Steel Food Can Recycling Impact Calculator - Calculation Explanations and Sources

Below is an explanation of the calculations utilized in the Steel Food Can Recycling Impact Calculator and the sources accompanying the impact metrics.

Absolute Impact | Economic Impact | Energy Savings | C02e Emissions Avoided  


Absolute Impact

MEGAJOULES SAVED

Formula:

[Energy savings per kilogram of steel recycling in megajoules] / [grams in a kilogram] * [Grams of metal in average steel food can] * [estimated yield of steel recycling]

17.47 / 1000 * 43.1 * 0.9 = 0.68

Explanation:

The energy savings per kilogram of steel recycling in megajoules comes from worldsteel’s life cycle inventory methodology report and accompanying study report, based on the energy used to make primary steel and recycled steel, as well as the yield of steel recycling (0.9). For purposes of this calculator, the assumption is no energy is lost in transit so 100% of the energy savings is usable energy. Then divide by 1,000 to get the per kilogram energy saved by steel recycling to per gram. That is multiplied by 43.1 to get the energy saved by recycling steel per can since there is about 43.1 grams of metal in the average steel food can.

Sources:

  • Energy savings per kilogram of steel recycling in megajoules | worldsteel life cycle inventory study (2017)
  • Grams of metal in average steel food can | Average weight of the most popular size steel food can (2-piece 15 ounce drawn-and-ironed) from Silgan, the largest steel food can manufacturer in the United States
  • Estimated yield of steel recycling | worldsteel life cycle inventory data (2020 data release)

KILOWATT-HOURS SAVED

Formula:

[Energy savings per kilogram of steel recycling in megajoules] / [megajoules in a kilowatt] / [grams in a kilogram] * [Grams of metal in average steel food can] * [estimated yield of steel recycling]

17.47 / 3.6 / 1000 * 43.1 * 0.9 = 0.19

Explanation:

The energy savings per kilogram of steel recycling in megajoules comes from worldsteel’s life cycle inventory methodology report and accompanying study report, based on the energy used to make primary steel and recycled steel, as well as the yield of steel recycling (0.9). For purposes of this calculator, assume no energy is lost in transit so 100% of the energy savings is usable energy. Then divide by 3.6 to convert the energy savings to electricity. This is because 3.6 megajoules is equal to 1 kilowatt hour. Then divide by 1,000 to get the per kilogram electricity saved by steel recycling to per gram. That is multiplied by 43.1 to get the electricity saved by recycling steel per can since there is about 43.1 grams of metal in the average steel food can. The last step is multiplying by 0.85 since that is the roughly estimated yield of steel recycling.

Sources:

  • Energy savings per kilogram of steel recycling in megajoules | worldsteel life cycle inventory study (2017)
  • Grams of metal in average steel food can | Average weight of the most popular size steel food can (2-piece 15 ounce drawn-and-ironed) from Silgan, the largest steel food can manufacturer in the United States
  • Estimated yield of steel recycling | worldsteel life cycle inventory data (2020 data release)

GRAMS OF CO2e AVOIDED

Formula:

[(Carbon footprint of primary steel, per gram) – (Carbon footprint of recycled steel, per gram)] * [Grams of metal in average steel can] * [estimated yield of steel recycling]

[2.36-0.13] * 43.1 * 0.9 = 48.97

Explanation:

The carbon footprint of primary steel per gram (2.36), and the carbon footprint of recycled steel per gram (0.13) come from the worldsteel life cycle inventory study. By subtracting the carbon footprint of the primary metal by the carbon footprint of recycled steel and multiplying by 0.90 (the estimated yield of steel recycling) gets the emissions avoided by using recycled steel, per gram. That is multiplied by 43.1 to get the emissions avoided by using recycled steel per can since there is about 43.1 grams of metal in the average steel food can.

Sources:


Economic Impact

ECONOMIC VALUE WHEN SOLD

[Short ton value of steel food cans] / [(pound in a short ton) * (cans per pound)]

[$200] / [2000 * 10.52] = 0.01

Explanation:

The value per short ton of steel food cans is $200. Divide that by the number of cans in a short ton to get the value per steel food can recycled. You get the total amount of food cans in a short ton by multiplying 2,000, the number of pounds in a metric ton, by 10.52, the amount of cans per pound. The cans per pound number is derived from taking the number of grams in a pound, 453.592, and dividing it by the weight in grams of the steel food can, 43.1.

Sources:

  • The value per ton of steel food cans recycled | Recyclingmarkets.net (the average price per ton of steel food cans in 2018 was $200; this number was used because it’s less than the $250 per ton seen in mid-2021 but also more than the slightly less than $100 per ton seen in 2020)
  • The steel cans per pound | Average weight of the most popular size steel food can (2-piece 15 ounce drawn-and-ironed) from Silgan, the largest steel food can manufacturer in the United States 

Energy Savings

HOURS CAN POWER A U.S. HOME

Formula:

[438,443 * 365 *24] / [2,192,252,718 * 10.52]

[3,840,760,680] / [23,062,498,591] = 0.17

Explanation:

