Cooking
Cooking is the most often overlooked area when renewable
energy is one of the primary concerns in home design. It is
the largest energy use, after heat, hot water and
electricity. In some homes, energy used for cooking may
even exceed the home's electrical energy consumption. The
question of energy sources and equipment for cooking was
one of the more difficult and complex decisions we had to
make. Because we love to cook both simple and gourmet
meals, and because we preserve food grown in the garden, it
was very important to pick the cookstove that we use
multiple times every day, and virtually constantly during
the fall harvest.
Because we were committed to avoiding the direct use of
fossil fuels, LP gas was not an option. We do not have
natural gas available, and wouldn't have chosen it if it
were. Electricity is problematic because of our plan to
generate all the electricity we need from renewable sources
on site - hydro and solar. Electricity is a problematic
cooking fuel because so much power is needed at one time,
for example several pots on the stovetop and an oven being
used. This would require far more energy than we could
generate at any given time from our micro-hydro-electric
generator or solar panels, and therefore a huge supply of
batteries along with a huge inverter would be needed simply
to supply the electrical needs for the short period of time
that it took to cook a meal. This was possible, but not
ideal.
We have a wood cookstove, and experience has taught
us that it's certainly possible to cook with wood, but it's
hard to control the temperature of the oven and stovetop.
Being "possible" does not mean easy or ideal, especially
when trying to coax a delicate sauce to perfection while
attending to the rest of a complex meal. It's very nice not
to have to worry about getting dirty hands tending a fire,
or a temperature drop in the oven as the cake is rising, in
the midst of making dinner! A wood cookstove would
certainly be a good backup option to use in the absence of
some other easier option, but not our first choice.
This was a problem! We talked and talked about what energy
source to use for cooking. We looked into methane
generation: It's possible to generate cooking gas from
collected animal manure and other biomass at home. This
seemed to be a lot of work for a little cooking gas, and we
learned that open gas flames give off toxic fumes, which is
a special concern in a modern well insulated home. We
looked at stoves fueled by oil, hoping that we could
substitute some bio-diesel, alcohol, or other vegetable
based oil for the petroleum required by these stoves. We
couldn't find a stove we liked, and the thought of
producing oil at home was daunting.
This led us back to considering electricity and wood. The
main problem with electricity was the need of a lot of it
for a very short period of time. The main problem with wood
was maintaining temperature by adjusting a fire that is not
easy to control like gas or electricity.
AGA Cooker
Finally we decided on an electrically fueled
AGA cooker. An AGA is a heat storage
cooker that is very popular in England. It uses only a
small amount of electricity at any given moment, but
is on all the time. It is well insulated so that not
too much heat is lost to the room. Here's how it
works: A small heat source in the center warms up a
large amount of cast iron that is insulated from the
room. The cast iron forms four ovens and two "burners"
on the cook-top. The burners are covered by lids to
retain heat when not in use. Each oven is kept at a
different temperature based on its proximity to the
heat source and position in the cooker. One oven is
450 degrees and is used for roasting. Another is 350
and is used for baking. A third is 250 and is used for
simmering food that might be cooked on the top of a
conventional range, and the forth oven is for keeping
things warm at 150 degrees. The two "burners" on the
cook-top are also at pre-set temperatures. One is set
to precisely simmer without scorching, and the other
provides maximum heat possible to boil water, sear
meat, and other high heat intensity needs. The AGA is
designed for most of the cooking to take place inside
the ovens, however the cook-top just like any other,
with the temperature adjusted by moving a pot away
from the center of each "burner." Each of these
"burners" is called a hotplate, and is large enough to
accommodate three pots. As food is cooked, the thermal
mass of cast iron inside slowly reduces in
temperature, and after cooking is completed, the small
heat source slowly brings the cooker back up to ideal
operating temperature. Though the temperature of the
cooker goes down during cooking, this is not enough to
affect cooking. And once the cooker is back to it's
ideal temperature, the heat source turns off,
requiring very little energy to maintain the
temperature. By choosing this solution, we have
eliminated the main drawback of cooking with
electricity - the sudden need for lots and lots of
electricity that would overload a modest renewable
energy electrical system. And in the winter, any heat
lost from the AGA would be a welcome addition to our
home.
Tulikivi Masonry Heater Cookstove
In addition, we've decided on a wood cookstove as a
backup and an additional source of heat in winter.
Tulilkivi Masonry Heaters were
mentioned earlier in the section on
Active
Heating, and they also make a cookstove variation
of their masonry heater. With a masonry heater, you
create a fire just once a day, which heats up a large
amount of soapstone quickly, and then the heat is
radiated into the room for 24 hours. Burning wood in a
masonry heater achieves about 90% efficiency - it is
the most efficient way to burn wood. With Tulikivi's
cookstove, the fire has burned out and the soapstone
is warm long before you begin cooking. The temperature
stays relatively constant in the oven during cooking.
This feature of masonry heaters addresses one of the
major drawbacks of wood cookstoves that we have
experienced in the past. In addition to the oven,
there is a cast iron cook-top which is kept quite warm
by the masonry below. In order to cook on the
cook-top, a small supplemental fire is built in a
separate firebox to raise the temperature of the
cook-top from warm to hot. Because this fire is only
supplemental, rather than the only heat source, it's
easier to maintain an appropriate temperature. And,
like most wood cookstoves, the pots can be moved to
different areas of the cook-top to adjust the
temperature.
And finally, after making all these difficult decisions, a
family member who has an AGA told us that in the very
hottest couple of weeks in summer, she always feels the
need to turn off her AGA. She told us that we just had to
have something simple to use during those hot periods. We
took her advice, and decided upon a grill outdoors, a two
burner electric hotplate and a small electric oven
connected to the grid - not through our renewable energy
system - to be used only when the AGA is off.
By making these decisions, we can cook gourmet meals and
meet our renewable energy goals at the same time.
