Categories
Interesting Questions

What is the best energy source?

Since our worldwide energy consumption continues to grow each year1, it is not a mystery that energy sources are a constant topic of debate. I regularly find myself discussing the subject with people on both sides of the political divide. Yet, I have only recently realized that I have been discussing the subject without really having any knowledge in the area. Like you, I have heard different things from different sources – often contradicting each other – leaving me confused about what is true. Who are we supposed to believe?

Finally, I decided that it was time to consult the scientific literature, as I should have done a long time ago. With a topic this complex, however, it took me a few days of initial research to figure out what energy sources to compare and which dimensions to compare them across. It quickly became obvious that the scope needed to be limited to the most important pieces, lest I get lost in the realm of scientific research and never come to any conclusions that can be used in daily life. What is presented below is the synthesis of my findings from this journey. I hope it is as illuminating to you as it has been to me.

Sources and Dimensions

As stated above, I have narrowed the scope to focus on our main energy sources to avoid making this synthesis too complex. This narrowing has the added benefit of only including sources that might be considered legitimate alternatives for the future and have substantial amounts of research data tied to them on which to base conclusions. As such, I have chosen to focus on the following sources of energy:

  • Nuclear
  • Wind
  • Solar
  • Hydro
  • Natural gas
  • Oil
  • Coal

These sources have been compared on a global scale (ignoring local peculiarities – such as more or less sun or wind) across seven dimensions to form a clearer picture of how they match up against each other on a macro level. Where relevant, all metrics are measured on a per-unit basis to control for differences in total energy production. The dimensions that have been focused on are:

  • Danger to Humans
  • Danger to Animals
  • Emissions
  • Power Density
  • Cost of Energy
  • Energy Return on Investment (EROI)
  • Reliability

Danger to Humans

Let us first look at how many human lives are lost in the production of energy. It should be noted that these numbers include deaths from clearly traceable accidents and, to a large extent for coal and oil, estimates based on the known mortality rates from air pollution. The lack of anti-pollution regulations in places like China accounts for a substantial portion of the estimates2, 3.

Considering the air pollution resulting from the combustion of coal and the dangerous nature of its mining and transportation, it may not be a surprise to most that it performs poorly on this dimension. What might come as a shock, however, is the low number of deaths resulting from nuclear power. Despite the prominent accidents of Chernobyl, Three Mile Island, and Fukushima, nuclear power is surprisingly safe. In fact, though these numbers are from before the Fukushima meltdown, the per-output-unit death rate will be lower now; a lot more power has been generated since then and the number radiation-related deaths from the event were in the low single-digit range4, 5, 6. The vast majority of deaths were caused by the earthquake/tsunami and the ensuing evacuation6.

Danger to Animals

Unfortunately, there are no concrete numbers for all animals killed by the production of energy. Numbers for avian deaths are the most commonly researched and thus the most generalizable across the different energy sources. No such number was found for hydropower, as the technology has minimal impact on birds, but it is clear from the research that hydro plants disturb river systems and thus the wellbeing of the inhabiting species. Examples of such species include salmon and river dolphins. The use of dams necessitates the flooding of areas that would otherwise have been habitat for other species. From this, we can conclude that though some sources of energy have a larger impact on animals, the very act of energy production cannot be carried on without wildlife incurring negative externalities.

This is not to say that we should not try to minimize the extent of said negative impact; quite the contrary. In instances like these, we are obligated to look to the research so we might properly consider wildlife welfare as part of the complex problem of determining the future of energy production. Once again, fossil fuels come out unfavorably on this dimension. Though it may be easy to disregard these technologies at this point, there are confounding factors to consider. Fossil fuels continue to lessen their negative impact through stricter safety standards for waste and emissions. At the same time, increasing efficiency for wind (through larger turbines) and solar (through concentrating the sunlight) seems to increase the number of animals killed by these technologies7, 8 – muddying the already murky waters further.

Emissions

On to the hot topic of emissions. At this point, it is clear that humans are having a heating effect on the environment12. The implications, however, are far from certain – though it is reasonable to assume it will be detrimental for some species and beneficial for others, just like past environmental changes. Our worry regarding this environmental change, at its most fundamental, is that the world will be less beneficial to us, as our species has thrived under the current conditions*. It is natural then, to examine the energy sources based on emissions, which is related to this heating process.

