Wednesday, September 27, 2006

Solar Hot Dogs

The "El Solito" (little sun) parabolic solar barbecue is increasingly popular with folks who want to cook outdoors, but who don't want to pollute while they do it. The El Solito features a highly polished aluminum parabolic dish reflector which focuses sunlight on a focal point, where the pot holder sits. Anything that you put at the focal point will become very hot, when the barbecue is properly focused.

During a sunny break, we set up our El Solito to grill some hotdogs for the staff at 2 Matilda St. Here are the results.

Before cooking.

During Cooking.

Ready to eat!

The results - crispy on the outside, incredibly moist and suculent on the inside. We're doing this again!

Monday, September 11, 2006

Solar Cooking Accessories

When cooking with solar energy, it's very important to use the right pots and pans. If you use the wrong cookware, you might not get the highest temperature, or the best results out of your cooker.

Most of us have shiny stainless steel or copper cookware. There are many different quality grades in this type of cookware, but generally speaking the heavier the pot is, the better it is thought to be. Heavy cookware more evenly transmits heat to the food when used over a flame or in a gas or convection oven. High quality metal cookware often features a heavy, thick metal base. And of course proud foodies like to keep their pots nice and shiny.

When cooking with solar we want precisely the opposite qualities in our pots and pans.

Solar appropriate cook pots should never be shiny, because shiny pots reflect sunlight - fuel - away from the metal. Cookware should me matte black if possible. Dark coloured cookware is also OK. Avoid white. Aluminum foil is a big no no.

Heavy pots work less efficiency in solar cooking than do lightweight vessels. This is because of a quality called "thermal mass" - the same quality that makes heavy cookware desirable when used with intense, on-demand energy sources.

The heavier an object is, the more energy it takes to heat it up. When used over a flame (which is wasting much of the energy in the fuel, and this can be felt as ambient heat in your kitchen from the stove) a heavy pot or pan stores up energy - it stays hot long after you take it off the heat source. This can be very desirable, or not.

In solar cooking, there is not a great deal of extra energy to work with, very little heat is wasted, so we want all the energy we're collecting from the sun to go into cooking the food, not heating up a big piece of metal. Lighter pots work better in solar cookers. Less mass, less energy. If you try to put a massive cast iron pot in a solar cooker, you will see the temperature in the oven drop dramatically. This is because the heat energy is literally being sucked up by the mass of the metal. You want the mass of the food to absorb the energy, because that's where the real work is being performed. Solar cooking is highly efficient in this way.

The laws of thermodynamics tell us that the temperature of objects reverts to the mean, with a tendency of hot objects to become cooler. Objects in highly excited energy states (hot objects) tend to loose their energy over time, and cool down. This is one way of looking at entropy.

For a practical example of this phenomenon, if you put a hot plate of food outside, the temperature of the food will cool off to equal the ambient temperature of the room, or of the outside air. This is why a solar oven is well insulated - to trap collected solar energy and to prevent it from escaping into the ambient air. We're holding off entropy so that our collected solar energy can do some work for us before dissipating.

Solar pots and pans - they're out there

It's easy to find a great variety of solar appropriate cookware from high quality manufacturers. In addition to the solar cook pots provided with our Sun Cook, and in addition to the black enameled steel roasting pans that most people have in their kitchens, there are many other types of cookware that can be used in a solar oven or on a parabolic solar cooker. Here's what I picked up.

This 10 cup espresso maker is from the Italian manufacturer Palazzetti. The red model, which I use in my kitchen, also works just fine. The grey colour will absorb the solar energy that is focused on the base of the pot. Use it at the focal point of your parabolic solar cooker.

Here's a lightweight, restaurant grade black steel frying pan from the French maker, de Buyer, which has been making cookware since 1830. It cost me ten dollars at a sale, and it's a quality, restaurant grade product. This could be used in the Sun Cook, or in a parabolic cooker.

Lastly, here's a non-stick loaf pan that's solar appropriate. Use it in the Sun Cook.