Electricity supply largely from solar and wind resources in Japan
Highlights
► We developed a dynamic simulator on the renewable electricity supply in Japan. ► Statistical analysis shows that the optimal mix is 75% solar and 25% wind. ► We introduced the sum of back-up, excess power, and battery loss as a criterion. ► Dynamic simulations show it is minimum at the above combination of solar and wind. ► They show the battery effects become less when the battery capacity increases.
Introduction
Domestic renewable energy sources have gathered great attention from the viewpoint of safety, security, energy independence and zero carbon emission. It is not difficult to determine the national electricity supply provided mainly by renewable resources, such as photovoltaic (PV), wind, hydro, biomass and geothermal power. Such accounting is static, but in the case of the electricity supply, it is necessary to analyse demand-supply matching and the scale of electricity storage to absorb the fluctuations caused by solar and wind power. We developed a computer program to simulate renewable electricity supply with energy storage to satisfy the hourly electricity load throughout one year.
Section snippets
Mismatch equation
There are pioneering studies conducted by Heide's group on the fully renewable energy supply provided by the combination of solar and wind power using data regarding electricity load and weather in Europe [1], [2]. The statistical analysis performed by the researchers showed that the optimal mix of solar and wind power can be found using only monthly data. We tried to follow their research methodology using Japanese data.
They defined the equation for the mismatch, D(t), of load and supply as
Dynamic simulator of electric supply from renewable sources
A dynamic simulator was designed to estimate the hourly renewable electricity supply using meteorological data. At the beginning of the simulation, the future electricity load and energy storage capacity must be set.
Analyses of simulation results
After running many cases with different simulation parameters, the following points for discussion arose.
Conclusions
The optimal mix of solar and wind power was analysed following statistical methods reported in European studies. Using national weather data from Japan, dynamic simulations of the annual renewable electricity supply and the analysis of the results are presented.
The main conclusions drawn are as follows,
- 1)
Preliminary statistical analyses show that the standard deviation and the stored energy derived from the mismatch equation for Japan are smaller than the results reported for the European case.
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