  Rapid economic growth in China has lead to an increasing energy demand in the
country. In combination with China's emission control and clean air
initiatives, it has resulted in large-scale expansion of the leading renewable
energy technologies, wind and solar power. Their intermittent nature and uneven
geographic distribution, however, raises the question of how to best exploit
them in a future sustainable electricity system, where their combined
production may very well exceed that of all other technologies. It is well
known that interconnecting distant regions provides more favorable production
patterns from wind and solar. On the other hand, long-distance connections
challenge traditional local energy autonomy. In this paper, the advantage of
interconnecting the contiguous provinces of China is quantified. To this end,
two different methodologies are introduced. The first aims at gradually
increasing heterogeneity, that is non-local wind and solar power production, to
minimize production costs without regard to the match between production and
demand. The second method optimizes the trade-off between low cost production
and high utility value of the energy. In both cases, the study of a 100%
renewable Chinese electricity network is based on 8 years of high-resolution
hourly time series of wind and solar power generation and electricity demand
for each of the provinces. From the study we conclude that compared to a
baseline design of homogeneously distributed renewable capacities, a
heterogeneous network not only lowers capital investments but also reduces
backup dispatches from thermal units. Installing more capacity in provinces
like Inner Mongolia, Jiangsu, Hainan and north-western regions, heterogeneous
layouts may lower the levelized cost of electricity (LCOE) by up to 27%, and
reduce backup needs by up to 64%.
