New model to deploy cheaper PV at coal power plants

An international group of scientists has estimated that China may deploy around 3.96 GW of PV at its 1,082 coal power plants if a flexible model for solar power generation is adopted.

The proposed model, which is mostly aimed at reducing the costs of the coal plants, is considered particularly suitable for countries with a high share of coal-fired power generation, such as China itself, India, and Poland. The new approach was outlined in the paper Using Existing Infrastructure to Realize Low-Cost and Flexible Photovoltaic Power Generation in Areas with High-Power Demand in China, published in iScience, by researchers from Sweden's Mälardalen University, China's Shandong University, the Shanghai Jiao Tong University, the Fudan University, and the East China University of Science and Technology.

The approach consists of deploying PV systems on the rooftops of a coal power plant's suitable buildings and the coal storage sheds. One of the main advantages of this method in terms of costs is that the PV arrays are not only connected to the plant grid infrastructure to inject solar power into the external network but also to the plant's internal grid, which makes it possible to distribute surplus PV electricity to auxiliaries, such as pumps and compressors, to avoid curtailment. The first of the two options is considered more profitable, but the second is advised when grid congestion issues arise.

Another advantage of the proposed model is that its developer must not pay land rent, rooftop rent or grid connection fees for the PV system and its costs may be reduced by up to 21%.

The academics presented a case study of a 3.84 MW PV plant deployed at a coal power plant in Xinjiang with an available area of 23,931 square meters. “The potential PV generation is estimated to be 5.16 GWh annually,” the group specified. “In comparison, the annual electricity demand of the plant is 162.80 GWh, according to the actual data provided by the case power plant.” The ratio of PV output to the local electricity demand is only 3.17%.

The researchers found that the PV system has an LCOE of CNY 0.27 ($0.0451)/kWh. “In contrast, the LCOEs of the distributed PV system, the centralized PV system, and the stand-alone PV system are CNY 0.31/kWh, CNY 0.34/kWh, and CNY 0.54/kWh, respectively,” the authors of the paper explained.

The ideal PV system to be developed with this approach should have a size between 2 MW and 5 MW. Jiangsu was found to be the Chinese province with the highest potential PV capacity at 321 MW, while Tibet showed the lowest potential with only 3 MW. “In addition to the many technical advantages, PV systems also have excellent economic performance,” the research group concluded. “Their good profit potential and short payback periods are significant to coal-fired power plants, as many of them have been suffering from financial loss.”

In another research published in July, researchers from the Mälardalen University came up with a new rotating PV array concept for vertical deployment on the cooling towers of thermal power plants. The proposed model is described as an “adaptive celestial motion-based solar PV system” that can rotate around its own axis and revolve around the cooling tower to follow the sun. The scientists selected three thermal power plants with cooling towers in China for a case study.

“In China, there are more than 2,000 cooling towers of thermal power plants – thus, we predict that the cooling tower-based PVs has huge potential for bringing considerable economic and energy benefits in the future,” the research group said.