Bio Solutions Deliver Performance While Meeting Sustainability Goals – Road Construction and Power Generation Sectors Show Proven Results

August 12, 2020 |

By Marty Muenzmaier, Cargill’s sustainability and external affairs lead for the Bioindustrial group

Special to The Digest

Historically, many in manufacturing believe going with bio-based ingredients for various manufacturing applications from wood panels and furniture adhesives, foams and flooring, paints, inks and coating, asphalt hot-mix additives to dielectric fluids for electrical transformers means a loss of quality and performance compared to conventional petroleum-based ingredients.

In reality, however, bio-based manufacturing applications are delivering the same reliability and performance results that uphold products and additive solutions the same way petro does. But, in addition to meeting and exceeding performance expectations, plant-based solutions help businesses achieve an overarching sustainability objective while lowering costs over the long-term.

Two industrial areas that are seeing impressive performance year-over-year with plant-based applications, while helping deliver sustainability advancements, is road construction and power generation.

Road construction firms around the world are finding cost savings, reliability and environmental benefits by moving to a recycled asphalt pavement method, compared to using only virgin aggregate for paving needs. A plant-based rejuvenator, like Cargill’s ANOVA, allows state departments of transportation, municipalities, commercial road owners and contractors to realize budget savings as road projects use more recycled material, reducing waste and producing high-quality surfaces that last over time.

Wisconsin Town Paves the Way with Recycled Asphalt Using Plant-Based Rejuvenator

One such case study that road owners should consider as they strive to maintain highways during uncertain financial times is that of the City of Janesville in Wisconsin. Located in the south-central part of the state, just north of the Illinois border, the City of Janesville is responsible for maintaining approximately 345 centerline miles of municipal roadways and alleys that serve a population of 65,000. In addition, the city performs routine maintenance on 11 centerline miles of state highway that are within city limits. In 2014, Janesville was rehabilitating its streets at an average of 6.3 centerline miles per year — 5.2 miles resurfaced and 1.1 miles reconstructed.

The city was rehabilitating asphalt pavements every 54 or 55 years on average, according to Lisa Wolf, Janesville assistant city engineer. “This is a completely unrealistic expectation, especially in our Midwest climate where we have multiple freeze-thaw cycles and older infrastructure within the city that’s already been milled a few times,” she said. In Wisconsin, the average service life for an asphalt surface is around 18 years for new pavement and 12 years for an overlay, according to Wolf. By the time she joined the city in 2014, the average condition of the city’s streets was declining. The city council decided that more yearly rehabilitation work was needed before the overall condition of its streets declined further.

In 2014, the Janesville City Council committed to funding 12 miles of street rehabilitation annually, doubling its program. Part of the strategy to rehabilitate more miles per year is adjusting the mix designs for the pavements and “increasing the use of recycled materials in the asphalt,” said Wolf.

The city began working with a local firm based in nearby Beloit to develop new mixes that would incorporate higher recycled content into Janesville’s asphalt pavements. The firm also helped revise the city’s specifications for resurfacing and reconstruction projects, streets in new developments, new street extensions, and more. The revised specifications increase the use of reclaimed asphalt shingles (RAS), RAP, and fractionated reclaimed asphalt pavement (FRAP) in Janesville.

“The first season of production included trial sections that used softer virgin binders and various additives to offset the harder asphalt from the RAP, FRAP and RAS,” said Wolf. “Subsequent tweaks to the specifications included requiring additives in surface mixes where the ABR is over 30 percent.”

Since the revised program went into effect in 2016, Janesville has been reaping the benefits. Performance testing specifications ensure the high recycle mixes are resistant to cracking and rutting. In addition, prior to 2016, Wolf said, prices for hot mix asphalt were steadily rising per year. After increasing its use of recycled asphalt material, Janesville saw the price per ton for a typical local road asphalt mix drop about 6 percent from the 2015 price. “There are real cost savings in utilizing more recycled asphalt material,” said Wolf.

Recycled asphalt, through the use of a plant-based rejuvenator, contributes to a circular supply chain and economic system. From supporting farmers producing a renewable, raw ingredient year-over-year, that then allows old aggregate to have a second life instead of going into a landfill, the circularity process creates a mutually beneficial outcome for multiple economies and long-term environmental benefits.

