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I’ve already touched on this topic on the sister SE site once or twice. To summarize what is told there (check for more detail), there would be several considerations as related to energy use and sustainability: Idling in itself wastes fuel for no good reason, and that adds up. In US (country whose residents drive probably more than anyone else on Earth, to ...


25

This is a really big question, and @EnergyNumbers' answer addresses some of it. I'll try to address some more. Battery End-of-Life Your question is obviously referring to standard car batteries, which are used to power the car's starter motor. These are generally lead-acid batteries. A true Electric Vehicle (EV) may have a small battery just like this ...


20

EVs offer some definite advantages, and lots of advantages that depend on the specifics. short answer: yes, it's better than driving a fossil-fuel car. Long answer: it may seem to make less sense if you only consider a very small range of impacts, where all of the costs are visible, but only some of the benefits. Only when you zoom out to the long-term ...


11

There isn't a single reliable way that fits all circumstances. What we can do, is look at some of the factors that influence the pros and cons. Uncertainties within the green electricity tariff If it was absolutely clear that some of the money you spend on electricity goes to increasing the amount of renewable energy going into the grid, then that would ...


9

From the general principles outlined in Sustainable Energy--without the hot air by David J.C. MacKay (http://www.withouthotair.com/c20/page_118.shtml): In short-distance travel with lots of starting and stopping, the energy mainly goes into speeding up the vehicle and its contents. Key strategies for consuming less in this sort of transportation are ...


9

Solar thermal Given your limited criteria, solar thermal is in fact the ideal solution. I assume you say that "[solar] heating is so inefficient and the materials for solar panels introduce a can of worms sustainability", you refer to PhotoVoltaic panels, and not solar concentrators (mirrors and lens), which are silly cheap and sustainable. A large ...


7

I think that you can assume, worst case, that your car will be no worse than the 10-15 seconds break-even given in the linked answer. Since your car is engineered for start-stop, if there are easy improvements to be made to minimize the cost of restarting then the manufacturer may have made them, but in any case it should be no worse than average. The ...


7

OK, one possible setup (and assuming both my math and memory are right, neither of which is certain): Planting Douglas Fir, which is fairly fast growing (one to two feet a year) and a good wood for lumber and for burning, planted around 16'-18' apart (or half that, and thinned as they grow). They become large enough to be commercially valuable at around 30 ...


6

You will always put more energy into generating this gas mixture than you will get back by burning it. The second law of thermodynamics (which for this context can simply be thought of as saying that nothing can be 100% efficient) guarantees that. So rather than using energy to split water to produce gas for burning, you would be better off using that same ...


6

In large numbers, horses are more problematic than cars. According to Eric Morris, in 1898 delegates from around the world gathered to discuss urban planning. The issue they were "desperate" to solve was what to do about horse manure. Rutgers University has a fact sheet about horses and manure. It states that a 1000 lb horse will produce about 9.1 tons of ...


6

There is probably not a lot in the choice but some considerations are listed below. A significant consideration is that while Propane is superior environmentally, individual purchasing decisions are not likely to alter the overall Propane to natural gas mix overall. If users encourage Propane separation because it is popular they effectively degrade the ...


6

Looking through some of your sources and thinking about the problem, it sounds like there isn't necessarily a definite answer, but a set of tradeoffs. NOx is associated with smog and acidification, particulates are related to respiratory health, and fuel efficiency is related to global warming (among other things like cost). This problem would seem to be ...


6

A life cycle assessment of windrow composting systems (pdf here) shows that fuel consumption by machinery to transport and process compost, next to energy consumption, indeed seems to be the main impact factor. In this study 0.005 litre of fuel (diesel) are being used to process¹ one kg of compost. The scale of operations seems to be large with machinery ...


6

I have been using this method for years, on both my Toyota and my Ford Explorer. I save lots of gas, nothing has ever happened to my batteries, and have never had a mechanical problem. You need to use common sense. I typically shut it off when it's a long light and I'm in a long line, railroad crossings, and any other situation where it's going to be at ...


6

According to this answer over on mechanics.SE, below a certain engine RPM, your vehicle automatically disengages the torque converter. That is to say, when stopped, there isn't a fundamental difference between having the transmission in drive or neutral. On the other hand, shifting back and forth each time you're at a stop light does cause a bit of wear, ...


