Author: acl

Lincoln, Neb., April 20, 2014 — Using corn crop residue to make ethanol and other biofuels reduces soil carbon and can generate more greenhouse gases than gasoline, according to a study published today in the journal Nature Climate Change.

Corn residue is being baled on a University of Nebraska-Lincoln field experiment site in Saunders County, Neb. Credit: University Communications/University of Nebraska-Lincoln

The findings by a University of Nebraska-Lincoln team of researchers cast doubt on whether corn residue can be used to meet federal mandates to ramp up ethanol production and reduce greenhouse gas emissions.

 

Corn stover — the stalks, leaves and cobs in cornfields after harvest — has been considered a ready resource for cellulosic ethanol production. The U.S. Department of Energy has provided more than $1 billion in federal funds to support research to develop cellulosic biofuels, including ethanol made from corn stover. While the cellulosic biofuel production process has yet to be extensively commercialized, several private companies are developing specialized biorefineries capable of converting tough corn fibers into fuel.

 

The researchers, led by assistant professor Adam Liska, used a supercomputer model at UNL’s Holland Computing Center to estimate the effect of residue removal on 128 million acres across 12 Corn Belt states. The team found that removing crop residue from cornfields generates an additional 50 to 70 grams of carbon dioxide per megajoule of biofuel energy produced (a joule is a measure of energy and is roughly equivalent to 1 BTU). Total annual production emissions, averaged over five years, would equal about 100 grams of carbon dioxide per megajoule — which is 7 percent greater than gasoline emissions and 62 grams above the 60 percent reduction in greenhouse gas emissions as required by the 2007 Energy Independence and Security Act.

 

Importantly, they found the rate of carbon emissions is constant whether a small amount of stover is removed or nearly all of it is stripped.

 

“If less residue is removed, there is less decrease in soil carbon, but it results in a smaller biofuel energy yield,” Liska said.

 

To mitigate increased carbon dioxide emissions and reduced soil carbon, the study suggests planting cover crops to fix more carbon in the soil. Cellulosic ethanol producers also could turn to alternative feedstocks, such as perennial grasses or wood residue, or export electricity from biofuel production facilities to offset emissions from coal-fueled power plants. Another possible alternative is to develop more fuel-efficient automobiles and significantly reduce the nation’s demand for fuel, as required by the 2012 CAFE standards.

Liska said his team tried, without success, to poke holes in the study.

 

“If this research is accurate, and nearly all evidence suggests so, then it should be known sooner rather than later, as it will be shown by others to be true regardless,” he said. “Many others have come close recently to accurately quantifying this emission.”

The study’s findings likely will not surprise farmers, who have long recognized the importance of retaining crop residue on their fields to protect against erosion and preserve soil quality.

 

Until now, scientists have not been able to fully quantify how much soil carbon is lost to carbon dioxide emissions after removing crop residue. They’ve been hampered by limited carbon dioxide measurements in cornfields, by the fact that annual carbon losses are comparatively small and difficult to measure, and the lack of a proven model to estimate carbon dioxide emissions that could be coupled with a geospatial analysis.

 

Liska’s study, which was funded through a three-year, $500,000 grant from the U.S. Department of Energy, used carbon dioxide measurements taken from 2001 to 2010 to validate a soil carbon model that was built using data from 36 field studies across North America, Europe, Africa and Asia.

 

Using USDA soil maps and crop yields, they extrapolated potential carbon dioxide emissions across 580 million 30-meter by 30-meter “geospatial cells” in Corn Belt states. It showed that the states of Minnesota, Iowa and Wisconsin had the highest net loss of carbon from residue removal because they have cooler temperatures and more carbon in the soil.

 

The research has been in progress since 2007, involving the coordinated effort of faculty, staff and students from four academic departments at UNL. Liska is an assistant professor of biological systems engineering and agronomy and horticulture. He worked with Haishun Yang, an associate professor of agronomy and horticulture, to adapt Yang’s soil carbon model, and with Andrew Suyker, an associate professor in the School of Natural Resources, to validate the model findings with field research. Liska also drew upon research conducted by former graduate students Matthew Pelton and Xiao Xue Fang. Pelton’s master’s degree thesis reprogrammed the soil carbon model, while Fang developed a method to incorporate carbon dioxide emissions into life cycle assessments of cellulosic ethanol.

