|April 14, 2010|
Out of the Frying Pan...
|For those who missed it, yesterday the impossible happened. The New York Times, that great beacon of hope and truth shining light into the dark places of the earth, actually bothered to publish an article explaining, in a straightforward manner, the dependence of the United States on landfilling and the benefits that could be achieved if it burned more of its trash instead, like Europe. And it wasn't an op-ed from someone in the trash business; it was on the front page. Below the fold, sure, but part of the image published with the piece did reach above the fold a little bit. Here is the prime mover, if you will, as it appeared in the online edition:|
Europe Finds Clean Energy in Trash, but U.S. Lags .
It didn't stop there. NYTimes' GreenInc. blog published this piece on the aesthetics of waste-to-energy plants, where you can check out my comments below the main story. They also published this item in their "Room for Debate" feature, which actively seeks reader input on pressing and controversial issues of the day. Go tell 'em what you think!
And the Times wasn't the only paper onto the big story this week. Inspired by the unprecedented candor on the issue coming hot off the New York presses this week, those snoops over at the Washington Post published the following editorial cartoon:
I never thought I'd say it, but waste-to-energy is blowing up! OK, admittedly it has only been a couple of years I have been a proponent, or even really had any idea of what was going on in this area at all, but given the political climate in this country, where the word "incinerator" is sure to spark a fiery discussion at any Los Angeles cocktail party, it seemed reasonable to assume that landfilling sixty-plus percent of the solid waste generated in this country would remain the norm for the foreseeable future. Could all that be about to change? Or is this bit of media attention all just a flash in the pan?
In any case, was refreshing, to say the least, to see a fresh take on WTE in the popular media. While the Times piece that sparked this whole discussion did contain a few of what I would call "technical difficulties" (I am not sure whether their statement that most facilities in the U.S. are privately owned is true, and moreover I feel it is more accurate to say all existing plants are public-private partnerships on some level), the general gist of the piece and the follow-ups was correct and on point. The technology has long been the Rodney Dangerfield of renewables, earning little respect and a great deal of disrespect from environmentalists conjuring up sour images from the industry's past with black, particle-laden smoke billowing out of smokestacks towering over the landscape. And while images of modern incinerators are quite different (you can find quite a few on this site if you know how to poke around), they do not suit the political agenda of the majority of the Environmental Protection Agency, the Sierra Club, Greenpeace, the Public Interest Research Groups, "zero waste" organizations, and a host of other establishment left-greenish groups that often like to think they exercise a stranglehold over public environmental policy. Fortunately, there are also scientists who have worked tirelessly yet unsuccessfully for decades to get the word out about trash as a clean, renewable energy source that can substantially displace fossil fuels, which is why it was a bit surprising, to be honest, to see the New York Times suddenly and enthusiastically take up their cause after many years of neglect. But I suppose that is what happens when you leave the task of educating the public about science to the scientists.
With so much attention being focused on WTE as a renewable power source presently, and hopefully futurely, it is worth taking a moment to (relatively) briefly explain the concept behind waste-to-energy, how the process works, and how and why North America, and the United States in particular, can do more to utilize this domestic resource. If you already know the basics about WTE, you can skip the next two sections; for advanced students, I am sure I will cover the process in more depth in the coming days and weeks.
What It Is
I'm going to keep this discussion relatively brief, as I don't want to get bogged down in too many details right now. But it is necessary for newcomers to the discussion to understand some of the underlying concepts and technologies behind waste-to-energy before it is possible to understand why the critics have it wrong, and why it is important to build more of the infrastructure used for the purpose of burning waste. The basic idea here is that, when you throw something out and it gets collected in your weekly visit from the trash people, that material will end up meeting one of two fates: it will be either buried, or burned and then buried. If it is burned, the process of burning that trash releases a good deal of heat, enough once you have enough tons of trash all together burning at the same time that if you want, you can use a portion of that heat to generate electricity. In other words, the stuff you throw away because it is no good to you anymore is still good for something: it is good for keeping the lights on and the air conditioner running.
How It Works
There are a number of specific processes for burning trash at industrial scales, but the most reliable by far is the "mass burn waterwall" combustion facility. "Mass burn" refers to the physical burning mass of trash that forms the core of a waste-to-energy plant and ignites incoming trash more or less instantaneously, releasing hot gases into the heat recovery boiler; "water wall" refers to the wall-shaped boiler itself, where that heat generates the steam used to produce all the forms of energy exported by the plant. I will not discuss other processes for energy recovery here in detail except to say that all of them involve processing, sorting and separating waste to a larger extent than mass burn facilities, which burn "as-received" waste out of the back of a packer truck, all of which increases the risks associated with processing solid waste and none of which has so far demonstrated any substantial, convincing benefit over the mass burn process. Air pollution control devices are used to neutralize, remove, and in some cases recycle harmful components of the exhaust stream, such as particulates, acid gases, and smog-forming compounds. Ash is expelled from the bottom of the furnace using a hydraulic ram or other device and either recycled or sent to landfills, where it occupies just 10% of the volume of untreated waste.
