We have arrived a long way from the days when people debated whether global warming is real, some of us would ridicule our ageing nerves and heightened perceptions for it. The days people debated whether global warming is anthropogenic-contributed by human activity are long gone. There was a time when countries debated whether they need to mitigate aggregate or per capita GHG emission to reduce long term global average temp rise by 2 Deg Centigrade. Now we stare at runaway global warming, the frightening prospects of white layers of glaciers melting and the earth as a consequence receiving more heat, the corpses lying under deep snow cover exposed rotting and emitting more methane thickening the GHG layer further. As a result, the target of long term global average temperature rise is stiffened to 1.5 Deg Centigrade and countries have declared their dates to achieve Net Zero. India has declared 2070 as the year to achieve Net Zero. As per a Deloitte report, climate change is a 35 Trillion threat for India and a 11 Trillion dollar opportunity. Thus 46 Trillion Dollars is up for grab [6].
For a country with the dubious distinction of 14 out of top 20 polluted cities this could be a big win-win in the triad of energy autonomy, environment and economy.
In order to meet the targets of the Paris Agreement it was necessary to reduce the energy related CO2 emissions by almost 3.5% per year till 2050, followed by more reductions eventually. Considering additional reductions from direct use of renewables, 75% share is increased whereas when energy efficiency is added, the share increases to 90%. The Indian government committed to deploy expansive solar and wind energy capacity and foster the necessary climate actions to forge a low carbon future. Due to the arduous efforts of the government, India made remarkable progress in meeting targets of Paris Agreement. India has committed to achieve about 40% of cumulative electric power installed capacity from non-fossil-fuel energy resources by 2030. The prime minister of India has committed in the UN’s climate Week in New York to a target of 450 gigawatts (GW) of renewable energy installations, likely by 2030- equivalent to five times more than India’s current installed renewable capacity (82.6 GW) and bigger than the size of India’s electricity grid size in 2019 (362 GW). India aims to reduce the emissions intensity of its GDP by 33 to 35% by 2030. Over the period of 2005-2014, India’s emission intensity has reduced by 21%.
Yet, Electricity constitutes only 18% part of India’s total energy consumption, which can be decarbonized using RE. Balance 82% includes hard to abate sectors like Oil Refining, Steel, Cement, Fertilizers, Transport etc. Some of them can’t be fully decarbonized as they need decarbonisation to meet the COP 26 commitments. Besides, India’s installed capacity at about 392 GW including about 150 GW RE including large hydro. Maximum peak load is hardly 200 GW and baseload is much less. The COP 26 target of 500 GW RE entails substantial difficulties in Grid stability and is highly intermittent in nature. It requires energy storage to meet demand supply mismatch and make RE despatch available round the clock.
India imports more than 70% of its petroleum requirement, so has a huge energy security concern, which is bound to increase over the years. Disruptions like COVID or Russo-Ukrainian war may only aggravate the situation further. India’s effort to tap its reserves of natural gas, KG Basin has not yielded the desired result. While there is growing demand for natural gas, which is a cleaner fuel in comparison with coal – besides it is fuel on the road (CNG), fuel for the kitchen (PNG), raw material for fertilizer plants and fuel for power plants CCGT with 55% efficiency. This situation can be improved if we tap methane from bio-waste and utilize to bridge the gap between demand and supply of natural gas. We can improve the situation further if we produce hydrogen from methane, hydrogen from natural gas and mix it with natural gas to increase heat value of the fuel besides reducing GHG emissions. 20-30% of hydrogen can be blended with Natural gas and can be used with existing engines and turbines.
Hydrogen Economy Perspective
The perspective for hydrogen economy has to be understood keeping the above background in view. Hydrogen can provide required storage and also can supply baseload Power through Fuel Cell reducing dependency on Fossil fuels. Hydrogen Storage Systems (HSS) can provide large scale energy storage of the order of 1 GWh to 1 TWh, Batteries in contrast store between 10 kWh to 10 MWh, compressed air storage & pumped hydro between 10 MWh to 10 GWh. Converting excess power to Hydrogen using when required in microgrids for desired application at convenient locations.
As a step in this direction on August 15, 2021, during the 75th anniversary of India’s independence, Prime Minister Narendra Modi announced the commencement of the National Hydrogen Energy Mission (NHEM), with the goal of reducing carbon emissions and increasing the use of renewable energy sources. The mission’s broad goal is to increase Green Hydrogen production and promote its applications while also aligning India’s efforts with worldwide best practices in technology, policy, and legislation. The NHEM has identified pilot projects, infrastructure and supply chain, research and development as broad activities for investment proposing a financial outlay of Rs 800 crores for the next three years. NHEM targets to utilise the abundantly available Hydrogen element for clean energy initiative.
