Where do greenhouse gasses come from? (chapter 1)
The original article was published on my blog here:
This is the first instalment in a series of articles in which I would like to give a look into the topic of: “who is emitting green house gasses?”. Why is this important? Because the reduction of greenhouse gas, whatever your position might be on the topic and whichever might be your political extraction, is going to happen and it is not going to be cheap.?And how those costs are allocated is going to ultimately make or break the effort to reduce emissions.
Also, being climate a fairly complicated matter, I believe that there is a dire need to shed some light on the underlying data on emissions.
This exercise has a two-fold aim: to present in laymen terms the facts and to cut through the ideological positions that, on a regular basis, present this or that industry as the straw-man, the bad actor that sabotage the carbon-free future that we all need.
I apologize, in the beginning, for some freedom in choosing language and in some language imprecisions I will inevitably be guilty of. This is by no means a scientific work. Hence, simplicity of exposure will inevitably take precedence on rigorous terminology.
So let’s dive into the topic.
As the IPCC report plainly points out, we desperately need to reduce CO2 emissions, and not only those.(there is also methane, for example). Fine, I wholeheartedly agree.
I am NOT going to dwell into which country is the worst offender, as this is a very politically charged debate, (China, no India, no US etc.). I would like to give a look on the emission by source ie sector.
And here things get interesting.
According to this source https://ourworldindata.org/emissions-by-sector, 73.2% of all emissions are generated by Energy production and heating. 18.2% (in CO2 equivalent, as there is also a lot of methane) are generated by agriculture, and 3.2% by waste and other residual sources.
Fine. Hence 90% of all emission is generated by Energy production and Agriculture. So it makes logical sense to start the analysis here. Not an easy task, but we need to start somewhere.
If we drill down further into the 73.2% of industrial and energy production, we find out that the following breakdown, as of 2019, was:
·???????24.2% is direct industrial use of energy, of which the relative majority is due to Steel and metallurgic industry (around 7.2%, million of tons plus or minus)
·???????16.2% is transportation of which the majority is road transportation (both passenger and freight) at around 11.9%, Aviation 1.9%, Shipping 1.2% Rail 0.4% and pipeline 0.3%.
·???????17.5% is due to Energy in use in building (10.9% residential, 6.6% commercial buildings)
·???????7.8% is unallocated fuel combustion: emissions from other form of energy production such as biomass or nuclear (nuclear, contrary to popular belief, is not emission-free)
·???????5.8% is fugitive emissions from energy production: mostly gaseous (methane being the worst offender) leakage from extraction and transport of liquid hydrocarbons and coal
·???????Energy use in Agriculture and fishing industries, such as fuel usage for agriculture machinery use (this is not included in direct emissions in agriculture)
So this is the lion’s share, of the GHG emission by sector. We will look at the other parts of the equation (Agriculture and direct industrial processes) in later chapters.
The first consideration is that, at the heart of the problem, is energy itself. The greenhouse gas equation is essentially an energy production equation. And this is something we can further elaborate by looking at some of the offenders.
For a start something that has always puzzled me, is the excessive focus, relative to the size of emissions, on certain usages.
领英推荐
At the end of the day, what matters in terms of climate change is the total amount of emissions, rather than emissions per capita or other relative measures.
Hence I would expect the biggest focus being put on issues like energy usage in buildings and or in steel production. Yet, for some interesting reasons(which I believe being mostly political) the focus on the media is very high elsewhere
For example: aviation
Aviation counts for a relative small percentage of emissions. 1.9% of total according to my source. This is significant, yet far too small to make an actual difference in terms of GHG reductions. At the end of the day, if we would stop air travel altogether, we would still need to contend with 92% of the remaining emissions. Probably the issue of aviation emissions could be well solved with a carbon pricing scheme, rather than?a blunt taxation or by imposing caps on travel.
However in the media, from time to time, air travel bashing gains tractions (the case of Greta Thurnberg the first that comes to mind). This concentration on such a relative small portion of emissions is baffling unless we assume that this is a clear case of “virtue signalling”: air travel is mostly leisure hence god forbids people do something to enjoy themselves. It’s true to a point that leisure travel is somewhat superfluous, however tourism accounts for an important chunk of GDP mostly in developing countries (which, due to geographical reasons, are practically only reachable via air travel). So maybe this seemingly superfluous activity has in fact a certain importance to the livelihood of many people around the world. Does it deserve such a bad rep? In my view No.
What about electric cars?
Electric cars seem to be the future, the bright solution that will carry us to an environmentally friendly carbon free world. Except things are a bit more complicated than that, as usual.
If we consider in terms of emissions, road transport accounts for 11.9% of the global emissions. Hence going electric would single-handedly reduce emission by more than a tenth, right?
No. This is not correct. We are not touching here the very important topic of the manufacturing and mining of all the metals needed to power electric vehicles. We are just talking about emission connected with the operation of endothermic engines. ?
If we consider the engine as a power generator (which is essentially what it is) we would need to switch from a local source of energy to a remote source. Hence to replace the power generated by cars and trucks engine, we would need to add enough power generations. Not the same amount of power mind you, there would still be an advantage, even if we would generate all of the electricity by burning fossil fuels. Why? Because the endothermic engine has a theoretical efficiency of around 0.4 (bit higher for diesel, bit lower for gasoline). The efficiency of an electric motor is in fact much higher, something in the 0.9 region, everything considered. Hence for each Kwh of energy produced by a gasoline engine, we need to burn almost 60% more. So even assuming that all the energy is generated via fossil fuels, there is still a substantial gain to be had, bigger than eliminating air travel, most likely.
Now, that said, as usual, things are a bit more complicated. Whereas for passenger cars the technology makes it already viable to compare a gas engine with an electric one, for road freight the technology, and power needed, seems still pretty far to be commercially viable. Truth to be told, 60% of transport emissions come from passenger cars and personal transportation, so already addressing that would be a good step. But nowhere close as the hype that this vehicles receive on media.
hen we are talking about passenger cars, we need as well to consider the issue of the developing world, where the car fleet is usually old and in variable state of decay, making the actual energy efficiency much lower than the aforementioned 0.4. Already replacing this junk with more modern vehicles, would probably make a dent not only in GHG emissions, but also in other pollutants (in a country like Nigeria, for example, the cars and ubiquitous minibuses that are vital to the country transport needs and that make the air of places like Lagos unbreathable are all old Japanese and European used cars in various state of disrepair). Also it is much easier to keep a big power plant in good state of maintenance and hence with minimal emissions, than a few million private vehicles.
As a matter of fact, the real benefit of electrifying the transport, is more local, as in the reduction of various pollutants such as NOx and particulates than GHGs.
This is by no mean a small feat, and one well worth tackling. But, in climate terms, is not so relevant.
And the reduction would be the bigger, the higher proportion of electricity is generated by cleaner sources, being it renewables or, at a minimum, natural gas.
And, of course, we need a way to transport this energy. The investment needed is gargantuan.
So in terms of how high is the cost of the transition compared to the benefit in terms of GHG reduction, road transport might not be as good as the hype around Tesla et al would make you think
Am I advocating not to transition towards better alternative than fossil fuel powered transport?
No, I am all for it. Cars and lorries are dirty, noisy, old tech things. However I believe that any benefit shall be always factually weighted against its costs.
And when we look at the numbers involved, even superficially as I did in this blog post, ?there seem to be more compelling places to start from.
As a matter of fact though, the decisions are a matter of policy, but policy shall be grounded in facts. Topics like this are way too important to be left to ideologues and demagogues.
Next up: Energy use in buildings.