Comparison of Lifecycle Greenhouse Gas Emissions of Various Electricity Generation Sources


The following is excerpted from an email conversation on the Baucus proposal. My engineer friend emailed:

This one caught my eye: “…the bill would take the entire life-cycle into account when judging the fuel.” Ha, does anyone really know how much energy is required to produce that gallon of gasoline, 

Good question, how do we know the life-cycle GHG emissions? Fortunately there are a lot of Life Cycle Analysis studies (LCA) published – it is the bread and butter of the energy business. I am aware of a number of those relevant to electricity generation (not so much those in the transport sector). E.g., this is a good resource because it is a meta-study of a range of LCA by universities, government agencies and industry-associations: Comparison of Lifecycle Greenhouse Gas Emissions of Various Electricity Generation Sources. The chart above summarizes the results of that WNA meta-study.

especially if the base material comes from tar sands?

I’ve not read any of the LCA studies on tar sands. But Mr. Google finds this meta-study of thirteen studies that looks credible: Understanding the Canadian oil sands industry’s greenhouse gas emissions

Off the cuff I wouldn’t expect a lot of precision to be so critical for tar sands because they are so off scale no sane formula would incentivize their production. The LCA for tarsands oil & gas varies due to energy sources, local infrastructure and energy supplies. E.g., if instead of natural gas as the heat source, you installed SMRs (small modular reactors) at the site to generate process heat, then the carbon emissions from the natural gas feedstock would go away. Even using nuclear process heat tar sands would not be competitive carbon-wise with conventional oil.

As far as I know, no oil company has published the calculation mapping the full energy content of just the refining process, never mind all the ancillary energy costs such as transportation/distribution… ignoring the energy content of the capital investment in the first place…

Refining is a well-understood and researched technology. The purpose of LCA is to capture everything from mining/extraction to construction to operating to decommissioning of plant. It is a lot of work, and not trivial to understand the results. And not trivial to assess the validity of a specific methodology. For me that means I need to assess whether the people are trustworthy. I have read through all the detail of one of the Sydney University studies – they could hide dozens of errors that I will not find because I’m not motivated to audit their work. Instead I focus on auditing the source of the product – the people or the institution. The LCA work from IEA, US EIA, OECD, IAEA is excellent.

Still there are scope differences – e.g., coal is never charged with waste management cost (waste is just piled into mountains next to plant, and of course dumped into the atmosphere). Similarly wind and solar are never properly charged for the cost of intermittency. In contrast the LCA for nuclear is charged for every gram of “waste”, even though roughly 98% of the “waste” is actually high value fuel for fast reactors.

Sadly, publishing and interpreting life cycle analysis is not good for TV ratings. Not good for media ratings in general.