- Hydrogen can help with energy time-shifting, peak load capacity substitution, load following, renewable dispatch and curtailment avoidance.
- The use of hydrogen produced for grid services and FCEVs could lead to a viable commercial solution.
- Studies indicate 18-20% hydrogen blended with methane reduces CO2, CO, and total hydrocarbon (HC) emissions associated with NG burning.
- The lean burning capacity of natural gas will be extended due to the lean burn properties of hydrogen, and the lean burning capacity will rise with the amount of hydrogen added.
- The thermal efficiency of the hydrogen-added natural gas is improved due to hydrogen’s excellent combustion characteristics. When hydrogen is added to natural gas, a higher percentage of energy is successfully used. Except for NOx, all emissions were decreased to near-zero levels since hydrogen has no carbon particles.
- Many researchers have sought to reduce NOx emissions, and they have done so by switching to a leaner mixture below 0.7 and recirculating exhaust gas. This will lower the flame temperature, lowering the NOx level without sacrificing thermal efficiency.
- The transportation industry is one of the most significant contributors of greenhouse gas emissions. Using hydrogen-added natural gas resulted in lower power output. As a result, further study is needed to make hydrogen competitive, as well as ascertain the environmental benefits of green hydrogen use in various industries. Research, development, and innovation are required throughout the value chain to reduce the cost of green hydrogen and to optimise it.
Hydrogen can be classified into four categories based on the source of production and carbon emission:
Green Hydrogen from Bio-Waste
In case of Hydrogen generation from renewable sources like bio-waste whatever CO2 gets released was absorbed by plants during growth unlike fossil fuels. Hydrogen from waste can be produced in very cost-effective manner and also can help in waste management and unlocking precious Landfill sites. Also, it can utilise sewage sludge, agro-waste and other biowastes and avoid water contamination through leachate and air pollution and methane escaping with decomposition of waste. Additionally, the by-products like green manure, biochar etc., help in natural carbon sequestration by a reduction in use of synthetic fertilisers. Various wastes may include wet waste, organic waste, garden waste, jungle waste, sewage sludge, food waste, mandi waste, slaughter house waste, etc. These waste when these rot in landfills emit methane generated by the action of anaerobic bacteria. Methane has 25 times GWP in comparison to Carbon Dioxide. At COP 26 in Glasgow more than 100 countries signed the Global Methane Pledge to cut emissions by 30% from 2020 levels by 2030. Thus, this H2 can be highly carbon negative.
The thermochemical processes of gasification and pyrolysis is faster than the biochemical fermentation has higher stoichiometric hydrogen yields, higher conversion efficiencies and shorter reaction times. However, biochemical processes are less energy intensive as they operate under moderate energy conditions leading to lower hydrogen yields. [1].
The picture below depicts one of the most widely used methods of Waste to Hydrogen wherein, the arrows indicate flow direction or transport from various sources. Ideal locations for the development of biochemical systems would be the ones closest to the sources of raw materials in order to limit various operation and transportation costs.
- Gasification
- Plasma Gasification
- Pyrolysis
- TAD (Thermally accelerated Anaerobic Digestion)
- Converting waste/biomass to methane and then to Hydrogen.
These processes however, require biomass and residual waste to be treated before going forward with the above processes. But technologies like plasma gasification do not require any pre-treatment. The pre-treatment is mainly carried out in three different stages to separate the heavy metals, non-ferrous and ferrous metal.
…To be continued
References
[1] M. Hu, D. Guo, C. Ma, Z. Hu, B. Zhang, B. Xiao, J. Wang Hydrogen-rich gas production by the gasification of wet MSW (municipal solid waste) coupled with carbon dioxide capture
[6] https://m.economictimes.com/industry/renewables/climate-change-it-can-be-11-trillion-opportunity-or-a-35-trillion-threat-for-india-says-deloitte/articleshow/85554191.cms
[7] https://www.hydrogen.energy.gov/pdfs/06-Goldmeer-Hydrogen%20Gas%20Turbines.pdf
[8] https://www.ge.com/gas-power/resources/case-studies/australias-first-dual-fuel-hydrogen-plant
Suraj Prasad is working as a QA Automation Engineer at Esko, A Danaher Company. He is a graduate from Manipal Institute of Technology, in Print & Media Technology.
Dr. Bibhu Prasad Rath is a graduate in Mechanical Engineering and has worked in various functions in NTPC – including Operation & Design. He is presently the Additional General Manager in Project Engineering division. His qualifications include ICWA (Inter-1995), M.Tech (IIT Delhi-2002) and PhD (in Business Administration-2015) from Aligarh Muslim University.
