Thanksgiving is one of the most wonderful time of the year, when families gather and spend time together while the smell of Turkey seeps in from the other room. You’ve probably never given much thought to the energy use or environmental impact behind that intoxicating turkey smell coming from the kitchen, and in fact the country’s overall energy use drops on Thanksgiving because the increase in kitchen power use is offset by the drop in energy use from office and commercial buildings that are closed for the holiday.
Recipes
- Roasting;
- Braising;
- Deep frying;
- Grilling;
- Smoking;
- Spatchcocking; and
- Sous vide.
For each of these cooking methods, I’ve sought out a recipe either from a well-known chef of repute or directly from the manufacturer of the turkey or the cooking apparatus in question. By using these recipes, ideally these authorities will have an air of authority to them. Because each recipe offers cooking times based on various size turkeys, this analysis will normalize each recipe for a standard 15 pound (lb) turkey as the size recommended for a dinner of 12 people.
Roasted turkey
Braised turkey
Braised turkey is a great segue from the traditional to the more novel turkey-cooking methods, as it doesn’t stray too far from the original whole turkey roasting method. You are still cooking the turkey fully in the oven, but with the main difference that the turkey is sitting in a pan of vegetables and stock to bring in more moisture to your turkey.
For the braised turkey, we’ll stay with household names and use Bobby Flay’s recipe for herb roasted and braised turkey. This recipe calls for an oven preheated to 450oF with the 17 pound turkey and a bed of vegetables cooked for 45 minutes before the temperature is reduced to 350oF and cooked an additional 2 to 2 hours 15 minutes longer (while basting with warm chicken stock). After the whole bird is cooked, the legs are removed and braised in a roasting pan with stock for an additional 1 hour at 350oF.
Deep fried turkey
If you can manage to get it done without an explosion or trip to the hospital, deep frying turkey has become one of the more exciting and talked about cooking alternatives. Bobby Flay’s colleague at Food Network, Alton Brown, has one of the most used deep fried turkey recipes for those who love the science and Internet-trends of cooking.
For a 13 to 14 pound turkey, Alton has you heat up a 28 to 30-quart pot of oil to 250oF, add in the turkey and raise the temperature to 350oF, and once at that temperature cooking for 35 minutes.
Grilled turkey
The grilled turkey recipe chosen comes straight from Butterball, the turkey supplier that accounts for 20 percent of total turkey production in the United States. Among grilling aficionados, the debate to grill by charcoal or by gas is one of the most heated. In addition to differences in taste, ease, and convenience, the choice of grill type also affects the end energy use to cook. Luckily for us, Butterball provides instructions for both a charcoal and gas grill.
Butterball’s recipe for charcoal grilling says that the 10 to 16 pound turkey will be cooked over 50 to 60 charcoal briquettes (after those initial briquettes have been burned for 30 minutes). At that point, the turkey is to be placed on the grill for 2 to 3 hours, with 12 to 16 briquettes being added every 45 minutes to 1 hour. To normalize at the 15 pound turkey, we’ll estimate that initially 60 charcoal briquettes will be used and, during the cooking process, 50 more briquettes will be added for a total cooking fuel of 110 charcoal briquettes on a charcoal grill over the course of 3 hours.
Smoked turkey
Where deep frying or grilling the turkey may have once held the title as the ‘macho’ way to prepare a Thanksgiving turkey (whatever that may mean), smoking the meat might just have taken that crown. Using lower heat over longer periods of time, smoking turkey evokes the expert barbecue pit masters of the country to impart full flavor without drying out the turkey. Butterball once again provides authoritative guidance to smoking your Thanksgiving dinner, again allowing the consideration of two different fuel types.
Butterball’s recipe for preparing a turkey in a water smoker uses 10 pounds of charcoal briquettes (pre-burned for 30 minutes) to start the cooking process, adding in 12 to 14 more charcoal briquettes every 1 hour 30 minutes to ensure the temperature remains at 250oF through a total cooking time of 6 to 10 hours for a 12 to 18 pound turkey. For our 15 pound turkey, we’ll call that cooking fuel of 10 pounds plus 70 briquettes of charcoal over a cooking time of 8 hours in the water smoker.
Spatchcocked turkey
Sous vide turkey
Sous vide cooking, or the process of cooking food that is vacuum-sealed in a plastic pouch by placing it in heated and circulating water bath, has been around for decades. The method has gained traction more recently, however, as home cooks are increasingly getting their hands on the cooking equipment necessary that was previously only available in professional kitchens. The cooking method allows meat to be cooked at lower temperatures and thus cooked more evenly, safely, and while retaining moisture.
