This era in history may be remembered as the "Peak Age", a brief time when nearly all materials used to power and create our society reach the maximum extraction and production potential. Past this point, all of these resources become increasingly difficult to extract until they are no longer economically viable resources to be using. There are hundreds of examples of resources, currently embedded in our industrial society, which have reached their peak in the 50 years surrounding 2010, but the one which will most impact our society is petroleum.

The goal of living for 100 days without oil is to understand the extent of our dependance on oil in American society today. Specifically, how it will affect my life, as a 25 year-oil living in Minneapolis, MN. By using myself as a metric I can take a close and conscious look at where oil dependance occurs in all aspects of our daily lives : How we transport ourselves from one place to another, what we eat, how much waste we create, how water is cleaned and transported, where oil is used as; an energy resource, in conventional medicine and for hygiene and how oil affects how we entertain ourselves and communicate with others. By demonstrating how someone would be forced to live without using any oil resources, outlining both what the sacrifices will be as well as the benefits, we can can identify the many systems which will have to be re-designed in a world without cheap oil, and explore a new way of living in which we live in an energy balance.

(At the bottom of this page is a link to my version of a flow diagram of 'Where Petroleum Exists in Our Daily Lives' (using information from the Energy Information Administration-Annual Energy Review 2008 fig 5.0 Petroleum flow) click and zoom to enlarge)


Sunday, October 10, 2010

DAY 52_FOOD PRESERVATION ENERGY COMPARISON

5 October 2010

The growing season in Minnesota is coming to a close.  Local available produce is already down to;

_only apples for fruit
_a few types of hardy greens grown in season extensions; kale, chard, mustard greens, mizuna, collards
_a few types of peppers
_garlic, shallots and onions
_potatoes
_lots of squash
-tomato and fresh herb supply comes and goes

While this still isn't bad, I'm guessing by the end of the project I may only have potatoes and maybe squash left to buy locally (both of which can last for months), so I am experimenting with different methods of preserving foods: dehydrating, freezing, and canning. 

This website (National Center for Home Food Preservation) http://www.uga.edu/nchfp/how/can_home.html is an excellent resource for 'how-to's on all types of food preservation.

DEHYDRATING:
The water content in most fresh foods is what makes them very perishable.  My roommate's dehydrator is an old (1970's) convective heat only dehydrator.  This is nice because it uses less energy and is quieter than types with fans, but it also takes quite a while to dry (half a day for herbs and about a day for bell peppers/fruit).  Most fruits are best when dipped in a honey or lemon dip before drying (to avoid browning).  My experience with dehydrating foods showed that foods that are already fairly dry (herbs, hot peppers and apples) dried better (and faster) than foods which contain quite a bit of water (bell peppers, cranberries).  Anything you dehydrate needs to be soaked in water for 10 minutes before cooking with it.  If doing rice with vegetables, you can simply put the dried vegetables in with the rice water. 


CANNING:
Canning removes oxygen, destroys enzymes and prevents the growth of undesirable bacteria, yeasts and molds to preserve food.  I haven't done this yet, but have a stock-pile of Roma tomatoes to can with soon. 
The method for tomatoes is:

1_sanitize canning jars and lids by boiling in water for a few minutes
2_put tomatoes is boiling water for 30-45 seconds and then dip in a waiting ice bath to get skins to slide off easily (skins get tough when canned)
3_cut off tough parts of tomato (halve and squeeze out seeds and juice if making paste)
4_pack tomatoes into jars
5_add 2 tbsp of lemon juice (tomatoes are low in acid and the lemon juice helps to preserve them)
6_fill remaining space with boiling water (up to 1/4 inch from the top of jar)
7_free any trapped air bubbles out by moving a spoon around in the jar
8_screw lids on snugly (but not too tight) and place cans in a large pot of boiling water for about 45 minutes
9_remove from water carefully and let cool
10_test for seal by removing ring and pressing on center of lid (if it doesn't pop back up, it is sealed)

FREEZING:
Almost anything except herbs and milk products can be frozen fairly effectively.  The best way to preserve nutrition in frozen foods is to blanch them first.  Blanching is scalding vegetables in boiling water or steam for a short time, this stops enzyme actions which can cause loss of flavor, color and texture.  It also helps to clean the vegetables and retains color and vitamin loss.  Over blanching, however, has the opposite effect and can cause flavor and nutrient loss.  To blanch, use 1 gallon of water per pound of vegetables and begin the count when water is boiling.   A list of blanching times is found here: http://www.uga.edu/nchfp/how/freeze/blanching.html. Blanching can also be done by steaming. This takes 1 1/2 times longer than water blanching, but is recommended for some vegetables.  After blanching, the vegetables should be immediately cooled in water 60 degrees or less. 

Other preservation methods I haven't explored are; curing/smoking, fermenting and pickling. 

While many foods can be preserved using any of the above methods, some are definitely better suited for certain purposes:

BEST DEHYDRATED:
herbs:
The herbs are easy to do, you simply cut the long end stems off and spread them on the tray.  When they are dry, put them in a bowl and crush with your fingers and then put in a jar.  Don't crush them too much, because before you use them you can crush them a little bit more so the taste is fresher.  If there is any condensation on the jar after about a day, you haven't dried them enough.  I dried a bunch of cilantro which filled an entire spice jar.  Freezing can alter the taste of herbs or make them strong

hot peppers:
Cut into thicker slices than you would if cooking fresh (they will shrink down when drying) and place on tray.  These took about a day to dry in the dehydrator and about 10 (mix of hot wax peppers and sweet hot red peppers) filled a 24 ounce mason jar. 

apples

BEST FROZEN:
bell peppers
meat products
fruits if moisture needs to be retained

BEST CANNED:
high acid fruits/vegetables (don't need any additives)


With all of this in mind, there are definitely differences in how much energy is needed for each type of food preservation:

Dehydrating:
The dehydrator I am using uses 0.1 kWh/hour.  For a day of dehydrating this translates to 24 kWh of total energy needed.

Canning:
About one hour of boiling time is needed (15 min to sanitize and boil skins off and 45 min for whole cans to seal).  This uses about 1.2 kWh total.

Freezing: (biggest energy user)
My fridge uses 0.068 kWh/hour.  Granted, this is both the fridge and the freezer, but in most cases, people don't have a separate freezer so I am using these numbers to calculate a typical scenario.  In one month, the freezer/fridge will use 48..96 kWh.  If I canned in late October and preserved food in the freezer for 6 months (till the end of April) I would use 293.76 kWh total.  Freezing for only 18 hours is equal to the amount of energy used for canning, freezing for 36 hours is equivalent to dehydrating. However, these numbers are for only one use of the dehydrator, and only about 6-8 cans of canned food. If canning or dehydrating exclusively, these numbers would need to be increased.  I haven't calculated how much food you would need to store to eat throughout the winter  (more on this later). To compare visually I've made the graphic below: 


As you can see, although canning and dehydrating use a lot of energy up front, they are 'one time' energy users.  Freezing demands a continuous supply of energy which adds up to be significantly more than either of the other methods when storing until the growing season starts again.
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1 comment:

  1. AydanOctober 11, 2010 at 5:08 AM

    Your posts on preserving food inspired me to try to preserve some bell peppers for the winter. I don't have a dehydrator, so I used an oven set on low, and now I'm sun-drying them for the next week. If these turn out okay I'm going to try apples.

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