“Clean-coal”---Pre combustion

Some ideas before get into further:

---integrated gasification combined cycle (from thermo to chemical)

---expose coal to controlled amounts of O2 and high temperature steam

---coal breaks down without burning and energy is released as hydrocarbon converting to CO, H and other gases

---a products from electricity to hydrogen generated

More details on pre-combustion technology:

            Pre-combustion technologies involve removing CO2 before combustion the coal and the only product is hydrogen. Why we need hydrogen? Obviously that the hydrogen combustion does not emit any CO2 the only product is H2O and release heat at the same time.  The whole idea is to achieve a zero emission of CO2 goal in the future. Once there is less inputs of CO2, we can maintain the current CO2 level and prevent any worse situation will happen.

            The process consists of three stages. Methane or gasified coal that any kind of hydrocarbon fuel or mixture is injected into power plants and converted into CO that is the first step. And then, the shift conversion happens: let CO react with water and then we get CO2. At last, the carbon that contained in CO2 is separated from the hydrogen. The CO2 will be transferred to other places to store securely.  

Another way to lower the CO2 emission level: Post-combustion capture

What exactly is post-combustion capture?

            According to Herzog, “this refers to the capture of CO2 prior to combustion. This is not an option at the pulverized coal (PC) power plants that comprise most of the existing capacity. However, it is an option for integrated coal gasification combined cycle (IGCC) plants. In these plants, coal is first gasified to form synthesis gas (syngas, a mixture whose key components are carbon monoxide and hydrogen). The syngas then undergoes the water-gas shift, in which the CO reacts with steam to form CO2 and additional H2. The CO2 is then removed, and the hydrogen is diluted with nitrogen and fed into a gas turbine combined cycle. The advantage of this approach is that it is much less expensive than the post-combustion capture process. The disadvantages are that there are only a few IGCC plants in the existing coal fleet and IGCC plants are more expensive than PC plants when costs of CO2 capture are not included.”

            There are pros and cons with post-combustion capture.

Pros:

1.     it’s easy to spread to industrial and power plant stations with renovations(UK 400 MW retrofit by 2014)

2.     it has already existed for more than 60 years

3.     it’s adaptable to current fossil fuel plants

4.     Cryogenic capture reduces cost by 40% in experimental plants

Cons:

1.     it’s a high cost program for dealing with the solvents, generating the machine and also using a lot of water, leading to other problems with the replacement

2.     this technology has not been widely used and lacking of experience on large scale

3.     it has large footprint

Reference: Herzog, Howard, Jerry Meldon, and Alan Hatton. "Advanced Post-Combustion CO2 Capture." Clean Air Task Force. (2009): 3-38. Print.

More detials on CCS (Carbon Capture & Sequestration )

       

This video shows how carbon capture & sequestration work in the reality. The main body is the same as last blog I have wrote, but by watching this video you will easily understood the progress of CCS within minutes. We can see from the video that injecting the CO2 into oil fields, it tends to rise, as it is lighter than surrounding materials. But the cap rock prevented the CO2 of any further emission. The cap rock layer is impervious barrier that can keep CO2 underground forever. Over time, the CO2 will dissolve with oil remaining or salt water and then sink to the bottom of the layer. After thousands of years, the CO2 and naturally minerals react with each other and form stable minerals such as CaCO3. This process will help people prevent the re-entry of carbon back to natural cycle again. On the other hand, this video reveals the fact that when we injecting CO2 into oil fields, it can help us produce more undiscovered oil than before. And this oil recovery process may enhance the oil that might be recovered by 15%!!! There is monitoring process of the migration of CO2 in the subsurface that helps people find any leakage before, during and after injection of CO2.

What about capturing CO2 during its combustion process?

CCS stands for Carbon capture and storage (or carbon capture and sequestration) that means CO2 capture during combustion. By doing this, it could lower the emission from energy production by 20%.

