Consider a simplified representation of the production of power from coal fired power stations:• Bituminous coal (most common for power in Queensland) is burned in a furnace where most of theenergy liberated by the combustion reaction is transferred to a power cycle.• Heat transferred to a power cycle is converted to shaft work via a power cycle.• Shaft work is converted to electrical work for the grid via a generator and transformer.• Electrical work is transported through the grid to a home.Based on this simple representation, we are going to determine the carbon footprint of 1 MWh ofelectricity delivered to a household. To do this, we will assume:Step EfficiencyHeat from combustion to shaft work 38% (based on HHV)Conversion of shaft work to electrical work in the grid 95%Delivery of electrical work from the power plant to a household 90%a) Draw a simple block diagram of the energy flows and transformations for power generation. Start withthe heat from the coal combustion and finish with the household. You only need shaft work, electricalwork, and heat as the energy transfers in your diagram.Quantify each energy transfer on your diagram to deliver 1 MWh to a household and put this on yourdiagram.b) What are typical ranges for the calorific value (HHV) for bituminous coal (in MJ/kg) and the carbonintensity of bituminous coal in terms of:• kg CO2e per kg of coal, and• kg CO2e per MWh (HHV)Please use high quality references for this information and reference clearly at the end of the question(not at the end of all the questions). Identify a “typical” number for kgCO2e per MWh (HHV) to usein the next question.c) What is the carbon intensity (in kgCO2e/MWh) for electricity delivered to a household? Use mid-point estimates from above, and assuming that the embedded emissions for coal (i.e. pit to gate) are20 kg CO2e per MWh (HHV) and other smaller embedded, direct and indirect emissions are about10 kg CO2e per MWh (HHV).
Question
Consider a simplified representation of the production of power from coal fired power stations:• Bituminous coal (most common for power in Queensland) is burned in a furnace where most of theenergy liberated by the combustion reaction is transferred to a power cycle.• Heat transferred to a power cycle is converted to shaft work via a power cycle.• Shaft work is converted to electrical work for the grid via a generator and transformer.• Electrical work is transported through the grid to a home.Based on this simple representation, we are going to determine the carbon footprint of 1 MWh ofelectricity delivered to a household. To do this, we will assume:Step EfficiencyHeat from combustion to shaft work 38% (based on HHV)Conversion of shaft work to electrical work in the grid 95%Delivery of electrical work from the power plant to a household 90%a) Draw a simple block diagram of the energy flows and transformations for power generation. Start withthe heat from the coal combustion and finish with the household. You only need shaft work, electricalwork, and heat as the energy transfers in your diagram.Quantify each energy transfer on your diagram to deliver 1 MWh to a household and put this on yourdiagram.b) What are typical ranges for the calorific value (HHV) for bituminous coal (in MJ/kg) and the carbonintensity of bituminous coal in terms of:• kg CO2e per kg of coal, and• kg CO2e per MWh (HHV)Please use high quality references for this information and reference clearly at the end of the question(not at the end of all the questions). Identify a “typical” number for kgCO2e per MWh (HHV) to usein the next question.c) What is the carbon intensity (in kgCO2e/MWh) for electricity delivered to a household? Use mid-point estimates from above, and assuming that the embedded emissions for coal (i.e. pit to gate) are20 kg CO2e per MWh (HHV) and other smaller embedded, direct and indirect emissions are about10 kg CO2e per MWh (HHV).
Solution
a) The block diagram would start with the combustion of bituminous coal, which generates heat. This heat is then transferred to a power cycle, where it is converted into shaft work with an efficiency of 38%. The shaft work is then converted into electrical work with an efficiency of 95%. This electrical work is then delivered to a household through the grid with an efficiency of 90%. To deliver 1 MWh to a household, you would need to start with approximately 2.63 MWh of heat from coal combustion, which would be converted into about 1 MWh of shaft work, then into about 0.95 MWh of electrical work, and finally delivered as 1 MWh to the household.
b) The calorific value (HHV) for bituminous coal typically ranges from 24 to 35 MJ/kg. The carbon intensity of bituminous coal is typically around 2.2 kg CO2e per kg of coal and around 94 kg CO2e per MWh (HHV).
c) The carbon intensity for electricity delivered to a household can be calculated by adding the carbon intensity of the coal combustion (94 kg CO2e per MWh) to the embedded emissions for coal (20 kg CO2e per MWh) and other smaller embedded, direct and indirect emissions (10 kg CO2e per MWh). This gives a total carbon intensity of 124 kg CO2e per MWh.
References:
- "Coal and the environment - U.S. Energy Information Administration (EIA)". www.eia.gov. Retrieved 2021-09-30.
- "Carbon Dioxide Emission Factors for Coal". www.eia.gov. Retrieved 2021-09-30.
Similar Questions
Suppose a household used 1.65 ¥ 104 kWih of electricity in one year. Thiselectricity came from a traditional coal-fired generating station. Based on the“Comparing Coal-Combustion Technologies” table on page 392 of the textbook,what mass of carbon dioxide gas was emitted to produce the household’s electricity?A. 1.7 ¥ 104 kgB. 1.3 ¥ 104 kgC. 8.2 ¥ 103 kgD. 2.3 ¥ 102 kg
14. How much of the energy in burning coal reaches the consumer as electricity?
From the power plant, it took 100 kJ of coal to produce the 15 kJ of useful energy in your home. What is the total efficiency?
When any fossil fuel is burned it produces emissions of carbon dioxide and water vapor. A typical household in a developed country will use approximately 70 kWh per month of electricity for computing and electronics. Each kWh of average coal burned produces 2.23 kg of carbon dioxide emissions while natural gas produces just 0.91 kg per kWh of carbon dioxide.How many more kg of carbon dioxide are produced by the coal plant compared to the natural gas plant from the computing and electronics alone, from a household over the course of one year?
Carbon footprint include ___________.Select one:a.Direct fuel use, employee commutingb.Purchase Electricity, Business Travelc.Construction, Server manufacturingd.All of these
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.