By Mark Kinver
BBC News science and nature reporter
In the 19th Century, the only "biofuel" that powered farm machinery was the hay and grain that fed the horses that pulled the plough to turn the soil.
Fuel of the future? Barley is used to produce ethanol
But the arrival of the industrial revolution, the advances in our knowledge of chemistry, and the utilisation of oil, revolutionised our lives.
Since then, societies around the globe have not looked back. Coal and oil have fuelled economic growth for more than 200 years.
But today, political leaders of all persuasions are having to think the unthinkable and look beyond the age of oil.
The upward trend in the cost of oil, fears over security of supplies, and the environmental consequences of burning fossil fuels are forcing the rethink.
It appears as if many nations are taking a leaf out of the history books and looking to home-grown solutions for an answer: non-food crops.
'Addicted to oil'
There is no definitive definition of what a "non-food crop" is. A committee set up by the UK government defined it as covering both plant and animal products that did not enter the food chain.
The crops are used in a range of materials, including polymers, lubricants, construction, pharmaceuticals, energy and fuel.
President Bush used his State of the Union address in January to pledge that plant-derived ethanol would be cost-competitive by 2012. In Brazil, 60% of all new cars can run on a fuel mix made up of 85% bioethanol.
And in the UK, the government announced last November that 5% of all fuel sold on the nation's forecourts had to be from renewable sources by 2010.
But is it that easy to break our "addiction to oil", as President Bush described it?
Jeremy Tomkinson, chief executive of the UK's National Non-Food Crops Centre (NNFCC), sounds a note of caution for those looking to quickly slip from the grip of petrochemicals.
"If you take plastics, there is only one plant in the world that can produce a truly biodegradable polymer, yet it is finding it very difficult to make any inroads into the market.
THE UK'S NON-FOOD CROPS
Biofuels - oilseed rape, wheat, barley, sugar beet
Energy crops - willow, miscanthus
Biopolymers - linseed, high erucic acid rape, cereals
Biolubricants - crambe,
Pharmaceuticals - borage, crambe, poppy, echium, chamomile
Construction - hemp
"People use plastics because they are very robust; they do not change state when they get wet and can withstand a wide variability of temperature," he told the BBC News website.
"We have moved away from wooden window frames to plastics ones, because plastic is low maintenance and lasts for many years. If you offered people window frames that biodegrade, they would think you were mad."
Research carried out by the NNFCC has focused on the requirements of manufacturers, rather than trying to find a market for a novel non-food crop-based technology.
"We looked at the functionality that businesses needed, and then we worked back through the supply chain to ensure that we satisfied that need," Dr Tomkinson added.
"This has engendered a far deeper understanding among companies of what non-food crops can do, and what systems we need to put in place in order to deliver."
Despite the centre's original aim to widen awareness of the role of non-food crops can play, Dr Tomkinson says interest in the sector boils down to energy crops.
"I would say that more than 50% of the inquiries we receive on a daily basis are about fuel and energy."
It also seems that the signals coming from the White House and Whitehall are being picked up by firms in the UK.
British Sugar is in the process of building a 55,000-tonne bioethanol plant that will process sugar beet; while Wessex Grain subsidiary, Greenspirit Fuels, has been granted planning permission to construct a 100,000-tonne plant in Somerset.
Meeting the need
Such a shift is seen as good news for farmers: "We see non-food crops as a way forward for agriculture," says Matt Ware, policy advisor of the National Farmers' Union.
He says growing energy crops in the UK would help cut harmful greenhouse gas emissions.
"Biofuels, based on current UK production methods, saves about 60-70% on carbon emissions in comparison to fossil fuels. This takes into account the whole process - seeds, planting, spraying, drying and transporting.
"It would save 100%, but 30% is lost in the processing of the crop into fuel."
Biofuels emit up to 70% less carbon than fossil fuels, research shows
Mr Ware said the figures came from the UK government's Central Science Laboratories, but added that some crops would result in a higher carbon saving, whilst others would perform less well.
The NFU rejects claims by some environmental campaigners that it would result in arable land becoming huge monocultures in order to meet the demand for energy crops.
"If 100% of the world's transport fuel was met by biofuels, then it would obviously lead to a conflict between food and fuel," Mr Ware said.
"Because of the climatic conditions in the UK, and the advantages it gives our arable crops, we produce three million tonnes of surplus a year. Figures show that we currently have enough surplus to produce 5% bioethanol."
He hopes that in the future, farmers will be able to set up co-operatives that produce the fuel itself, therefore keeping the extra revenue within the farming community.
Matching the scale
The NNFCC's Jeremy Tomkinson takes a different view. He says the long-term success of non-food crops should be based on large "biorefineries".
Such enterprises, he says, would help reduce the cost of producing base chemicals from crops - the main barrier preventing plant-derived products becoming competitive alongside their synthetic counterparts.
"If you have a plant producing 100,000 tonnes of bioethanol a year, you can see how easy it would be to integrate that production into larger refineries because you already have economies of scale.
"Petrochemical refineries are highly integrated and very dynamic. They have a wide number of processes to produce different products at different stages of the feedstock's journey through the facility.
"People have no problem with the processes within the refinery, because it is very efficient in its use of the raw material. What we do have a problem with is the feedstock - crude oil," Dr Tomkinson observed.
"But replace that with crops, and you have whole crop utilisation and a range of cost-competitive renewable products. It's a no-brainer."