Several gases contribute to this process. To make the comparison easier to follow, the overall emissions have been expressed in grams of CO2 equivalent per kilowatt-hour (g CO2e/kWh). The numbers reported are the total life-cycle emissions of the various power sources, including building and operating the plants, and transportation of necessary supplies/raw materials. As can be seen below, wind and nuclear power come out best on this dimension, while coal and oil are the worst.

Power Density

Here, unlike in the prior graphics, more is better. This metric shows how much power capacity you get out of 1 km2 of land – the power density. As our consumption of electricity keeps climbing, power density is important to consider. Denser energy sources leave more land available to other uses – such as farming or natural preservation – lessening the worry of overpopulation of the planet and increasing our ability to let natural environments remain untouched. By sparing natural landscapes from human intervention, wildlife is preserved together with the plants that pull CO2 out of the atmosphere. Since all sources of energy need to be connected to the power grid to be useful, consolidating the power supply to a smaller area also means less wiring. Thus, power density has a plethora of implications for the sustainability and environmental impact of electricity generation.

Cost of Energy

The cost of electricity impacts the entire economy, as few (if any) businesses or individuals conduct their daily business without it. It may be easy to overlook the importance of this fact, but as our peaceful global society is predicated on constant economic growth – growth largely fueled by cheap electricity – the stakes are enormous. People cannot be expected to take a long-term view of environmental health when they are busy worrying about feeding their families. This may seem hyperbolic, but to many people around the world, this is an everyday worry. As such, any viable alternative must at least be close to the lowest price in the market.

Energy Return on Investment

In addition to the monetary cost of energy, we must also consider the energy cost. Energy Return on Investment (EROI; also known as Energy Returned on Energy Invested, EROEI) captures the relative cost of producing energy. For example, an EROI of 2 means that every kWh of energy invested results in 2 kWh of output. That might seem like a good rate of return, but it means that only half of the energy output can be used consumed as the other half has to out back into the process of energy production. As such, every metric we have looked at so far will be affected by EROI.

Here, a quick demonstration is due. Consider the following: you need 2 MW of electricity for a factory and this is being supplied by an energy source with a power density of 1 MW/km2. If the EROI of that plant is 3, your factory will need 3 km2 worth of energy. The reason you do not need 2 km2 is that a third of the energy is going back into the production process. If the EROI was 2, half the energy would be used for the production of energy and you would need 4 km2 for energy production. The same phenomenon will apply to emissions, deaths, etc., as the total amount of energy that needs to be produced to supply the grid will vary greatly depending on the EROI.

Reliability

Finally, the critical factor of reliability, measured through the capacity factor**. Here, the actual output is compared to the theoretical maximal output, indicating the ability of an energy source to meet the demand from the grid. This is where the intermittency of solar power, for example, poses a problem. A temporary lack of sunshine (e.g. night time) can lead to a decrease in energy production, leading hospitals, businesses, and the government to rely on back-up generators or batteries to avoid shutting down.

The implications of such uncertainty surrounding energy production are wide-ranging. Let us consider a few: The need to include batteries in the calculation would lessen the environmental benefits of renewable energies, not to mention the fact that batteries run out – a fact that anyone living in our technological world can relate to. Backup generators will likely rely on fossil fuels and are not as efficient as larger power generators, leading to higher emissions than current fossil fuel powerplants. To meet the demand most of the time, the overall capacity would have to far exceed the energy demand of the grid***.

So what energy source is the best?

Throughout the process of doing this research, I found myself changing my mind several times, depending on the dimension I was currently focused on. Looking at emissions, wind looks like the clear choice, but what about when you have to consider land use or reliability? Suddenly, other options look far superior. And we have only considered a few of the most prominent factors; there are yet more to consider if you dig into the research. If anything has become clear, it is that if an option looks clearly superior to its alternatives, you are probably not considering all factors.

That being said, a decision needs to be made. We cannot delay decisions forever and must, therefore, accept some level of informational incompleteness. From this standpoint, the best option seems to be nuclear power, which has consistently been among the best alternatives across all the examined dimensions. The major detriment of nuclear technology is the public fear of nuclear disasters. Yet, when the data is examined, we find that nuclear powerplants are incredibly safe. The low number of casualties at the Fukushima meltdown – caused by a natural disaster that will not be a threat to most powerplants (a tsunami will not be a threat inland) – should serve as a testament to the safety of newer nuclear plants. And the Fukushima plant was commissioned in 197121. Newer plants have gone on to improve safety even further.

