August 27, 2008

Reforming hydrogen from ethanol

There are so many "discoveries" these days I would hate to have to handicap the winners. Some reports inspire confidence that we are on track to make the leap from today to tomorrow - and the next day.

One thing to know about ethanol is that it is a carrier for hydrogen. That means you could deliver ethanol from origin to distribution point and extract the hydrogen from the ethanol. The question has always been how do you do it without expending excess energy or spending money on expensive reforming processes?

Below is an article from Biopact that demonstrates how research focused to answer such questions can lead to discoveries with game-changing results.

What it means is that gas stations that currently service demand for petroleum products but that could eventually sell blends of ethanol may provide a smooth transition to a hydrogen energy economy. They will be able to cheaply reform hydrogen from their stores of ethanol to fill clean hydrogen fuel cell vehicles.

Scientists develop cheap catalyst for hydrogen production from biofuels

Scientists from Ohio State University have developed a very cheap non-precious metal catalyst that converts biofuels like ethanol into hydrogen with an efficiency of up to 90%. This development opens up a future of decentralised, on-the-spot hydrogen production for use in fuel cell cars. What is more, it makes the prospect of a carbon-negative transportation fuel more realistic.

The rationale behind converting biofuels to hydrogen is simple: you no longer need an expensive hydrogen transportation infrastructure, because you can transport the fuel safely in the form of the biofuel and turn it into hydrogen wherever you want; using hydrogen in fuel cells is also far more efficient than using biofuels in internal combustion engines.

Best of all, when the carbon dioxide that is released during the conversion process is captured and sequestered, a truly carbon-negative fuel is obtained. The more you were to use of this fuel, the more you were to combat climate change, because you would be actively removing CO2 from the atmosphere (earlier post, and see schematic).

Umit Ozkan, professor of chemical and biomolecular engineering at Ohio State University, says that the new catalyst is much less expensive than others being developed around the world, because it does not contain precious metals, such as platinum or rhodium. Rhodium is used most often for this kind of catalyst, and it costs around $9,000 an ounce. The new catalyst costs around $9 a kilogram - that's about 35,000 times less.

The new catalyst allows us to over come the many practical issues that need to be resolved before we can use hydrogen as fuel - how to make it, how to transport it, how to create the infrastructure for people to fill their cars with it.
Our research lends itself to what's called a 'distributed production' strategy. Instead of making hydrogen from biofuel at a centralized facility and transporting it to gas stations, we could use our catalyst inside reactors that are actually located at the gas stations. So we wouldn't have to transport or store the hydrogen - we could store the biofuel, and make hydrogen on the spot. - Professor Umit Ozkan

The catalyst is inexpensive to make and to use compared to others under investigation worldwide. Those others are often made from precious metals, or only work at very high temperatures. Precious metals have high catalytic activity and - in most cases - high stability, but they're also very expensive. The scientists' goal from the outset was to come up with a precious-metal-free catalyst, one that was based on metals that are readily available and inexpensive, but still highly active and stable. This sets Ozkan's team apart from most of the other groups in the world.

The new dark gray powder is made from tiny granules of cerium oxide - a common ingredient in ceramics - and calcium, covered with even smaller particles of cobalt. It produces hydrogen with 90 percent efficiency at 660 degrees Fahrenheit (around 350 degrees Celsius) - a low temperature by industrial standards.

Whenever a process works at a lower temperature, that brings energy savings and cost savings. Also, if the catalyst is highly active and can achieve high hydrogen yields, one doesn’t need as much of it. That will bring down the size of the reactor, and its cost.

The process starts with a liquid biofuel such as ethanol, which is heated and pumped into a reactor, where the catalyst spurs a series of chemical reactions that ultimately convert the liquid to a hydrogen-rich gas.

