President Biden has stepped up and made a commitment for the US to reduce carbon emissions 50% by 2030 versus 2005 levels. 50 by 30! We need to do it and we can do it! But what is the best path?
There is strong underlying logic behind this new commitment. The math is simple but daunting. The experts working through the Intergovernmental Panel on Climate Change (IPCC) have conducted “assessment reports” every 5 years or so, and the conclusion continues to be that we must keep average temperature rise below 2° C, and preferably below 1.5° C, to avoid the most devastating effects of climate change. Either of those goals restrict how much CO2 we can cumulatively add into the atmosphere, establishing a basic “carbon budget.” The math is illustrated most easily by understanding that if our emissions were to stay constant from 2018, the carbon budget associated with the 1.5° C goal would be completely used up by 2030. On the other hand, if we can cut our global emissions in half by 2030 and completely by 2050, we will come close to staying within 1.5° C. Emission cuts to this degree would be difficult, so many are suggesting that we need to cut as much as possible by 2050 and then actually take carbon out of the atmosphere in the years after.
Our cumulative carbon emissions are already so close to the carbon emissions budget that we need to take dramatic action now. Indeed, the carbon budget is global, and I believe the US should be a leader, with even faster reductions in emissions. I think a reasonable pathway is a 50% cut by 2030, 75% by 2040, and 100% by 2050. In two earlier articles here and here, I created a thought experiment that assumed 100% reductions by 2050, basically a very simplified spreadsheet analysis similar to Mark Z. Jacobson’s work at Stanford best illustrated in his new book 100% Clean Renewable Energy and Storage for Everything. Using the same simple framework below, I illustrate how we can get to 50% reductions by 2030. We can do it, but it’s all hands on deck!
Where We Are Now
First, we need to understand our carbon emissions, assuming 2019 as a base year for the analysis, broken out into direct fossil fuel and electric consumption for each major economic sector.
Study Table 1 for a moment. The emissions for each sector are broken down by electricity production and direct fossil fuel, with electricity production totaling 32% and direct fossil fuel use 68%. If we completely decarbonize the electric grid, and do nothing else, we will only reduce carbon emissions by 32%. Obviously, we need to do more than just green the grid to achieve a 50% reduction by 2030. By consolidating the electric column in Table 1 to just show the electric sector as a whole and incorporating the energy consumption (in equivalent terawatt-hours/TWh) for each sector for 2019 from EIA data, Table 2 shows the carbon intensity of each sector in 2019.
It’s no wonder that many are saying the first goal is to green the electric system, because the electric system has the highest emissions per TWh. The next priority is transportation, with the second highest sector emissions per unit of energy. As readers of CleanTechnica are well aware, we are making great technical progress in electric cars and trucks. We will start from this table and incorporate more assumptions to get a vision of the evolution of the energy system that will get us to 50 by 30.
A Recipe for 50 by 30
The 2050 goal combines three key ingredients to get us there:
- Major investments in energy efficiency
- Greening the electric grid
- Electrifying all end uses.
Getting to 50% requires us to combine these ingredients to get there in just 10 years.
The good news is that the US has already made progress. Emissions in 2005 were 5789 megatons (million metric tons, MT), whereas in 2019 they were 5161. By 2019, we had already achieved a 10.8% reduction. And we can expect those gains to continue as our economy becomes more efficient in the “business-as-usual scenario” from now to 2030. But gains in efficiency will be offset by increases in population and economic growth. I constructed a simple forecast of business-as-usual (BAU) energy demand by extending ongoing trends for population and energy use per capita. That analysis shows that the carbon emissions increase due to growth more than offset efficiency gains and that our 2030 emissions will be at 10.7% of 2005 levels. And we will have exhausted our share of the carbon budget. So that 10.7% is progress, but we’ve still a long way to 50%!
Ingredient: Energy Efficiency
The first ingredient of our recipe is to engage in efficiency efforts that go beyond just the business-as-usual (BAU) efficiency gains we might otherwise expect. Government and non-profit programs targeted at this effort will make a huge difference and will be helpful for low-income households. This effort needs to speed up the ongoing efficiency gains and we can only take credit for gains above and beyond what are in the business-as-usual case. However, I know from personal experience that many more gains in efficiency are possible in residential and commercial buildings, and much new spending in those areas has already been proposed by Biden. For our thought experiment, I assume that we can wring an additional 10% of efficiency gains out of the direct use of fossil fuels for the residential and commercial sectors by 2030, focusing mainly on insulation and weather sealing. We also assume that we can achieve 5% additional efficiency in the use of electricity. By just doing these efficiency programs, we will reduce overall emissions from the BAU of 10.7% to a reduction of 13.1%. Still not there.
