13

No. There is no readily available supply of net-positive-energy hydrogen on Earth, where most human power usage takes place. Hydrogen fuel cells may be a useful component of a total energy system but they are not a source of generation capacity. Hydrogen is more like a battery than a supply of energy. Hydrogen can be liberated from water by using energy. ...


10

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 ...


9

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 ...


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 ...


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

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 ...


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

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

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-...


6

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 ...


6

The Umweltbundesamt (sort of German EPA, I figure) recently released a new study on the "Ecologisation of online shopping" - which obviously is in German. Anyway, core findings are that individual shopping using your own car is the worst (CO2-wise) with 600 to 1100 g CO2 (for a 5 km ride to the store), while delivery is better due to optimized ...


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

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

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'...


4

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 ...


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 ...


4

There are a ton of different factors to take into consideration here. Lets make sure we keep net GHGe and tailpipe GHGe separate here. Net GHGe Net GHGe: Since 2015, satellite observation as well as international agriculture reporting data have started to show that the original assumptions surrounding Indirect Land Use Change (ILUC) for generation I and ...


3

Instead of comparing the impact of each travelling modality with 1 traveller, you want to compare modalities per passenger-kilometer or passenger-mile with average load. This means that you divide the total impact by the number of passengers and the distance travelled. Energy efficiency or CO2 emissions is almost always used as a proxy for impact as it is ...


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

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

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

The simple answer is because any feature costs money, so car makers won't include it unless they're forced to. On some models it's available as an option for extra cost - which relies on the purchaser wanting it. On others, where there's no option, it hasn't been designed for that model, so there's design cost as well as per-unit cost to consider. As this ...


3

Under RDE [Real Driving Emissions test], a car is driven on public roads and over a wide range of different conditions..... Conditions include: Low and high altitudes Year-round temperatures Additional vehicle payload Up- and down-hill driving Urban roads (low speed) Rural roads (medium speed) Motorways (high speed) Source: https:/...


3

This is simply a fancily designed chain of cities based on the about 40 years old idea of the "compact city". The idea is to reduce urban sprawl, reduce traffic and improve living conditions. Each link of the chain in itself will be not self-sufficient, but provide all necessary (daily) needs to its inhabitants, including doctors and if not a ...


2

I'm trying this out just now, car in question 1.2 carburetor astra mk 4/ astra g estate/caravan/station. Thus far I seem to be making a saving, (as long as I allow the engine to warm up a little) but it's entirely possible my general fuel conscious driving is making more of a difference than turning off the engine. *related though another matter... ...


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