Solar ponds. All you need is a basin and salt. This gives you low temperature heat and thermal storage that lasts all winter. You could use it for:
a. Canning. Stashing food in there will keep it sterile. People will observe this as food is accidentally left in there for a few weeks and is still good to eat. Wax layers on top of cans or jars is an obvious next step. They already had "potted" meats with layers of tallow or lard or schmaltz.
b. Desalination. Hot water will flash to steam pretty easily after you pull it out and let it dump hot vapor to a cooler environment. This is not really going to be cheap enough for agriculture, but it will be cheap enough for caravan routes.
c. Salt precipitation. Salts precipitate differently if you heat their solutions instead of evaporating them at a room temperature. You get CaCO3 and MgCO3 and CaSO4 and MgSO4 out right away instead of the CaSO4.2H2O and MgCl2.6H20 you ordinarily get when you room temperature evaporate. This is important because it separates out the KCl or K2SO4 that is important for fertilisation from the six times more common MgCl2.6H2O that is not, making the observation of increased fertility more noticeable and decreasing the cost of transport. You can also separate the Na2SO4.10H20 out by freezing over the winter and then precipitating as Na2SO4 by heating during the summer.
d. Bathing. Bathing in cold water is not enjoyable. Bathing in warm water is. Increased sanitation will have an effect. Decreased sanitation by sharing used bathwater will also have an effect.
e. Pasteurisation. Not quite the same as canning. Milk can be kept for children during the winter months. Increased survival rates for children is a result. Especially royal children. Fruit juice for everyone else is also a good idea in terms of scurvy control.
f. Pest control. Heating used clothes eliminates not just fleas and lice (black plague and typhus), but also smallpox, etc.
g. Central heating. Less demand for firewood from any area with salt available by sea, river, canal, salt spring or salt mine.
h. Rendering. Removing fats and oils is easier if the material is kept hot. More olive oil, more butterfats, more oilseeds oil in general.
What can you suggest?
a. Canning. Stashing food in there will keep it sterile. People will observe this as food is accidentally left in there for a few weeks and is still good to eat. Wax layers on top of cans or jars is an obvious next step. They already had "potted" meats with layers of tallow or lard or schmaltz.
b. Desalination. Hot water will flash to steam pretty easily after you pull it out and let it dump hot vapor to a cooler environment. This is not really going to be cheap enough for agriculture, but it will be cheap enough for caravan routes.
c. Salt precipitation. Salts precipitate differently if you heat their solutions instead of evaporating them at a room temperature. You get CaCO3 and MgCO3 and CaSO4 and MgSO4 out right away instead of the CaSO4.2H2O and MgCl2.6H20 you ordinarily get when you room temperature evaporate. This is important because it separates out the KCl or K2SO4 that is important for fertilisation from the six times more common MgCl2.6H2O that is not, making the observation of increased fertility more noticeable and decreasing the cost of transport. You can also separate the Na2SO4.10H20 out by freezing over the winter and then precipitating as Na2SO4 by heating during the summer.
d. Bathing. Bathing in cold water is not enjoyable. Bathing in warm water is. Increased sanitation will have an effect. Decreased sanitation by sharing used bathwater will also have an effect.
e. Pasteurisation. Not quite the same as canning. Milk can be kept for children during the winter months. Increased survival rates for children is a result. Especially royal children. Fruit juice for everyone else is also a good idea in terms of scurvy control.
f. Pest control. Heating used clothes eliminates not just fleas and lice (black plague and typhus), but also smallpox, etc.
g. Central heating. Less demand for firewood from any area with salt available by sea, river, canal, salt spring or salt mine.
h. Rendering. Removing fats and oils is easier if the material is kept hot. More olive oil, more butterfats, more oilseeds oil in general.
What can you suggest?