Planning to Switch Coal Power to Gas Fired? Check if Justified by Reduction in Emissions Across the Value Chain

The economic case to make this switch need to be based on the facts not on the common beliefs or what various writers or agencies suggest or talk about. Such as switch is expensive and can need an investment in the order of of $ 100+ MMs’ to Billions and take the capex $s’ away from other essential services, especially in developing countries. Thus, necessary to estimate the CO2 & CH4 emissions across the entire value chain of Coal, LNG, or pipeline Natural Gas, from extraction to transportation to processing to transportation and delivery to the end user and finally the power generation itself and any associated clean up facilities.

This article is only for educational sharing of my opinion and can have inaccuracies and omissions.?This is not professional advice for any real situation of any kind. Readers assume all risks for any deduction or extrapolation. The Disclaimer at the end of this Article should be reviewed. It applies to the entire content and any comments or responses

The logic of switching coal power plants to gas fired is the belief that NG based facility generates 20-40% less CO2 emissions, thus contributing to the country strategic goal to reduce the emissions by ~ 50% by 2030-2035. However, in my opinion, this applies only the power producing facility part where fuel is combusted due to higher efficiency of gas turbines and NG being a denser fuel in terms of available carbon. This is also, in my opinion, only true for cases where the extracted NG has very little CO2, is transported in a domestic pipeline for a short distance only, Methane (CH4) leaks are controlled and mitigated, and the Coal Power Plant uses sub-critical technology with lower efficiency.

However, picture changes if any of the above factors change: If the imported LNG is based on NG that has a high CO2 content; Liquefaction is done in a facility that does not have a CCS facility; Power supply in the LNG producing facility is fossil based; Sea transported and then go through revaporization at the customer LNG terminal.?Each of the above steps, where applicable, increase the CO2 emissions profile and, if all are applicable, then the emissions level may reach to the level of a coal power generation. In such as case, especially if the coal is high quality, has low sulfur content and uses the more efficient ultra-critical boiler, there appears to be little justification for switching from coal to gas fired facility.

Similar arguments can be made for the pipeline provided NG where it is transported thousands of miles to reach the customer. The Russian NG pipelines providing gas to EU, that may have originated from the gas fields development in Siberia, is an example. The amount of power to extract the gas offshore or from below ice, treat and clean and compressed in multiple stations to transport large quantity across various countries adds considerably to the emissions footprint of the gas. Add to this the Methane leaks (CH4) all along the way, which is 86 times more powerful in producing the greenhouse effect, the total emissions of CO2 plus CH4 may reach t the level of existing high efficiency coal plants operating in EU and are already equipped with low Nox burners and SCR and DeSox scrubbing technologies.

The coal burning power plants have come a long way from the original design of 35-38% efficiency. With development in materials the newer ultra-critical boilers can attain an efficiency of 42-45% with subsequent reductions in the Nox and Sox produced. The icing on the top is that coal extraction produces very little emissions, may be less than 5% of what is produced in developing the NG reserves as LNG or pipeline gas. Moreover, coal does not need much treatment and, domestically, is usually transported in rail cars which can be easily configured to use clean renewable energy.

Thus, let us assumes that in a gas fired power plant, about 2/3 of the emissions is produced in the combustion process and has, say, a 30% higher efficient than coal, while the preceding processes generates the balance of 1/3 emission. Comparing this with a coal power plant the CO2 emission from the preceding processes is almost zero but the combusting efficiency is 30 lower. This basically means that when looking at comparison of coal versus NG, the baseline is only 2/3 f the total emissions from the NG value chain, including both CH4 and CO2.

?In my opinion, such as analysis allows an apples-to-apples comparison and provides a truer picture. This can also allow many developing countries and others with large coal reserves to keep using coal without impacting the Paric Accord goals if appropriate measures are taken to cap and trade the emissions or adjusting the energy price to reflect carbon tax, where applicable or taking offsetting measures in terms of investing in renewable energy and CO2 agri sinks.?????

Disclaimer: This is not professional advice, directly or indirectly, and can be edited or deleted at any time. Anyone accessing this Blog unconditionally agrees that the expressed views are only the personal opinions of the Author for educational sharing only, basis author’s knowledge only, and may contain omissions and inaccuracies. It must not be used for any actual new project or on an existing facility. Readers accept all risks and responsibility for any interpretation or extrapolation and any consequences stemming from such reliance