Project Willow: Grangemouth opportunities at a glance

The Grangemouth industrial complex is one of Scotland's major manufacturing facilities - but the imminent closure of Scotland's only oil refinery threatens 400 jobs.

Project Willow, a £1.5m feasibility study funded by the UK and Scottish governments, looks at potential low-carbon alternative uses for the wider site.

Consultants EY evaluated 300 technologies - and came up with nine ideas that could be developed with private sector investment.

This involves breaking down hard-to-recycle plastics such as clingfilm-type products to produce naptha and pyrolysis oil vapour.

Currently these plastics are usually incinerated or go to landfill.

They could instead be reused in plastics production or refined as renewable diesel and sustainable aviation fuel.

It would require about £150m-£250m of capital investment, create 35-60 jobs and operations could start before the end of 2028

This uses chemicals to dissolve waste plastics such as polyethylene and polypropylene.

The material can then be reused to create new plastic products or packaging.

Between 35 and 45 jobs could be created, with operations commencing late in 2028.

A relatively low amount of capital investment of £25m-£30m would be required.

Such technology could make use of plastic derived from bottle deposit return schemes when they are introduced across the UK.

Waste and by-products from sectors like food, drink, packaging and agriculture could be fermented using bacteria.

This could produce low-carbon chemical products such as acetone, butanol or ethanol.

Raw materials are plentiful - the amount of paper and cardboard waste currently produced in the UK is about 50 times the capacity of the plant being proposed for Grangemouth.

EY believes 80-100 jobs could be created through £215m-£265m of capital investment, with operations starting in 2030.

Sustainably-sourced Scottish timber and timber waste could be broken down and fermented to produce bioethanol.

This is used in fuel blending, cosmetics and pharmaceuticals.

This option would compliment plans to scale up the amount of softwood production through forestry in Scotland.

Between 50 and 60 jobs would be created from £350m-£430m of investment with production starting in 2032.

Anaerobic digestion is already carried out at dozens of small-scale plants across Scotland.

The process takes animal waste and sewage sludge and ferments it into biomethane.

The gas can then be used by local industry or injected into the gas grid.

Although burning it releases carbon dioxide, it is considered carbon neutral because the carbon originates from the atmosphere rather than underground.

The report says an investment of £15m-£25m would create 5 -10 jobs by 2028.

Fats, oils and certain crops potentially grown in Scotland can be converted into sustainable aviation fuel and renewable diesel.

The process would require hydrogen - but that could be produced sustainably.

China is currently investing heavily in this kind of fat and oil conversion technology, so an adequate supply of raw materials from Scotland would have to be secured.

This would come in part from used cooking oil, tallow and fish oil but would need to be supplemented by oil seed crop production.

It would require hefty investment, from £740m-£900m, but would also save a lot of carbon emissions and support 90-120 jobs. Production could start by 2032.

Hydrogen can be produced from water using a process called electrolysis. It requires electricity but this could come from renewable sources provided it is cheap enough.

Low-carbon hydrogen could then be used as a replacement for natural gas in industrial processes.

The reports says the UK government should reform the energy market to reduce the cost of renewable electricity to industrial consumers, making green hydrogen production more commercially attractive.

About 25-30 jobs would be created by late 2030 with £210m-£250m of investment required.

If enough low-carbon hydrogen is produced at a reasonable cost, this could in turn be used to make methanol - which can be converted to aviation fuel.

Grangemouth is already a supplier of far less environmentally-friendly jet fuels to Scottish airports.

Such manufacturing facilities could create between 240 and 270 jobs but it would be 2036 before production gets under way.

This option would also require around £2bn of new investment in the site.

Another potential use of low-carbon hydrogen is to turn it into ammonia.

This could be used to decarbonise shipping, as ammonia-powered engine technology develops, and it is also used by the chemicals industry.

As with e-methanol production, it requires electricity to be cheap enough to make the large-scale production of green hydrogen more commercially viable.

The amount of hydrogen required is so large that so-called "blue hydrogen" could also be necessary, produced from natural gas with the carbon dioxide by-product piped to north-east Scotland to be buried underground.

The proposed Project Acorn carbon capture scheme at Peterhead missed out on a first round of UK funding but an update on support is expected this summer.

EY estimates it would take a decade or more before e-ammonia production would start but between 180 and 210 jobs would eventually be created and there would be significant emissions benefits.