It is four o'clock in the morning and Cicero Montiro de Silva is up and getting ready for the field.
He is a sugarcane cutter and it is harvest time. He leaves home as dawn breaks. Climbing on board a bus packed with other cutters, he heads out into a landscape covered in ripe sugarcane.
Cutting sugarcane with machetes is back-breaking work
Across Brazil at this time of year hundreds of thousands of cutters are making the same journey, sharing the long, hard days of the harvest.
"I'm used to it now," he says, "but it's exhausting. I wish I could do something else but this is what I have to do to eat."
The work of the harvest has not changed much since the Portuguese introduced sugarcane to Brazil 500 years ago - it involves machetes and hard labour.
The difference is that the cane hacked from these fields is part of an energy revolution. Brazil believes sugarcane can provide an alternative to petrol.
The sugarcane cut in these fields will be distilled into ethanol and then used to power cars and lorries across Brazil, or be shipped around the world.
With an industry that began in the 1970s, biofuel has made Brazil an agricultural superpower. The country was hit hard by the oil crisis and the then military government launched a subsidised drive to embrace the alternative energy source.
Watch an extract of Richard Bilton's film
Now, Brazil is the world's second biggest producer and is also considered the most efficient. Biofuel - if based on sugarcane as opposed to corn - produces carbon dioxide emissions about 90% lower than petrol.
So it is hardly surprising that, for a while at least, biofuel looked like the energy of the future.
But Brazil has watched as, around the world, the biofuel dream began to get complicated.
Environmentalists - once ardent supporters of generating energy from plants - now describe with horror the consequences of increased production of biofuel crops.
They talk of forests and villages cleared so biofuel crops can grow, of food prices forced up when land is diverted to growing crops for biofuels, and of human rights abuses. Countries, like the UK, that have embraced biofuels and demand a small percentage in every litre of petrol sold, have started to think twice.
A man gets fed up with this day after day. But we need to be strong. We need to pay the bills.
But the Brazilian authorities argue that sugarcane covers only 5% of Brazil's arable land. Food prices, they insist, are not affected and the rainforests will be left alone. Slavery and child labour have been a problem but strong laws and big fines are stamping it out.
There is independent approval. Oxfam has described Brazil as a leader in the development of biofuels - the most sustainable on the market. But they also flag up the issue of worker conditions.
I travelled through the sugarcane-covered hills and it did not take long to find the illegal harvests, where the underage and the desperate are given work. There are children who have dropped out of school and widows with nowhere else to get money.
Labour conditions are worse on illegal sugarcane plantations like this one
No-one is bothered about safety in these places, all that matters is how much you cut.
Back down in the valley, Cicero's day is drawing to an end. His plantation is legal so he is only allowed to work in the heat for 10 hours. The cane has been burned to make it easier to cut, but every slash throws up a cloud of hot, dry ash. He is shattered and filthy.
He has cut four and a half tons, for which he will get less than the equivalent of $10 (£7).
"A man gets fed up with this day after day," he says. "But we need to keep working. We need to be strong. We need to pay the bills."
That is what Brazil is doing. It leads the world in harvesting this green fuel. But change can feel a long way off for those toiling in the fields.
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