“From smaller towns in the Midwest to large metro areas around the world, rejuvenated RAP is not only consistently proving to be a reliable performance solution, but real cost savings are also being realized,” said Dr. Hassan Tabatabaee, global technology manager for asphalt solutions with Cargill’s Bioindustrial Group. “We’re excited to see results like the city of Janesville is experiencing. This data, captured over a long period of time in real world applications, can help inform the industry when developing asphalt rehabilitation strategies for the future.”

Plant-Based Power Generators Spark Savings and Mitigate Risk

In addition to road construction, the world of power generation and power distribution is moving more-and-more to natural ester (plant-based) transformers given lower risks and cost and  greater sustainability benefits over traditional mineral oil units.

Natural ester is also biodegradable and based on renewable agricultural sources. This benefit is driving a number of energy organizations to place ester transformers in sensitive eco environments.

For example, the United States Bureau of Reclamation chose to install natural ester transformers positioned just a few feet above the Colorado River at the Glen Canyon Powerplant.

The retrofit of the dam, which started in August 2017 and will continue this spring, was part of a $37 million contract with Yellowstone Electric Co. of Billings, Mont., including the replacement of 14 single-phase transformers designed for natural ester insulating liquid.

“Bringing sustainable design to our powerplants is key to guaranteeing their length of service,” said Upper Colorado Regional Director, Brent Rhees. “It is important to our region and across Reclamation that we support green initiatives when and where we are able.”

Italian transmission system operator, Terna, is one of many organizations that tested natural ester extensively before making the switch from mineral oil for their equipment. Under a European Union directive, Terna examined ways better address community concerns over the safety of its power grid while delivering on its environmental and economic goals.

In its research and development stage, Terna tested several different natural esters to identify the most suitable for their applications and purchased a prototype transformer. After conventional and special tests, the firm selected Cargill’s FR3Ô fluid.

“Adoption of natural ester as alternative fluid to mineral oil in big power transformers is due to many technical and strategical reasons,” said Fabio Scatiggio, chemical laboratory manager with Terna Rete Italia. “Transformer life extension, overloadability, low environmental impact in case of catastrophic breakdowns, simplification for environmental and safety regulations and reduction of erection costs and low insurance premiums. But especially improvement of the company’s outlook by shareholders and stakeholders.”

Following the prototype testing, four similar autotransformers were built for active, two-year service and Terna is planning the installation of more than 30 new power transformers filled with natural ester for its country-wide system.

Pacific Gas and Electric, another major power cooperative in California, has seen successful in switching from traditional mineral oil transformers to natural ester. As safety and reliability concerns continue to grow for the region, natural ester is one step the cooperative feels will help mitigate risk.

And in addition to minimizing risk with more fire safety, PG&E’s addition of more natural ester has allowed them to prolong the life of their transformers and eliminate two standard sizes of overhead transformers from their system, saving them millions of dollars each year.

“I wanted to switch from mineral oil filled distribution transformers to natural ester filled just for improved safety in the event of an explosion, but I was worried about how to justify the cost increase to upper management,” said Dan Mulkey, principal with Mulkey Engineering, and an ex-PG&E engineer.

“Surprisingly, just a very slight increase in life made the switch economic, and the switch to natural ester became a no-brainer.”

In addition to the improved fire safety and being more environment friendly, natural ester brings significant reliability and longevity benefits to its users that are less known.

Compared to mineral oil, natural ester offers a great advantage regarding lifetime expectancy, extending the lifespan in 1.33x or more. When the comparison is with cast resin (dry types), the amplification factor is even higher.

And even with that longevity, maintenance interventions should not be necessary as natural ester is “self-drying” and does not generate sludge like mineral oil. So, differently from a traditional transformer, the capacity to withstand over voltages, such as the ones generated by lightning impulses, is not

depleted along the years in service. Moisture content in the insulating paper does not increases along the years.

About the Author

Marty Muenzmaier is Cargill’s sustainability and external affairs lead for its bioindustrial group. He oversees sustainability efforts related to bio-based manufacturing applications in the areas of asphalt rejuvenation, natural ester power transformers, beauty products, polyols and other innovations.

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