This study is aimed to systematically estimate marginal land resources with different grades (total area; land with certain eco-environmental-economic feasibility; centralized reserve land) in China, and evaluate potential energy production from microalgae on marginal lands in the long-, mid- and near-term, based on a model. The annual potential energy production from algae in total marginal land of China (APEMC) was estimated to 4.19 billion standard coal equivalent (tce), far more than total annual energy consumption equivalent in China (TECCE) in 2007. For microalgae with 35% lipid content, the APEMC in the mid-term would be 37.6-65.8% of the TECCE in 2007. The corresponding annual CO2 emission mitigation by replacement of fossil fuels by algal bioenergy would be 4.27-7.44 billion t. Although Southwest China provides the highest potential algae production in the long-term, Northwest China provides the highest value in the near-term. (C) 2011 Elsevier Ltd. All rights reserved.