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If we have biodegradable plastic, why don't we use it?

In recent years, the "plastic ban" action started all over the world and has given full attention and considerable development to biodegradable plastics. It seems that biodegradable plastics will completely replace traditional plastics and become the plastics of the new era. However, the fact is that traditional plastics are still being produced. and widespread use, while we are still working hard to promote the benefits of biodegradable plastics, the industry and the public are still taking a wait-and-see attitude.

The pollution problem caused by plastic waste is already very serious, and we have biodegradable plastic, why don't we use it?

First of all, it needs to be clear that It's not that we don't use biodegradable plastics, but compared with traditional plastics, biodegradable plastics still have some deficiencies. These deficiencies make it impossible to completely replace traditional plastics for the time being, so We are still producing and using traditional plastics.

Degradation problem of biodegradable plastics

Biodegradable material sounds like if you just throw it anywhere, there will be bugs to climb up and destroy it, but the fact is that some biodegradable materials have more stringent requirements for the degradation environment, they must be degraded rapidly under composting conditions. If it cannot be decomposed quickly in the composting environment, it will remain in the environment for a long time like traditional plastics, and eventually become plastic particles, causing the same pollution problems as traditional plastics.

In addition, due to the high requirements of these biodegradable plastics for degrading the environment, it is impossible to decompose them together with any garbage. These plastic bags or other commodities must be separated from other garbage, and then Composting alone requires a very complete garbage sorting mechanism, which is not available in every country or region, so it limits the use of biodegradable plastics.

It is also important to note that composting requires a relatively high temperature to proceed smoothly (sometimes it needs to reach 50-60 degrees Celsius). Although composting can generate enough temperature inside the compost pile when it occurs smoothly, it still depends on Relatively high external temperature, if it is to achieve such internal temperature without external heating, it is difficult for many countries or regions such as Canada, Nordic countries and other high-latitude countries to meet this demand, because the winter in these regions is Quite a long time, and if artificial heating needs to be provided, this will create additional carbon emissions issues.

The raw material problem of biodegradable plastics

For bio-based degradable plastics that can be degraded in the natural environment, the raw material is usually food. Take polylactic acid (PLA) as an example, which is synthesized from corn starch, or sugar from sugar cane and sugar beets. At present, Natureworks, the company with the largest polylactic acid production capacity in the world, produces polylactic acid by fermenting corn starch. Another example is that polyhydroxyalkanoate (PHA), which is also a biodegradable plastic, is synthesized by bacteria, and the raw material is also a sugar solution for culturing bacteria.

This means if this situation does not improve, in the current global food shortage situation, if the production of bio-based plastics continues to increase, there will be less and less food available for human consumption. At this stage, there are also some corresponding solutions, such as the use of non-grain starch such as tapioca starch as much as possible, and the use of expired strategic grain reserves as raw materials for a biorefinery to a certain extent.

The cost problem of biodegradable plastics

Still taking polylactic acid (PLA) as an example, in 2021, the average transaction price of polylactic acid (PLA) will be about 3.3-3.5 thousand US dollars/ton, and the price is much higher than polyethene and polypropylene 0.8-2 thousand US dollars per ton s price. In addition, low economic benefits also limit the large-scale promotion of PLA in the early stage, slowing down the process of PLA marketization.

There are technical problems, production capacity problems, and raw material problems. In recent years, the synthesis technology of biodegradable plastics has continued to break through, and the production capacity has also expanded rapidly, which can indeed reduce the cost of biodegradable plastics to a certain extent, but the problem of raw materials cannot be completely solved. Petroleum-based degradable plastics can only be an excessive product, and bio-based plastics will eventually be thoroughly developed. In the next few years, the cost of biodegradable plastics will definitely drop, but it is difficult to be cheaper than traditional vinyl plastics. Therefore, over a long period of time, the problem of the high cost will be a very important reason to limit the application of biodegradable plastics.

In general, biodegradable plastics will eventually be applied on a large scale and replace traditional plastics, which is good, but now, there are still many deficiencies in biodegradable plastics, and some of these deficiencies will soon be solved, and there are some solutions that cannot be found in a short period of time. Ultimately, whether it is from the perspective of cost, or from the perspective of carbon emissions and environmental pollution, the more ideal method is to try to do as much as possible to reduce the use of such single-use plastic bags.


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