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, August 22, 2010

DAY 6_SOLAR POWER

20 August, 2010

miles biked-14
water used - 7.3875 gallons (7.6125 surplus)

While I got some initial calculations from Jamie Borell at Innovative Power Systems, I needed some specific information about  my hypothetical PV solar array to maximize my electricity budget.  While most solar arrays are sized to the need of the particular house, my solar system was sized in the opposite way-maximizing the amount of sun energy I can capture to determine what my electricity budget will be.

Here is how it was calculated:

There are 3 main factors to consider when sizing a solar array:

1_The square footage of your house
2_Options for solar panel orientation
(A) Solar panels can be angled at 45 degrees (for a MN climate) in which case they are maximized for the most energy captured per panel.  however, with this system there must be room left for shadows which will fall on panels located behind.  This reduces the sq footage of the roof available for sun capture by a factor of 2.5.  (The square footage of your house divided by 2.5)
(B) Solar panels can be placed flat on the roof.  This way, you are able to use the most roof area for solar energy capture, however, the angle is not ideal and the efficiency of the panels is reduced by 20%.
3_There are different "efficiencies" for solar panels, outputs range from 8watts/sq ft to 20w/sq ft (and probably more options exist).  Generally the most expensive the panel, the greater energy output in watts/sq ft you can achieve. 

To calculate the amount of solar power you can capture on your own roof:

1_Find the square footage of your house (mine is 1790 sf)
2_Decide if you would like to go with 45 degree panels (cheaper) or flat panels (more panels required=more expensive)
    Divide the square footage of your house by 2.5 for 45 degree angle panels (this is your available sq footage)
3_Determine the watt/sq ft output of your panels (this information is found on manufacturer's websites) (I'm going with 8w/sq ft)
4_Calculate:

(Available square footage of your house for solar) x (Efficiency of panels in watts/sq ft) = Size of your system in watts

(Size of your system in watts) x Either (1.28 kWh/watt installed for 45 degree panels) or (1.043kWh/watt installed for flat panels)
=kWh/yr

Divide by 365 for kWh/day

Being that my goal is to maximize my solar power (regardless of cost) I am going with the flat solar panel arrangement. This system would be more expensive (because there are more solar panels involved, but would result in a higher energy output, see calculations below):

45 degree angle option(1790 sq ft/2.5) reduction in sq footage due to shadows:


1790 sq ft/2.5=716 sq ft x8w/sf =5728 w system (5.7kw system)
(5.7 kw) x1.28 kWh/watt installed =7331 kWh/yr =20.08 kWh/day (3.35 kWh/person/day)

vs.

Flat solar panels option covering all 1790 sq ft:

1790 sq ft x 8w/sf =14,320 watt system (14.3 kw system)
(14.3kw) x1.043 kWh/watt installed = 14,935 kWh/yr (14.9 kWh/yr) =40.9 kWh/day (6.82 kWh/person/day)

so my electricity budget per day is 6.82 kWh.

(Thanks to Pat Smith at CSBR! (numbers from previous Weidt Group calculations))

Other noteworthy things happening today was it was the first time I've eaten at a restaurant since the project began.  Common Roots http://www.commonrootscafe.com/ is only a block south of me and an excellent source of local foods.  As much as possible, their food and drinks are local.  While I have to ask about specific meals because the sourcing changes constantly, they are a great local restaurant option (they are gonna get really sick of me by the end of this project).  I had radish cakes / seared and topped with sunflower sprouts and toasted hazelnuts and a local Brau Bros (Lucan, MN) sheephead ale :)  I also got some great advice from friends about local food options and extras from gardens.  Thanks Dan, Nate, Sarah and Katy! Get me that garlic Dale :)

3 comments:

  1. My ears go up when I hear comments like, "my solar system was sized in the opposite way-maximizing the amount of sun energy".

    I'm not seeing any variables for the issue of cloudy days, snow cover, your total solar window, and other factors. Maybe you just didn't mention them.
    Did they run a RETScreen, TRNSYS, or PVWatt analysis of your property?

    I would suggest you get a solar assessment from an independent Certified Residential Solar PV assessor. There is a list of those at MREA, which certifies those people (http://www.mreacsa.org/). There is a specific process for assessing, which is followed by Certified Assessors.

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  2. Richard-thats a good point, I havn't accounted for cloud cover and snow load. Of the options I saw for efficiency of panels w/sf I chose the lowest I saw on some manufacturer websites (8w/sf), so I was guessing that even with cloudy days at least this amount would be able to be captured. However, I certainly havn't wrapped my head around these calculations totally yet so looking into what it takes to get a Solar PV assessor to look at my house is a good suggestion

    ReplyDelete
  3. You might qualify for a new solar energy rebate program.
    Find out if you're eligble now!

    ReplyDelete