Los Angeles County Public Works Department Exploring State-of-the-Art ‘Waste-to-Energy’ Technology

Coby Skye

The ability to convert waste to energy mitigates two environmental issues with one process: first, reducing the amount of waste that heads to landfills; second, providing a renewable, carbon-free form of energy. As a result, waste-to-energy is a hot-button technology, essential in the carbon mitigation efforts of public agencies such as the Los Angeles County Department of Public Works (DPW). Having just completed Phase II of a report evaluating waste-to-energy conversion technology, DPW associate civil engineer Coby Skye shared with VerdeXchange News several applications of this promising emerging technology and its potential to transform the sustainable practices of waste management operators.

VerdeX: L.A. County just released Phase II of a report called “The Los Angeles County Conversion Technology Evaluation Report.” What was the report’s ambition, and what are its important findings?

Skye: For the last several years, we’ve been evaluating what we term “conversion technologies.” These are thermal, chemical, and biological processes that take municipal solid waste—that’s the trash that’s left over after we’ve pulled all the recyclables out of it—and convert that very heterogeneous material into energy, fuel, and products, without burning the trash. The county has been working to identify those companies and those technologies that we feel are viable and capable of developing successfully in Southern California.

VerdeX: Elaborate on the mix of conversion technologies the county is considering. What’s already in market? What’s about to be in market? What’s needed in market?


Skye: For example, in the Phase II report, we identified four companies that we’ve recommended as viable and capable of handling solid waste and converting it into renewable resources, specifically a biological technology, anaerobic digestion, and three thermal technologies. Anaerobic digestion is just one example of these unique processes. Essentially, this particular company takes trash and puts it into a water vat. The water allows the technology to separate out the different components in the waste stream, targeting the organic fraction of the waste—the biogenic fraction that is easily compostable or biodegradable. It feeds that part of the waste stream into an upflow anaerobic digestion process, which breaks down the organic material into methane—basically natural gas—which you can use for producing electricity, chemicals, or other products.

We have three other companies that use thermal technologies. The similarity between them is that they use a high-temperature process in the absence of oxygen, so it’s like you’re cooking the waste. That breaks down the chemical bonds in the waste material, separating out the usable materials. In some of the technologies, the metals and the inert materials actually melt, and you can separate those off into a slag or aggregate material. You can recover and recycle the metals, and the inert materials become something very similar to sand. You can use it in construction; you can make bricks out of it; you can use it for roads. The other materials in the waste—basically, the carbon-based materials—are turned into a synthesis gas. If you think about the elements that make up food waste or paper or plastic, it’s a lot of strings of carbon, hydrogen, and nitrogen. When you break all of those bonds by heating up the material in a very high-temperature process, you can then reform them into usable things. We can even strip out the hydrogen separately.

We then use it to produce other fuels: synthesis gas, ethanol, and biodiesel, different blends of fuel materials. We can very efficiently clean that synthesis gas, taking out any of the contaminants that would otherwise create air emissions problems. So, these projects are incredibly clean—cleaner than driving a car or running a lawnmower. We’re taking about really amazing projects. They’re able to recover, in some cases, 100 percent of the material that would otherwise just be thrown into a landfill, wasted for eternity, creating all sorts of issues in terms of potential air emissions and water contamination. This is a real step in the right direction.

VerdeX: Is thermal another name for incineration?

Skye: A lot of people have that misconception about thermal conversion technologies because you think of high temperature and that they must be burning the materials. There have been many waste-to-energy facilities developed—the traditional mass burn combustion or incineration facilities—that are still operating throughout the country.

The difference between incineration and conversion technologies is fundamental. When you look at a waste to energy incinerator, you’re going to see an open flame and the waste being thrown into what’s called a pit, where it’s set on fire. The high-temperature heat that’s created is used to create steam, and that steam is used to drive a steam generator for producing electricity. But once you’ve burned that material, you get this ash material that then has to be managed in some way. You also aren’t able to produce the synthesis gas or the other fuels or products that we can get from thermal conversion.

The other critical difference is that, with burning the waste, everything that’s in that waste is then volatized, and then you have to add on these air pollution controls at the end of the pipeline to try to remove all the contaminants from that process. With conversion technologies, that cleanup step is much simpler.

VerdeX: How does your department evaluate what new waste-to-energy technologies to implement?

Skye: That’s the reason we’ve been going through this conversion technology evaluation process. Our Phase I report, adopted back in 2005, went through the hundreds of different companies using similar technologies. We cast a very wide net to evaluate the most technologies and companies that are trying to develop processes capable of managing solid waste. The primary requirement for us was that they focus on municipal solid waste and that they produce marketable products from that material.

We evaluated those different companies based on a list of criteria that were critical to us. One criteria is how much of the material they are able to divert from landfill disposal. We also looked at their net environmental impacts: what would their air emissions be, their emissions for groundwater contaminations, or any of those issues? We came up with recommendations for those technologies that we felt were the most viable and politically feasible to develop in Los Angeles County. We also considered the obstacles we might have in terms of permitting and development in Southern California, since we’re in the most restrictive air quality management district in the country and have a lot of permitting requirements from the state and local levels.

