Replacing some existing vegetable oil crops with camellia plants could boost cooking oil production while reducing greenhouse gas emissions, water use and pesticide use, according to a modelling study.
That is because camellia is a high-yielding shrub that can thrive in places where some other oil crops struggle. The properties of camellia oil, also known as tea seed oil, suggest it could also be one of the healthier oils, but it is currently little-known and hardly used outside China.
Around the world, about a third of farmland is used to grow vegetable oils. This area is expanding, contributing to deforestation, global warming and the loss of wildlife.
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鈥淚t is a shocking figure,鈥� says at Westlake University in Hangzhou, China. 鈥淚t is why it is so important to look at what we鈥檙e doing with our vegetable oils.鈥�
So his team has looked at where the six main vegetable oil crops 鈥� soya, palm, rapeseed, sunflower, groundnut and olive 鈥� are grown and estimated their impact in terms of greenhouse gas emissions, water use, land use and pesticides.
The team estimates the production of oil from these six crops produces the equivalent of 1.2 gigatonnes of carbon dioxide per year, mainly from the use of fertilisers and deforestation. For comparison, total CO2 emissions from the burning of fossil fuels were around 37 gigatonnes in 2023.
Next, the team explored how the environmental impact would change if some of these crops were replaced with Camellia oleifera, which is a relative of the tea plant (Camellia sinensis). Compared with other oil crops, C. oleifera has several advantages, Wanger says.
For starters, it can yield up to 2.8 tonnes of oil per hectare, second only to palm oil. It can also thrive in many different conditions, he says, including in comparatively poor soil and on steep slopes.
Its oil also has desirable properties. Like olive oil, it consists mostly of oleic acid. Oils high in oleic acid when consumed in place of other oils and fats.
Camellia oil also has a higher smoke point than most other oils, meaning it can reach higher temperatures before starting to burn. This, along with its composition, should reduce the formation of and aldehydes during cooking.
If camellia replaced other oil crops on 11 per cent of the land where those crops are currently grown, the same amount of vegetable oil could be produced while reducing greenhouse gas emissions by 14 per cent, water use by 5 per cent, land use by 7 per cent and pesticide use by 9 per cent, the team concluded.
These numbers are for a 鈥渃onservative鈥� scenario where camellia yields are just half of what is thought to be achievable. If producers achieve higher yields, the benefits would be even greater.
While these results suggest camellia oil is potentially the greenest vegetable oil, they are contingent on how it is grown, Wanger says. 鈥淭he benefits depend strongly on where it is planted and to replace what.鈥�
This means planting camellia where existing crops are being grown on land that is not well-suited to those crops, for instance. 鈥淚t鈥檚 actually a crop diversification strategy,鈥� says Wanger. Diversifying crops can have wider benefits beyond those examined in the study, such as making food systems more resilient to extreme weather and diseases.
The necessary changes could be brought about either by government actions or by rising consumer demand encouraging farmers to switch, Wanger says. 鈥淭he price currently is very high, and so I think the consumer might be a bit reluctant,鈥� he says. 鈥淚n China, it鈥檚 certainly something that will be driven by government directives.鈥�
If production is ramped up, prices should come down as growers achieve economies of scale, he says.
There are definitely opportunities to boost production or reduce impacts by growing new crops that thrive in particular conditions, says independent , who has studied how the increasing demand for biofuels made from vegetable oils could lead to big rises in CO2 emissions.
鈥淏ut the commercial reality is that new oil crops won鈥檛 achieve a large market share unless production can compete in the market,鈥� Malins says. 鈥淲hile I am very supportive of this sort of work in principle, I have been in the field long enough to have seen a lot of claims made about the opportunities for this or that oil crop, and most of them haven鈥檛 hit successful commercialisation on a global scale 鈥� yet.鈥�
bioRxiv
