Capture and sequestration

A key rationale for moving to a hydrogen economy is to minimize carbon emissions. Producing hydrogen from coal actually could result in increased carbon dioxide emissions, unless carbon capture and sequestration is an integral part of these plants. 

Technically, it is far simpler to remove the CO2 from either natural gas reformation or coal gasification as the carbon already is being separated from the hydrogen. Estimates of the technically recoverable CO2 range from 87% (Williams 2001) to 92% (NAE 2004). Williams 

Assumes a natural gas cost of 5.92 /MBtu each 1 increase in natural gas price increases the cost of produced hydrogen by 0.16. 

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Develop practical and environmentally responsible methods of carbon dioxide capture and sequestration. 

For each ton of hydrogen produced from hydrocarbons, approximately 2.5 t of carbon is vented to the atmosphere [44-47], However, for each ton of hydrogen produced from current coal technology, approximately 5 t of carbon is emitted to the atmosphere. Principally, C02 capture and sequestration is a precondition for use of these fossil fuels. However, the sequestration necessity varies, because the relative atomic hydrogen-to-carbon ratios are 1 2 4 for coal oil natural gas. There are two basic approaches to C02 sequestration either at the point of emission (in situ capture) or from the air (direct capture). In either case, C02 must be disposed off safely and permanently. With the capture and sequestration of C02, hydrogen is one path for coal, oil, and natural gas to remain viable energy resources [46]. Carbon sequestration technologies are discussed in detail in Chapter 17. 

Nelson, T.O., P.D. Box, D.A. Green, and R.P. Gupta, Carbon Dioxide Recovery from Power Plant Flue Gas using Supported Carbonate Sorbents in a Thermal Swing Process, Sixth Annual Conference on Carbon Capture and Sequestration, Pittsburgh, PA, May 2007. 

Once the C02 is captured and compressed, it needs to be transported to the sequestration or utilization locations, unless the capture and sequestration processes are located at the same site. A C02 transportation infrastructure could be done with a rather conventional approach. On land, pipelines for long-distance C02 transport already exist. For example, a pipeline system more than 500 mi. long connects C02 fields in Southern Colorado to oil fields in West Texas. The C02 is purchased at about 15/ton for tertiary oil recovery. The cost of C02 transportation is a function of distance, whereas the costs of pipeline construction vary significantly by region (Doctor et al., 1997). The construction and operation of pipelines for ocean would be quite different from land-based pipelines. Generally, C02 is transported at supercritical pressures (-2000 psi). If C02 is sequestered at geological formations, the transferred C02 may require additional compression at the injection site depending on the specifics of the reservoir (Doctor et al., 1997). 

Shevalier, M., Nightingale, M., Johnson, G., Mayer, B., Hutcheon, I., Perkins, E. 2008. Geochemical monitoring of the Penn West CO2-EOR Pilot, Drayton Valley, Alberta. 7th Annual Conference on Carbon Capture and Sequestration, Pittsburgh, Pa. 

If H2 is made from renewable fuels such as biomass, or nuclear energy, or fossil fuel resources with C02 capture and sequestration, it would be possible to generate emission-free electricity in the future. 

Today s rapidly increasing activities on hydrogen focus mostly on vehicle applications and less on stationary applications. For fuel cells, stationary applications are also relevant, but natural gas will be the dominant fuel here. The dominance of the transport sector is also reflected in the hydrogen roadmaps developed, among others, in the EU, the USA, Japan, or at an international level. Whereas in the beginning, onsite or decentralised production options based on fossil fuels or electricity are seen as the major option for hydrogen production, later on central production options will dominate the market. Here, several options could play a role, from coal, with carbon capture and sequestration, through natural gas and renewables (wind, biomass) to nuclear. A C02-free or lean vision can be identified in every roadmap. The cost... 

Central production Natural gas Coal Steam methane reforming Coal gasification with carbon capture and sequestration Liquid-H2 truck Compressed-gas truck H2-gas pipeline... 

All coal and central natural-gas hydrogen plants are assumed to have carbon-capture and sequestration (CCS). Biomass hydrogen plants are assumed to be smaller (30-200 tonnes/day), compared with 50-400 tonnes/day for natural gas central SMRs, and 250-1200 tonnes/day for coal plants. We use a regional biomass supply curve (which specifies the amount of biomass available at a certain /tonne) (Walsh et al., 1999), to reflect biomass feedstock cost increases as demand grows. 

Figure 15.14. Optimal infrastructure configuration at different market penetration levels for a coal-based hydrogen supply system with carbon capture and sequestration in Ohio, USA (Johnson et al., 2006).

Using hydrogen to produce electrical energy from fossil fuels in large centralised plants will contribute positively to achieving important reductions of C02 emissions, if this is combined with C02 capture and sequestration processes. Such plants will also help to increase the diversification of resources, since a variety of fossil feedstocks can be used, including resources such as coal and waste that otherwise cause major impacts on the environment, as well as biomass. 

Storage of carbon dioxide by carbon capture and sequestration solutions for fossil fuels this is often not seen as a long-term solution and exploratory studies indicate that carbon sequestration may not be acceptable to the public (Whitmarsh et al., 2006) ... 

When the supply to the electricity and transportation sectors is jointly taken into consideration, one is led to conclude that the energy supply diversity is best served by allowing green electricity to maximally penetrate the electricity sector and simultaneously swing the deployment of NG and coal to instead serve the transportation sector. (Note that there may well be synergies between hydrogen fuel production and clean power production. These will be briefly touched upon in Section 15.6 for coal below.) The extent to which one thereby accommodates the objective of C02 emissions reduction depends on the mode of hydrogen production and distribution, and the extent to which it enables carbon capture and sequestration. To a discussion thereof we now turn. 

Advanced Oxyfuel Boilers and Process Heaters for Cost Effective COj Capture and Sequestration. This project is to develop a novel oxy-fuel boiler to reduce the complexity of CO2 capture. 

FlyPOCEN will explore the limits of using hydrogen as a means of de-carbonising fossil fuels and therefore its potential to bridge to a future hydrogen economy. The aim of the project will be to develop and operate a pilot demonstration plant and prove the feasibility, safety and economics, of carbon capture and sequestration. 

Yamasaki, A., Iizuka, A., Kakizawa, M., Katsuyama, Y., Nakagawa, M., Fujii, M., et al. (2006) Fifth Annual Conference on Carbon Capture and Sequestration, Alexandria, Virginia, USA. 

In this chapter, we briefly discuss the rise in atmospheric C02, and the reason, from a sustainability perspective, of why capture and sequestration are necessary. Recent advances in capture and sequestration technology are given, as is the latest thinking on putting a price on C02. 

C02 sequestration [14] in geologic formations includes oil and gas reservoirs, unmineable coal seams, and deep saline reservoirs. These are structures that have stored crude oil, natural gas, brine, and C02 over millions of years. Many power plants and other large emitters of C02 are located near geologic formations that are amenable to C02 storage. Further, in many cases, the injection of C02 into a geologic formation can enhance the recovery of hydrocarbons, providing value-added by-products that can offset the cost of C02 capture and sequestration. 

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