There are several components to the calculation to get the homes that can be powered for one year if all steel food cans are recycled. The pounds of steel food cans available for recycling is equal to the pounds of steel food cans shipped minus exports of unfilled steel cans plus the imports of unfilled steel cans. That is 2,505,049,580 – 101,985,937 + 32,772,710 = 2,435,836,353. The pounds of steel food cans available for recycling is multiplied by the pounds to kilograms conversion factor so that the per kilogram of steel recycling energy savings equal to electricity can be used to calculate the total electricity savings from all steel food cans shipped assuming they were all recycled. The pounds of steel food cans available for recycling is also multiplied by the estimated yield of steel recycling since not all of those pounds will be included in a new product given the tiny losses involved in the recycling process. The per kilogram of steel recycling energy savings equal to electricity in kilowatt hours is calculated by taking the per kilogram of steel can recycling energy savings equal to electricity in megajoules and dividing it by the conversion factor of kilowatt hours to megajoules of 3.6 megajoules to 1 kilowatt hour. So, 17.47/3.6 is 4.85. Note that this assumes no energy is lost in power generation. The number for the homes that can power for one year if all steel food cans are recycled is calculated by taking the total energy savings that would come from all steel food cans available for recycling being recycled and dividing it by the energy use of a typical household. The typical energy use for a U.S. household in one year is 11,000 kilowatt hours per year. This ultimately gets to 438,443 homes that could be powered for one year with the electricity generated from recycling all steel cans that are shipped out.

The homes that can be powered for one year if all steel food cans available for recycling are recycled was multiplied by 365 and then by 24 to get the number of homes that can be powered for one hour if all steel food cans available for recycling are recycled.

The second part of the formula multiples the pounds of steel food cans available for recycling in one year by the steel food cans per pound. This gives the total number of steel food available for recycling. This was multiplied by the estimated yield of steel recycling since not all of those pounds will be included in a new product given the tiny losses involved in the recycling process.

Then divide the total number of homes that could be powered for one hour if all steel food cans available for recycling are recycled divided by the total number of steel food cans available for recycling to get how many homes for one hour could be powered per steel food can recycled.

Sources:

HOURS CAN POWER A 45" LED TV

Formula:

[kWh saved per steel food can recycled] / [kilowatt hours needed to power a 40 to 50 inch LED TV per hour]

[0.1885] / [0.071] = 2.65

Explanation:

See above for explanation of how kWh saved per steel food can recycled was calculated.

The amount of kilowatt hours saved per steel food can recycled was divided by the kilowatt hours needed to power a 40 to 50 inch LED TV per hour to determine how many hours that TV could be powered by the energy savings from recycling one steel food can.

Sources:

SLICES OF BREAD TOASTED IN A 2-SLICE TOASTER

Formula:

[kWh saved per steel food can recycled] / [(kilowatt hours needed to power a 2 slice toaster) / 2]

[0.1885] / [0.04 / 2] = 9.43

Explanation:

See above for explanation of how kWh saved per steel food can recycled was calculated.

The amount of kilowatt hours saved per steel food can recycled was divided by the kilowatt hours needed to toast each slice of bread in a toaster. The per slice electricity was calculated by taking the kilowatt hours needed to power a two slice toaster and dividing it by two.

Sources:

HOURS CAN POWER A LAPTOP

Hours can power a laptop

[kWh saved per steel food can recycled] / [kWh needed to power a laptop per hour]

[0.1885] / [0.035] = 5.39

Explanation:

See above for explanation of how kilowatt hours saved per steel food can recycled was calculated.

The amount of kilowatt hours saved per steel food can recycled was divided by the kilowatt hours needed to power a laptop per hour to determine how many hours a laptop could be powered by the energy savings from recycling one steel food can.

Sources:

LOAD OF LAUNDRY

Formula:

[kWh saved per steel food can recycled] / [(kilowatt hours per warm wash cycle) + (kilowatt hours to run dryer cycle)]

[kWh saved per steel food can recycled] / [kilowatt hours to run both warm washer and dryer for one cycle]

[0.1885] / [4 + 2.3]

[0.1885] / [6.3] = 0.03

Explanation:

See above for explanation of how kilowatt hours saved per steel food can recycled was calculated.

The amount of kilowatt hours saved per steel food can recycled was divided by the kilowatt hours needed to run a warm wash cycle and a dryer to determine how many loads of laundry could be completed per steel food can recycled.

Sources:

HOURS CAN POWER A REFRIGERATOR

Formula:

[kWh saved per steel food can recycled] / [(kilowatt hours to run a refrigerator per month) / (days in a month) / (hours in a day)]

[0.1885] / [150 / 30 / 24]

[0.1885] / [0.208] = 0.90

Explanation:

See above for explanation of how kilowatt hours saved per steel food can recycled was calculated.

The amount of kilowatt hours saved per steel food can recycled was divided by the kilowatt hours needed to run a refrigerator per hour to determine how many hours a refrigerator could be run per steel food can recycled. The kilowatt hours needed to run a refrigerator for a day was divided by 30 and then by 24 to get the amount of kilowatt hours needed to run a refrigerator per hour.

Sources:


CO2e Emissions Avoided

MILES DRIVE BY AN AVERAGE PASSENGER VEHICLE

Number: 0.123

Explanation:

This number was provided by the U.S. Environmental Protection Agency’s Greenhouse Gas Equivalencies Calculator. The calculator displays the miles driven by an average passenger vehicle per any amount of greenhouse gas that is entered into the calculator. When 0.04897 kilograms, the kilograms of CO2e avoided per steel food can recycled, was entered into the calculator, it said that equals 0.123 miles driven by an average passenger vehicle

Sources:

NUMBER OF SMARTPHONES CHARGES

Number: 6

Explanation:

This number was provided by the U.S. Environmental Protection Agency’s Greenhouse Gas Equivalencies Calculator. The calculator displays the number of smartphones charged per any amount of greenhouse gas that is entered into the calculator. When 0.04897 kilograms, the kilograms of CO2e avoided per steel food can recycled was entered into the calculator, it said that equals 6 smartphones charged.

Sources:

Note: worldsteel LCI data is available on request via worldsteel.org, or in proprietary databases such as GaBi, SimaPro, etc. 


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