Ingredient: Greening the Grid
Biden has proposed a net zero grid for 2035, and one might think that the 50 × 30 goal would reflect a speed up of that ambition to 2030. But reflecting on the challenge of intermittency as I reviewed in an earlier article here, it seems logical to not completely green the grid so fast. We can green the grid to 90% clean energy at far less cost and achieve most of the carbon reduction benefits by continuing to rely on the most efficient natural gas units to support the greatly expanded fleet of solar and wind power that we will need. Building out the grid in this way will also require far less new transmission and far fewer batteries. This conclusion is reached in 2035 The Report: Plummeting Solar, Wind and Battery Costs Can Accelerate Our Clean Energy Future. And it just makes sense. The cost of that last 10% of greening the grid could better be spent on enhanced electrification and energy efficiency programs. The investment in the extra batteries we would need to green the grid to 100% would better be used to electrify transportation. This small remaining use of fossil fuels will use the most efficient production of electricity from fossil fuels available — combined cycle natural gas combustion turbines, which will primarily be used to meet demand in months when solar and wind do not meet the full need for electricity, especially since electric demand will also be growing due to the electrification going on at the same time.
With this program, we will have eliminated coal. Jacobson points out that the extraction and refining of fossil fuels is a huge use of energy itself, and that by eliminating fossil fuels we will net reduce overall energy use by 12%. I need to dig deeper into these numbers, but in the case of the electric sector, for now I will make the conservative assumption that the energy saved by eliminating coal mining is balanced by the energy consumed in building out the renewable energy fleet.
In summary, by greening the grid 90%, we reduce our carbon emissions from the 13.1% above to 38.6%.
Last Ingredient: Electrification
The finals step is to make assumptions about a target for electrification for each of the main sectors of fossil fuel use — residential, commercial, industrial, and transportation — to get us from 38.6% to 50% reduction in carbon emissions. I wrote earlier articles here and here that summarize the impact of electrification. The key to the carbon impacts of electrification is to quantify the efficiency gains of electricity, such as the four-to-one gain for air source heat pumps or electric vehicles or the five-to-one gain of geothermal heat pumps. These gains are mostly in transportation along with residential and commercial. They are much less in the industrial sector. We will assume the following electrification efficiency factors to understand electrification’s impact on direct demand for fossil fuels by sector:
- Residential, Commercial, and Transportation: 25% (75% efficiency gain)
- Industrial: 80% (20% efficiency gain)
We must make one additional assumption before we can complete the electrification analysis. Jacobson references a 12% reduction of overall energy use because we currently use a lot of energy to mine, transport, and refine fossil fuels. We discussed that in the case of greening the grid and coal, above, but we must also consider the impact of this on oil and natural gas and consider what the impact would be of a decrease in transportation fuel refining and transport. We will assume 25% reduction in transportation energy demand below and with that assume an additional reduction of 1% of transportation demand and 4% of industrial demand by 2030 to account for less need to mine, transport, and refine transportation fuel.
Utilizing these factors, we can make modest assumptions about electrification to get us to the 50% reduction goal.
Table 3: 2030 Energy Use and CO2 Emissions After Electrification
|Business as Usual Energy||Business as Usual CO2||Assumed Electrification Percent||Energy After 90% Grid & Electrification||CO2 After 90% Grid & Electrification|
|Residential & Commercial||2,973||514||12%||2,616||452|
Or comparing it to baseline 2019, we have:
This possible pathway to 50% by 2030 shows a 90% fossil fuel free grid and electrification of 25% in transportation, 12% in residential and commercial buildings, and 7% in the industrial sector. These are significant electrification goals, but they are achievable. Moving all new residences and commercial buildings to electricity for heating plus beginning to convert existing buildings should accomplish a great deal toward that goal. Certainly, industry could contribute just 7% over the next 10 years, probably more. The big challenge will be getting to 25% in transportation, but momentum is building toward meeting that challenge.
