CO2 geological sequestration Nagaoka Project


Evaluation of Effectiveness


To tackle various technical problems related to CO2 geological storage and to show its effectiveness, the following endeavors were conducted.

Setting of storage system types and estimation of costs
Calculation and evaluation of economically-rational storage amount using an integrated economic model
Identification of future challenges and preparation of a schedule for actual application


Cost Analysis

The CO2 geological storage systems were divided into four types and their costs were analyzed based on the hypothesized actual-scale injection plan adopted in the model site survey. According to this estimate, the costs of geological storage using presently-available technologies is 7,000-15,000 yen per ton.

Typical cost analysis based on the model site survey

Standard conditions Capture and isolation 1 Mt/yr (excluding EOR), transport distance 20km, pressurization 10MPa, Injection method ERD, injection amount per well 100,000 t/yr
Coal-fired power plant (common) Electricity 5 yen/kWh, existing coal-fired plant: steam supply by auxiliary boiler
Steelworks Steam 2,500 yen/t, electricity 10 yen/kWh, EOR: separation & capture from a new coal-fired plant 200,000 t/yr

It was revealed that the relevant costs in Japan, particularly the transport and storage costs, are much higher than those in overseas countries. The transport cost in Japan is high because the vehicles pass through densely-populated areas. The storage cost is also high because Japanese formations have a low permeability compared with those found in overseas countries and thus the injection amount per well is rather limited.

Comparison of geological storage costs between Japan and overseas countries
Case New coal-fired
- aquifer storage
New coal-fired
- aquifer storage
- aquifer storage
New coal-fired
- pressurization
4,200 29 - 51 37 - 74 29 - 51
Transport 800
1 Mt/y - 20 km
1 - 8
5-40 Mt/y - 250 km
Injection 2,300
0.1 Mt/y·well, ERD
0.5 - 8 -10 - +16
Total 7,300
1 Mt/y - 20 km, ERD
30 - 70 40 - 90 9 - 44

Based on the above comparison, the following must be addressed hereafter for actual application.

Cost reduction for the separation and capture process which accounts for more than 60% of the total cost.
Utilization of reservoirs near the emission sources because the transport cost is higher than that in overseas countries.
Technological development to increase the injection amount per well.


Overall Economic Evaluation

In the overall economic evaluation of CO2 geological storage, a mathematical model was constructed and a cost analysis and a storage capacity survey were performed.

The geological storage costs in Japan are relatively higher than those in overseas countries. However, we have little option in terms of ways to reduce CO
2 in large scale at a low cost, because the potential of renewable energies is limited and because the energy-saving aspect has already been largely exploited. Therefore, even though the geological storage costs are higher than those overseas, it is still relatively inexpensive compared with other measures. Thus, it can be said that the important function of geological storage has been demonstrated quantitatively.

In the cost calculation for A2 type reservoirs (potential storage capacity: 5.2 Gt ), for which basic boring data exists, it was found that about half of the storage would be economically justified if the CO
2 reduction target per GDP in 2050 was set at half of the 2004 emissions. This suggests that as the reservoir area is expanded in the future, the economically-competitive storage capacity would be increased significantly.

CO2 emissions and storage capacity in Japan

Click to enlarge


Road Map

Based on the various effectiveness scenarios as well as overseas trends in CO2 geological storage, the issues that need to be addressed were extracted and a road map was prepared by setting FY2015 as the start for full-scale implementation. The road map is aimed at defining a route for technological development and its diffusion as well as promoting understanding on geological storage among companies having large-scale emission sources.

In the actual implementation of geological storage, cost reduction is very important. The separation and capture costs which presently comprise a large percentage of the overall total must be reduced. The transport costs must also be drastically cut by focusing on the distance between emission sources and the reservoirs, etc. For this to happen, it is necessary to explore the technical storage potential of Category B aquifers, which are widely distributed in the coastal areas near emission sources, through basic demonstration tests, and to construct a storage model based on the test results. It is also necessary to conduct storage capacity surveys in coastal areas near the emission sources, together with the promotion of activities for a better understanding of geological storage.

Road map for CCS in Japan
(Source: "CCS2020" by the Industrial Science and Technology Policy and Environmental Bureau, the Ministry of Economy, Trade and Industry (METI))

Click to enlarge



It was identified that the geological storage cost using presently-available technologies is 7,000-15,000 yen per ton. The problems to be tackled relative to the storage cost were extracted.
Geological storage is a comparatively inexpensive technology. It is expected that the economically-competitive storage amount will increase from here on in as the available reservoir capacity expands.
A road map was prepared aiming at a full-scale implementation beginning in FY2015.


Future Challenges

It is necessary to improve the accuracy of the effectiveness scenarios and the road map for CO2 geological storage by taking into account the results of cost analysis, storage capacity surveys, domestic and overseas trends, etc.

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