The heart of any combustion plant and the most unique part of a WTE plant's design is the combustion grates. These grates are usually flat sideways-stair shaped platforms which support the burning mass of waste and charge it with air from below, while moving back and forth or "reciprocating" in order to achieve superior mixing of both the fuel itself and of air into the fuel to keep it burning at a consistent temperature, which minimizes the formation of pollutants.
Why We Should Do It More
The United States currently landfills over 250 million tons of municipal solid waste per year and combusts just 40 million tons for energy. Every one of those 250 million tons has the potential to produce enough base loading electricity to displace a quarter of a ton of coal and enough heating value to provide virtually the entire heating and cooling load of our cities in district energy systems. That we should do more to take advantage of this readily available, sustainable energy source goes without saying. To do otherwise is not just unreasonable, it is beyond insanity. And while energy to replace power from a coal-and-other-fossil-fuel-based system that is slowly but surely killing us and bound to collapse in its entirety at some point should be enough reason to get as much energy as possible from our trash, what if it could also help us conserve other scarce, non-renewable resources, besides just fossil fuels?
As it turns out, it can: waste-to-energy plants can be easily configured to retrieve metals from the post-combustion ash stream. These are metals recovered in addition to, not instead of, the aluminum and steel cans, white goods, and loose scrap metals typically targeted for household curbside recycling collection programs. They are metals that form intrinsic components of products, such as bicycle frames, that would be impossible to remove from the waste and valuably repurpose without combustion. Even loose metals that could otherwise have been recycled are far more easily recovered from WTE ash than from landfills, where they are buried and covered with many layers of soil. And landfill mining projects, heralded by many pundits as the saving grace for a resource-constrained future, have not turned up much in the way of metals so far (they have, however, turned up quite a bit of soil).
And if conservation of energy and recycling of otherwise unrecoverable metals were not enough, consider that WTE generates additional reductions in climate-warming greenhouse gas emissions even beyond displacing the emissions from coal-fired utilities and the mining and processing of metals. When simply piled up or stored in a landfill, the organic component of trash slowly decomposes in the presence of naturally forming anaerobic bacteria, which generate methane as their primary metabolic byproduct. Unless a methane capture system is installed at a landfill to collect and either flare the gas or combust it for energy, it is emitted to the atmosphere, where each carbon atom in those methane molecules warms the earth twenty times as much as if it were part of a CO2 molecule. Methane capture systems are not perfect, and even those sytems that recover energy from the gas have far lower energy output than a WTE plant that simply burns the trash in the first place.
(Sidebar: in addition to warming the climate, methane from landfills also has a few other nasty habits. For instance, it can enter leachate to degrade its quality and increase the cost of treatment, it can migrate through cracks in rock and pores in soil to emerge from the ground several kilometers from the landfill itself, and it can accumulate in confined spaces like bathrooms or landfill gas extraction wells themselves to create asphyxiation hazards for landfill personnel and neighbors. Oh yeah, it can also explode.)
Energy and resource conservation-related impacts are not the only reasons to prefer WTE over other solid waste management and energy production options. Consider the problem of solid waste in the first place: we cannot simply leave it in place, and something must be done with it. The only options available aside from landfilling and combustion are to let it just pile up in our yards and gutters; in fact, this is exactly what happens in many less developed countries. A common fallacy repeated by WTE opponents is that "incinerators promote garbage," also known as the "feed the beast syndrome." While it is true that WTE plants run optimally at or near their design capacity, this argument ignores the historical, physical evidence of what actually happens when localities fail to adequately plan for disposal: the trash does not, in fact, disappear. In fact, it doesn't even go "away," it goes nowhere. Just ask the people of Naples how they spent their summer in 2008: schools and businesses were actually closed because there was so much rotting trash blocking the sidewalks and roads and because the stench was so unbearable throughout the entire city. And if you don't believe them, why don't you go check out the gutters of Kingston sometime?
In other words, trash is, left to its own devices, pollution. In order to keep it from leaching poisonous compounds into our air, water, and soil, it is necessary to either bury it below many layers of soil and above many layers of liners, or to burn it to reduce its size as much as possible and recover as much energy from it as possible before doing the same thing to the ash that you would have otherwise done to the trash. Burning it for energy, which reduces the waste volume to its ash component and which makes it more likely that an extensive municipal solid waste management infrastructure is in place, makes it easier, not harder, to recover and recycle valuable materials from the waste stream. It promotes good sanitation and offsets far more pollution than it creates.
So what are we waiting for? Let's get this party started!
Posted by wastedenergy