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POWER TO GAS TECHNOLOGY

AND CHINA’S ENERGY INTERNET

INTEGRATION MODEL RESEARCH AND CASE ANALYSIS

By Tianqi Song, R&D Manager at the Aerospace Smart Energy at the physical network level is rare.
Research Institute (ASERI) and YPPC 2019 finalist In 2017 and 2018, abandoned power
in the nation came to 100.7 billion kWh
The energy internet The growth of renewable energy and 102.2 billion kWh respectively –
With the deepening of Chinese generation capacity more than the annual generation of the
energy structure reform, the ‘energy In recent years, more and more Three Gorges Dam (97.6 billion kWh).
internet’ has become a major trend. Its renewable energy (RE) is becoming part In addition, given the fluctuating
development in China has two main of China’s energy picture, as shown in and intermittent nature of this RE,
characteristics: renewable energy is Figure 1. While the problem of wind and mismatches between electrical
growing while the relationship between solar power accommodation in some supply and demand are a menace to
the two national-scale energy grids areas (and in certain periods) still exists, the security and stability of the grid.
(power and gas) remains weak. integration between gas and electricity This must be tackled by developing
innovative energy storage solutions.
However, current storage systems
FIGURE 1 DEVELOPMENT OF RENEWABLE ENERGY IN CHINA FROM 2015 TO 2018 present low energy density or limited
storage potential.
45
800 Weak power and gas grid integration
40 Compared with RE, traditional fossil
700 38.3
36.6 35 fuels are in the opposite position.
35 China’s foreign trade dependency on
600 30 natural gas has kept to a consistently
RE INSTALLED CAPACITY (GW) 400 20 25 PROPORTION IN TOTAL (%) LNG import volume remains the largest
high level of 45.3 per cent, and Chinese
500
in the world.
20
Therefore, a reliable and feasible
300
solution to improve RE accommodation
15
728
650
480
570
200
would be of great significance. Power to
10 and gas-electricity grid integration
gas (PtG) technology promises to be an
100
5 excellent potential solution. It not only
0 achieves large-scale and long-periodic
2015 2016 2017 2018 0 energy storage, but also provides a way
to convert electricity into gas and form
a closed loop together with the gas-to-
FIGURE 2 POWER TO GAS ROUTES power equipment.
RENEWABLE ENERGY PtG techniques
Technical features and trends of PtG
POWER GRID Many pathways exist for the
POWER-TO-GAS POWER-TO-GAS transformation of RE into gaseous or
(2-STEP) H20+CO2 H20+CO2 3-STEP) H20 liquid fuels. This paper will focus on
ELECTROCHEMICAL CO-ELECTROLYSIS ELECTROLYSIS power to methane (PtM) processes,
REDUCTION RWGS ALKALINE PEM SOEC which convert excess electricity into gas
SYNGAS (H2+CO) that can be injected into the national
CO2 H2 grid, allowing the connection of power
INDIRECT HYDROGENATION RWGS and gas networks.
CATALYTIC METHANATION Nowadays, the green path depicted
BIOLOGICAL METHANATION in Figure 2 is the most popular
process and includes two main steps:
electrolysis and methanation.
SNG & RNG Electrolysis is an endothermic

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