In the case of EVs, we need to move quickly to electrify all new light-duty vehicles (cars, SUVs, and small trucks) by 2030 to achieve an overall reduction of 25% in transportation energy. By my calculation, by 2030 we would need to have increased EVs to an almost 100% market share for new cars to have a 30% energy share for all cars. Putting it another way, almost all new cars would need to be electric by then for electric cars to be 1/3 of the total cars on the road, assuming an average life of 15 years for cars on the road. Other transportation energy uses — airplanes, boats, or long-haul trucks — will likely be electrified more slowly than light duty vehicles, so we probably do need to get to be electrified at above 30% for light duty to be electrified at 25% of transportation overall. Nevertheless, I think this degree of change is doable and would put us on the right track.
A recent 2021 study points the way on electrifying US transportation and confirms my general conclusions. Earlier I discussed 2035 The Report (2020) in the context of their analysis of a 90% fossil fuel–free grid. The 2021 installment of this study, titled 2035 The Report: Transportation, builds on this earlier excellent work with a detailed analysis of the transportation changes that would be consistent with halving carbon emissions overall by 2030. Their focus is on a scenario that builds to 100% electric penetration of light duty vehicles (cars, SUVs, and small trucks) sold by 2030, followed by 100% of medium-duty and heavy-duty vehicle sales all being electric by 2035. Their rapid ramp up of electric vehicle penetrations is slightly more aggressive than our 25% total electrification assumptions in Table 3. Such an advance is not limited by technical or economic feasibility, the study concludes, but rather by up-front vehicle cost and charging infrastructure. The study also builds a strong case that electric car total cost of ownership will soon be lower than gas or diesel cars and trucks, with the upfront cost becoming lower in the late 2020s or 2030s. The study also outlines the numerous climate, employment, and health benefits that will come from making this transition. It is well worth a read.
A Much Larger Electric Sector
With all these changes, we must prepare for the electric sector to be much larger as well, growing from 4,046 TWh in the business-as-usual case to 5,007 TWh to get us to a 50% CO2 reduction by 2030. Even though we are continuing to use some fossil fuels, we will still need to account for intermittency and seasonal imbalances. Much of this will require new storage resources on the grid, but it will also benefit from overbuilding the wind and solar resource, which my calculations show will require another 5% of solar and wind production which we won’t actually be able to use. This growth in the electric sector, plus the overbuilding, represents 2% per year growth in electric production from 2019 to 2030. An electric sector growing at 2% a year is an increase from the almost zero growth in electricity production over the last 20 years, but it is much less than the growth rates before 2000. The gigawatts (GW) of solar and wind we need to make this forecast are in the range of 125 GW per year from 2021 through 2030, which is over 5 times the amount added in 2020.
A 2040 Scenario
It is helpful to think about where we go from 2030 to 2040. After cutting emissions in half by 2030, we need to cut them in half again by 2040. The transportation transition will be moving apace, with 10 years of just producing electric cars, SUVs, and light trucks and 5 years of only producing medium-duty and heavy-duty trucks. We will also have stepped up our research on electrification of airplanes, heavy industry, and hard-to-decarbonize cement, with many pilot projects and initial deployments underway. We will need to be rapidly decarbonizing building and transforming industry as well. We will have made continued investments in overall energy efficiency. Our grid could be 95% green at that point. Table 4 summarizes the 2040 scenario.
During the 2030s, electricity use will be growing about 3.5% per year, with all new growth supplied by wind and solar. Our overbuilding of wind and solar will have increased to 12% and we will need to continue to build about 130 GW of wind and solar every year, only a small bit more than what we need to build in 2019–2030.
By the 2040s, the end of our decarbonization of energy will be in sight. At the same time, research into our hard-to-decarbonize sectors will be paying off. If we depend on utilizing overbuilding as our main solution to intermittency, the wind and solar buildout will continue at 130 GW a year or so. If other technologies to solve intermittency become viable, then the growth rate of wind and solar may slow. We don’t need a table to summarize the result — 100% clean grid and all direct fossil fuel end uses converted to electricity. While life will be improving as soon as we start the transition, the full vision of the benefits of the transition, as I summarized in another earlier article, will be upon us.
Carbon Pricing Will Guide Us
I present here one scenario of transition, but what is the best actual plan? I don’t really know. What I hope will happen is that we get to the root of the problem and price carbon, because economy-wide carbon pricing will help us find the best path forward. It will encourage conservation, grid transformation, and electrifying everything. Carbon pricing will help our economy weigh the extra benefit of going from a 90% clean grid to one that is 91% green compared to the benefit of additional electrification or additional conservation. The cheapest form of carbon reduction will continue to win. By embedding the cost of carbon in our decisions throughout the economy, we won’t have to make all the decisions as central planners — the individual planners in enterprises throughout the economy can make those decisions for us. And there are already carbon pricing proposals out there.