Conclusion

If we are to improve the conditions under which we and our descendants will live, it is necessary to face our fears and question the common knowledge we think we have. Surprisingly often, our fears are not founded on reality and our “knowledge” is simply regurgitated rumor. In the case of energy production, the best solution is being sidetracked by the battle between ideologues so deeply entrenched for either renewables or fossil fuels they forget why they are fighting. Taking a step back from the battle affords a view of the big picture, allowing us to reorient ourselves and get back to the main problem we were initially trying to solve. Thus, instead of putting our heads down and marching forth toward the perceived enemy, we must fight the urge so we might together find the real enemy: the stagnation of progress.

Notes:

* This topic brings to mind George Carlin’s brilliant bit about saving the planet. It is certainly worth 8 minutes of your life.
** Capacity Factor = actual energy output / maximum possible output
*** A cushion of additional supply beyond the demand would allow even sub-optimal performance of energy production to satiate the demand. However, the construction of the additional capacity would impact the costs – monetary, environmental, and in terms of energy investment – per unit of output.

Sources:

  1. Enerdata. (2019). Global Energy Statistical Yearbook 2019. Retrieved on 2020-04-25 from: https://yearbook.enerdata.net/total-energy/world-consumption-statistics.html
  2. National Academy of Sciences (2010) Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use Committee on Health, Environmental, and Other External Costs and Benefits of Energy Production and Consumption. DOI: https://doi.org/10.17226/12794
  3. Conca, J. (2012). How Deadly Is Your Kilowatt? We Rank The Killer Energy Sources. Forbes. Retrieved on 2020-04-25 from: https://www.forbes.com/sites/jamesconca/2012/06/10/energys-deathprint-a-price-always-paid/#3a2bffa4709b
  4. Leppold, C., Tanimoto, T., & Tsubokura, M. (2016). Public health after a nuclear disaster: beyond radiation risks. Bulletin of the World Health Organization, 859-680. DOI: http://dx.doi.org/10.2471/BLT.15.168187
  5. Reich, M. R., & Goto, A. (2015). Towards long-term responses in Fukushima. The Lancet, 386(9992), 498-500. DOI: https://doi.org/10.1016/S0140-6736(15)61030-3
  6. Ritchie, H. (2017). What was the death toll from Chernobyl and Fukushima? Our World in Data. Retrieved on 2020-04-25 from: https://ourworldindata.org/what-was-the-death-toll-from-chernobyl-and-fukushima
  7. Thaxter, C. B., Buchanan, G. M., Carr, J., Butchart, S. H. M., Newbold, T., Green, R. E., Tobias, J. A., Foden, W. B., O’Brien, S., & Pearce-Higgins, J. W. (2017). Bird and bat species’ global vulnerability to collision mortality at wind farms revealed through a trait-based assessment. Proceedings of the Royal Society B. DOI: https://doi.org/10.1098/rspb.2017.0829
  8. Walston, L. J. Jr., Rollins, K. E., LaGory, K. E., Smith, K. P., & Meyers, S. A. (2016). A preliminary assessment of avian mortality at utility-scale solar energy facilities in the United States. Renewable Energy, 92, 405-414. DOI: https://doi.org/10.1016/j.renene.2016.02.041
  9. Sovacool, B. J. (2009). Contextualizing avian mortality: A preliminary appraisal of bird and bat fatalities from wind, fossil-fuel, and nuclear electricity. Energy Policy, 37(6), 2241-2248. DOI: https://doi.org/10.1016/j.enpol.2009.02.011
  10. U.S. Energy Information Administration. (2020). Wind explained. Retrieved on 2020-04-25 from: https://www.eia.gov/energyexplained/wind/electricity-generation-from-wind.php

Sources (continued):