6

I am not able to find any studies comparing the energy consumption. But if we look at a paper investigating emissions directly, which one could argue is an even better proxy for sustainability than energy, it seems that although the emissions from construction for railways is more than twice as large as that from the construction of airports, on a passenger-...


5

I think the main problem is that commuting is almost never "eco-friendly". There's a lot of energy that's needed to carry your behind (and your carriage) from your home to your workplace. I think the most efficient way to commute it is to use public transport, for which the weight-of-vehicle to weight-of-passenger ratio is lowest. For trains, the amount of ...


5

CO2 is produced by burning the carbon in the fuel, so if your driving style causes you to use twice as much fuel, you will produce twice as much CO2. Driving aggressively can have a big impact on fuel consumption. It's hard to quantify, but a 50% increase in fuel consumption and CO2 emissions is certainly possible. Conversely, the CO2 emissions will be ...


4

No, we're not running out of fuel. Peak oil never made sense as a problem, and still doesn't. I know that's an inconvenient truth for anyone who'd vested a lot of time and effort into the question of peak oil; but it doesn't help anyone to continue with a pretense that it's a problem. That's because we can't afford to burn the fossil fuel reserves we do ...


4

A quick look doesn't show a clearcut weight difference. The claim is more for a 'rounder' wheel and a 'stiffer wheel' First order approximation fuel economy depends on the weight of the vehicle, given the same engine. Suppose that your vehicle weighs 1 metric ton -- 1000 kg -- 2200 lbs. Suppose that an alloy wheel was 5 kg lighter. That would be 20 ...


4

I've done this calc for my farm here in Alberta. I know that it takes 5 cords a year to heat my house. The average lifespan of trembling aspen is about 40 years. At that point it's about 40 feet tall, and 8" diameter. The average spacing in my woods is about 10 feet. So 100 ft2 into 40,000 ft2/acre gives me about 400 trees per acre. So with 400 per ...


4

The issue here is using the word "sustainable" as something like "healthy" - the more the better - when it actually refers to a balance between, say, resources used and resources generated. If I buy a plastic thing for putting leftovers in, and then throw it away, that's not sustainable, it will lead to landfills full of plastic. If I fly all over the world ...


3

In the USA the Daimler/Mercedes "Smart" Fortwo car is the obvious choice, rated at 41mpg on the highway. Those look silly but are quite safe and very fuel efficient, as well and being ridiculously easy to park. In parts of Europe it's legal to park them across a roadside car parking space (so you can get two cars into one spot). The efficiency is all-round ...


3

Generally a driver doesn't know the exact angle of the hill at any point in time, nor do they generally know the exact combination of gear and gas-pedal that will be the most efficient. Maybe some day those things become standard features, and maybe the car could even calculate where the top of the hill is and work out how to optimise fuel consumption too. ...


3

Yes. Moz's comment is correct. When burning wood, you are in essence just shortcutting the rot process. Which means that instead of fungi and bacteria and bugs getting lunch, you get warm. These critters have their place, so it's not a good idea to intercept all of the production of a given forest. For this reason a high efficiency stove can be more ...


3

It is appealing to use wind or PV whenever they are available, and to have heating when it is required - and something is required to help those align in time. Using the energy to synthesise storable fuels is one way to do it. However, you need special burners to make the most of burning a mix of hydrogen and oxygen. You need special equipment to store the ...


3

Theory The calculation in the other answer is rather naive. I haven't done the calculation myself, but there are a few things to consider. First of all, lighter wheels mean more than just lower overall vehicle weight. Advantages are: lower overall vehicle weight: lower inertia of the car lower weight of the wheel (rotating part): lower rotational inertia (...


3

Depending on where you are, the natural gas may be mostly propane ;-) The answer from Russel McMahon gives an excellent summary of the chemistry. However, I suspect that the differences there will easily be outweighed by differences in distribution. Since you refer to "natural gas" rather than its specific contents, I assume that you have the option of "...


3

Yes, many tuning stations offer a range of options. The most popular is to offer power upgrades, usually at the expense of fuel economy, for example improving fuel/air/compression balance at low speeds for high acceleration, or altering tuning at high revs to increase top speed. One of the tuning techniques to improve fuel consumption is to alter your car'...


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