Calculations
These recipes use a wide variety of cooking apparatuses and fuels, so the methodology of calculating the total energy use and associated CO2 emissions will vary. Much like the Halloween-themed post on the most sustainable way to light your Jack-O’-Lantern, this post will thus be calculating very rough estimates using educated choices of data and assumptions. The final numbers should be considered back-of-envelope calculations and not scientifically or rigorously tested. There are also various aspects to the cooking process that would impact the end result that will not be accounted for, as well as variables to your individual cooking efforts that would change the final result (e.g., size of oven or grill, the energy mix of your power supplier, what type of propane or charcoal you buy from the store).
All that said, if you have ideas or suggestions on how to refine any of the numbers calculated here, then please reach out and/or leave a comment! (For one, I’ve assumed an oven is using a uniform amount of power regardless of the temperature at which it is set. While the difference of power use at 350oF and 450oF is not likely that much, it is definitely measurable. However, after much digging I was still unable to find any way to estimate the power difference among different temperatures, so a uniform power consumption was chosen and used for all use of the oven.)
Regardless of fuel type, all final energy numbers are calculated in kilowatt hours (kWh) and all CO2 emissions are calculated in lbs.
Roasted turkey
We are assuming the use of an oven for 3 hours 15 minutes. The oven will also need to preheat the oven, which we’ll assume to take 15 minutes. All together, the energy use and CO2 emissions will be associated with using an oven for a total of 3 hours 30 minutes.
Electric oven:
Electric ovens use about 2.0 kilowatts (kW) of power. Assuming this power usage for the entirety of the recipe, the energy use of roasting the turkey in an electric oven is about 2.0 kW times 3.5 hours, or 7.0 kWh.
The latest data available from the Department of Energy says that for every kWh of electricity produced in the United States, 1.096 pounds of CO2 are released. Thus for this recipe in an electric oven, the CO2 emissions are equal to 1.096 lbs/kWh times 7.0 kWh or about 7.7 pounds of CO2.
Electric ovens use about 2.0 kilowatts (kW) of power. Assuming this power usage for the entirety of the recipe, the energy use of roasting the turkey in an electric oven is about 2.0 kW times 3.5 hours, or 7.0 kWh.
Gas oven:
Gas ovens use about 0.112 therms of natural gas per hour. Over the course of the 3 hours 30 minutes, this would result in the use of 0.392 therms. In order to convert this amount of natural gas to kWh for comparison’s sake, we use the energy equivalence of one therm being about 29.3 kWh, meaning the energy use of a gas oven for this recipe is 11.5 kWh.
Braised turkey
The braised turkey recipe also uses a oven, but this time for 15 minutes of preheating and 3 hours 30 minutes of cooking for a total of 3 hours 45 minutes. Again, this process can be done in an electric or a gas oven using the same assumptions as the roasted turkey.
Source
Electric oven:
Using the same assumptions as above for 3 hours 45 minutes of 2.0 kW power usage, the braised turkey recipe uses 7.5 kWh. Using the same assumption of 1.096 lbs of CO2 per kWh results in the CO2 emissions of the braised turkey in an electric oven being about 8.2 lbs.
Gas oven:
Repeating the assumptions above again gives an approximate energy use of 0.420 therms, or 12.3 kWh, and would result in emissions of about 4.9 lbs of CO2.
Deep fried turkey
The assumptions we can make here are that a propane cooker uses 65,000 British thermal units (BTUs) per hour and preheating deep fryers takes about 30 minutes. That means the total energy use would be 65,000 BTU/hour times 1 hour 10 minutes for a total of 75,833 BTU. Converting the propane use in BTU to approximate energy use in kWh gives a final result of approximately 22.2 kWh.
Grilled turkey
Charcoal grill:
When the grilled turkey recipe for a charcoal grill is used, 110 charcoal briquettes are used over the course of 3 hours (after 30 minutes of pre-burn of charcoal).
Experiment shows that the energy content of charcoal is 7.33 kilojoules (kJ) per gram, while a single briquette of charcoal weighs about 25.7 grams. All together, this means a charcoal grilled turkey takes 20,733 kJ, which is converted to about 5.8 kWh.
Propane grill:
When prepared on a gas grill, propane is needed to preheat for about 15 minutes and then cook the turkey for 3 hours.
Smoked turkey
For the smoked turkey recipe, we again have two options for cooking fuel– either a charcoal fueled water smoker or an all electric smoker.
Charcoal powered water smoker:
Electric smoker:
Spatchcocked turkey
Electric oven:
Gas oven:
Sous vide turkey
Last but not least is the sous vide turkey, which requires the use of an immersion sous vide immersion circulator for 2 hours 30 minutes (after a 15 minute preheat time). Given that the power rating of a sous vide from Williams Sonoma (the source of our recipe) is 1,100 W and the total operating time is 2 hours 45 minutes, the electricity use comes out to about 3.0 kWh. At 1.096 lbs of CO2 per kWh, that means the sous vide turkey accounts for about 3.3 lbs of CO2.
