The ultra-clean, synthetic diesel fuel is made from animal fats, such as beef tallow, pork lard and chicken fat.

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Effluent waste from these concentrated animal facilities are undermining what little clean water and healthy micro-nutrient cycles still exist out there.

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Once everyone is tired out, organisers like Newmindspace in New York collect pillows to donate to no-kill animal shelters and remind participants to clean up any mess.

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Experts from the animal welfare charity the SSPCA have been trying to clean up the birds, but so far it has been possible to release only two of them.

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My own company began by delivering clean energy (in the form of natural gas) to rural China, where families still used animal dung for cooking fuel.

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