  1. Loss, S. R., Will, T., & Marra, P. P. (2013). Estimates of bird collision mortality at wind facilities in the contiguous United States. Biological Conservation, 168, 201-209. DOI: https://doi.org/10.1016/j.biocon.2013.10.007
  2. Cook, J., Oreskes, N., Doran, P. T., Anderegg, W. R. L., Verheggen, B., Maibach, E. W., Carlton, J. S., Lewandowsky, S., Skuce, A. G., Green, S. A., Nuccitelli, D., Jacobs, P., Richardson, M., Winkler, B., Painting, R., & Rice, K. (2016). Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters, 11(4). DOI: http://dx.doi.org/10.1088/1748-9326/11/4/048002
  3. OpenEI. (2020). LCA Harmonization. Retrieved on 2020-04-25 from: https://openei.org/apps/LCA/
  4. Intergovernmental Panel on Climate Change. (2014). Fifth Assessment Report, 511-898. Retrieved on 2020-04-25 from: https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_chapter7.pdf
  5. Intergovernmental Panel on Climate Change. (2014). Fifth Assessment Report, 1329-1356. Retrieved on 2020-04-25 from: https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-iii.pdf
  6. World Nuclear Association. (2011). Comparison of Lifecycle Greenhouse Gas Emissions of Various Electricity Generation Sources. Retrieved on 2020-04-25 from: http://www.world-nuclear.org/uploadedFiles/org/WNA/Publications/Working_Group_Reports/comparison_of_lifecycle.pdf
  7. Van Zalk, J., & Behrens, P. (2018). The spatial extent of renewable and non-renewable power generation: A review and meta-analysis of power densities and their application in the U.S. Energy Policy, 123, 83-91. DOI: https://doi.org/10.1016/j.enpol.2018.08.023
  8. OpenEI. (2020). Transparent Cost Database. Retrieved on 2020-04-25 from: https://openei.org/apps/TCDB/#blank
  9. Walmsley, T. G., Walmsley, M. R., Varbanov, P. S., & Klemeš, J. J. (2018). Energy Ratio analysis and accounting for renewable and non—renewable electricity generation: A review. Renewable and Sustainable Energy Reviews, 98, 328-345. DOI: https://doi.org/10.1016/j.rser.2018.09.034
  10. Hall, C. A. S., Lambert, J. G., & Balogh, S. B. (2013). EROI of different fuels and the implications for society. Energy Policy, 64, 141-152. DOI: https://doi.org/10.1016/j.enpol.2013.05.049
  11. Wikipedia. (2020). Fukushima Daiichi Nuclear Power Plant. Retrieved on 2020-04-26 from: https://en.wikipedia.org/wiki/Fukushima_Daiichi_Nuclear_Power_Plant

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Categories
Things Explained

Flattening the curve

Since all we seem to hear about these days is COVID-19 I have tried to not write anything on the topic. However, the phrase “flattening the curve” keeps coming up and few people seem to comprehend what it means. I have a suspicion that most people have never actually considered what the graph they are referring to would look like or what it depicts, so let’s take a quick look and see if that clears up some confusion. 

Flattening the curve is done to bring the number of people in need of hospitalization at any time below the healthcare capacity.

The first graph depicts the expected progression of the virus with no intervention. In this case, it spreads to the whole population quite quickly. Eventually, the size of the population limits any further spread, as most people have had it already. 

In the second graph, the spreading of the virus is slowed down after the initial peak. However, social distancing does not completely prohibit the virus from spreading since it is done imperfectly and some people are still working. The lower-than-normal interaction among people keeps the number of infected people at any given time down. 

In either case, the number of people that are expected to get infected and need medical assistance – the area under the curve – is the same. It is the blue area – the area under the curve but above hospital capacity – that we are concerned with. A certain amount of people will get infected and not make it, despite getting the medical attention they need. There is not much we can do about that. The deaths we are trying to avoid are the deaths in the blue zone, where people need attention but do not get it. In order to make this group as small as possible, we need to either increase the capacity (shifting the red line up) or keep the number of infected people down (flattening the curve). 

Increasing the capacity sounds like a good idea, but it is tough in practice. Hospitals take time to build doctors and nurses take time to train, and making more equipment takes time too. Time we do not have available. In different circumstances, it might be possible to get doctors and surplus equipment from other places to temporarily increase the capacity and set them up in temporary hospitals – this would take relatively little time. Yet, as the rest of the world is in the same boat or anticipating that they will be, shortly, there is no surplus to borrow. 

