Questions tagged [fuel-efficiency]

Reducing the amount of fuel used to accomplish a given amount of work, such as in a vehicle or generator.

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Are fuel cell electricity generators a sustainable way of making electricity?

Since 75% of the universe is hydrogen, would it be sustainable to use fuel cell electricity generators? Fossil fuel generators won't last forever, because there is not an endless supply of fossil ...
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EU Real Driving Emissions testing (RDE) - does it factor in real driver behaviour and the inefficient driving habits they often exhibit?

Drivers often floor it at the lights, a large number switch off their start/stop systems, they might idle for an hour to listen to the radio, exceed the speed limit and exhibit other inefficient ...
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Why are new cars being built in the UK / europe without Start-Stop technology when it seems it can lower pollution?

Everything I have read online seems to indicate that start / stop technology reduces air pollution, is (marginally) better for the engine, reduces emissions and is more economical (link1, link2, link3)...
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Carbon emissions from Ethanol car fuel

I understand that much of the low CO2 emissions for ethanol as vehicle fuel are related to its entire lifecycle (CO2 is sequestrated when the crop is grown and released when it combusts so it is ...
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1answer
62 views

To what extent do CO2 emissions from motor vehicles vary?

Do the CO2 emissions from petrol / gas vehicles vary depending on driving style? Are emissions a function of the engine type or the fuel efficiency? If a motor car is rated at 105 g/km, but it is ...
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Does a short-term shut down of a coal plant cause more CO2 emissions than keeping it running?

According to this article from Reuters, it takes up to eight hours for a coal plant to reach maximum generation. This means that four up to eight hours after it starts up, the plant is burning coal at ...
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Is flying more sustainable than taking the train?

This paper argues that flying and taking the train compares in terms of energy - can this really be true? I am thinking that energy is a reasonable measure of sustainability although comparing ...
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329 views

Carbon footprint of CNG vs. Diesel as a vehicle fuel

What is the benefit, in terms of carbon footprint, of replacing a diesel fueled vehicle with an identical one with a CNG engine? I'm not convinced I can simply take the carbon intensities of these ...
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505 views

Water heater vs stovetop: most efficient way to heat water using natural gas?

When I am going to boil a pot of water for cooking, will the total energy consumption be less if I start with hot water from the tap? A few considerations: Both the water heater and the stove burn ...
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1answer
196 views

Does putting an automatic car in neutral when stopped help save petrol?

In Australia, most cars are automatic, and most people stay on "drive" while braking when stopped at a red light (i.e. if they weren't breaking, the car would drive forward). I was wondering if ...
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How to choose a more sustainable vacation option?

Background In general, for a given transportation medium, modes of transport that are more densely populated are more efficient than those that are more sparsely populated. For example, it is not a ...
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Size of wood lot required for cooking/heating (US west coast)?

On the west coast of the US (WA, OR) how many acres of trees would be required to keep a single family home supplied endlessly? If I and my family plant a tree for everyone tree we cut for fuel, how ...
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Is it possible to calculate energy efficiency of a flat by knowing how much energy was consumed for heating?

During 6 days my heating system consumed 11,4 m3 of natural gas keeping its temperature at 20 degrees of Celsius. No human or other energy source (except for refrigerator) was inside the flat at that ...
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How efficient are tiny cars compared to others?

I may be purchasing a new vehicle soon (still doing the whole cost-reward calculations). When looking for a new vehicle fuel efficiency was important to me, both for savings considering how much I ...
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Fuel efficiency when decelerating on a hill

Another efficiency question from me out of curiosity. Let's say that I am driving at a decent efficiency rate (say 40 MPG) and am coming up on a hill, with no cars immediately behind me or traffic ...
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Impact on environment: a million horses vs a million cars

Would commuting on a horse be more eco-friendly? What if there were millions of people did that? Would millions of horses be better than millions of cars?
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Are we running out of fuel?

It's just a matter of time, Peak-Oil will happen. There is no logical argument to assume it will not. We are doing efforts to replace petrol based products with something else, for fuel in combustion ...
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Oxyhydrogen as home heating method

I'm curious about the efficiency of using Oxyhydrogen as a home heating method. Oxyhydrogen can be generated from water. I understand the fact that it takes more energy to generate the oxyhydrogen, ...
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Can alloy wheels (for a car) pay for themselves through fuel savings?

Magnesium alloy wheels (aka mag wheels) are desirable to car enthusiasts due to an increase in performance, but with reduced weight there would also be a fuel saving. Obviously prices and fuel ...
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168 views

Burning wood efficiently via rocket stove

Is burning wood considered sustainable if the efficiency can be improved up to 90% compared to the 50% of conventional burning stoves?
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1answer
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What would be the most sustainable biomass source for (100%) ethanol production?

So I have read that sugar (cane) is way more efficient than corn, (and that Brazil leads the way in taking initiative to actually bother with this advance in biofuels sustainability), and that, based ...
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What is the most environmentally-friendly fuel source (e.g. wood, coal, oils, alcohols) for campfire cooking?

When factors like emissions, renewability, and heat / energy efficiency are all taken into account, what would be the very best fuel source(s) to use for camping cooking, with sustainability and ...
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Is it better to use propane or natural gas as a heating fuel?

Given the choice to adjust a new furnace to either propane or natural gas (?), is one less unsustainable than the other?
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When does using a car's start-stop system become more economical?

In this question it was asked how economic it is to turn your car's engine off when waiting for a traffic light. In the accepted answer it is said that it becomes more economical to turn it off if you ...
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Can chip tuning make a car more fuel-effective?

I'm considering to have my car engine chip tuned. I'd like to increase the fuel efficiency of the engine. Increasing the power of the engine would be only a secondary advantage of doing so. Most of ...
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420 views

Efficiency of car-sized vehicles running on train tracks

New Zealand doesn't have particularly advanced technology for its railroads, but I have seen pickup trucks that have wheels that can run on railroad tracks as well as a separate set of wheels with ...
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What is the fuel-use of an industrial sized diesel-machinery-based composting business?

As I understand it, the bulk compost made by one of our local businesses is produced by using heavy machinery to regularly scoop up and turn the source material and keep it active. How much fossil ...
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How effective is turning a car's engine off while standing at a traffic light?

I know some countries enforce having cars automatically shut down the engine when stopping at a traffic light. How much resources are really saved by this process? Does the car need to be ...
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Are electric cars as environmentally friendly as we think they are?

Given the fact that the average lifetime for a car battery is 3 years and all of the batteries end up at a landfill at the end of their lifetime, how sustainable are electric cars in providing a ...
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Propane vs. Electric vs. Heat Pump

Is there a relatively reliable way to figure out what energy source to go with when upgrading appliances? We need a new hot water heater, for starters. Our current one is propane. Options include ...
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Is my car more sustainable with or without an EGR?

I drive a 2003 Volkswagen Jetta with a 1.9 liter turbo-diesel engine. I often get well over 50mpg on the high way, and I love the fact that I have such a fuel-efficient car that is also fun to drive. ...