Three Innovative Ways to Power Clean Transportation with Wastes

December 8, 2015 | 10:00 am
David Babson
Former contributor

Last month I attended the National Renewable Energy Laboratory’s (NREL) Industry Growth Forum in Denver, CO to see which renewable energy technologies were getting the attention of clean-tech investors. Although I was most interested to learn about new renewable transportation fuel technologies, the most immediately promising transportation sector technology dealt not with generating renewable fuels, but rather minimizing transportation fuel use by capturing and reusing kinetic energy during vehicle braking.

Hybrid vehicle technologies, like that of Lightning Hybrid’s hydraulic hybrid technology which won recognition at the NREL summit, recover energy that would otherwise be wasted. But the idea of using and not wasting available energy extends far beyond hybrid vehicles to the fuels used to power them. Here, I will highlight three important low carbon renewable fuel pathways that could take advantage of underutilized wastes – pathways that I believe will improve the sustainability of renewable fuels and challenge the misperceptions we have about them. And, in the coming weeks and months I plan to prepare additional posts on each of these pathways—so stay tuned.

Our wealth of wastes is a wealth of resources

Addressing the monumental challenges posed by climate change will demand innovation and cooperation to rapidly transition to a highly carbon constrained economy – an economy in which our traditional carbon-rich fossil fuel sources are severely limited by choice and design (there needs to be lots of unused fossil fuel left in the ground).

Waste Biomethane Potential_Map_new

Vast waste resources, including solid waste and wastewater, are available for energy recovery. Municipal wastes are distributed throughout the country and are proportional to local population density and energy demands. Figure: UCS 2015

Achieving greater sustainability will require the concept of “waste” to evolve and advanced technologies to be developed that allow value and utility to be gleaned from such “wastes”. The casual link between waste, reuse and feedstock will need to become the status-quo; our waste and wastewater loops will need to be closed to establish more fully integrated and sustainable fuel systems.

Moving beyond first generation biofuels, such as corn ethanol and soybean biodiesel, to second generation biofuels produced from agricultural residues, municipal waste and wastewater, and  third generation renewable (bio)fuels produced from carbon captured directly from industrial waste gases or the atmosphere will substantially improve fuel sustainability and change our perception of renewable fuels at the same time. Wastes and residues are abundant and underutilized resources. And, not too many next generation fuel technologies have been deployed at scale. However, by investing in the right technologies, establishing the correct infrastructure, and implementing good policies, we can substantially increase sustainable production of low carbon renewable fuel.

The pathways:

1.) Electricity as a biofuel


As more EVs and plug-in hybrids come to market, a cleaner electricity grid – boosted by low-carbon, waste derived fuel – will mean a cleaner transportation sector as well. Photo source

In July of 2014, the EPA determined that electricity generated from waste derived biogas used in the transportation sector could generate biofuel credits under the federal Renewable Fuel Standard (RFS) program.

This could be a really big deal. I discuss this pathway first because while burning biogas generated by decomposing wastes is not a new or groundbreaking way to produce electricity, leveraging federal policy to add value to low carbon waste derived electricity is rather innovative. In fact, when well-designed policies lead the market to value clean fuels more highly than dirty fuels, the potential of these technologies can take off. Valuable clean fuel credits for electricity will help catalyze the transition away from petroleum fuels and internal combustion engines to renewable fuels and more efficient electric vehicles.

And, the potential is huge! A recent UCS analysis found that as much as ten and a half million metric tons of biomethane could be generated from U.S. municipal waste sources each year. This waste derived biomethane would be sufficient to power nearly 14 million electric cars; displacing enough petroleum for nearly 43 million gasoline powered cars, and allaying unwarranted fears that we cannot meet transportation sector electricity demands cleanly.

But how we view these resources and how the incentives are structured by clean fuel standard regulations will determine whether this concept remains of marginal importance or whether it drives sizeable investments into both electric vehicle adoption and waste derived electricity production.