I’m a longstanding supporter of Citizens Climate Lobby and was heartened to see the reintroduction of the Energy Innovation Act in the House, and I like the carbon fee plan introduced by Dick Durbin in the Senate. Both of them put a fee on carbon and return all (or most in the case of Durbin) of the revenue to legal residents of the US.
Based on the ambition of the 50 by 30 goal, I think the Energy Innovation Act probably needs to have a higher carbon fee up front, perhaps starting at the $40 per ton rate in Durbin’s proposal, and having more aggressive targets that trigger even higher fees if the targets are not met.
What To Do Now?
It helps to keep the vision in mind, but all we can do is what we can do now. That means focusing on the 2030 goal of 50% reduction. As individuals, we must become aware and advocate for change, and we must take actions in terms of our personal, business and community energy use. We can all use less energy at home or work, commit to our next new car being electric, advocate building out the electric charging infrastructure, and seek incentives to speed up the transition, such as carbon pricing or EV tax credits. And we can drive less, carpool, bike, walk, and use most efficient modes of transportation when we have the choice. We can make personal investments in efficiency and electrification. We can install solar on our rooftops. And we can work in our businesses, churches, communities, and states to do these things faster and bigger. And, obviously, we can advocate for a price on carbon at a national level combined with the infrastructure investments and research funding we will also need.
And We Need A Climate Warrior Army
I hope you can see we are living in the crucial decade. With our carbon budget depleting rapidly, I believe that what we do in the 2020’s will be determinative. It is time to take radical change to begin the process of a complete change out of the energy economy. In addition to enlightened leadership, it will take an army of ordinary citizens like you and me each doing everything that we can, from making our desire for government change to making decisions in our own personal lives to lowering our carbon footprints. Climate warriors, step up!
- Levin, Kelly (10-7-2018). According to New IPCC Report, the World Is on Track to Exceed its “Carbon Budget” in 12 Years, https://www.wri.org/blog/2018/10/according-new-ipcc-report-world-track-exceed-its-carbon-budget-12-years (accessed March 8, 2021)
- Jacobson, Mark Z. (2021) 100% Clean, Renewable Energy and Storage for Everything, Cambridge University Press
- Amol Phadke, Umed Paliwal, Nikit Abhyankar, Taylor McNair, Ben Paulos, David Wooley, Ric O’Connell, Goldman School of Public Policy, University of California, 2035 The Report: Plummeting Solar, Wind and Battery Costs Can Accelerate Our Clean Energy Future (June 2020), https://www.2035report.com/, (accessed 3/11/2021)
- Amol Phadke, Nikit Abhyankar, Jessica Kersey, Taylor McNair, Umed Paliwal, David Wooley, Ric O’Connell, Olivia Ashmoore, Robbie Orvis, Michael O’Boyle, Utkarsha Agwan, Priyanka Mohanty, Priya Sreedharan, Deepak Rajagopal, Goldman School of Public Policy, University of California, 2035 The Report, Transportation: Plummeting Solar, Wind and Battery Costs Can Accelerate Our Clean Energy Future” (April 2021), https://www.2035report.com/, (accessed 4/16/2021)
About the Author: Brad Rouse is a self-styled “Climate Warrior” living in Asheville, NC. He is deeply involved in local efforts around the energy transition. He lobbies Congress for carbon fee and dividend as a volunteer for Citizens Climate Lobby. In 2016 Brad started a non-profit — Energy Savers Network — that mobilizes volunteers to help low-income people save energy, and he has participated in over 200 on-site weatherization projects himself. He has rooftop solar and his family cars are a Tesla Model Y and a Toyota Prius Plug-in Hybrid with 150,000 miles and still about 9 miles of EV only range. Brad worked for 20 years developing long range planning studies and computer software for utility companies. He has been studying energy economics for over forty years and holds a BA in economics from Yale University, where he learned about pricing pollution in freshman economics. He received his MBA from the University of North Carolina at Chapel Hill and he practiced for over 10 years as a Certified Financial Planner. Brad is writing a forthcoming book on his experiences as a Climate Warrior and his vision of our energy future and how to make it happen. You can follow Brad on Facebook at https://www.facebook.com/brad.rouse.5 or Twitter at https://twitter.com/BradRouse74.
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