Showing posts with label butanol. Show all posts
Showing posts with label butanol. Show all posts

Friday, October 29, 2010

Ammonia As An Alternative Fuel?

In the last seven years I've written extensively about a wide variety of alternative fuels, including ethanol, methanol, and higher alcohols like butanol, along with compressed and liquefied natural gas (CNG and LNG), hydrogen, and electricity, but I find I haven't said anything about anhydrous ammonia. It turns out that there is a small but enthusiastic group of people promoting its use as an alternative fuel, going back to at least the 1940s. Much of the recent interest in this stems from the fact that ammonia releases little or no greenhouse gas when burned, and that it's possible to produce it by means that involve minimal GHG emissions throughout its lifecycle. However, when you dig into this a little deeper, you discover that almost all ammonia today is produced by the Haber process, using hydrogen sourced from natural gas. And if that weren't enough of a deterrent, the physical properties of ammonia render it an unattractive candidate for a mass-market fuel.

So-called "green ammonia" would avoid natural gas by substituting hydrogen from electrolysis using wind, solar or other renewable electricity. As long as natural gas remains abundant, it's hard to envision this growing beyond a small niche, because the price of ammonia will ultimately be set by the price of natural gas, which remains a cheaper source of hydrogen than electricity from any source, let alone from expensive renewable power sources. Moreover, electricity is fungible, and the best use of renewable or other low-emission power (e.g., nuclear) is probably in backing out power from higher-emitting sources, rather than diverting it into inefficient production of chemicals. As a result green ammonia, like green power, would require subsidies for at least the near-to-medium term if it is to compete with conventional ammonia, which seems like a crucial prerequisite for competing with conventional fuels. And without green ammonia, the whole rationale for an ammonia fuel-and-vehicle network looks questionable--why not just use the gas as CNG or LNG instead, with a fraction of the headaches?

Even if that weren't the case, ammonia faces serious obstacles as a consumer fuel, compared to either conventional fuels or to many other alternatives. Start with energy density, which is less than half that of gasoline by weight, and about 40% by volume. So a gallon of ammonia would only take you about 40% as far as a gallon of gas, even if you could burn pure ammonia in your engine--and from what I've read it still requires help from another fuel to sustain combustion. (That means two fuel tanks, which constitutes another major hurdle with consumers.)

Then there are the economics. Ammonia itself isn't exactly cheap, if you adjust for its energy content. The price of bulk ammonia for agricultural use appears to be around $550-$600/ton, which equates to $1.55-1.70/gal. But when you factor in its lower energy density, that raises it to at least $3.85/gal. of gasoline equivalent, without any fuel taxes. And while a distribution system exists to supply farms with ammonia, this is a long way from what would be required to fuel anything beyond farm vehicles. Because ammonia boils well below ambient temperature, it must either be refrigerated or stored under pressure, and dispensed through special equipment. And if all that weren't daunting enough for any service station owner considering adding an ammonia pump on the forecourt, the safety aspects of ammonia handling look even worse.

A glance at a typical material safety data sheet (MSDS) for anhydrous ammonia reveals that the recommended exposure limits are very low, under 50 parts per million in air, and the consequences of exposure include caustic burns and much more serious outcomes. Gasoline has its own issues, but spilling some on your hand won't send you to the hospital, and a larger spill or leak doesn't require first responders in hazmat suits. I simply can't imagine any fuel retailer wanting to take on the liabilities that would go along with this, even if there were an attractive margin in it, which there doesn't appear to be.

I concluded long ago that we're heading into a period of much greater fuel diversity, and that certainly seems to be true, with LNG catching on for big-rig trucks and CNG for a few cars but more fleet vehicles and buses, and even hydrogen appearing in a few places for fuel cell vehicles. However, it's very hard to imagine a substance with as many drawbacks as ammonia coming into wide use for consumers or even fleets. Our range of alternative fuel options seems sufficiently broad already, without having to consider a fuel that turns into a poison gas at atmospheric pressure and temperature.

Thursday, February 04, 2010

EPA's New Biofuel Rules

Yesterday the administration issued an important set of new rules and proposals relating to energy, mainly dealing with expanded biofuel production and the biomass supply chains that must be developed to sustain it, as well as addressing carbon capture and storage (CCS.) There's far more here than I could cover in one posting, so I've chosen to focus on the EPA's finalized Renewable Fuels Standard (RFS) rules, which were first proposed last May and have been the subject of intense study and considerable controversy ever since. While the print edition of the Washington Post characterized these as "A boost for corn-based ethanol" I'm not so sure. In the process of laying out a roadmap for how new corn-based ethanol facilities can contribute to the expansion of biofuel in the US, the EPA effectively froze the output of a large number of older facilities, unless they invest in significant upgrades. It also raised big questions about the future of E85, a blend of 85% ethanol and 15% gasoline that has so far failed to attract much interest from consumers, while suggesting that ethanol might have to share the ultimate 36 billion gallon per year biofuel target for 2022 with large volumes of other, more advanced biofuels.

