Estimating Emissions: Progress is being made on the path to net zero

Published On
Jun 15, 2021

Emission-reduction targets are pegged to 2005 levels. So President Joe Biden’s plan to cut total U.S. greenhouse gas emissions by 50%–52% by 2030 is based on percentages compared to 2005 emissions levels. A report from the Lawrence Berkeley National Laboratory in Berkeley, Calif., looks at where federal energy officials in 2005 thought we would be by now and how much they thought renewable-energy initiatives would add to electricity bills. Turns out, they notably underestimated progress and overestimated their cost.

“Halfway to Zero: Progress Towards a Carbon-Free Power Sector” focuses on emissions related to electricity generation. It compares 2020 emissions and costs to projections for the same year from the U.S. Energy Information Administration’s (EIA) 2005 Annual Energy Outlook. Biden has set the goal of a carbon-free power sector by 2035, so the report’s authors wanted to understand how much progress we have already made toward reaching that target. When looking at where the EIA thought we would be in 2020, we are already halfway toward that goal, and we haven’t paid more to get here, at least in terms of electricity costs.

In 2005, EIA’s business-as-usual projections, which made no assumptions of possible incentives or mandates, anticipated the power sector’s 2020 carbon dioxide emissions would reach 3,008 million metric tons (MMT). Actual emissions, however, were only 1,450 MMT, roughly 50% lower. Of course, as the report’s authors note, 2020 figures for just about any performance metric come with a big asterisk given the COVID-19 pandemic’s impacts. Looking at 2019 emissions instead, it still comes up with a 46% reduction versus the 2005 projections.

One big difference between the 2005 projections and actual 2020 performance lies in the EIA’s assumptions regarding electricity demand, which was 24% lower in 2020 than forecasters anticipated. In fact, last year’s demand figures were almost the same as 2005’s. Lead author, Ryan Wiser, senior scientist at Berkeley Lab, attributes this to big improvements in energy efficiency, thanks to technological advancements and efficiency-focused government policies.

Wind and solar energy also play much bigger roles today, delivering 13 times more generation than the 2005 projections anticipated. Again, federal and state policies, including investment tax credits, helped drive uptake of these renewable resources, along with the falling prices that greater demand helped foster. To illustrate just how quickly the cost of renewables has fallen, EIA’s projected capital cost for utility-scale solar in 2025 was more than twice as high as that for actual plants built in 2019.

The rapid displacement of coal generation by inexpensive shale gas, along with renewables, also helped push emissions lower than expected. Looking only at stack emissions and not natural gas emissions related to methane leaks in gas extraction and transmission, the switch from coal to gas could account for 48% of total emissions reductions since 2005.

Lower-than-expected emissions also led to significant health benefits versus 2005 projections. Reduced sulfur and nitrogen emissions meant premature deaths from power-sector air pollution were only 8% of what was anticipated. And 2020 health costs related to that pollution were 90% lower than projected. Additionally, the power sector is now providing 29% higher employment than what might have been the case under the 2005 business-as-usual scenario. So even with coal-related job losses, natural gas and renewable energy jobs now total more than 920,000.

Of course, a more important metric for measuring actual progress toward zero emissions is the difference between actual 2005 and 2020 emissions. That comparison shows a 40% reduction over the last 15 years. Using 2019 figures, which could help address the impact the pandemic has had on electricity use, the reduction is 33%, meaning the U.S. power sector is one-third of the way to a zero-emissions future.

Wiser and his co-authors note that power-sector performance needs to continue to outperform expectations to reach zero emissions by 2035. EIA completed a new business-as-usual projection for the next 15 years that shows emissions dropping only to 1,180 MMT by 2035. The authors point to other research indicating that eliminating emissions would require adding about 70 gigawatts (GW) per year of wind and solar capacity, roughly double the 34 GW added in 2020 (which, they add, was double the 17 GW added annually, on average, between 2017 and 2019). About 660 GW of such projects were seeking transmission interconnection at the end of 2020, and developers of 570 GW of that total have proposed coming online by the end of 2025. Another 200 GW of storage capacity is also in the project approval/interconnection queue.

Of course, not all of these projects will make it through that queue. But, the authors add, hopefully, the data does indicate the level of interest among investors and the strong track record the solar, wind and storage industries demonstrated in scaling up far more quickly than expected.

About the Author

Chuck Ross

Freelance Writer

Chuck Ross has covered building and energy technologies and electric-utility business issues for a range of industry publications and websites for more than 25 years. Contact him at

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