The management of a fitness facility in Sheffield is looking to replace their current system of...

 

  

Transcribed Image Text:

The management of a fitness facility in Sheffield is looking to replace their current system of reliance on grid gas and electricity with a biomass powered Combined Heat and Power (CHP) system for meeting their energy needs. This is also expected to reduce their carbon footprint significantly. The site consumes 8,000 MWh of gas (gas input to the site) and 5,000 MWh of electricity per year. The gas boiler has an efficiency of 88%. Gas tariff is 3.7 p/kWh and electricity tariff is 17.3 p/kWh in the day and 13.5 p/kWh at night. 70% of the electricity usage is at the day tariff. The site has an availability of 2,000 kVA. Availability charge for the site is 4 p/kVA/day. The CHP unit will cost £2.2 million and will run on locally sourced wood chips which are purchased at £115/ton. The annual CHP maintenance cost is £40,000. The thermal efficiency of the CHP system is 33%. The CHP is sized to match the current electrical demands of the site. If the CHP generates excess heat beyond the needs of the site, it will be wasted. On the other hand, if the heat from the CHP is insufficient to meet the heating demands of the site, it can be sourced from the existing gas boiler. The heat exchanger which captures the waste heat from the CHP has an efficiency of 80%. The average greenhouse gas (GHG) emissions from the fuels in use here are shown in Table 1 Below: Table 1 GHG Emissions from Fuel Use Fuel Electricity Natural Gas Wood Chips GHG Emissions (kg CO₂/kWh) 0.233 0.184 0.027 You need to perform a fuel analysis to determine if this investment will be profitable. A sample of the wood chips weighing 1.50 g was taken to a lab for proximate analysis. First, the sample was crushed and then placed in an oven at 110°C for 48 hours. After removing from the oven, it weighed 1.21 g. It was then placed in a pyrolysis furnace at 500°C in an inert atmosphere. The sample was then removed and it weighed 0.88 g. Finally, the sample was burnt in a bomb calorimeter and the ash weighed 0.14 g. The bomb calorimeter contained 2.2 kg of water. The temperature of water in the calorimeter rose from 15.0°C to 17.9°C after burning the fuel sample. The specific heat capacity of water is 4,193 J/kg.K. The apparatus had a heat capacity of 400 J/K. Conversion factor: 1 MWh = 3.6 MJ 1.1 Complete the following fuel analysis table and show the steps and reasoning for your answers. Moisture Volatiles Char Ash Heating Value Mass Mass Mass Mass Mass Mass (%) (g) (%) Mass Mass MJ/kg (g) (%) (g) (%) (g) [10 marke 1.2 Determine the annual costs of energy under the current system in £/yr. 1.3 Determine the fuel price for biomass in p/kWh. 1.4 Determine the annual costs of energy using the biomass CHP system in £/yr. 1.5 Determine the payback period for this investment. [5 marks] [3 marks] [12 marks] [5 marks] 1.6 Determine the annual GHG reduction with the proposed biomass CHP system (ton CO2/yr). [5 marks] The management of a fitness facility in Sheffield is looking to replace their current system of reliance on grid gas and electricity with a biomass powered Combined Heat and Power (CHP) system for meeting their energy needs. This is also expected to reduce their carbon footprint significantly. The site consumes 8,000 MWh of gas (gas input to the site) and 5,000 MWh of electricity per year. The gas boiler has an efficiency of 88%. Gas tariff is 3.7 p/kWh and electricity tariff is 17.3 p/kWh in the day and 13.5 p/kWh at night. 70% of the electricity usage is at the day tariff. The site has an availability of 2,000 kVA. Availability charge for the site is 4 p/kVA/day. The CHP unit will cost £2.2 million and will run on locally sourced wood chips which are purchased at £115/ton. The annual CHP maintenance cost is £40,000. The thermal efficiency of the CHP system is 33%. The CHP is sized to match the current electrical demands of the site. If the CHP generates excess heat beyond the needs of the site, it will be wasted. On the other hand, if the heat from the CHP is insufficient to meet the heating demands of the site, it can be sourced from the existing gas boiler. The heat exchanger which captures the waste heat from the CHP has an efficiency of 80%. The average greenhouse gas (GHG) emissions from the fuels in use here are shown in Table 1 Below: Table 1 GHG Emissions from Fuel Use Fuel Electricity Natural Gas Wood Chips GHG Emissions (kg CO₂/kWh) 0.233 0.184 0.027 You need to perform a fuel analysis to determine if this investment will be profitable. A sample of the wood chips weighing 1.50 g was taken to a lab for proximate analysis. First, the sample was crushed and then placed in an oven at 110°C for 48 hours. After removing from the oven, it weighed 1.21 g. It was then placed in a pyrolysis furnace at 500°C in an inert atmosphere. The sample was then removed and it weighed 0.88 g. Finally, the sample was burnt in a bomb calorimeter and the ash weighed 0.14 g. The bomb calorimeter contained 2.2 kg of water. The temperature of water in the calorimeter rose from 15.0°C to 17.9°C after burning the fuel sample. The specific heat capacity of water is 4,193 J/kg.K. The apparatus had a heat capacity of 400 J/K. Conversion factor: 1 MWh = 3.6 MJ 1.1 Complete the following fuel analysis table and show the steps and reasoning for your answers. Moisture Volatiles Char Ash Heating Value Mass Mass Mass Mass Mass Mass (%) (g) (%) Mass Mass MJ/kg (g) (%) (g) (%) (g) [10 marke 1.2 Determine the annual costs of energy under the current system in £/yr. 1.3 Determine the fuel price for biomass in p/kWh. 1.4 Determine the annual costs of energy using the biomass CHP system in £/yr. 1.5 Determine the payback period for this investment. [5 marks] [3 marks] [12 marks] [5 marks] 1.6 Determine the annual GHG reduction with the proposed biomass CHP system (ton CO2/yr). [5 marks]

Answer rating: 100% (QA)

Fuel Analysis Moisture Mass in oven after drying 121 g Initial mass 150 g Moisture content Initial m... View the full answer