2.) Refining biointermediates from cellulosic and lignocellulosic wastes and residues


Pyrolysis oils (just one type of many potential biointermediates), generated from biomass wastes or residues can possess many of the same qualities as petroleum oils, and in some cases could be refined or co-processed into finished fuels using existing refining capacity. Photo: Flickr

Biofuels made using thermochemical processes have great potential. One major benefit is that they can take advantage of a vast knowledge base developed by chemical engineers working in the oil industry over the last century. Our traditional petroleum based fuel system is complex, and its overall supply chain is compartmentalized. Oil feedstocks from all over the world are aggregated and refined to produce a broad swath of fuels that are then distributed to consumers. Oil extraction, oil refining, and fuel distribution are distinct parts of the supply chain that can be optimized independently. And, these same configurations could be projected onto biofuel systems to allow greater overall efficiency. There is no reason to establish single use biofuel systems, new infrastructure, and unique supply chains for biofuels, when existing infrastructure could be leveraged to produce them.

Producing consistent intermediate bio-feedstocks (biointermediates), such as pyrolysis oils or synthesis gases that can be processed using currently available refining capacity or larger unique processes taking-in biointermediate feedstock from several sources and taking advantage of economies of scale could provide greater fuel volumes with fewer lifecycle carbon emissions. Such configurations would offer greater overall efficiency by allowing different portions of the biofuel supply chain to be independently optimized while allowing for innumerable combinations of waste and residual biomass. When fitted together with appropriate conversion technology, they would provide the most efficient use of available resources and infrastructure.

A promising signal for such configurations was recently sent by EPA when it acknowledged the importance of biointermediate pathways and resolved to figure out how to incorporate them into the RFS program. This is good because engineering biofuel systems that can make use of existing fuel production capacity or that can take advantage of greater economies of scale makes sense, and it is an important pathway for producing greater volumes of low carbon advanced and cellulosic biofuels from available biomass wastes and residues.

3.) Carbon capture and utilization of industrial emissions

Waste gases and flue gases generated by industrial emitters and power plants could be captured and used to generate renewable fuels. These technologies, which would make use of engineered microorganisms that capture and use carbon from waste gases, will be made possible by advances in biotechnology, and will allow the environmental footprint of biofuel production to be substantially reduced compared to traditional terrestrial crops.


New technologies are being developed to allow industrial emissions to be captured and used as inputs for third-generation renewable fuel generation. Photo: Flickr

Breakthroughs in biotechnology and engineering will push these processes beyond “algae” based systems, and some carbon capturing fuel processes may be engineered to avoid the need for photosynthesis all together. Photosynthesis typically serves as the mechanism to capture carbon and power its conversion into biomass, but it can be somewhat inefficient and it requires lots of sun exposure. Powering biomass or organic intermediate generation using electricity could allow third-generation biofuel processes to be deployed in more diverse environments, to require less land, and to demand little or no sunlight. Moreover, such processes would become more sustainable as the power grid becomes cleaner, allowing the “reducing power” needed to generate these fuels to be provided cleanly.

There are even ways to generate third generation biofuels without photosynthesis or electricity, which I will detail in a later blog.

Industrial carbon emissions do not need to be viewed as pollution and do not need to be wasted. Innovative technologies have been and are being developed to provide value and utility from emissions that would otherwise be dumped directly into the atmosphere.

Moving forward – advancing the production of advanced fuels

We have already established an enormous capacity for producing first-generation biofuels such as corn ethanol, which has become a significant part of our fuel mixture. But since we have unused, non-food based waste resources (lots of them actually) and the corresponding technologies to turn them into valuable low carbon biofuels, the challenge and opportunity is to develop next generation fuels. In fact, producing more second- and third-generation renewable fuels must be the priority going forward. We need to take stock of our unused waste resources, identify the technologies that best convert these to useful fuels or intermediates, and establish the necessary policy frameworks to promote the resulting low carbon fuels we are seeking.

Future posts will take a closer look at each of the pathways outlined above. I will discuss their potential, their role for improving waste management, environmental protection and sustainability, and I will also identify flexible policy frameworks that support the entrepreneurs, engineers, scientists and investors who can bring these clean fuels to market.