So how is this process work in reality? First, at mining of fuel locating offshore or near the coal mine, methane gas is produced. All the gases are brought up onshore by pipes that under the sea level or transport by other ways. The oil refinery technique will help us separate different types of gases and also give us CO2 and hydrogen at the same time. The final goal is separate CO2 and then pumps them into an offshore-abandoned oil/gas fields.  By separating CO2 from the mixture we get, a new designed membrane can filter larger CO2 molecular from that. The pipeline, which used for transporting CO2, needs to be resistant with corrosion. The oilfields, which used for storing CO2, are located few kilometers below the sea level. Under most circumstances, the oilfields are arch and have steady landform. The aquifer above the storage points is impermeable that will guarantee the CO2 will not get into the ocean and threat the ocean environment. When inject CO2 into oilfields, it’s a great waste of space if we inject CO2 in its air form. Instead, when inject CO2, reducing the pressure and making CO2 into liquid form can maximize the CO2 storage sites’ usage. 

Reference: http://www.co2storage.org.uk/ 

Current projects that in use to lower the CO2 emission worldwide:

---Saskatchewan Canada: 1 million tons of carcon dioxede per year pumped into active oil well

---Berlin Germany: 100,000 tons of CO2 in 3 years. Liquefied CO2 from coal, which started from 2009.

---Price Utah: 900,000 tons in 4 years. Pumping CO2 into saline groundwater. Anticipates future coal plant development. Started in 2008.

---Netherlands: 200,000 tons per year. K12-B natural gas site, CO2 re-inject

---Norway Barents sea: 2008 700,000 tons per year and it is 2600meters below the sea floor

---Australia: 3.3 million tons per year. Biggest project. CO2 from natural gas injected into saltwater and it is 2300 meters below Barrow island.

---Tianjin China: 1million tons per year CO2 from gas field coal injected into oil wells

This coal-based power plant in Tianjing was put in use in 2009, which aim to put zero emissions of CO2 in reality. 
“This pioneer project would be country's first commercial-scale "clean coal" power plant. It will gasify coal to extract the hydrogen while sequestering the CO2 emissions, popularly known as CCS – carbon capture and storage. The carbon dioxide will then be pumped into oil wells to aid in petroleum recovery.”

 (http://www.china.org.cn/business/2009-06/18/content_17975137.htm)

In China, the electricity used up 50% of carbon emission in last 5 years. There is more 200 million tons of coal being used per year than 10 years ago. Tianjin facility removes CO2 before burning coal which can removes the carbon from coal and then injected into oil wells. By capturing CO2 like this, we can spend less amount of money compare with other possible solutions and minimize the affluence of carbon dioxide emission.

If CO2 is the main causes that leading to global warming...

Although causes for global warming are complex and sometimes difficult to trace, it doesn’t mean that there is nothing we can do to stop it. Global warming is a global issue that needed the whole world’s efforts to solve it. Though the earth belongs to everyone on this planet, not all of them are willing to spend their money or time on lower the level of carbon emissions. Sometimes protecting the environment needed to sacrifice someone's benefits. Still, each step of lower the carbon dioxide level is important and also essential.

We can think from the start. In the intro, we have mentioned that global warming is mainly caused by carbon dioxide. If the leading cause for that is too much carbon dioxide, what we should do is lower the level of CO2. We need to separate this procedure into two. First, find ways to lower the current emission level and then find other possible solutions to lower the excess carbons that human dumped into the atmosphere before which including explore something that can absorb carbon dioxide. 

Cautions! The temperature for tomorrow is 150 F!!!!!

Just Kidding.

But we all know that the globe is getting warmer and warmer compare with historical records and we can feel that too.  Since the industrial revolution, there are enormous amount of industries, cars and explore new resources etc under using, these events became leading causes of global warming. Human have interrupted the natural cycle of the whole system, for example, the carbon cycle.

“Global warming is primarily a problem of too much carbon dioxide (CO2) in the atmosphere—which acts as a blanket, trapping heat and warming the planet. As we burn fossil fuels like coal, oil and natural gas for energy or cut down and burn forests to create pastures and plantations, carbon accumulates and overloads our atmosphere. Certain waste management and agricultural practices aggravate the problem by releasing other potent global warming gases, such as methane and nitrous oxide. See the pie chart for a breakdown of heat-trapping global warming emissions by economic sector.”

(http://www.climatehotmap.org/about/global-warming-causes.html)