Renewable Energy Integration into the Japanese Electricity Grid: Dealing with Intermittency through Smoothening and Ocean Energy

Following the 2011 Fukushima nuclear disaster, Japan is having to re-think its overall energy policy, as the country has been increasingly reliant on imported fossil fuels, though it will eventually have to decrease the amount... [ view full abstract ]

Following the 2011 Fukushima nuclear disaster, Japan is having to re-think its overall energy policy, as the country has been increasingly reliant on imported fossil fuels, though it will eventually have to decrease the amount of greenhouse gases emitted into the atmosphere under the COP21 climate pledges. Increasingly, renewable energy sources such as solar and wind are seen as being destined to play a major role in the power generation mix. However, detractors of intermittent energy sources often claim that they cannot be used to reliably power a country, given that there are times of the day when little solar or wind power is generated at a given point. Essentially, these intermittent generation sources can only really work if integrated over a large grid, where an excess of production in one region can compensate for adverse weather in another area, an effect known as smoothening. However, to date comparatively little work has been done on developing actual realistic simulations of how such a system would work, which require the input of hourly meteorological data to calculate how much electricity would be produced, and whether this could meet demand.

Essentially, smoothening becomes more pronounced as more types of renewable energy are introduced into the mix. In the present paper the authors have built a grid-simulation tool that simulates the hourly future electricity production based on wind, solar, wave and tidal data. The system uses pump-up storage and electric batteries to balance the daily fluctuations in supply and demand, essentially demonstrating how a viable system can be created in the middle to long term. The results have import implications at the policy making level, as they shows how such a system is technically able to increase the share of renewables in Japan up to 100%, guaranteeing a stable and reliable supply.