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Sunday, March 29, 2020
Renewable synthetic methane gas (RSMG) and Ramana Power Cycle (RPC) for Zero emission base load power.
RSMG is an abbreviation for ‘Renewable synthetic methane gas’ and it is a new form of a Carbon negative synthetic fuel to substitute natural gas. It is synthesized using CO2 extracted from the sea or from power plant using Oxy combustion CO2 power cycle at the site such as CES, Graz cycle or Allam cycle (using supercritical CO2 as working fluid) and Renewable Hydrogen (RH) by the following reactions using a renewable energy source.
1. CO2=> CO + ½ O2 (electro-chemical reduction)
2. CO + 3 H2=> CH4 + H2O (catalytic conversion)
There are other methods too can be applied but our patented process uses a unique method to synthesize RSMG from CO2 and renewable Hydrogen with a heating value (LHV) around 52 Mj/kg.
By using only, the sun and sea water, RSMG is continuously synthesized using continuous renewable energy such as OTE (ocean thermal energy) on 24 x 7 basis. Ocean is the largest reservoir for clean drinking water, Carbon dioxide, Hydrogen and thermal energy and it is imperative that the absorbed CO2 is extracted along with stored thermal energy in order to restore the warming ocean to pre-industrial state to mitigate climate change. The success of the system depends on the availability of the lowest cost of renewable energy on 24 x7 basis such as Hydro or OTEC. Alternatively, the cost of renewable energy should be less than a $0.05/kwh.
What is RSMG?
RSMG is like natural gas with higher heating value consisting of pure methane and Hydrogen with no other impurities such as sulfur compounds or CO2. It is synthesized using a proprietary technology using CO2 extracted from seawater and renewable hydrogen (RH) using a renewable energy sources such as OTEC or Solar/wind etc. It can be compressed like CNG or liquified like LNG and can be transported or shipped to various destinations. RSMG is a Carbon negative fuel because it uses already absorbed CO2 from the sea and not from burning fossil fuel and it is also renewable because the O2 from CO2 emission is substituted with renewable Hydrogen (RH) constituting synthetic CH4. The purpose of this technology is to recycle Carbon indefinitely at the site of usage and that is why transportation in the form of CNG or LNG is discouraged.
Ramana Power Cycle (RPC)
RPC is a new patent (pending) technology to generate a base load power 24 x7 using a renewable synthetic methane gas (RSMG) with Zero emission. By constantly recycling CO2 in the form of RSMG during Oxy combustion CO2 power cycle we can eliminate usage of fossil fuel completely. Moreover, there will be no need to extract further CO2 from seawater for a specific power plant because Carbon is being recycled constantly. Only further RH will be required to run the base load power plant.
How RPC works?
RPC uses an Oxy combustion power cycle such as CES, Graz cycle or Allam cycle (using super critical CO2 as a working fluid) to generate a base load 24 x7 power. It uses 80% of CO2 generated internally leaving 20% high purity pipeline grade CO2 which is used to synthesize RSMG at site for recycling. That is why RSMG is renewable. Thus, RPC continues to generate a base load power with Zero emission. The electric efficiency of RPC is nearly 70 % and the cost of power is competitive to any other power source. By continuously generating RSMG and recycling CO2 it achieves Zero emission without any requirement of fossil fuel such as natural gas. Thus, the process can decarbonize the fossil fuel industry completely at the fastest time frame. Using 100% renewable hydrogen (RH) in gas turbine is still a long way off to achieve a commercial reality. Currently only up to 30% RH has been tested along natural gas (30:70) and there are several technical problems to be solved with combustor. Moreover, the maximum efficiency in Hydrogen based gas turbine will not exceed 35% at the maximum.
How RPC is different from Allam cycle, for example?
Allam cycle has been selected by IEA (International energy agency) as the most efficient (electric efficiency at 55.4%) Oxy combustion power cycle to generate a base load power using natural gas. It generates 20% pipeline grade CO2 as by-product suitable for CCS applications. It requires natural gas as a fuel. It generates pure Oxygen from air using ASU (air separation unit) by cryogenic process. Air separation is an energy intensive process consuming as much as 15% generated power internally thereby reducing overall electric efficiency of the system. Moreover 20% CO2 discharged from the plant requires long distance piping and sequestration both are expensive thus increasing the cost of power.
RPC uses pure Oxygen generated as by-product of renewable hydrogen (RH) by electrolysis for Oxy combustion of RSMG and to continue to generate a base load power at highest electrical efficiency at competitive rate. Synthesis of RSMG is highly exothermic chemical reaction which generates superheated steam as a by-product which generates additional power using steam turbine thus enhancing the overall electric efficiency of RPC.
RPC is suitable only for large power generation such as 100 Mw and above. The process requires the cheapest and continuous renewable energy source such as OTEC, offshore wind turbines supplemented by PV solar. The main advantage of the system is it does not require large scale energy storage and the base load power can be exported directly to the grid using a substation as it has been done over several decades.
RPC has the potential to decarbonize the fossil economy at the fastest rate than any other methods currently used.
Any power generation technology should be able to meet the following seven criteria in order to be successful.
4.Lowest levelized cost of power
5.Potential to decarbonize the fossil economy at the shortest time frame.
6.Potential to Completely eliminate fossil fuel
7. Sustainable and has a potential to achieve circular economy.
RPC can meet all the above seven criteria.