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Energy Modeling Challenge After Fukushima

Basically, the long-term energy model as explained in this chapter serves to yield a normative future scenario for the energy systems under specific given conditions, and it is currently difficult to develop a future scenario explicitly considering the unexpected impact of short-term disruptive events such as the Fukushima incident in a consistent way. The challenge in energy modeling is to consistently incorporate both long-term structural risks, such as climate change and energy resource depletion, and short-term contingent risks, such as disruptive shortages of energy supply as observed in Fukushima and fuel embargo, in order to allow us to effectively evaluate the concept of resilient energy systems. After Fukushima, resilience is regarded as an indispensable element in energy systems under various unanticipated risks for short-and long-term perspectives.

The Fukushima nuclear disaster triggered the shutdown of all of the country's nuclear power plants, which produced 30 % of the country's electricity supply at that time. Since the utilization of nuclear power generation significantly declined due to the accident and to political reasons, fossil fuel consumption for power generation shows the highest level in the last three decades. This meant Japan's fuel imports bill jumped immediately as power companies ramped up gas-fired (LNG-fired) and petroleum-fired power generators, as illustrated in Fig. 5.5. In particular, a radical shift to LNG occurred to compensate for the loss of nuclear energy, and its imports dramatically increased.

In addition, the nuclear suspension and the rise in Japan's LNG import added pressures to push up its already high prices even higher. Japan's LNG is traded at the highest price over the world at around $15/MMBtu, while U.S. natural gas is priced at around $5/MMBtu, as shown in Fig. 5.6. The total import costs of LNG for power generation increased by 64 % after Fukushima, causing the balance of payments to turn negative in fiscal year 2011 for the first time since 1980. Before

Fig. 5.5 Fuel import cost for power generation in Japan before and after the Fukushima nuclear plant accident [4–6]

Fig. 5.6 Gas price movement between U.S. and Japan [5, 7]

the Fukushima disaster, nuclear power was considered to serve as a bargaining chip for Japan to purchase LNG at affordable prices.

Resilience is expected to play a role in building a robust energy system to contend with such aforementioned emergent events. The future energy model should enable us to evaluate the amount of adaptive capacity needed to withstand extreme shocks with minimal disruption, to facilitate a recovery from the shocks, and to provide favorable persistent features such as stability, sufficiency, affordability, and sustainability. This model also needs to serve as a platform for discussing appropriate wider responses to the growing risks faced by societies and economies and for suggesting the shortand long-term countermeasures to intensify diversification, redundancy, and emergency responsiveness of energy system.

Conclusion

The calculated result indicates that nuclear power plants with fuel recycling, renewable energies, and CCS technologies are estimated to play significant roles to reduce CO2 emissions. Under a great deal of uncertainty it is difficult to draw firm conclusions as to which options have the greatest potential in achieving significant CO2 reduction. However, the simulation results in the model indicate that massive CO2 mitigation targets can be achieved with the large-scale deployment of innovative technology, highlighting roles for nuclear, renewables, efficient use of fossil fuel, and CCS. The results support the simultaneous pursuit of multiple technologies, rather than focusing merely on realistic technological options based on current perceptions.

Although we assumed the availability of fuel recycling of nuclear spent fuels and the upper limits of intermittent renewables in the total power generation capacity, the validity of those assumptions should be critically evaluated in the new technical and political contexts that exist after the Fukushima accident. The Fukushima nuclear disaster has caused increased concerns about nuclear safety and has heightened the uncertainty of nuclear energy in the long-term energy scenario, although considerable growth of nuclear energy utilization in emerging Asian countries is actually projected even after Fukushima. Consequently, in order to effectively position nuclear power in the long-term energy mix, nuclear policy needs to highlight nuclear safety even more by developing advanced nuclear technologies and by upgrading nuclear safety standards continuously after Fukushima.

The quantitative value of uranium as an underground natural resource is estimated to be equivalent to that of conventional oil if we consider light-water reactor use only, and it is far less than that of coal. If we abandon the technological option of nuclear fuel recycling, it is self-evident that we will deplete uranium resources within a few decades, rather than conserving it for future generations.

The extensive introduction of intermittent renewable power generation in power systems is definitely considered to have significant influences on power system operations and their optimal configurations. However, nobody knows the clear answer to the question of to what extent power systems should rely on intermittent renewables.

 
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