Graphical results and conclusions
With all those calculations and assumptions out of the way, we can finally look at all the results in one table:
Click to enlarge
These numbers can also be displayed graphically to show the overall level of ‘green-ness’ of each cooking method:
Click to enlarge
- In terms of the amount of CO2 emissions, the two options that use charcoal (smoked in a charcoal smoker and grilled on a charcoal grill) are by far the greatest emitters. This result shouldn’t be surprising, as charcoal (with anthracite coal as one of its ingredients) is one of the more carbon intensive fuels you can use in your homes. However it is interesting to note that, despite their higher CO2 emissions, they are in the same ballpark in terms of energy use as the other cooking methods. This result shows how charcoal is an efficient fuel source, it just happens to also be dirty.
- In terms of the total energy use, the two options that use propane (deep fried and grilled on propane grill) require the greatest energy. The higher energy needed is likely due to the cooking source being less efficient than others, with gas/propane burners typically being only 40% efficient with the remaining 60% of energy output being lost to heating the surrounding air or as visible light.
- The two best cooking methods in terms of both minimal energy use and CO2 emissions are the sous vide turkey and the spatchcocked turkey (in either a gas or electric oven). The reason these reign supreme is telling, and different for the two of them.
- For the sous vide turkey, the turkey is vacuum sealed and cooked in heated water the size of a typical pot. The result is that a smaller volume has to be heated up when compared with a larger oven, deep fryer, smoker, or grill that needs to heat up and keep heated the larger surrounding area. By focusing the heat in a smaller area, the total energy use is greatly reduced. In all cooking, the smaller the area you are heating up the more energy efficient the cooking process will be, which is why it is actually advisable to cook using smaller, dedicated appliances (e.g., toaster ovens, panini press, etc.) than to use the oven or stovetop for everything.
- For the spatchcocked turkey, the reduced energy use and associated CO2 emissions is simply attributed to the largely reduced cooking time. Outside of the deep fried recipe, which uses the aforementioned inefficient propane, the spatchcocked recipe is the only one that takes under two hours of cooking. Obviously, the less time you have to have your appliances working, the less energy you’ll use. So while spatchcocking may have become popular due to the convenience of reduced cooking time, the relative efficiency is also among its virtues.
- When comparing the recipes that use either the gas oven or the electric oven, the final figures show that the gas ovens use more energy but emit less CO2. What is important to note about the CO2 difference, however, is that the numbers are based on the average U.S. figure for CO2 emitted per kWh. This number can vary greatly depending on your power company and where you live. For example, if you live in Vermont then your power likely comes from a greater proportion of renewable energy than in other states, which would reduce the relative CO2 emissions of your electric oven. Of course the opposite is true if your power company uses more coal in its fuel mix than the national average.
- One last point is that the relative energy use here does not correlate to the relative cost to the consumer for preparing the turkey. Certain fuel types are much cheaper than others, which is part of the reason they are popular to use in the first place. For example, just because grilling by propane uses almost six times the energy as grilling by charcoal, the relative prices of the fuels actually results in grilling by gas being less costly per hour for a consumer.
According to the National Turkey Federation, 46 million turkeys are roasted each Thanksgiving. Various outlets have attempted to estimate the actual energy use of those turkeys cooked in aggregate, with answers ranging from 48 million kWh to 792 million kWh (quite a wide range, showing just how uncertain the true number is). Using the numbers calculated here, if all 46 million turkeys were cooked sous vide then that would be 138 million kWh, whereas if they were all grilled on a propane grill then that would be over 1.5 billion kWh. Concerning CO2 emissions, the 46 million turkeys could account for 152 million lbs (sous vide) or over 4 billion lbs (grilled on charcoal grill)– for context, a passenger vehicle emits about 10,000 lbs of CO2 per year. That’s all to say, the small decisions everybody makes individually can add up to make a large difference in total energy use or CO2 emitted– even when talking turkey.
In the end, though, there isn’t too much reason for you to stress. There are plenty of methods you can use to cut down on energy use while cooking if you choose to do so(see some examples here and here, or you can even invest in a solar cooker that uses just the sun and reflectors to cook at temperatures up to 400oF!). But again, the overall energy use on Thanksgiving is lower than the average Thursday. It’s a time to relax and be grateful, not necessarily to measure out your exact briquettes to minimize energy spent. But you can come to the Thanksgiving table with some of these fun facts handy to impress your family, just be sure to praise the cooking of the chef first– he or she spent plenty of time making that dinner!