 

Liska also worked with Maribeth Milner, a GIS specialist with the Department of Agronomy and Horticulture, Steve Goddard, professor of computer science and engineering and interim dean of the College of Arts and Sciences, and graduate student Haitao Zhu to design the computational experiment at the core of the paper. Humberto Blanco-Canqui, assistant professor of agronomy and horticulture, also helped to address previous studies on the topic.

 

http://www.sciencenewsline.com/articles/2014042115260026.html

토요타가 새 가솔린 엔진을 공개했다. 새로 개발된 가솔린 엔진 패밀리는 효율을 극대화 하는데 포커스가 맞춰졌다. 일반 엔진에도 앳킨슨 사이클이 적용된 게 가장 큰 특징이고 우선적으로 1리터와 1.3리터 두 가지가 선보였다. 토요타에 따르면 연비는 최소 10%가 좋아진다. 열효율도 38%까지 높아졌다. 토요타의 새 가솔린 엔진 라인업은 총 14가지로 나오게 된다.

일본 메이커는 다운사이징 터보의 도입에 소극적이었다. 최근 들어서야 다운사이징 터보를 내놓기 시작하지만 유럽 메이커에 비하면 그 수는 매우 부족하다. 일본 메이커는 하이브리드에 주력해 왔고 내연기관도 여전히 자연흡기에 무게가 실려 있다. 토요타가 이번에 공개한 새 가솔린 엔진도 자연흡기 방식을 유지하고 있다. 최근 트렌드와는 반대되는 행보지만 자연흡기 엔진의 새 가능성을 엿볼 수 있다는 의미도 있다.

이번에 공개된 새 엔진은 3, 4기통 가솔린 엔진이다. 배기량은 1리터와 1.3리터 두 가지이고 이는 토요타의 소형 엔진 중에서는 핵심 유닛이라고 할 수 있다. 토요타의 1리터와 1.3리터는 1999년 데뷔한 이후 조금씩 개선이 되어왔지만 이번에 가장 큰 변화를 맞게 됐다.

가장 크게 달라진 것은 오토 사이클이 아닌 앳킨슨 사이클이 적용된 것이다. 앳킨슨 사이클은 이미 하이브리드의 엔진에서 흔하게 볼 수 있지만 일반 자동차의 엔진에는 거의 쓰이지 않는다. 앳킨슨 사이클이 효율은 좋지만 고회전에 불리하고 이에 따라 리터당 출력도 낮기 때문이다. 때문에 앳킨슨 사이클은 하이브리드의 내연기관에만 쓰이고 있다.

하지만 새 1리터와 1.3리터는 일반 자동차용 엔진으로 개발됐다. 차후 하이브리드나 터보 모델이 추가될 수 있지만 일단은 일반 자동차에 먼저 탑재된다. 토요타의 일반 엔진에 앳킨슨 사이클이 쓰인 것은 이번이 처음이다. 핵심은 크게 빠른 연소와 높은 압축비, 그리고 펌핑 로스와 마찰 저항을 줄이는 것이다. EGR도 기본이다. 빠른 연소를 위해서는 인테이크 포트를 새로 디자인했다. 새 디자인은 빠른 공기의 흐름을 유도하며 차후 터보의 세팅까지도 감안한 디자인이다. 접시 모양의 피스톤 역시 마찬가지다. 이 엔진에 적용된 전자식 가변 캠 페이징 기구는 VVT-iE(Variable Valve Timing-intelligent Electric)로 불린다.

연소 효율을 위해서는 압축비도 높였다. 압축비가 높아지면 효율은 좋지만 노킹 현상이 발생한다는 우려가 있다. 토요타는 노킹이 발생하기 전에 연소를 빠르게 진행하는 한편 실린더 월의 온도를 정교하게 컨트롤해 노킹 없이 연소 효율을 높일 수 있었다고 밝혔다. 압축비는 13.5:1까지 높아졌다. 마쓰다 스카이액티브의 14.0:1보다는 낮지만 일반 엔진보다는 크게 높은 것이다. 참고로 마쓰다 차기 가솔린 엔진은 압축비가 18까지 올라갈 것으로 알려졌다.

