First US shale gas arrives at Ineos plant in Scotland
The first shipment of US shale gas to be delivered to the UK remains anchored in the Firth of Forth, unable to dock because of strong winds.
It arrived amid a fierce debate about the future of fracking in Scotland and the rest of the UK.
The tanker, carrying 27,500m3 of ethane from US shale fields, is bound for the Grangemouth petrochemicals plant owned by Ineos.
Ineos said the gas would secure the future of the plant's workforce.
But many politicians and environmental groups have criticised the shipment.
They claim the process of injecting water, sand and chemicals into the rock at high pressure damages the environment.
Drilling for shale gas is only at an exploratory phase in the UK.
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The Scottish government has placed a moratorium on all fracking in Scotland while a study into its impact is carried out.
It said ministers were "unavailable to attend" the arrival of the shale gas shipment.
The tanker had been due to dock at midday. A fresh attempt will be made at about midnight.
By John Moylan, BBC employment and industry correspondent
Ineos says access to cheap US shale gas will transform the economics of Grangemouth.
And it believes that the creation of a chemical and manufacturing hub around the plant could pass that competitive advantage on to others.
But cheap US ethane won't just help Grangemouth.
Ineos has also signed a long term supply agreement with the Exxon Mobil/Shell Ethylene plant in Fife.
A pipeline will also carry ethane from Grangemouth to Ineos's plant in Hull where it recently announced a multi-million pounds investment to take advantage of shale gas economics.
Now rivals are responding. US shale gas will soon be coming to another petrochemicals plant on Teesside, where the Saudi chemicals firm SABIC has also announced a "very significant" investment.
Some say this could amount to a renaissance for our chemicals industry which provides key products for manufacturers across the UK.
At the very least it should boost its global competitiveness and help safeguard jobs for years to come.
Jim Ratcliffe, Ineos founder and chairman, said shale gas had helped to secure 10,000 jobs.
He told BBC Radio Scotland's Good Morning Scotland programme that the chemicals industry was "not perfect" and that there would be the "occasional" environmental issue.
Mr Ratcliffe added: "What I am saying is I don't think it is any different to the chemical industry - there isn't a product that you buy or consume that doesn't require a chemical of one form or another.
"And the chemical industry is extremely good at managing environmental issues and safety issues, but it is not perfect. It is like a puncture in your car - occasionally you get a puncture and occasionally we have an accident in chemicals."
The company said the shipment aboard the carrier Ineos Insight was the culmination of a £1.6bn investment resulting in eight tankers forming a "virtual pipeline" across the Atlantic between the US and the UK and Norway.
Ineos argues that with the North Sea's supply of ethane dwindling, the shipments from the US are the only way of bringing in sufficient gas at low enough prices to maintain its olefins and polymers business at Grangemouth in the face of global competition.
It believes the US shale gas will provide sufficient raw material to run its manufacturing site at full rates, something that has not been possible for many years.
By BBC Scotland energy and environment correspondent Kevin Keane
Most people imagine shale gas as something you burn to create electricity and energy. What Ineos will do with it at Grangemouth is take ethane from the gas and create plastic pellets for general manufacturing.
It's something that's already being done at the plant and up until now Ineos has been getting that ethane from North Sea natural gas.
The company says that previously there have been plentiful supplies in the North Sea, but for the past three or four years it's been diminishing and the pellet-making process has been running at half speed.
The US shale gas means Ineos can push Grangemouth back up to full production with weekly deliveries creating a "virtual pipeline" that will allow them to keep supplies topped up.
The Grangemouth facility is home to Scotland's only crude oil refinery and produces the bulk of fuels used in Scotland, with the site said to contribute about 3% of Scottish GDP.
It is also home to Europe's biggest ethane tank, which is capable of holding 60,000m3 of gas after it arrives by tanker.
Ineos has said the shale shipments should safeguard the future of Grangemouth's 1,300 workers.
The company has signed 15-year contracts with suppliers to pipe ethane from the shale fields in the US to purpose-built export facilities on the east and Gulf coasts of America.
From there, the gas will be shipped across the Atlantic in a fleet of eight specially-designed Dragon-class ships commissioned by Ineos.
Ports in Norway, Portugal, and Spain have all received shale gas shipments this year following the lifting of a ban on the export of US oil and gas, but the arrival of the Ineos Insight will be the first to the UK.
Unconventional oil and gas extraction remains controversial in the UK, with the UK Labour Party following Scottish Labour in backing a ban on fracking if it wins the next general election.
Despite pleas from Ineos to embrace shale gas drilling, the Scottish government moratorium on the practice remains in place, in contrast to the pro-fracking stance of the UK government.
The Scottish Parliament voted to support an outright ban on fracking in June after SNP MSPs abstained.
The Scottish government said it had commissioned a series of independent research projects into unconventional oil and gas to examine potential environmental, health and economic impacts to inform its "evidence-led approach" to the issue.
A spokesman said these projects were due to report later this year, with the public consultation taking place during winter 2016-17.
He added: "The moratorium will remain in place throughout this process and the Scottish government will use the results of the consultation to inform its decision on the way forward."
Mary Church, head of campaigns at Friends of the Earth Scotland, said: "It is completely unacceptable to attempt to prop up Ineos's petrochemicals plants on the back of human suffering and environmental destruction across the Atlantic.
"The fact that Scottish public money is tied up in this project is disgraceful.
"Setting aside the devastating local impacts of fracking, the climate consequences of extracting yet more fossil fuels are utterly disastrous."