One of the biggest challenges the researchers faced was how to prevent "coking" -- the formation of carbon fragments on the surface of the catalyst. The combination of metals - cerium oxide and calcium - solved that problem, because it promoted the movement of oxygen ions inside the catalyst. When exposed to enough oxygen, the carbon, like the biofuel, is converted into a gas and gets oxidized; it becomes carbon dioxide.

At the end of the process, waste gases such as carbon monoxide, carbon dioxide and methane are removed, and the hydrogen is purified. To make the process more energy-efficient, heat exchangers capture waste heat and put that energy back into the reactor. Methane recovered in the process can be used to supply part of the energy.

Though this work was based on converting ethanol, Ozkan's team is now studying how to use the same catalyst with other liquid biofuels. Her coauthors on this presentation included Ohio State doctoral students Hua Song and Lingzhi Zhang.

The research was funded by the U.S. Department of Energy.

Ohio State University: A Better Way to Make Hydrogen from Biofuels - August 20, 2008.

technorati , , , , , , , ,

August 22, 2008

U.S. Demand for Renewable Power

The U.S. Department of Energy / Energy Efficiency and Renewable Energy has published a June 2007 chart of the states whose legislatures have mandated that a certain percentage or volume of their electricity will come from renewable sources - wind, solar, geothermal, hydro, tidal, and bioenergy.

This policy is called a "renewable portfolio standard" and it is interesting to note that a federal RPS was considered for inclusion in the 2007 Energy Independence and Security Act (EISA). It did not pass because the Southern states would be at a disadvantage meeting the standard because of the lack of wind and solar resources. Should the march of state-by-state standards be implemented throughout the South - like the new RPS for Virginia (enacted April, 2007) and North Carolina (enacted August, 2007) - the bulk of the renewable power would have to come from biomass.

Florida is in full legislative consideration of a large Renewable Portfolio Standard. Their charismatic governor, Charlie Crist, advocates a 20% mandate.

The U.S. Department of Energy's version of the map below is imaged mapped to an expanded description of each state's policy. Their listing includes links to the administering organizations.

A renewable portfolio standard (RPS) is a state policy that requires electricity providers to obtain a minimum percentage of their power from renewable energy resources by a certain date. Currently there are 24 states plus the District of Columbia that have RPS policies in place. Together these states account for more than half of the electricity sales in the United States.

Four other states, Illinois, Missouri, Virginia, and Vermont, have nonbinding goals for adoption of renewable energy instead of an RPS.

Summary of State Renewable Portfolio Standards
The following table gives a rough summary of state renewable portfolio standards. Percentages refer to a portion of electricity sales and megawatts (MW) to absolute capacity requirements. Most of these standards phase in over years, and the date refers to when the full requirement takes effect.

*Three states, Missouri, Virginia, and Vermont, have set voluntary goals for adopting renewable energy instead of portfolio standards with binding targets.

technorati , , ,

July 8, 2008

Greener buildings in our future

What is the most environmentally sustainable construction material available for erecting homes and buildings? If net carbon emissions per ton of material is the key measurement, the answer is framing studs and medium density fiberboard made from wood.

That is one of the key messages from a new issue of Eco-link, a publication of the Temperate Forest Foundation's Research and Education division, which focuses on Consumer Choices; Greening Your Purchases.

How much more efficient is wood over the other materials when all steps in their manufacture is taken into consideration? Taking a look at the following chart from the U.S. Environmental Protection Agency gives us the answer to this question.

At the extreme, virgin aluminum requires 137.3 times more carbon emissions per ton of material than wood.

Of course every material has its specific uses. You wouldn't build a skyscraper with wood beams and little glass. But with new Leadership in Energy and Environmental Design LEEDs® rating systems receiving much more prestige among builders, any material that raises energy efficiency while lowering its carbon materials footprint is going to garner more ratings credit.

Combined with the insulation superiority of wood over other more modern materials (steel and glass) that require much more energy to heat and cool, wood would appear to be on the verge of making a comeback.