This leaves only the option of flattening the curve. As can be seen in the second graph above, the idea is to keep the number of infected people at any given time below hospital capacity. Done properly, people still get infected, but the ones who need medical treatment still have it available. It follows then, that once the social distancing regulations are made more lenient, we should still expect new cases. Hopefully just not enough to exceed the capacity line. 
The strategy in Sweden – another popular topic – is based on the idea that the health care system will have the capacity to deal with the outbreak without slowing it down. Theoretically, no more deaths should result from this strategy, but the death toll early on will be higher due to the number of people infected. Their graph would look something like this:

Think about it as paying for something in installments. For the sake of ease, picture buying a car that costs $10,000. Most people do not have the capital available to pay the full amount upfront. Instead, they choose to pay monthly installments of $364 for 30 months. Essentially, this is what most countries are doing. They do not have the money (hospital capacity) to pay the full amount upfront, so they are prolonging the payment period and paying in smaller amounts – Sweden, having the available cash, is simply paying the full amount upfront. As most people know, these installment plans are not free though and you need to pay interest. The interest being paid for flattening the is the cost of shutting down large parts of the economy to facilitate social distancing to the maximal (practical) degree.


Ideally, we would all want to pay the full amount upfront and avoid the steep interest rate charged, but without the available resources, we are forced to pay in installments and eat the interest costs. We simply have no choice if we wish to avoid higher death rates. 

Categories
Interesting Questions

What is the best bag for the environment?

What is the best bag for the environment? It is a simple question, but there is more to it than you might think. What do you think now, prior to reading the rest of this? Paper? Cotton, which can be used many times, maybe? It must be one of these two at least, right? I think the answer will surprise you, but first, let us look at how we make decisions.

How we make decisions

Ultimately, I believe most peoples’ actions are motivated by a desire to do the right thing. With this in mind, it is important to appreciate that even people you disagree with are likely seeking the same thing as you: A future that improves upon the present. In the course of writing this piece, I had to return to this fundamental belief often, reminding myself that it is not a lack of good intentions that most often leads to poor decisions, but a lack of relevant knowledge. As the information we have available guides the choices we make, our decisions will change when new, relevant information is made available. At least, that is how it would ideally work.

Allow me to crudely illustrate: 
Dan wants to visit Mary and wants to get there as soon as possible. He has no car. 

Unknown path to Mary's house

There are two routes to Mary’s house. Route A is 10 km; Route B is 12 km. 
Which route should he choose? 
At this point, Route A is the painfully obvious choice but bear with me.

Path A or B based on distance alone

What if Dan has a bicycle, which can only be used on Route B, since Route A is not paved? 
This new piece of information shifts the preference to Route B.

Path A or B based on distance and new information

Though I acknowledge most decisions are far more complex than this, the principle applies in the real world just as well: New information can radically change our decisions if we keep our minds open to it. 

We currently live in a world where ideological polarizations (political, religious, dietary, etc.) cause many of us to oppose any idea presented to us by someone we dislike or disagree with – anyone outside our group. This phenomenon contributes to the stagnation of humanity’s progress, as agreement becomes nearly impossible on larger issues. Many good ideas get lost in the no-man’s-land between the increasingly entrenched opposing forces and only the anomalous few prevail to become widely held among the majority of the population. As time passes, it is hard to believe that ideas we now take for granted – gender and racial equality come to mind – ever had substantial opposition. Yet we are currently debating concepts that will, in time, join the list of basic principles that future generations will take for granted. 

This common source bias does have benefits, don’t get me wrong. Letting our group make decisions for us – particularly macro-level decisions that often do not directly affect our daily lives – frees up our time and mental resources, allowing us to focus on micro-level decisions that only we can make. If we all had to thoroughly understand all the policies that are proposed by the government, no one would have the time to decide what we should have for dinner or what shirt to wear. Group cohesion also ensures that every idea has plentiful opposition, which means it will be properly dissected and its flaws will be exposed; this inclination to skepticism is fundamental to science. However, when skepticality turns to blind opposition, it holds the hold world back from the progress we all seek. We should be wary of new ideas, but when overwhelming evidence suggests we are wrong, we need to change our minds so that we might improve individually and as a society. 

Thus, as we proceed into this potentially contentious subject, please keep an open mind. Let me preface the rest of what you are about to read with this: I think we should take care of the beautiful planet we are living on, lest we make it a worse place for future generations to live. However, this cannot be achieved by blindly following the ideas that are most widely held by the general population. Sometimes efforts to do good lead to the opposite effect of what is desired, and there are few better examples of this than the condemnation of plastic bags.

The best bag for the environment

Following the narrative spun by mainstream media, the conclusion is unambiguous: “Plastic bags are ruining the environment and we should do our best to use alternatives (mainly paper or cotton) that are biodegradable and/or can be used many times.” The evidence, however, tells a different story.

