price. However, those early adopters only take a market so far. At the ...
410 gone's user avatar
  • 14.7k
4 votes
Accepted

What capacity solar system is required for new homes under the California 2019 Building Energy Efficiency Standards (Title 24)?

From Greentech Media's recent article, Everything You Need to Know About California’s New Solar Roof Mandate: The solar mandate will be climate zone-specific and based on the floor area of the ...
LShaver's user avatar
  • 11.9k

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