Most of the cooking oils in general use are derived from plants, whether they are grains, nuts, seeds, fruits, or legumes. Some of these "vegetable" oils, like olive and canola oils, are popular in home and restaurant kitchens. Others, like sunflower, soybean, and palm oils, find use in many familiar foods, cosmetics, and hygiene products. This versatility means that as the world's population grows and becomes more affluent, the demand will continue to rise from 199.1 million metric tons in 2020 to 269.2 million metric tons in 2027.
Demand may be an abstract concept, but oil crops already account for over 300 million hectares of arable land, which accounts for more than 20% of all such land on the planet. As a result, concerns are growing over the sustainability of vegetable oils. However, each crop faces its own environmental (and sometimes social) issues. This article will highlight the significant obstacles that prevent the most prevalent cooking oils from becoming more sustainable.
The Most Important Global Vegetable Oils
Palm, soybean, canola, and sunflower oil account for over 85% of the world's vegetable oil production. Therefore, any sustainability issues (positive or negative) among them have an outsized impact relative to other popular sources of culinary fat like olive, coconut, and avocado. One study examined the sustainability of soy, palm, canola, and sunflower oil crops and compared their performance regarding CO2e emissions, land use, and water consumption.
There Is Huge Variability in Emissions Among Common Oils
The study points out that the median emissions rate of all global oil crops is 3.81 kilograms of CO2e per liter of oil. Canola yields 2.49 kg of CO2e, while sunflower and palm emit slightly more. However, all three produce less than the global median. Of the four oils included in the study, soybean oil was the only one to emit more CO2e than the global median (4.25 kg).
However, the amount of CO2e produced by each oil is hugely variable and depends on geography, farming, refinement, and production methods. For example, some Indonesian palm farmers have converted peat swamp forests into palm plantations. These operations have a substantial CO2e impact due to the lost carbon storage capability of the swamps. Likewise, no-till canola farming systems in Canada have less than half the emissions of conventional tilling methods.
The unfortunate consequence of this variability in emissions for the oils is that each one faces its own unique, sustainable emissions concerns. Practically, no single vegetable oil is necessarily more sustainable than another. For example, sunflower fields in Russia and Ukraine often use synthetic fertilizers, which require lots of energy to produce and release N2O, a GHG 300 times worse for the environment than CO2.
It's Not Just Emissions
Emissions are not the only sustainability factor that further complicates oil crop production. For instance, while canola oil generally has the lowest emissions, sunflower oil has the lowest water consumption. In addition, palm oil (representing 40% of all global vegetable oil) is the most land-efficient crop, producing 81 million tons of oil from 19 million hectares of arable land. In comparison, the second and third most prevalent oils combined (canola and soybean) produce the same amount of oil but require about eight times as much land (160 million hectares).
There Are Opportunities for Improvement
Although palm oil is highly land-efficient and produces much less CO2e than the global median, there is still a significant opportunity to reduce its emissions further. This potential is because the pressing phase of palm oil production yields palm oil mill effluent (POME), a wastewater product high in methane. Some facilities have the technology to capture POME and convert it to valuable biogas, hugely reducing their emissions footprint.
For other crops, nitrogen pollution represents the most significant opportunity to improve sustainability. Some vegetable oil producers avoid synthetic fertilizers and use organic ones as strategically as possible to reduce N2O emissions. Using nitrogen-sparing cover crops like legumes as part of a crop-rotation protocol is an effective way to reduce dependence on fertilizer further.
Each Oil Faces Its Own Challenges
In practical terms, each cooking vegetable oil has its own strengths, challenges, and opportunities for improvement. For example, palm oil is very land efficient, but plantations that replace rainforests eliminate some of the most reliable carbon sinks in the world. Furthermore, POME can release methane if left as wastewater. Alternatively, sunflower oil is the most water-efficient, but intensive farming in the largest producing countries degrades millions of acres of land.
On the other hand, canola oil has the lowest emissions at the cost of land, while soybean oil is a land hog with high emissions, but it is tied to soy protein, an important human food source. Unfortunately, there are no global standards for vegetable oil production. For consumers, buying organic whenever possible is the best way to encourage more sustainably produced oils. It is not foolproof, but it reduces the likelihood of unnecessary emissions and soil degradation.
Try New Oils – Chances are, if you're a westerner, you don't cook with palm oil. However, it is by far the most popular vegetable oil worldwide. In addition, its high land efficiency and relatively low emissions make it one of the safest cooking oil choices for the planet.
Do Homework – The complex issues surrounding cooking oil sustainability may come down to the brand rather than the oil. Find out which brands available at your grocery store have the most sustainable practices,
Try Healthy Oils – Human health is also an essential aspect of sustainability. Coconut, olive, and avocado oils are loaded with healthy saturated fats but may be pricier than more common alternatives. Most other vegetable oils like soybean and canola are hydrogenated, which can be unhealthy.