Canola biofuels reduce emissions but require more land, fertilizer and subsidies than oil. A closer look shows the environmental picture is more complex.

The push to turn canola oil into diesel fuel is often presented as a simple environmental win — a renewable, Canadian-made alternative to fossil fuels. But a closer look at the data on energy, land, water and cost shows the picture is far more complex.

As refiners increasingly blend canola oil into existing petroleum infrastructure through co-processing, and Ottawa's Clean Fuel Regulations drive demand for renewable diesel, much of the environmental case rests on lower greenhouse gas emissions. On most other measures, the comparison is less favourable.

Analysts measure fuel efficiency using energy return on investment (EROI), which compares how much usable energy is produced for every unit of energy invested.

Conventional crude oil still performs better, with an EROI of about 4.5:1, while canola biodiesel generally ranges between 2:1 and 3:1. That means conventional oil delivers roughly twice as much usable energy after production costs are considered.

However, much of North America's new production now comes from shale, tight oil and oil sands, where EROI estimates have fallen to around 2:1 or lower. Against those unconventional sources, canola biodiesel performs much more competitively.

Land use remains one of biofuels' biggest challenges.

A shale well occupies only a few acres and can produce energy for decades. By comparison, an acre of canola typically produces 70 to 160 gallons of biodiesel annually, requiring the crop to be replanted every year.

A mid-sized biodiesel plant producing five million gallons annually may require 50,000 to 80,000 acres of canola, while larger facilities need hundreds of thousands of acres. In terms of energy produced per acre, oil and gas remain significantly more land-efficient.

Hydraulic fracturing uses large volumes of water, but most of it is consumed once when a well is completed.

Canola generally has a relatively low water footprint among oilseed crops. Its larger environmental challenge comes from fertilizer. Researchers consistently identify nitrogen fertilizer and the resulting nitrous oxide emissions as major contributors to canola biodiesel's environmental impact. Fertilizer runoff into waterways also remains an ongoing concern because crops are replanted every year.

Oil and gas wells require significant upfront investment but can remain productive for decades.

Renewable diesel follows a different economic model. Feedstock costs often exceed the value of the finished fuel, making government support such as carbon credits, blending mandates and tax incentives an important part of the industry's economics.

Refiners are also seeking additional federal incentives for using Canadian-grown canola in co-processing to improve competitiveness.

A single oil or gas well can produce energy for decades from one location.

Although Canadian canola crush capacity is expected to grow from about 11.3 million tonnes to 18 million tonnes over the next several years, biofuel production still represents only a small share of the liquid fuels supplied by Canada's petroleum industry.

Blending canola oil directly into existing refineries avoids building new biodiesel plants and reduces infrastructure costs.

However, it does not change the agricultural footprint. The same land, fertilizer and crop production are still required to grow the canola used in the process.

The strongest environmental argument for biofuels is lower greenhouse gas emissions. Crop-based biodiesel can reduce lifecycle emissions by roughly 40 per cent, while fuels made from waste oils or animal fats can reduce emissions by as much as 86 per cent compared with petroleum diesel.

Those gains come with trade-offs. Conventional oil remains more efficient in energy output, requires far less land and currently operates without the same level of policy support required by renewable fuels. Biofuels compare more favourably with unconventional oil production, but the advantage narrows when land-use changes and ongoing agricultural inputs are considered.

The environmental case is also strongest when biofuels are produced from waste products such as used cooking oil or animal fats rather than crops grown specifically for fuel.

In the end, biofuels can reduce carbon emissions, but they are not without environmental and economic costs. Whether they are the "greener" option depends on which impacts are given the greatest weight.