10.1: Carbon sequestering
(1) Storing pool of CO2 in the oceans floor more than 3km deep
The Carbon Capture Storage (CCS) technology is suitable for deep storage of CO2 on ocean floors. It involves the direct injection that has been captured in tanks and pipelines. This artificial methodology (CO2) involves the compression and the transportation to the ocean site where it is injected underground for permanent storage. In this CO2 sequestration process, It is important to capture the primary source. An example of a source is the CO2 emissions that largely come from coal-fired power plants, captured, isolated, and then injected into the ocean. In a normal or more 500 MW power plant produces can produce over 130 kg/s of CO2 whereby the gas gets captured, transported to the ocean through piping or physical shipping to the ocean for direct injection. In this, CCS technology is important and has the climate benefits of reducing CO2 emissions. This aspect significantly reduces climate-related damage that can be harmful to human health by 74% for PC, 78% for IGCC, and 68% for NGCC power plants with CCS, compared with conventional power plants without CCS.
(2) Discharging supercritical CO2 in a deep saline aquifer
The technology of deep saline injection entails the supercritical CO2 getting injected into a deep saline aquifer. A two-fluid-phase system is created, with the supercritical CO2 and the brine as the two fluid phases. In this method, the CO2 gets slightly miscible with the brine, up to a few percent, by mass dissolving into the brine. The need and importance of physical trapping mechanisms in this technology are that deep saline aquifers aim to provide the greatest volumetric potential for storage anywhere in the world.
(3) Discharging supercritical CO2 into petroleum reservoirs for enhanced oil recovery
The technology used in this process for the Injection of supercritical carbon dioxide (CO2) is the use of enhanced oil recovery (EOR), which aims to minimize the impact of CO2 emissions promoting positive climate change. The CO2-EOR is known as the oil recovery technique in which the supercritical CO2 is intentionally and precisely injected into the reservoir to stimulate oil production from depleted oil fields. In this technology, the CO2-EOR has the purpose of combining with CO2 storage with the benefit of mitigating the emissions levels to the atmosphere. It is estimated that 80% of oil reservoirs globally can be suitable for utilizing CO2 injection to enhance oil recovery. The availability and CO2 cost have limited the purpose and need for the enhanced oil recovery operations with CO2.
(4)Fertilizing the ocean with iron
Ocean fertilization (OF) technology is very important on occasions that iron is required in the ocean. It is known as the theoretical CO2 removal technology that entails the dumping of large amounts of micro- or macro-nutrients that usually includes iron and urea into ocean regions with low biological productivity. This technology aims to stimulate the growth of phytoplankton. This method is crucial as it helps in increasing the photosynthesis and removal of large amounts of CO2 from the atmosphere. Recent experimental studies assert that every ton of iron added to the ocean could remove 30,000 to 110,000 tons of carbon from the atmosphere.
10.2: Carbon management through ambient air cleaning
1 Mt/y CO2
If a device capture area is 1000m3 = earth surface of 2m s-1
1000÷2= 500 devices needed
The volume of all water would be about 332.5 million cubic miles (mi3), or 1,386 million cubic kilometers (km3). A cubic mile of water equals more than 1.1 trillion gallons. A cubic kilometer of water equals about 264 billion gallons (1 trillion liters). In the US, the daily usage of water is 322 billion gallons of water.
Over 16,000 wastewater treatment plants in the US are effectively functioning, on average, at 81% of their design capacities, while 15% have reached or exceeded it. About 20 % of US homes and residential houses tend to use septic systems that locally treat their wastewater. If the septic system is improperly managed, elevated nitrogen and phosphorus levels can be released into local water bodies or groundwater.
For $80 per ton, then the approximate mass to be used. The global lime market accounted for 99.5 million metric tons of the industry occupied around 59% of the global hydrated lime market in 2015. So we calculate $80 × 99.5 million tons= $ 7960 million.
10.3: Carbon capacity of ocean water
Computing total dissolved carbon concentration/ TDC is equal to the mass concentration of C in the form of Carbonate, carbonic acid, and bicarbonate
The equations for the calculations based on pKA are
K*1= [H2CO3]/pCO2
K*2= [HCO3-][10^-pH]/[H2CO3]
K*3= [CO3 2-][10^-pH]/[HCO3-]
With K*1, K*2, and K*3 being the three dissociation constants
K*1= 3.75E-02; K*2= 8.73E-07; K*3= 5.58E-10
In this cases, the Ph is 8.15 and 7
It can be suggested that a pH is below about 8.5; one can estimate that the alkalinity is approximately equal to the hydrogen carbonate concentration: Log[HCO3-]=LogKH+LogPco2+LogKs1+pH.
At 20 °C LogKH= -1.41 and LogKs1 = -6.380