앳킨슨 사이클은 압축 행정 중에 순간적으로 인테이크 밸브의 오픈 시간을 늘려 효율을 높인다. 흡기 밸브가 열려 있는 시간이 오토 사이클보다 길고 피스톤과 크랭크샤프트의 연결 구조는 좀 더 복잡하다. 팽창비와 압축비를 다르게 하면서 펌핑 로스를 줄일 수 있고 이 때문에 오토 사이클에 대비 연비가 10% 내외로 좋아진다. 대신 고출력이 힘들다는 단점이 있다. 토요타는 낮은 리터당 출력은 높은 압축비를 통해 해결했으며 풍부한 저속 토크로 상쇄가 가능하다고 밝혔다. 그리고 피스톤 스커트의 디자인을 개량하는 한편 코팅 처리된 베어링을 적용해 마찰 저항도 줄였다.

새 1.3리터 가솔린은 고성능 엔진만큼이나 압축비가 높다. 열효율은 38%로 가솔린 엔진 중에서는 가장 높은 수준이다. 현행 유닛은 열효율이 35%이고 현재 프리우스 엔진의 열효율이 38.5%이다. 토요타에 따르면 기존 엔진 대비 최대 15%의 연비 개선 효과가 있다. 내년에 나올 프리우스의 가솔린 엔진은 열효율이 40% 이상 올라갈 것으로 알려졌다. 토요타가 2011년에 선보인 퓨처 컨셉트 2는 열효율이 43.7% 이상이었지만 상용화될지는 미지수이다.

새 1리터 엔진도 열효율이 37%로 상승했다. 이 1리터 엔진 역시 1.3리터와 비슷한 인테이크 포트, EGR이 적용됐으며 압축비도 11.5:1로 높였다. 스톱 스타트까지 더할 경우 연비 개선 효과는 최대 30%이다. 1리터 엔진은 자회사인 다이하쓰와 공동으로 개발했다. 새 가솔린 엔진은 자연흡기가 기본이지만 하이브리드에도 적용이 가능하고 직분사와 터보도 조합이 가능하다.

이번에 공개된 가솔린 엔진은 토요타의 핵심 파워트레인 전략 중 하나이다. 내년에 나오는 TNGA(Toyota New Global Architecture)의 모델에 가장 먼저 탑재되며 토요타 시티의 뉴 PJDB(Powertrain Joint Development Building)에서 개발을 맡은 첫 번째 엔진이기도 하다. 앞으로 2년 동안 토요타 엔진 라인업의 30%를 커버하게 된다.

아직 출력의 수치는 공개되지 않았지만 적어도 효율 면에서는 지금보다 좋아질 게 확실하다. 반면 앳킨슨 사이클의 약점을 얼마나 메울 것인지가 토요타의 숙제이다. 토요타의 새 가솔린 엔진은 기본적으로 전기 모터가 보조하는 하이브리드에 적합한 유닛이다. 일반 모델에 적용된다고 하지만 차후 하이브리드가 나올 때 별도의 튜닝 없이 그대로 적용할 수 있다는 이점이 있다. 다른 장점으로는 터보 엔진 대비 제작 비용이 낮다. 토요타의 새 가솔린 엔진은 자연흡기 방식의 새 가능성을 제시하는 한편 효율과 생산 비용까지 고려한 해법이라고 할 수 있다.

 

http://www.global-autonews.com/board/view.php3?table=bd_019&gubun=1&idx=10123

Wait a minute,” you must be saying. “Haven’t we been hearing from the oil industry and from government and international agencies that worldwide oil production has been increasing in the last several years?” The answer, of course, is yes. But, the deeper question is whether this assertion is actually correct.

Here is a key fact that casts doubt on the official reporting:When the industry and the government talk about the price of oil sold on world markets and traded on futures exchanges, they mean one thing. But, when they talk about the total production of oil, they actually mean something quite different–namely, a much broader category that includes all kinds of things that are simply not oil and that could never be sold on the world market as oil

I’ve written about this issue of the true definition of oil before. But Texas oilman Jeffrey Brown has been bending my ear recently about looking even deeper into the issue. He makes a major clarifying point: If what you’re selling cannot be sold on the world market as crude oil, then it’s not crude oil. It’s such a simple and obvious point that I’m ashamed to have missed it. And, Brown believes that if we could find data that separates all these other non-crude oil things out, the remaining worldwide production number for crude oil alone would be flat to down from 2005 onward.

