Weve been looking at glycol free coolants for work . A non glycol type coolant (ELI - extended life inhibitor) has better cooling properties than a glycol based coolant (ELC - extended life coolant) . worth a couple of degree cooler running (it is in our case anyway , where we were looking for any benifit we could get) .
The other bonus of running an ELI is reduced risk of fire, If you boil of the water and leave the glycol . you can then ignite the glycol .

However ELI cannot protest against freezing , which is why it's not recommended for below freezing temperatures .
Theres quite few companies doing glycol free coolant now to.