At the heart of the new biofuel rules, which are designed to implement the goals established by the Energy Independence and Security Act of 2007, is the assessment of lifecycle greenhouse gas emissions from biofuels, including the highly-controversial "indirect land-use impacts" first highlighted in a landmark paper published in Science two years ago and confirmed by subsequent research. Although the EPA's final interpretation of the science has not turned out to be quite the catastrophe that the corn ethanol industry feared--and based on the quote in the Post from the lead author of the relevant research, Dr. Tim Searchinger, might have gone easy on them--it nevertheless constrains the future role of ethanol produced from this source. While clearly stating that facilities producing ethanol from corn starch using natural gas or biofuel for process heat and employing other efficient technologies would qualify for the least-stringent category of renewable fuel, many existing facilities would qualify only under grandfathering that restricts their output to historical levels. That includes newer facilities that started construction by 12/19/07, and essentially all that use coal for heat or dry all their distillers grains byproduct.

In contrast the biodiesel industry, which has been suffering recently, got a shot in the arm with a ruling that qualifies most biodiesel produced from soy oil or waste cooking oil or grease
for the tougher "biomass-based diesel" category, consistent with a 50% reduction in emissions. And the specific RFS quota for 2010 carves out a healthy 1.15 billion gallon target for biodiesel--including retroactive volumes from 2009 that could cause no end of confusion.

Perhaps the most urgent aspect of the requirements for 2010 was the EPA's concession to reality on its cellulosic ethanol quota. The original targets set by Congress called for the use of 100 million gallons of biofuel produced from cellulosic sources this year, but as I've pointed out frequently, bleeding edge technology doesn't just appear on command. The EPA's estimate of how much cellulosic biofuel will actually be available in 2010--and thus mandated for use--is just 6.5 million gallons. And if fuel blenders aren't able to acquire even that much, EPA has provided the alternative of paying $1.56/gallon in penalties, instead. That sounds cheap until you realize that this only pays for an attribute; they still have to buy the gasoline or conventional ethanol on which to apply this Renewable Identification Number, or RIN. Based on current prices, the total cost for such virtual cellulosic ethanol could thus exceed $3.50/gal., compared to around $2.00 for wholesale (untaxed) gasoline.

I confess I didn't make it through the entire 418 page "preamble" to the regulation, but what I found there was a fascinating picture of how much the official view of biofuels has evolved since the Congress set us on this path at the end of 2007. Then, hopes for E85 powering many millions of "flexible fuel vehicles" (FFVs) ran high. Today, reading between the lines, there are hints that EPA might regard E85 as a failed product that may no longer be necessary for pushing biofuel into the market. Their statistics on E85 paint a bleak picture. According to EPA, out of a total retail gasoline market of 138 billion gallons in 2008, E85 accounted for just 12 million gallons. Such low volumes are partially attributable to the fact that there are still only 2,100 retail facilities in the US with an E85 pump, and only 8 million FFVs on the road, out of a US vehicle fleet of 240 million or so. Yet after taking these constraints into account, the EPA calculated that FFV owners bought E85 just 4% of the time. They offer a variety of reasons for this, including concerns about reduced range on the lower-energy fuel, but mainly point to the much higher average price of E85 compared to unleaded regular on an energy-equivalent basis. In other words, consumers are choosing value and maximizing their miles per dollar. So it wouldn't just require a big increase in the number of E85 pumps and FFVs to make E85 successful; the product must be priced a heck of a lot cheaper than it has been, reducing the incentive for dealers to sell what today is a very low-volume product. Catch-22?

How much of a problem this poses for ethanol producers depends on whether the EPA relaxes the 10% limit on ethanol blended into normal gasoline, as the ethanol industry has petitioned them to do, against most auto industry advice. It also depends on how quickly non-ethanol biofuels such as biobutanol and biomass-derived hydrocarbons--gasoline or diesel from algae, bacteria, or gasification--that would be fully compatible with current cars and infrastructure take off. It's worth noting that the new rules explicitly qualify biobutanol from corn starch in the same category of renewable fuel as the best corn ethanol pathways, and leave the door open to qualify these other fuels if they satisfy EPA's emissions framework. The preamble includes one scenario in which such fuels account for nearly as much of the 2022 biofuel target as corn ethanol.

Needless to say, I haven't had time to go through all the intricate details of the EPA's new RFS regulations. Their ultimate impact may depend as much on some of those nuances as on the big-picture elements I spotted in my cursory review, and I can easily picture a host of law firm, trade association, and energy company personnel poring over them for the next couple of weeks. Still, although what I saw was hardly the death-knell for the existing corn ethanol industry that some might have expected or hoped for, in the process of codifying the means for implementing the intent of Congress in its 2007 legislation the agency has laid out a vision of a much more diverse and competitive biofuel industry than the architects of that bill could have guessed just a couple of years ago.