VerdeX: California has stepped up as national leader on climate change with the passage of AB 32 and is now moving into the implementation process mandated by that legislation. How does the implementation of this state policy affect what you’re doing at L.A. County DPW? Are radical changes in store?

Skye: We’re going to see some radical changes as the result of AB 32. All the regulatory agencies in Sacramento are being driven so much by implementing AB 32 and complying with AB 32. It’s the new framework under which everything is going to have to operate, and they are really significant goals.

Obviously, the initial goals of reducing back down to 2000 and then 1990 levels for emissions will be somewhat of a challenge, but the 80 percent reduction below 1990 levels by 2050 is going to require really significant changes to the way we do pretty much everything, including solid waste management and recycling, transportation, and energy. It’s going to affect every aspect of our lives.

Large government agencies like the county of Los Angeles and this department, in particular, need to step up to the plate. We need to start by auditing the amount of emissions that come from all of the services that we provide to county residents and all of the operations. For example, this department manages hundreds of miles of roadways throughout Los Angeles County. That obviously takes a lot of energy and resources. We oversee flood control infrastructure. We oversee street lighting, which takes electricity.

Beyond auditing, we need to start looking at where the largest sources of emissions are and start taking proactive steps to reduce emissions. This conversion technology project—is going to have a significant impact in terms of making positive changes that reduce our greenhouse gas emissions for several reasons. When we evaluated these conversion technologies, we found that they have the potential to reduce greenhouse gas emissions in three key areas. The first is that, by reducing the amount of waste we send to landfills, we’re avoiding the generation of greenhouse gas emissions at the landfills. That could be from methane, which is a significant greenhouse gas. It’s actually 21 times more potent as a greenhouse gas than CO2. There’s also nitrous oxide and other emissions that may be generated at the landfills. So, if we prevent that waste from ever ending up in the landfills, we avoid that emission.

We’re also avoiding transportation of the waste if we convert the waste on site nearby where it’s generated, rather than putting it in what is typically a diesel-powered truck, shipping it long distances to remote landfills that are becoming more and more remote as our landfills in the basin close down. We’re reducing that source of emissions. Finally, by producing energy, we’re offsetting the production of electricity or fuels from fossil fuel sources. That’s an additional reduction in greenhouse gas emissions.

What we’ve found statewide is that we can realize millions of tons of CO2 emissions reductions every year by using conversion technologies to manage our waste, rather than relying on landfills, where over 95 percent of the waste is currently being disposed.

VerdeX: How does the energy produced in the waste-to-energy conversion reach the power grid?

Skye: We’re looking at facilities that would be generating tens of megawatts, and generally we would need to partner with the local utility and connect to their network grid. In most cases it would be Southern California Edison; it may also be LADWP. What that means is, you’d have a base load supply of electricity for that particular area. The houses and businesses that are closest to that particular sub-station would be the ones that could utilize that electricity, and it would reduce the potential for brownouts or blackouts for that area.

VerdeX: How is L.A. County able to make the investments necessary for these conversion technologies when it is strapped for budgetary dollars and resources for health and welfare and other safety net programs?

Skye: The county of Los Angeles, because we’re not collecting the waste, wouldn’t own the facilities that manage this waste stream, although it could facilitate the private sector to develop these technologies. The way we do that is demonstrating that the technologies can work, being a third party independent validator for the technologies, and also offering some incentives for companies to come to Los Angeles County and develop. Knowing that we have significant challenges in permitting and public outreach, working hand in hand with these companies to overcome those challenges is important.

In terms of the financials, we see that a lot of financial institutions, despite all of the difficulties that the sub-prime mortgage situation has created, are very interested in investing in green technology. The primary driver is that these technologies can be profitable.

VerdeX: With a population in L.A. County of more than 10 million people housed over 4,000 square miles, what is driving the county’s adoption of conversion technologies and increased investment in recycling and reuse? Are international vendors and like agencies looking at what the county is doing? Where do you find examples of best practices?

Skye: The market drivers in L.A. County include diminishing landfill capacity. That’s a huge driver. The Puente Hills Landfill is going to be closing in 2013. It handles one-third of the county’s waste stream right now. That’s 4 million tons of trash a year, just in one landfill. When you lose that capacity, the cost for disposal is going to go up because we need to ship it farther. Rising energy costs and rising fuels costs mean it costs even more to transfer that waste to farther distances.

The production of electricity on a renewable basis at cost-competitive rates has a lot of people interested in developing these technologies. That’s why we’ve seen a huge surge of interest in the development of these technologies throughout California.
We’re looking at the successful implementation of these technologies in Europe and Japan. They’re about a decade or 15 years ahead of the curve in terms of developing, evaluating, demonstrating these technologies, and developing incentives to move toward a different way of managing our waste.

A lot of times we tend to continue doing things the same way until there’s a real need to change. Right now, global warming, the need to develop our energy independence locally, and the need to develop renewable energy sources are all drivers for change. They are forcing us to really reevaluate the way we manage our waste. •••