A comprehensive study1 commissioned by the Danish Environmental Protection Agency examined several alternative carrier bags to determine the environmental impact of each – evaluating each bag on their performance across 14 factors. The table below shows the results. To make the comparison of the bags easy to comprehend, a standardized unit of environmental footprint – Bag Environmental Footprint (BEF) – has been used.

1 BEF = the environmental footprint of one Low-density polyethylene (LDPE) bag – the bag you would get in most stores.*

Comparison of bag alternatives

The data boils down to this: If you get a paper bag the next time you are shopping, it has the same environmental impact as 43 plastic bags. Put another way, you need to use the paper bag more than 43 times before you are having a net positive relative impact on the environment, as compared to using plastic bags – and that is if you only use the plastic bags once each. If you typically use a plastic bag twice (e.g. home from the store and more the next time you go shopping), you now have to use that paper bag more than 86 times to save the environment from additional harm.** I have never been able to use a paper bag more than once or twice and though I am certain some people can stretch the usage numbers higher than myself, 43 uses seems incredible. As we need scalable solutions to have a real global impact, the paper-bag solution should be discarded – most people will not come near the number of uses required for a net positive impact.

Next on the docket is cotton. A quick search on Google makes it look as though cotton – organic cotton in particular – is the best solution for the environment. However, looking at the numbers, we find that the cotton bag (non-organic) has the same environmental impact as 7,100 plastic bags. If you use the cotton bag twice daily, 365 days a year, you need to use it for more than 9 years and 8 months before you are having a positive impact, relative to the use of plastic one-time-use bags. That is a long time to use one bag. For organic cotton, you have to use it nearly three times as long.

Matters are made worse for cotton bags when considering that the above number of uses is multiplied by how many times the plastic bag is used. This means that if you are able to use a plastic bag three times (e.g. home from the store, as a lunch bag to work, and once more shopping), the users of cotton bags need to use their bag 21,300 (3 * 7,100) times to break even. Users of organic cotton bags now have to surpass 60,000 (3 * 20,000) uses. With two uses every day, that is more than 82 years of the same bag. Thus, the cotton bags do not seem a good solution either, leaving polypropylene (PP) as the only viable alternative to LDPE. 

The main takeaway from this research is that focusing on using plastic bags (LDPE or PP) as many times as possible would be far better for our environment than changing to other materials at this time – though I am happy to welcome better alternatives as they are developed. 

The importance of following the science

As humans, we tend to be attracted to predictions of imminent doom, always believing that we need to change our collective actions or face the consequences of following a path headed toward a precipice that will be the end of our civilization. Whether the apocalypse will be caused by our religious or scientific sins, it will be caused by our wrongdoing. During the Cold War, we were scared of a nuclear holocaust; now, we are scared that climate change will leave the planet uninhabitable. The general narrative of a path leading to what I call the “Precipice of Doom” is illustrated below. For the current worry of climate change, the start of the path can be considered to be the Industrial Revolution, as that is when humans started to have a large impact on the global environment. 

Perceived path to the precipice of doom

When this is your model of the world, an urge to change our current behavior is understandable, laudable even. We do not want to keep repeating the same mistakes when this is our trajectory. However, if we want positive change we cannot blindly leap to actions that are not grounded in science. We cannot simply follow the “common sense” narrative that plastic is always worse for the planet than paper or organic alternatives. It simply is not true; paradoxically, common sense does not always make sense and actions that are taken to improve our situation might make matter worse. 

The problem with the model above is that it does not account for the power of innovation. The illustration below shows the path I believe we are on – one of technological development that will ultimately cause humanity to steer clear of the precipice. The red path is the one that virtue-signaling actions, blind to science might lead us down. Taking a step away from the path we are on will undoubtedly make some people feel better about themselves. However, before you take that step, I urge you to ensure that you are not engaging on a more expedient path to the very future you seek to avoid.

Technological development avoiding the precipice of doom

Notes:
* This is contingent on the bag being used as a garbage bag in most cases and therefore not ending up as litter.
** To get the total number of uses necessary, we need to divide the total BEF for paper bags by the BEF per use for LDPE bags when used twice (1 BEF / 2 uses = 0.5 BEFs per use). As such, the number if uses necessary for paper bags 

Sources:
1 Danish Environmental Protection Agency. (2018). Life Cycle Assessment of grocery carrier bags. Retrieved from: https://www2.mst.dk/Udgiv/publications/2018/02/978-87-93614-73-4.pdf