9

A related question was asked on SE Skeptics - Is this tealight-flowerpot heater more efficient than just tealights? In the third answer, it is claimed the heat produced by one tea light candle is 0.75 MJ per candle. Where I live, one of the domestic gas suppliers sells gas for 2.78 cents per MJ. The energy value of the gas is 38.713 MJ per cubic metre of ...


7

It depends. It is possible to farm wood sustainably, or unsustainably. Both ways happen now. It is possible to use wood pellets for energy while trapping particulate matter and other non-GHG pollutants. This sometimes happens, and sometimes it doesn't. It is possible to dispose of the resulting post-combustion products in a way that returns the nutrients ...


7

To encourage people to not use of purchase cars develop a public transportation system that is easily accessible by the to public and caters to the needs of the public so that people will use it. Additionally, the energy source for the public transport system must be electricity. Anything that is combustible, even bio fuels, will maintain a certain level of ...


5

Several reasons come to mind. 1. Population density Air pollution is mostly caused by people and the more people live together in a particular area the higher the air pollution generally is. If people are spread more evenly over an area, so is the pollution which means that overall pollution levels are lower. Both China and India have several cities in ...


5

You can use scrubbers to remove NO2 (or better NOX) and SO2 from exhaust gas emissions. Scrubbers are used in large industrial facilities, power plants, and large ships to clean-up the exhaust gas emissions -- mainly in order to comply with emission thresholds. They are not applied in small-scale combustion facilities such as cars or residential heating ...


5

Generally, the situation is becoming less sustainable. The demand for large scale electricity production with wood pellets is rising faster than their production, and ('fresh') trees are being used in their entirety for the production of pellets. Calculate the energy required for that production + worldwide transport and any ecological advantage quickly ...


4

Time span. Most of the others are short term. CO2 ultimately depends on the rate biomass increases, and the speed it mixes into the deep ocean. Processes that take very long periods (thousands of years) Methane and NOx both have half lives in the decades range. So you see CO2e of 20 on a short period (couple of decades) down to 7 over a longer period (...


4

Plant a lot of trees -- assuming you mean partciulate pollution: See for example Estimating the removal of atmospheric particulate pollution by the urban tree canopy of London, under current and future environments, Tallis et al. 2011


4

Although this may not be a direct answer to the question "Why is Delhi the most air-polluted city of the world?" I want to go against the statement that Delhi is the most polluted city since there are a lot of ways to measure this. The USA today article gives a list of "the world cities with highest pollution levels" ranked on "pollution level". Actually ...


3

This brochure of the European Environmental Bureau gives 12 good tips to reduce air pollution in a city. Here a summary and some extra information I added: Create Low Emission Zones (LEZ): charge or prohibit vehicles that do not comply with certain emission requirements. This is already done in for example London, and Berlin. In Madrid they propose to do ...


3

Delhi has acute pollution issues once a year during the time farmers around Delhi burn the waste after the crop has been harvested, this combined with adverse wind directions or weather conditions makes the problem worse. The major part of the problem come from outside Delhi rather than within Delhi, banning stubble burning would and should IMO to a large ...


2

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 ...


2

Idling is particularly bad for NO2 emissions, which are a major concern for air quality. Here's an old paper showing that an idling engine emits more NO2 than one driving at 40 km/h, despite emitting less NO; NO2 is much worse for human health. More recent studies that I've found don't change the conclusion. At a junction near me there's currently an ...


1

A car stationary but left running (idling) will cause pollution in that specific location; start stop technology could avoid the pollution responsible for idling. Here I will concentrate not on the global impact of the pollution but at the localised affected area. The differing scenarios are important to understand how much of an effect start-stop will ...


1

Just found a patent for this: https://www.google.com/patents/US20070154374 Method for removing sulfur dioxide and other acid gases, mercury, and nitrogen oxides from a gas stream with the optional production of ammonia based fertilizers


1

It's phenomenally complicated, poorly understood, and very difficult to model. It depends on the layout of buildings, where and when emissions happen, what the local winds are, and what's happening upwind. It's all a bunch of numerical approximations (so much turbulence, so no analytic closed-form solution), and very expensive to get a snapshot of the ...


1

I think biofuels are extremely destructive to the planet due the the vast amounts of land required to produce a small amount of energy. http://reports.climatecentral.org/pulp-fiction/2/ http://physics.ucsd.edu/do-the-math/2011/11/the-biofuel-grind/


Only top voted, non community-wiki answers of a minimum length are eligible