You are not buying green, or really any, electrons!
Note: This is an updated version of a post originally published in 2013.
How do you envision our electric grid works? It is probably that electricity, in the form of electrons, moves along wires from power plants to your office building, new electric car, and computer screen. This image is how almost everyone conceives of their consumption of electrical energy purchased from a utility company. But I am here to tell you that this image is factually wrong.
This belief produces a vision of electrons flowing through the wires of the electric power grid as if they are liquid in a pipeline. This belief also suggests that electrons behave like molecules and that we can then apply simple mass balance accounting — meaning that electrons into the grid equal electrons out. This depiction is repeated endlessly in the justification for voluntary green power markets that claim to substitute for the tracing of electrons from a wind turbine, through the grid, to a specific consumer. And so companies can then justify the need and use of illusory financial instruments like Renewable Energy Certificates (RECs) and Guarantees of Origin (GOs) as a substitute for electron tracking. Indeed, it is hard to find a reference on the topic of voluntary green power markets or reporting of corporate indirect (Scope 2) greenhouse gas (GHG) emissions that does not lean on or allude to this portrayal of the physics of electricity.
For those of you that have been long-time readers, you may remember I addressed this fallacy back in 2013. Unfortunately, the error is still pervasive in corporate GHG reporting and voluntary green power marketing.
First, let’s start with the basics. Electricity generators are connected to wires and other equipment (e.g., circuit breakers) that make up a transmission and distribution grid for electrical energy. But these generators do not “produce” electrons that flow through these wires that then reach your house or factory to offload energy into your devices. Physical electrons do exist in these wires, as they do in all matter. And these electrons (e.g., in atoms of copper or aluminum in the wires) do not sit still. They drift back and forth within the wires, but they do so at a velocity of roughly 1 meter per hour—a slow snail’s pace. This movement is important to the functionality of the grid but not what is conveying electrical energy. Instead, the electrical energy is in the electric field that propagates at the speed of light from the generators to all the devices plugged into an electrical outlet. And, prepare for the foundational shift in understanding electricity, this propagation does not even occur along the path of the grid’s wires. Luckily, you no longer need to rely on me to explain further how to correctly understand the physics of electricity. Like everything these days, there is a handy YouTube video to recommend on the subject. Take a look at this two-part explanation and then come back.
Portions of an electric field are not individually identifiable. There is just more or less total field in any given place. Everything physically connected and in proximity to the wires is contributing to the field. The consequence of this fact is that on a grid it is impossible for a single generator to supply electricity to a specific consumer. All that generators and grid operators can do is toss more or less energy onto the grid at different locations and let everyone collectively tap into the resulting electric field. And many things can interact with the magnetic field that corresponds to this electric field (as described in the YouTube videos).
This lesson in the physics of electromagnetism is relevant to GHG emissions accounting because the oversimplified and mistaken “electrons flowing in wires” mental model that so many believe has reinforced an inappropriate framing of a key question. The question concerns whether we can attribute or allocate generator-specific electricity consumption and account for indirect emissions from electricity consumption to entities.
Although the first law of thermodynamics does hold (i.e., total energy is conserved) for any electric power grid, this law does not justify applying conservation of mass framing to this question. A conservation of mass model would view the system as a bunch of generators contributing to a pool of electrons which then mixes and flows down wires and is “sucked out”—as if with a straw— by each company’s consumption. But as mentioned earlier, this analogy is the wrong way to think about it. There is no imaginary conservation of “electrical mass.” Instead, energy enters and leaves the system through many different routes in the form of both work and heat (e.g., line losses) and is affected by many different variables such as temperature, material properties, and interference by other electromagnetic sources like transformers.
At this point, you might find yourself nodding, while at the same time asking whether any of what I am saying really matters. After all, science is often simplified for policymaking. And that while the mental model used to justify voluntary green power purchasing claims may not meet the muster of an academic physicist, it is “close enough” to justify the status quo in GHG accounting. Further, transmission and distribution line losses in most places are small (~7-10%). So, what is wrong with ignoring the actual physics of electricity and bypassing the complexities of electromagnetics?
In general, I argue that basing our GHG accounting protocols and methods on an erroneous understanding of science leads to poor accounting rules, which in turn leads to ill-fitting and ineffective policies. Case and point, the supposition that every MWh of electricity is fungible with any other regardless of when or where it was added to the grid. The elaboration of this concept is that this pool of “electrons” can just be added up over a year and their “ownership” allocated to individual consumers, ignoring the realities of space and time and other variables. To a allow a buyer of RECs to claim the wind power electrons and leave everyone else with the coal power plant’s electrons is to buy into this flawed understanding.
The underlying truth in our mental models of the world matters. As GHG professionals, if we want to establish a reputation of technical credibility, we must ground our reasoning and GHG accounting frameworks on a sound technical understanding of the mechanics leading to emissions. In implementing climate programs, we face enough adversity as it is. We don’t need scientists telling us we are getting the basic physics wrong. If we want to assume a simplified mental model of the scientifically proven mechanics, then we should make our simplifying assumptions explicit and transparent. Quite simply, the way the policy tool that is RECs or GOs is used to make claims of zero-emissions electricity is divorced from physical reality.
So, the next time you hear someone talk about electricity or electrons flowing down a wire you can diplomatically intervene and correct them. You may risk sounding a bit pretentious, but you will have taken a baby step to elevate the scientific reputation of our profession in the process.
Lastly, I recognize that this post is missing a closing paragraph providing the GHG accounting solution that gets the physics of electricity correct. Instead, I will point you to a new FAQ on green power and GHG accounting. We are also working on a broader theoretical reassessment of attributional GHG accounting that will deconstruct the broader challenges of introducing market-based accounting approaches to physical GHG inventories. Stay tuned to the GHGMI newsletter for these updates.
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 For example see the GHG Protocol Corporate Accounting and Reporting Standard, page 61.
Cover image courtesy of Veritasium – screenshot from this video.
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