Brown says the current dual approach to price and supply is like asking the butcher the price of steak, and then, instead of finding out how much steak he has to sell, you inquire about how much beef in total he has on hand–which will, of course, include roasts and ground meat. And, then you proceed to calculate the butcher’s total supply of steak by lumping everything together and simply calling it steak.

“Basically, crude oil peaked [in 2005], but natural gas and natural gas liquids [including lease condensate] didn’t,” he believes. Natural gas production has continued to grow, and as it has, its coproducts have also grown–many of which have been lumped in with the oil production statistics.

The general message from the oil industry is that the free market should determine what’s best for our energy economy. There is much to dispute in this view. But, if we take the industry at its word, then we should see what Mr. Market has to say about all the things the industry lumps into total oil production.

Here’s what’s being added to underlying crude oil production and labeled as oil by the oil companies and reporting agencies:

 

• Biofuels – Essentially ethanol and biodiesel.
• Natural gas plant liquids – Butane, ethane, pentanes, propane and other non-methane components of raw natural gas.
• Lease condensate – Very light hydrocarbons gathered on leased production sites from both oil and natural gas wells, often referred to as “natural gasoline” because it can in a pinch be used to power gasoline engines though it doesn’t have the octane of gasoline produced at refineries.
• Refinery gain – The most puzzling addition of all to crude oil supply calculations. This is merely the increase in the volume of refinery outputs such as gasoline, diesel and jet fuel versus the volume of crude oil inputs. It is due entirely to the expansion of the liquids produced, but indicates no actual gain in energy. In fact, great gobs of energy are EXPENDED in the refinery process to give us what we actually want.

Let’s see if any of these non-oil things are acceptable as oil at major exchanges. Perhaps the most recognizable oil futures contract is the so-called Light Sweet Crude Oil contract. The exchange sponsoring that contract details in seven pages (of a much longer rulebook) what is acceptable to deliver to those who choose to take delivery on their contracts.

A search for three of the four items (and their subitems) listed above predictably comes up empty. But, the search for lease condensate produces a hit. Here’s what the exchange says about lease condensate when discussing acceptable delivery of oil: “For the purpose of this contract, condensates are excluded from the definition of crude petroleum.”

It’s true that some lease condensate does make its way into the crude oil production stream of refineries. But, its contribution is small and because of its chemical structure, it’s not very versatile compared to crude oil which can be refined not only into gasoline, but also diesel and jet fuel which are more valuable to refiners. Typically, crude oil blended with lease condensate is discounted to refiners in recognition of its lower value. (For the technically minded, this excellent article explains the growth and uses of lease condensate.)

It’s worth noting that the same futures exchange that sponsors the Light Sweet Crude Oil contract has separate contracts for biofuels.

Maybe across the ocean in Great Britain where the world’s other premiere crude oil futures contract is traded, the exchange is a bit more forgiving. Alas, the exchange sponsoring Brent Crude is exceedingly picky about what it will accept as proper delivery to those who take delivery on their contracts. The exchange accepts crude from only four North Sea fields: Brent, Forties, Oseberg and Ekofisk.

This look at what the market actually prices as oil tells us a lot about why Brent Crude, for example, has been trading at the highest average daily price ever for three years running, higher than even 2008, the year of the nominal all-time price peak.

So, if oil production hasn’t really been growing or at least not growing much in the last several years, what’s all the hoopla about? As petroleum geologist and consultant Art Berman likes to say, it’s a retirement party. There is one last, very difficult, costly and energy-intensive store of oil in low-quality deep shales containing crude. These shales–which are accessed using hydraulic fracturing or fracking–would never have been tapped if we were not already seeing a decline in the production of conventional, easy-to-get crude oil, the kind I refer to as Beverly Hillbillies bubbling crude as seen in the opening credits of the popular 1960s sitcom of that name.

