In California, there are many natural gas vehicle options that are being promoted as more sustainable than regular gasoline vehicles. Natural gas is a by product of the natural processes that create oil. I would think that should everyone change to use NG then we would just be creating new issues that would replace the issues we have with the use of gasoline. How is using natural gas more sustainable than gasoline?
The question starts with a premise that sustainability is relative. Natural gas is natural resource just like petroleum. They arise from similar processes and are generally found together although the ratios vary. Natural gas (particularly methane) is also produced by living organisms. As a natural resource, 'pure' sustainability would require you to consume at a rate less than it's produced by nature. Since petroleum and natural gas for the most part produced on geologic timescale, they would not generally be considered sustainable. However if you take the premise that sustainable is 'relative' than you could compare and contrast different non-renewable resources for their relative sustainability. For example, it appears new cheaper supplies of natural gas in the United States have led to reduced use of coal for producing electricity (ref).
Natural gas is considered cleaner burning than coal so that is generally seen as better for the environment. The WSJ article above quotes the Sierra Club president with:
Here’s our position on gas: it burns more cleanly than coal or oil, but it is not clean. When coal plants are retired (or new ones are not built), we believe that the right “loading order” for new energy sources would be: energy conservation and efficiency, solar and wind (preferring distributed over large-scale), geothermal and perhaps some wave energy, then natural gas to fill in the rest.
Whether 'better for environment' is a sustainability topic is probably a separate question for the meta site. Independent of the environmental issue, natural gas vs gasoline vs coal vs renewable resources is a relative. My guess is that it would be a similar list to the Sierra Club list above. However, to do it correctly, you really would need to get to specific sources. One measure might be the energy needed to create a unit of energy. This reference compares petroleum from sand oil vs others and takes into account mining, extraction, transportation, and refining. I could not find a source but my guess would be that on average it would be less for natural gas than petroleum. However, just like in petroleum, it might be dependent on the source of the natural gas.
Natural gas is not sustainable - it is a finite resource.
However, among fossile fuels natural has one advantage: Lowest CO2 emissions per energy content - because with Methane (the main component) the biggest part of the calorific value comes from the hydrogen.
Natural gas used to be flared off if extracted together with oil (because of the handling diffculties), using it instead adds little pollution.
I don't know if natural gas extraction and handling is significantly more or less pollution or energy intensive than natural gas.
In terms of NOx emissions, natural gas fired motors are not worse than gasoline/diesel fired ones and there' no inherent reason why they should be.
To sum it up, natural gas is a finite resource, there's no way to extract it in a sustainable manner. On the pollution side it may be the cleanest fossile fuel.
It's pure greenwash. Natural gas is not sustainable - it's the direct depletion of natural resources.
It is possible to generate methane (the predominant energy carrier within natural gas) sustainably, e.g. from biomass in anaerobic digesters; or synthetically, powered by renewable energy. However, unless you have a supplier that guarantees sustainable sourcing, then the methane gas you're getting is not sustainable.
There are four fatal flaws in the sustainability, any one of which in its own right makes natural gas unsustainable:
- Natural gas is a finite resource that is depleted by extraction and combustion.
- Extracting the natural gas is environmentally destructive around the area of extraction: either through the collateral damage at oil wells, or the contamination of fresh-water supplies, and earthquake damage at shale gas sites.
- Burning natural gas in vehicles creates local pollution including NOx and CO2 at rates that raise background levels of those pollutants, damaging economic productivity and public health.
- The whole supply chain for natural gas from extraction to combustion releases global pollutants: methane and CO2, and the overwhelming body of evidence is that these are leading us to catastrophic climate change. No sane, scientifically literate person honestly disputes that anthropogenic emissions exceed the rate at which the world sinks these emissions; hence the laws of physics tell us that global heat content is rising.
There are a couple reasons I would consider natural gas to be more sustainable than gasoline.
The first is that it is quite possible to produce a significant amount of a workalike using sources we currently discard. Sewage treatment facilities could be turned into methane factories if we wanted, for example, and the same goes with manure from farms and the like. Coming up with a sustainable workalike for gasoline is much harder, particularly if we want to use waste products to do it. For this reason natural gas poses less of a sustainability problem than petroleum. In combination with reduced consumption, this may be a step in the right direction.
However it isn't enough by itself to get there. The US consumes about as much oil as Saudi Arabia produces in each of three areas every year: agriculture, transportation, and everything else (this means we consume almost as much as the top three oil producing nations make combined).
I think the technology is more sustainable in the sense that if we use a lot less of it we can probably make sustainable sources of energy work instead.
I think then the key is not that natural gas is more sustainable but rather that it paves the way for some possibilities of more sustainable approaches, but these too must depend on reduced consumption and substituting one fossil fuel for another won't really have any positive impact (the coal will all be burned eventually and so will the oil).
A late-breaking development in this debate is recent data on leakage in natural gas production and distribution systems.
A group of researchers from universities, laboratories, and government labs around the U.S. published an article in Science earlier this year indicating that the magnitude of methane leaks from natural gas infrastructure has been underestimated for years. The article, "Assessment of methane emissions from the U.S. oil and gas supply chain", can be viewed in manuscript form here. Phys.org has a good summary. Here's the most significant finding (emphasis added):
[R]esearchers found most of the emissions came from leaks, equipment malfunctions and other "abnormal" operating conditions. The climate impact of these leaks in 2015 was roughly the same as the climate impact of carbon dioxide emissions from all U.S. coal-fired power plants operating in 2015, they found.
The reason for this massive impact, and why leakage is such a concern, is that methane as a greenhouse gas is 34 times more potent than CO2 on a 100-year timescale. Another reason for concern, and cause for some optimism, is that the leaks represent loss of up to $2 billion a year -- revenue which oil and gas companies will theoretically be interested in regaining.
Gasoline/petrol doesn't suffer from this issue because it is a liquid at room temperature, and doesn't need to be pressurized. Knowing this, it's hard to say that natural gas as a transportation fuel is any better than gasoline, even if it does burn "cleaner."
Carbon matter decomposes into carbon dioxide (CO2) in the presence of oxygen (aerobic) and decomposes into methane (CH4) without the presence of oxygen (anaerobic). It is interesting to study the difference between CO2 and CH4 as they relate to greenhouse effect. My research indicates that CO2 is a better greenhouse gas than CH4. And CH4 turns into CO2 when it is burned. It seems that it is better to burn CH4 and prevent it from escaping into the atmosphere.
The decomposition process occurs all of the time. Imagine that we intend to decrease aerobic decomposition and increase anaerobic decomposition while capturing all of the methane from our intentional anaerobic decomposition. This practice has the potential to be more sustainable because we are now extracting fuel from the decomposition process.
My vision of a sustainable lifestyle includes capturing and using methane from biological anaerobic decomposition systems (feces). I also believe we should be collecting carbon matter and extracting CH4 from it. Help prevent forest fires. Capture CH4 through anaerobic decomposition. And get your energy from your local "waste" processing center. Note that "waste" is all "decomposing carbon matter".