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November 09, 2021   |   Diesel Technology Forum

Policy Insider

The Future is Eclectic

Roles for hybrids and hydrogen in internal combustion engines exist today and into the future. Low carbon, renewable and e-fuels can deliver meaningful carbon reductions from large numbers of existing vehicles.

No that is not a typo. The statement that the future is eclectic embodies practical sensibilities of future propulsion systems and the fuels and technologies that will get us there. It’s not all electric, all gasoline, all diesel or all hydrogen; there is not a single best fuel. Both new and existing fuels have their pluses and minuses and places in the future. In their book Racing Toward Zero, scientists Kelly Senecal and Felix Leach peel back the many layers of the untold story of driving green. Is there a future for the internal combustion engine? Yes of course. Are battery electric vehicles and fuel cells the big winner for the future? Perhaps in some ways, less so in others. Roles for hybrids and hydrogen in internal combustion engines exist today and into the future. Low carbon, renewable and e-fuels can deliver meaningful carbon reductions from a large number of existing vehicles. 

The authors’ suggestions and recommendations are prescient ones now more than ever. They argue that (1) we must rethink emissions and move beyond the tailpipe, that zero emissions vehicles are not truly zero emissions; (2) there is no silver bullet and we must take an honest look at the pros and cons of each technology for each location and application, and use a mix of technologies going forward including battery electric vehicles, hydrogen, hybrids and internal combustion engine vehicles; (3) legislation and regulations should follow a technology neutral approach, with governments setting targets and engineers solving problems; and (4) to be wary of unintended consequences, and keep in mind consumer behavior.    

This week the Global Climate Conference of the Parties (COP26) continues in Glasgow, Scotland – attendees there are undertaking a form of “Racing Toward Zero” in their own right, seeking commitments and pledges for reducing greenhouse gas emissions with the hard work of details and follow through yet to come. With personal transportation and mobility now heavily invested in electrification, at some level this is a gamble. As battery electric vehicles gain market acceptance, the pressure to actually deliver truly clean and renewable electric power on a widespread basis is absolutely essential. And if battery electric vehicles are not right for everyone everywhere now, other options – hybrids, diesels, or advanced gasoline – all using much cleaner and renewable fuels are proven and available ways to make meaningful carbon reductions too. Why not embrace those as well?

The diversity of solutions available with new and existing internal combustion engines continues to grow. Refueling existing populations of vehicles with renewable biobased fuels or new e-fuels holds new promise. Hydrogen as a fuel for internal combustion engines is also gaining ground from passenger vehicle applications to heavier-duty truck transportation and even industrial power and equipment. The future is truly eclectic!


The book Racing Toward Zero is a thoughtful and easy read through the complex world of vehicle propulsion systems, fuels, engines and more. It’s a good mix of history, engineering and economics of engines and fuels and mobility, how we got to where we are today and how that influences future choices. Heavily referenced and sourced, for any policymakers or journalists, the book is a valuable resource, with the right mix of technical explanations, visualizations and policy context. It is available (digital or hardcopy) through the Society of Automotive Engineers bookstore (ISBN 978-1-4686-0146-6) and other booksellers.


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