Monitoring Household Greenhouse Gas Emissions

 Duane Pendergast - July, 2004

 Introduction

 A substantial portion of Canada’s emissions are due to the choices individuals make with respect to cars and housing. Environment Canada indicates we each produce about 5 metric tonnes annually[1]. On the other hand, per capita emissions in Canada were reported to be 23.1 tonnes annually in 2001[2]. Why would there be such a difference? How can we calculate our personal emissions? It turns out we can establish the data needed to calculate personal emissions very easily. Essentially, our electricity and fuel bills provide nearly all the information needed.

 Sources of Greenhouse Gas Emissions

 The bulk of household greenhouse emissions, over which individuals have some control, come from the burning of fuels used to produce electricity, heat our water and houses, and run our vehicles. These fuels are generally composed of the elements carbon, hydrogen, and possibly oxygen, in various ratios.  These fuels are combined with oxygen from the air we and our machines inhale and burn. Carbon from the fuel combines with oxygen to form carbon dioxide. Hydrogen combines with oxygen to form water vapor. These gases are expelled to the atmosphere through chimneys, exhaust pipes and power plant stacks.  Although the water vapor is a greenhouse gas, the quantity humans add to the atmosphere is insignificant relative to that present in and circulated through the atmosphere by nature. The carbon dioxide humans are collectively creating is significant relative to the amount normally in the atmosphere. It is the focus of efforts to reduce atmospheric greenhouse gas.

 Composition and Chemistry of Fuel and Combustion

 Fossil fuels are composed of mixtures of molecules formed from hydrogen and carbon derived from petroleum and natural gas. The more volatile components are the smaller molecules. Natural gas is mostly methane (CH₄) and may contain other hydrocarbons such as ethane (C₂H₆). Propane is mainly propane (C₃H₈) and likely includes some butane (C₄H₁₀). Gasoline is a mixture of hundreds of molecules with from 3 to 12 carbon atoms.  (ie. octane (C₈H₁₈)). Diesel fuel and kerosene are composed of still larger molecules, typically with 9 to 23 carbon atoms. Chevron[3] provides a wealth of detailed technical information on gasoline and diesel fuels.

 Calculating Carbon Dioxide Emissions

 Engineers have studied fuels and the burning of fuels for a couple of centuries now. There is a continual quest to make the process more efficient to extract a maximum of energy. The basic secret lies in providing just the right amount of oxygen to completely burn the fuel – maximizing carbon dioxide formation. Insufficient oxygen results in incomplete burning of the fuel and produces dangerous carbon monoxide. Excess oxygen reduces the temperature of the combustion products and thus reduces the mechanical or electrical energy which can be extracted by heat engines. Knowledge of fuels and combustion in engines and power plants allows for the relatively accurate calculation of carbon dioxide emissions from information on the quantity and nature of the fuel burned. Most burning of fossil fuels is done with air which is about 20% oxygen and 80% nitrogen. This introduces some additional complication to greenhouse gas calculation as some nitrous oxide is formed.  Combustion is not necessarily complete. Small amounts of methane are formed. Nitrous oxide and methane are two of the six gases formally included in greenhouse gas estimates. Detailed information on the methodology[4] used to calculate Canada’s greenhouse gas emissions is available from Environment Canada.

 Our Fossil Fuel Use

 The greenhouse gas emissions we are personally responsible for come primarily from fossil fuel combustion.  Overviews of our energy using facilities follow.

 Housing

 My wife and I live in Lethbridge, Alberta. Our house is a typical small bungalow with about 135 square meters of living floor area. It was built in 1999 to then current building standards. It is of 2 x 6 wood frame constructions with an attached two car garage of similar construction. The house is heated with natural gas. A small electric heater (1500 watt maximum) keeps the garage above freezing in winter. Additional natural gas appliances include two fireplaces, two water heaters, a kitchen stove, a clothes dryer, and a barbecue. It  equipped with the usual litany of electric appliances and lighting including a string of decorative Christmas lights and some yard lights.

 Vehicles

 We operate two vehicles. Both are gasoline fuelled. One, used mostly around town, is a Chevrolet Malibu of 2000 model year. The other is a 1999 Dodge Maxivan commercially converted to a very small and modest motor home. Still, it is a heavy vehicle weighing about 3300 kilograms empty and about 4000 kilograms loaded. We use it mainly for long trips.

 Electricity

 Our electricity is provided from the grid and is produced mostly in Alberta from coal, natural gas, water power and wind power. Water and wind power are minor contributors. One could say that the electrical utilities are the source of the emissions, rather than the homeowner. For the sake of calculating our greenhouse gas emissions, we are taking responsibility for establishing the electrical demand and thus the emissions.

 Our Greenhouse Gas Emission Calculations

 We are not involved in any sink activities to counter the emission from fossil fuel use, with the possible exception of waste material sent to the local landfill. That is neglected. We do have a small generator carried with our motor home which likely uses less than 10 litres of fuel annually. We neglect that too. Our lawnmower is driven by electricity so its emissions are included in our electricity usage.

 Many years ago, I established a habit which came in handy for calculating greenhouse gas emissions. I started to keep track of fuel consumption as a means of monitoring vehicle performance. We carry a fuel use and mileage log in our vehicles and fill it in at every fill up. That log combined with our electricity and natural gas bills provides the basic data needed to calculate our emissions consistently with Canada’s National Greenhouse Gas Inventory. Additional conversion factors needed to calculate emissions from our basic energy consumption data are publicly available. References to these sources of information on gasoline[5], natural gas[6] and electricity[7] emissions are provided here for the convenience of readers. Another document[8] illustrates the complexities of calculating emissions and provides some examples which deviate from the sources used herein.  Please note that the vehicle and natural gas related emissions calculated to not include the greenhouse gas equivalent of small methane and nitrous oxide emissions from combustion. This contribution is included in the estimate of emissions from electricity.

 Summary Results

 A summary of our emissions for 2001, 2002, and 2003 is provided in Table 1.

 Table 1 – Pendergast Family Greenhouse Gas Inventory -Tonnes Carbon Dioxide

 Additional information and calculation details are provided in the files below.

Discussion

 It is apparent that these annual emissions from just two people are much higher than those quoted by the government Canada The One Tonne Challenge program suggests each Canadian is responsible for about five[9] tonnes. We are emitting over fifteen tonnes/person and the trend is toward an increase. Why is there such a discrepancy? Emissions from electricity would be much lower for most Canadians. Ontarians and Quebeckers derive most of their electricity from emission free hydro and nuclear power. Alberta’s electricity comes mainly from coal and natural gas. Our household includes no children. If we had two children,   and electricity emissions consistent with average Canadians, per family member emissions would be on the order of five tonnes.  The introduction notes that Canada’s per capita emissions were 23.1 tonnes annually in 2001. Emissions from industry, commercial buildings, agriculture, forestry and other activities makes up the big difference from emissions attributed to individuals.

 Conclusions

 It is quite easy, if tedious, to establish a greenhouse gas emission inventory   for a typical family. The necessary data for natural gas and electricity is available from utility bills. A record of vehicle fuel consumption is easily established. Data from combustion calculations and records is readily available to complete the calculation of a personal inventory which is essentially consistent with Canada’s national climate change inventory.

Important Notice – The data and calculations of greenhouse gas emissions made available in this article and the associated spreadsheets are not intended to be used for regulatory or legal purposes. The information is intended solely for educational purposes.

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