The oil from deep shales (properly called “tight oil”) is allowing production to grow in the United States even as production sinks elsewhere in the world. Other countries having shales containing oil will likely try to exploit them. But, the retirement party will only be a few years later for them as a result.

Despite what the public is being led to believe, oil wells in deep shales suffer from very high annual production decline rates–40 percent per year compared to the worldwide average of 4 percent. This implies that swiftly rising production will be followed by equally swiftly declining production in a compressed time frame–a classic boom-bust pattern.

Okay, so what do the worldwide oil production numbers actually look like if we strip out all the non-oil componen

ts? Well, we don’t actually know. Brown has been unable to find such numbers anywhere. While the search continues, he thought he’d do a back-of-the-envelope calculation of his own. Here’s what he came up with:

Estimated Global Crude Oil Production

2002 to 2012 in million barrels per day
2002: 60
2003: 62
2004: 65
2005: 67
2006: 65
2007: 65
2008: 66
2009: 64
2010: 66
2011: 65
2012: 67

(For the technically minded, here are the assumptions behind his numbers: The global condensate to crude plus condensate ratio was 10 percent for 2002 to 2005–versus 11 percent for Texas in 2005–and condensate production increased at the same rate as the rate of increase in global dry processed gas production from 2005 to 2012, 2.8 percent per year, according to the U.S. Energy Information Administration. Crude oil is defined as oil with an API gravity of 45 or less per RBN Energy. Data are rounded off to two significant figures.)

This is really a guess based on incomplete information. But if Brown is roughly correct, his estimate explains why crude oil prices remain near record levels (based on the average daily price) despite all the talk about abundance and an oil renaissance in the United States. Simply put, there is no new abundance. Oil supplies remain constrained.

This does not deny that natural gas production continues to grow and that natural gas and its coproducts (butane, ethane, propane, and pentanes) are useful. But our current infrastructure is desperate for oil, particularly the transportation sector which is still dominated by oil derivatives. Some substitution in various areas including transportation and chemical feedstocks is taking place. But the rate is slow and the conversion can be costly.

Moreover, the energy content per unit of volume is significantly lower for natural gas plant liquids, between 30 and 40 percent lower than crude oil. To say that barrels of butane are equivalent to barrels of crude oil is more than just a rounding error.

Brown says the reason for the seeming stall in world oil production is actually quite simple. The remaining oil is harder to extract. We’ve taken the easy oil out of the Earth first. He explains that in the seven years ending in 2005, the oil industry invested $1.5 trillion on finding and developing new oil and natural gas fields and the capacity to refine and distribute the products that come from them. During that period oil production consistently rose. In the seven years after 2005 the industry spent $3.5 trillion for what Brown believes is no net increase in the production rate of actual, honest-to-god crude oil.

The notion that oil is becoming abundant all over again is contradicted by the levitating price and by the evidence that actual worldwide crude oil production is either flat or growing at an infinitesimal rate. But the industry doesn’t want the public or policymakers to know this because the current belief in abundance tends to slow down an energy transition away from fossil fuels and toward renewables.

That transition must come sooner or later. But the industry would like to see it come later. And, if policymakers are fooled by the abundance story, that transition will almost certainly come later.

http://peakoil.com/production/did-crude-oil-production-actually-peak-in-2005

승용 디젤, 최근 10년 동안 20% 효율 향상

영국의 SMMT(Society of Motor Manufacturers and Traders)는 지난 10년 동안 승용 디젤의 효율은 20% 이상 좋아졌다고 밝혔다. 2003년의 승용 디젤과 비교했을 경우 오염 물질 배출은 21%가 감소했고 연비는 27%가 좋아졌다.

작년 기준으로 영국에서 팔린 승용 디젤의 평균 CO2 배출량은 128.3g/km이었다. 이는 2000년 이후 30% 가까이 감소한 것이다. 그리고 승용 디젤의 평균 CO2 배출량이 130g/km 이하로 감소한 것도 작년이 처음이다. SMMT는 발전된 커먼레일과 피에조 인젝터, 스톱 스타트 같은 기술이 추가되면서 디젤의 효율이 계속 발전했다고 밝혔다.

 

http://www.global-autonews.com/board/view.php3?table=bd_009&gubun=1&idx=10279