Misconceptions about carbon emission reduction
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This post was last edited by cuikk on 2022-10-27 23:41. Misconceptions about carbon emission reduction: As the **\"dual carbon\" goals advance, some people see difficulties, while others see business opportunities; even worse, some take advantage of the situation to make huge profits. The end result will be an increase in carbon dioxide emissions! This is just the theoretical data I know, for everyone’s review. The currently popular method of producing methanol from \"green electricity\" involves using hydrogen generated by electrolyzing water powered by wind or solar energy, along with carbon dioxide, to synthesize methanol thereby reducing carbon dioxide emissions. 1. For coal-fired power generation, based on the current highest efficiency levels, 250 grams of standard coal are required per kilowatt-hour. Assuming a carbon dioxide emission factor of 2.7 for standard coal, the amount of carbon dioxide emitted per kilowatt-hour is 250 g × 2.7 = 0.675 kg. 2. Hydrogen is produced by electrolyzing water; 56 kilowatt-hours of electricity are required to produce 1 kg of hydrogen. To produce 6 kg, 3 kmol, or 67.2 NM3 of hydrogen, 336 kilowatt-hours of electricity are needed, with 1.5 kmol and 33.6 NM3 of oxygen being produced simultaneously. The energy consumption for oxygen production via air separation is calculated at 0.4 kilowatt-hours per NM3; to produce 6 kg, 3 kmol, or 67.2 NM3 of hydrogen, 336 – 33.6×0.4 = 322.56 kilowatt-hours of electricity are required. 3. Methanol is synthesized from hydrogen and carbon dioxide, via the reaction CO2 + 3H2 = CH3OH + H2O + 59.6 KJ/mol; that is, 3 kmol of hydrogen, equivalent to 67.2 NM3, can capture 44 kg of carbon dioxide. The heat generated during this methanol synthesis process is fully utilized, which is equivalent to 16.56 kilowatt-hours of electrical energy. As a result, producing 1 mol of methanol through water electrolysis directly fixes 44 kg of carbon dioxide, with 322.56 – 16.56 = 306 kWh of electrical energy being consumed ； By directly replacing coal-fired power generation with this electrical energy, 306×0.675=206.55 kg of carbon dioxide can be reduced. According to the system’s calculations, in the process of producing methanol through water electrolysis, for every 1 kmol of methanol produced, 206.55 kg of carbon dioxide is emitted; thus, per ton of methanol, the carbon dioxide emissions amount to 1000÷32.042×206.55 kg, which is equivalent to 6.446 tons. In contrast, direct carbon emissions from coal gasification for methanol production are approximately 2.4 tons. There are countless similar examples; we hope for correction at the **level!
You might be calculating correctly, but the volume is too low； Driven by interests
But there have to be different voices, right?
This post was last edited by yyszyj on 2022-10-26 02:16; likes are used, so green electricity should be employed.
Hydrogen production by electrolyzing water should refer to electricity generated from wind and solar power, commonly known as green energy. Due to the special nature of wind and solar power generation, it is almost impossible to integrate them into the power grid. At present, only the Longyangxia Hydropower Station in China has implemented a combination of hydroelectric and solar power (for details, please refer to relevant sources); this is why \"green electricity can be used to produce hydrogen\", and this process does not generate CO2. Hydrogen production using green electricity is an intermittent process; hydrogen cannot be produced at night when there is no light. Therefore, storage facilities for hydrogen are necessary to enable continuous production in the chemical industry. China currently emits about 10.3 billion tons of CO2 per year, with over 50% of these emissions coming from thermal power generation; therefore, it is not possible to use coal-fired power generation for \"water electrolysis to produce hydrogen\". The information provided may not be accurate; we encourage fellow sailors to share their suggestions.
Aren’t carbon dioxide emissions mainly caused, as experts say, by people in rural areas cutting wood for cooking? How could it be coal? Impossible, impossible~~~ Closing stoves is a faster way to reduce carbon emissions!
Have we calculated the carbon emissions generated during the manufacturing of equipment such as wind turbines and photovoltaic panels?
I think there’s some confusion here; the sources of photovoltaic and wind power cannot be compared to conventional coal-fired power generation. Carbon reduction simply involves making use of energy from nature, so it can’t be compared to coal power
Please learn about the synthesis of methanol from carbon dioxide, and the production of gasoline from carbon dioxide!