Monday, February 11, 2013

Carbon Footprint-Restaurants vs Home Cooking


Though last week I said that Greenhouse Gas Emissions no longer matter, I only meant that no action that we as a nation could take would stop the further increase in carbon dioxide, CO2, concentrations from the emergence of China from a developing nation to developed nation and the ecological consequences from the increasing CO2 concentrations in our atmosphere. It’s done, whatever is going to happen will happen because the earth’s atmosphere is interconnected, and worldwide CO2 emissions will continue to grow. That fact does not absolve me from the responsibilities of sustainable living. Of the developed nations, the United States has the second highest per capita greenhouse gas emissions or CO2 equivalent (CO2e) generation rate. (It’s nice not to be the worst of the developed world.)  Policy mandates to have the United States adopt constraints on fossil fuel energy consumption will have little impact on the global level of CO2e emissions because the United States CO2e emissions are 16% of world CO2e emissions and falling. Our nation’s CO2e emissions are fairly stable at this time while our per capita CO2e emissions appear to be slowly decreasing. Still, as a nation, we should be more sustainable. Making sustainable choices is a moral choice.

 In the real world of finite resources, careful consideration must be given to how and when we expend our resources- money, manpower, water, fuel or land. The CO2e footprint has become shorthand for how sustainable you are. However, the method of calculating that footprint and assumptions made will determine if that measurement is an accurate reflection of how sustainable your life is. When seeking to determine the amount of CO2e emitted from an activity or a life choice, it is impossible to measure the emissions directly. Emissions are estimated from a known quantity such as fuel burned, or units of electricity consumed, but that can be misleading. While the combustion of fuel is a chemical reaction where the mass of CO2 emissions is directly related to the type and quantity of fuel burned, only heating your home is a simple calculation. For every kWh of energy supplied by gas the CO2 emissions are 0.206 kgCO2.

The energy consumed to create, manufacture, distribute and deliver any product is complicated and much of the work that has been done is based on averages, which can be misleading. Nonetheless, the information can be useful. I ran across a paper “The American Carbon Foodprint: Understanding
your food’s impact on climate change,” by Mathew Kling, and Ian Hough (2010). The paper was  sponsored by Brighter Planet, Inc., a company whose technology platform calculates the carbon, energy, and resource impact of a variety of real-life emission sources. Brighter Planet sells consulting, but gives away really interesting research including the Carbon Foodprint study.  According to the authors food represents 21% (5.46 metric tonnes CO2e emission) of the typical American’s 26 metric tonne total annual carbon footprint. The actual CO2e emissions associated with your food consumption is dependent on where, how much and what you eat, how the food is grown, transported, processed, prepared and what you do with the leftovers.

The transportation of the food from farm to store was a surprisingly small contributor to the total CO2e emissions embodied in the food. A larger source of CO2e emissions in food are from the delivery of inputs like, fertilizer, water, and animal feed. So that grass fed beef that is pasture raised would have a much smaller CO2e emissions than beef that is feed with remotely sourced grain. (In addition, pasture raised cows are less flatulent than grain fed cows.) Crops grown without irrigation, conservation agriculture and organic agriculture all have different ecological and CO2e emission footprints versus the “conventional agriculture” similar products. One farmer may be more sustainable than another for a variety of reasons. However, most of the food’s transportation related CO2e emissions are from travel to the grocery store and restaurants by the consumer. Personal food-related driving comprise 14% of the average family’s carbon footprint.

It is much more sustainable to eat at home.  The average American eats out at a fast food or full service restaurant about 4.5 times a week, or roughly 20% of the time. The Carbon Foodprint study tells us that restaurants and food service operations consume roughly the same amount of energy as home kitchens producing only 20% of the meals in America– and that's before you consider the carbon impact of traveling to the restaurant. A typical restaurant meal’s CO2e emissions if 3.67 times the CO2e emissions of a meal prepared and eaten at home. Cooking and eating at home is a simple way to reduce your carbon footprint. It is also healthier and saves money.

In addition with some planning and thoughtful actions you can significantly reduce the CO2 emissions associated with your kitchen. The authors tell us that kitchens consume 21% of total household energy and are one of the most energy-intensive rooms in the house. Over 35% of the kitchen energy use is for heating, cooling, and lighting the kitchen itself, with the remainder related to the cooking process and food storage. Refrigeration is the biggest energy hog in the kitchen. On average a refrigerator consumes 30% of all kitchen energy, and emits 650 Kg of CO2e. A modern Energy Star refrigerator performs considerably better than that. Cooking food consumes an average of 293 Kg of CO2e, 14% of the total energy used in a kitchen. Microwaves are the most energy-efficient followed by induction, and traditional burners. Ovens are the least efficient cooking method. Cleaning up and washing dishes uses 14% of kitchen energy. The most energy efficient method to wash dishes is to use a modern Energy Star dishwasher- running it when it is fully loaded.

Recycling, waste reduction and reuse all have an impact on CO2 emissions. Americans discard over 280 billion Kg of garbage each year (excluding recycling and composting) of that trash 29% is food related. The trash is collected and trucked to landfills and accounts for 143 Kg CO2e per person per year that is responsible for 28% of landfill gas emissions each year. In Prince William County about 36% of all trash is recycled and includes packaging and containers, but not food scraps. Knowing how to deliciously use up leftovers will also reduce your carbon footprint.  By simply cooking all your meals at home the average person can reduce their carbon footprint by 1.39 metric tonnes of CO2e a year. Other steps to reduce your carbon footprint further would be: eat more plants, buy unprocessed, whole foods, minimize car trips to the grocery store, use all your leftovers, recycle and compost, buy Energy Star appliances. All of these steps will reduce the per capita carbon emissions further, but will not stop the climate of the earth from changing.  Certainly, anthropogenic activity has been a significant contributor to the 150 parts per million (0.015%) increase in carbon dioxide in the atmosphere over the past 113 years. The exact relationship of greenhouse gasses to climate is not fully understood, but if all of the United States (or even mankind) were suddenly wiped off the face of the earth climate change would not stop. Nonetheless, dine at home.



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