• Jamie McCroskery

Trash bags with the smallest carbon footprints

Updated: Sep 3, 2020

Truelabel uses algorithms based on climate research to estimate the carbon footprint of products, helping you reduce your impact while you shop without needing a Ph.D. in climate science.

We do this research because we believe people have a right to know the impact of what they’re buying (we do not take samples or funding from companies). Our research is based on Life Cycle Assessments, the gold standard for evaluating a product’s global warming impact holistically across its ingredients, manufacturing, packaging, etc.

Does using a small-carbon-footprint trash bag even matter?

We think about plastics ending up in the ocean, but they also are a major emitter of greenhouse gasses. In fact “over the past four decades, global plastics production has quadrupled. If this trend were to continue, the GHG emissions from plastics would reach 15% of the global carbon budget by 2050” (1). But what about garbage bags, can they really be that bad? Think about holding a box of garbage bags — pretty heavy right? For every pound of bags, 7 pounds of greenhouse gasses are put in the atmosphere. This adds up!

The average American family’s use of garbage bags equates to 46 hours of barbecuing or driving 139 miles (~56KG of CO2e).

If every US household switched to a low impact option, it'd be the equivalent of a forest 8 times the size of Yosemite sequestering carbon every year (2).

Plastics… so convenient, but so much carbon ultimately coming from oil production/burning and deforestation. So ideally we use less plastic and companies are better incentivized to make lower emission alternatives. But when you have to buy garbage bags, you can reduce greenhouse gas emissions by 90% by choosing the right product by 

  1. The best: bags made from recycled plastic, using renewable energy (up to 90% reduction in emissions)

  2. Next best: bioplastics that verifiably don’t lead to deforestation. These are hard to find. (up to 75% reduction in emissions)

  3. Third best: bags made from recycled plastic (up to 50% reduction in emissions)

OK, which garbage bags have the smallest carbon footprints?

Grove Collaborative's 100% Recycled Bags. Our algorithms estimate this bag reduces emissions by 55% compared to standard trash bags. This is one of the few bags that uses 100% post-consumer waste plastic.

Seventh Generation Recycled Bags. This bag uses 65% post-consumer plastic waste, reducing emissions by an estimated 36% compared to standard trash bags that use virgin plastic.

We actually couldn't find a garbage bag verifiably made with renewable energy, which when combined with recycled plastic reduces emissions by 90%. If you find one, let us know in the comments below!

But what about compostable or biodegradable trash bags?! Get them if you want, but know you’re not really going to be reducing greenhouse gas emissions or contribution to landfills unless you know your town uses an industrial composter. Why? See how to see through marketing below.

What other products did we look at?

We ran other major options from brands like Simplehuman, Hefty, Glad, Seventh Generation, to the long tail of biodegradable and compostable options on Amazon, including FORID, Hipposak,

For the data nerds, let's dive into why some trash bags have 90% lower carbon footprints

Emissions for any product come from raw materials & manufacturing, packaging, transporting the product to you, your use of the product, and throwing the product away (or recycling). For garbage bags, the largest source of emissions that you can reduce comes from 

  1. materials: 65% of emissions come from sourcing the plastic (3,4,5)

  2. manufacturing: 25% of emissions come from turning that plastic into bags

  3. packaging: <1% from the packaging of the bags 

  4. Transportation, use, and disposal: ~10%, these are pretty much the same for all garbage bags.

Emissions from Materials and Assembly

Garbage bags start from different types of plastic melts which can be sourced from non-renewable fossil fuels like petroleum or renewable resources like starches or common plants like corn or sugarcane (3). After the pellets are produced, they are melted and shaped into bags through mainly a blowing and sealing process that is energy intensive (4). In total, about 65% of the emissions of garbage bags come from sourcing of the main raw material, plastic, and 25% come from the factory and manufacturing processes of transforming hard plastic pellets into stretchy, strong bags. 

Using recycled plastic is the best way to reduce emissions. On average, this will reduce the greenhouse gas emissions compared to fossil fuel plastics are 56% (5). Buying from companies that use renewable energy will also significantly reduce the carbon footprint of your garbage bags. The best combination is using garbage bags with recycled plastic, made from renewable energy which can reduce emissions by almost 90%.

Emissions from Packaging

There’s a huge focus on developing packaging that’s small and sustainable, but the packaging of garbage bags is almost negligible, accounting for less than 1% of the total emissions. This is largely because the ingredients and manufacturing processes required for the production of the bags is the key player in climate change. So while reduced packaging is nice, it’s ~65x less important than finding a product that uses recycled materials when trying to reduce climate impact.

