Where Greenhouse Gases Come From and Where They Are Going

In 1898, Captain Matthew Henry Phineas Riall Sankey published a diagram demonstrating the thermal efficiency of a steam engine using arrows with widths proportional to heat loss. Engineers and scientists have been using them ever since to demonstrate energy flows, inputs, and outputs. Treehugger publishes "Lessons from the Lawrence Livermore National Laboratory" with Sankey charts showing American data every year.

The World Resources Institute (WRI) also produces a Sankey chart showing the world's energy flows, and it has just updated the chart using data from the International Energy Agency. There are lessons to be learned from their latest charts as well.

Conceptually, this is set up very differently than the Livermore charts, which have the inputs—the energy sources—on the left and the outputs in useful and rejected energy on the right. Here, it is the sector on the left, the activity in the middle, and the greenhouse gas on the right. You don't need a Sankey chart to tell you that energy for manufacturing and construction is going to go into buildings. One website devoted to the subject says, "A Sankey Diagram says more than 1,000 pie charts," but I am not sure that this one does.

But it is telling us which sectors are producing what gases in what proportions. Unsurprisingly, road transportation is the single biggest activity producing carbon dioxide at 12.6%. Operating buildings come next, with residential and commercial buildings together totaling 18%.

This doesn't include actually making the buildings or the cars, which would add cement, iron, steel, and a big chunk of chemicals and petrochemicals to those categories. It is my endless frustration while looking at these; iron, steel, cement and chemicals are not end uses. Bridges, buildings, and cars are.

Another big number is the 6.8% labeled "fugitive emissions." It's bigger than steel, but what is it? A report from Climate Chance, titled "Fugitive emissions: a blind spot in the fight against climate change," says, "They may be caused by the production, processing, transmission, storage and use of fuels and include combustion emissions only if they do not meet production needs." The vast majority of them come from the flaring or leakage of fossil gas, but also from oil wells, transporting gas, and during the refining of petroleum products.

Another source is coal; methane often escapes from coal seams during excavation and even during transportation. "In 2016, fugitive emissions reported by industrialised countries were 1.33 billion tonnes CO2 equivalent compared to 1.57 in 1990, about 85% of which were from the hydrocarbons sector, 15% from coal and a fraction from industry (UNFCCC GHG data)."

The authors conclude:

"Fugitive emissions are one of the blind spots in combating climate change. Much work remains to be done for better evaluation and reduction of fugitive emissions. The available information suggests that the extraction and, to a lesser extent, the processing and transportation of fossil fuels is the main source of fugitive emissions. Responsibility for their reduction therefore rests first and foremost in the oil, gas and coal companies."

These emissions are all CH4, aka methane, which has 86 times the warming effect of CO2. This is not usually counted against natural gas when they say that it is cleaner than other fossil fuels, but it should be. According to a study quoted in Desmog, if you include the fugitive emissions, "The greenhouse gas footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon, but particularly so over 20 years."

The WRI notes that industrial emissions tripled since 1990. "The growth in industrial emissions stems not only from CO2 emissions, but also the increased use of refrigeration and air conditioning. These activities produce hydrofluorocarbons (HFCs), which are potent greenhouse gases. Increased travel by automobiles is the predominant reason transportation emissions are on the rise."

One could dig down into all the carbon flows, but really, the answers to our carbon emissions problems smack you in the face every time you look at these Sankey diagrams: Stop building so many crappy buildings, stop driving so many cars, and stop eating so much red meat. The rest is commentary.