I recently found myself a Twitter debate about transportation and greenhouse gas emissions, which started from the question of whether or not solar could replace oil. This is really a question about transportation, which I don’t normally write about, as the focus of my work in the Energy Transition has been the electricity and heating sectors.
In the past I’ve been dismissive of the potential for electric vehicles (EVs) as a meaningful solution for reducing greenhouse gas emissions. I was partially wrong – and I find that my past statements need an update.
EVs can replace petroleum use for the majority of our transportation needs. This will reduce GHG if combined with a move to low- to zero-carbon electricity (I prefer that this low- to zero-carbon electricity be renewable, for many reasons). Key to this is the distinct technical advantage of EVs that they are three times as efficient as gasoline vehicles. In transportation, as in electricity, the burning of fuel results in more wasted than useful energy, as thermal generation for anything but heat or combined heat and power is inherently wasteful.
However, it is not that simple. First, when we talk about transportation, we’re not just talking about cars and light-duty trucks – though they do make up over half the GHG emissions from transportation in the United States. We still don’t have cost-effective, viable electric solutions for not only aircraft, but also medium- and heavy-duty trucks, or shipping. These together make up around 30% of transportation-related GHG in the United States – or about 8% of our total GHG.
My readers will forgive that this is not one of my areas of expertise, but from the cursory reading that I’ve done, it appears that we’ve developed viable electric heavy equipment and we’re pretty close to making it cost-effective. Medium-to-heavy trucks (20% of U.S. transportation GHG) are another matter. We’re not close at all on aviation (7% of U.S. transportation GHG).
This is in contrast to the renewable energy solutions that exist for electricity and heating sectors, which are already mature and only need to be deployed.
In the case of heavy trucks, one solution would be to move more transport back to rail, which is more efficient. And this gets to a larger point. Is a focus on electrification of transportation as a means to address GHG practical at this time? Is it our best option for this sector?
My first concern is the lack of a substantial recycling ecosystem. The poor economics for recycling lithium-ion batteries at the end of their lifetimes means that we are likely to end up with a lot of these in landfills and incinerators. The good news is that they are much less toxic than other battery chemicals.
A larger concern is that in terms of the EV infrastructure that we have built, it is not “clean” at present. In China it is allowing cars that are powered not by petroleum but mostly by coal. In the United States, these are mostly coal, gas, and nuke-fired cars (unless you live in Washington State, where you will have hydro-powered cars). So deploying EVs before the Energy Transition is mature in electricity is not necessarily going to immediately reduce greenhouse gases – because the inefficient, dirty thermal generation will be in a power plant, not in the gas tank. And the more we electrify transport, the more electricity we need, meaning that we will need to deploy larger volumes of renewables to reduce GHG in that sector.
We should consider these problems particularly as we already have a solution that will greatly reduce GHG emissions in transportation in urban areas: more and better mass transit. Now don’t get me wrong. Mass transit doesn’t work as well in rural areas, and here electrification may be a more viable option. But half of the world’s population lives in cities. This figure is 75% in the developed world – which is also where most of the GHG are coming from.
The benefit of moving to mass transit is not only GHG reduction. It is also better cities, healthier people and fewer deaths on the highway. In the United States, automobiles are in the top three leading causes of death between the ages of 5 and 34 – and are the leading cause of death between the ages of 10 and 24, responsible for a total of over 30,000 deaths each year. Prioritizing automobiles has led to atrocious land use planning in this nation, and gross cities in the Sunbelt. Why would we re-create this extremely wasteful and dangerous form of transportation in electric form, when there are better options?
From working on mass transit issues in Boston, I can tell you why. We would do it because we fail to advance mass transit in a meaningful way, as a result of broken political systems. We are caught in a cycle in many U.S. cities of low-quality public transit that people don’t use because they can’t rely on it and because they don’t use it they don’t want to pay for it.
The only solution to this is massive investment in systems that work, that then creates constituencies of commuters who are invested in these systems. This is politically difficult for the above reasons. The good news is that younger people want to live in walkable cities with good transit. And since mass transit brings up real estate values, there are other forces who are vested in expanding it – even if progress is painfully slow at present.
In the end, I believe that we will move away from GHG in transportation through a combination of electric vehicles and better mass transit in cities even in cities – in part because we will still need trucks and still want taxis. But the more and the earlier we move to mass transit, the fewer electric cars and charging stations we have to deploy. It’s a win-win.
Either way, a systemic transition in transportation is simply less actionable and strategic than in electricity generation and heating at this time. And when we do address transportation we need to emphasize mass transit as part of the Energy Transition, just as energy efficiency is an important part of the transition in the electricity sector. It will not be deployed in isolation or as a cure-all. But where it can solve our problems, it is simply the best solution.