Emissions from Transportation and Disposal

While no GHGs are emitted from using the bags, there are emissions from transportation and disposal associated with the product. Transportation includes the distribution of the product from the factory to the consumer. About 5% of the emissions come from transporting the product. Lastly 5% of the emissions come from the disposal of the bag (since they cannot be recycled as they are thrown out as trash), but this can change depending on how the trash is handled (5). Emissions can come from either the incineration or decomposition of the bags. The plastic that is incinerated emits the gasses, but the energy from the incineration can supplement the electricity grid (4). The energy produced and gasses emitted differ for each plastic type and there are different emission percentages for each end-of-life scenario, but bags sourced from bio-plastics tend to have lower emissions if they are composted or incinerated than those sourced from fossil fuels. On the other hand, the plastic can be decomposed efficiently in an industrial facility, but this is an expensive and involved processes. Realistically, most bags are thrown out into the landfill with the trash they contain and the carbon remains sequestered. Under these low oxygen and light conditions, any bags, compostable or not, do not break down and remain in their original form. 

How to see through marketing: 

Now you know the science, but how do you actually read product labels and see when you're at the store (hint: you can use the Truelabel extension when shopping online so you don't have to read labels)? Here are common tricks used in eco marketing and how you can see through it.

“Renewable energy”

Verdict: this matters, but don’t take the brand’s word that this means reduced emissions. Renewable energy can reduce emissions by 50%, but the type of renewable energy really matters (1). Ideally companies use their own solar panels or purchase-power-agreements that demonstrably add clean energy to the grid. For example, a company can be saying they use renewable energy by purchasing renewable energy credits, but that doesn’t necessarily mean that’s less dirty energy on the grid — they’ve simply bought the right to say they’re using green energy that’s already been produced. Some use alternative power sources like, hydroelectric energy requires the use of dams so water can turn turbines and produce energy. These dams lead to environmental degradation (including carbon release into the atmosphere), flooding, and loss of habitats.

“Bioplastics” like corn or sugarcane-based plastics

Verdict: it’s complicated. Bioplastics (corn or sugarcane-based) can reduce emissions by 25% only if a company can verify they’re not contributing to deforestation to grow plants needed to create the bioplastics. That certification doesn’t really exist though, so it’s hard to know whether your bioplastic is truly helping. The idea of bioplastics is compelling — they  absorb carbon during the growth stage of the plant and they minimize the net emissions from the production stages of the bag (1). But, because it’s difficult to prove trees weren’t cleared to grow sugarcane or corn, we can’t recommend them. Until that certification exists, buy bags made from post-consumer recycled plastic or use fewer bags.

“Compostable” or “Biodegradable”

Verdict: it’s complicated. These plastics are created to degrade more easily under various conditions. They can contain additive that help them degrade under specific environmental conditions, like sunlight or wind. Similar to bioplastics, compostable or biodegradable plastics do not necessarily have lower emissions, but if they are made with plant-derived products, they can be seen as sequestered carbon from the atmosphere. If these are then composted, the carbon is returned and no net change is seen. It is important to also keep in mind where the materials for the plastics are coming from: are forests in the Amazon being cut down to grow the necessary crops or are they grown sustainably? Lastly, some plastics may be advertised as compostable, but only in industrial composers where the temperature is increased to those not naturally found in your home compost pile. Reading the packaging will help to gain some clarity on this, but it is not always advertised. 

“Recycled” (post-consumer recycled, that is)

Verdict: yes this can reduce emissions by 50%. Just make sure that it’s post-consumer recycled. Companies often only add some recycled materials or use scrap plastic from other parts of their supply chain, so don’t be fooled! 

“HDPE with Prodegradant additive” - Verdict: this doesn’t mean much. Because plastic doesn’t biodegrade, some companies will add an additive to the fossil fuel plastic that make it decompose faster under normal environmental conditions. According to the Environment Agency. While this may seem like it is a win-win, it does not actually reduce the impact to climate change because emissions are not changed. The bag would similarly be incinerated or find itself in a landfill where its breakdown would see similar emissions as the HDPE bag itself. While this article focuses only on the impacts to climate change, evidence suggests that the additional steps in producing this type of bag contribute to the pollution and damages to the environment in terms of ocean acidification of aquatic environments and soils, human toxicity, and eutrophication. 

Limitations and assumptions

While a LCA is an accurate method for estimating emissions of a product, there are limitations and assumptions we want to point out. 

  1. We calculate our percent changes by identifying a baseline product representing an example of the most commonly used product in that category. For example, for tissue products we used virgin wood since it is most commonly used by the world’s major paper-producing companies. 

  2. We also focus carbon emission equivalents from the product to better understand the climatic impact, which doesn’t take into effect impact on other aspects of the environment like biodiversity, pollution, etc.

  3. Our data model estimates carbon emissions and therefore isn't 100% accurate, That said, we believe empowering you with enough information to reduce emissions without knowing with 100% accuracy what that reduction is. If you’re a consumer or manufacturer who thinks we’re wrong, let us know or better yet prove us wrong by showing us your emissions. Furthermore, we can’t see into company supply chains, but as they become more forthcoming, this limitation will lessen. Lastly, we know that science changes day by day. As new products, technologies, and methodologies are developed, we will also evolve. This means our ratings and methodology will be continuously improved to reflect the most up-to-date research and so you can continue making a difference. 

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