To the Editors-Sanchez et al. 1 provide a viable technological roadmap for using biomass energy with carbon capture and storage (BECCS) in the western United States 1. However, they oversimplify emissions accounting by assuming a zero or negative carbon emissions factor. Accounting for total lifecycle emissions is perhaps the greatest challenge in deploying biomass (in solid, gaseous, or liquid form) to reduce carbon emissions 2,3. When utilized to generate electricity, emissions sinks and sources for biomass occur in two different sectors. As plants grow, they take up CO 2 and store it. When combusted, the stored CO 2 is

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ABSTRACT:We present an integrated model, SWITCHChina, of the Chinese power sector with which to analyze the economic and technological implications of a medium to longterm decarbonization scenario while accounting for very-shortterm renewable variability. On the basis of the model and assumptions used, we find that the announced 2030 carbon peak can be achieved with a carbon price of ∼$40/tCO 2 . Current trends in renewable energy price reductions alone are insufficient to replace coal; however, an 80% carbon emission reduction by 2050 is achievable in the Intergovernmental Panel on Climate Change Target Scenario with an optimal electricity mix in 2050 including nuclear (14%), wind (23%), solar (27%), hydro (6%), gas (1%), coal (3%), and carbon capture and sequestration coal energy (26%). The co-benefits of carbon-price strategy would offset 22% to 42% of the increased electricity costs if the true cost of coal and the social cost of carbon are incorporated. In such a scenario, aggressive attention to research and both technological and financial innovation mechanisms are crucial to enabling the transition at a reasonable cost, along with strong carbon policies.

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