Joseph Lstiburek, Ph.D., P.Eng., is a principal of Building Science Corporation LLC and an ASHRAE Fellow. He has twenty-five years of experience in design, construction, investigation, and building science research. Through the Department of Energy's Building America program, Dr. Lstiburek has forged partnerships with designers, builders, developers, materials suppliers and equipment manufacturers to build higher performance homes across the U.S. His company specializes in building homes that require less energy to heat and cool. Their designs utilize wood for structural support and fiberboard sheathing of surfaces. His presentations include one that advocates that Wood is Good.

Climate-specific design and construction of high performance homes is a cornerstone of all BSC work. We recently modified both our criteria and our North American map for the hygro-thermal regions. The changes are not drastic but they are important because they make our criteria and map align with the International Energy Conservation Code (IECC) Climate Zones as developed by the Department of Energy. Whenever the building science community and the code community get on (literally) the same page, this is good news for builders of any homes, but particularly those that build climate-tuned, high performance homes.

Treated wood in an assembly performs better in a fire than steel studs, and wood is not thermally conductive. Don't believe me? Visit New Zealand and Australia and check out some of their 10- and 20-story buildings. They use concrete structural frames and treated wood frame wall infill assemblies with gypsum board linings on the inside and outside of the wood frame assembly covered with open rain screen vented fiber cement panels. These structures are exceptionally energy efficient, low cost and sustainable.

Sustainable management of wood resources, with forests being a significant part of the carbon sequestration equation, will play and increasingly important role in our climate change future.

technorati , ,

January 24, 2008

Surprising MPG results for low blends of ethanol

One of the "knocks" on ethanol (pun intended) is that for all the performance and emissions improvement that it provides as an oxygenate for gasoline, the more that you blend in, the lower the miles per gallon you should expect. For the lay person, that means more frequent stops to the filling station - roughly one extra fill-up for every three the vehicle currently requires. Even at price parity the annoyance of increased stops may deter some from using E85 (which is 85% ethanol/15% gasoline).

While it may be true for high blends of ethanol a new study provides laboratory evidence that E20 and E30 blends actually improved MPG on the automobiles tested!

The University of North Dakota Energy & Environmental Research Center (EERC) and the Minnesota Center for Automotive Research (MnCAR) conducted vehicle fuel economy and emission testing on four 2007 model vehicles. The vehicles tested included a Chevrolet Impala flex-fuel and three non-flex-fuel vehicles: a Ford Fusion, a Toyota Camry, and a Chevrolet Impala.

Highway Fuel Economy Test (HWFET) testing on ethanol blend levels of E20 in the flex-fuel Chevrolet Impala, E30 in the non-flex-fuel Ford Fusion and Toyota Camry, and E40 in the non-flex-fuel Chevrolet Impala resulted in measured miles-per-gallon fuel economy greater than predicted based on per-gallon fuel Btu content. It is notable that the non-flex-fuel vehicles obtained greater fuel economy at higher blends of ethanol than the unleaded gasoline. In the case of the flex-fuel Chevrolet Impala, the highway fuel economy was greater than calculated for all tested blends, with an especially high peak at E20.

While only three non-flex-fuel vehicles were tested in this study, there is a strong indication that non-flex-fuel vehicles operated on optimal ethanol blend levels, which are higher than the standard E10 blend, can obtain better fuel mileage than on gasoline. The Ford Fusion and Toyota Camry obtained a HWFET mileage on E30 of 1% greater than on Tier 2 gasoline; the flex-fuel Chevrolet Impala showed a HWFET mileage of 15% on E20 better than Tier 2 gasoline, as shown in Figure ES-1.

Exhaust emission values for nonmethane organic gases (NMOG), nitrogen oxides (NOx), and carbon monoxide (CO) obtained from both the FTP-75 and the HWFET driving cycles were at or below U.S. Environmental Protection Agency (EPA) Tier 2, light-duty vehicle, Bin 5 levels of 0.090, 0.07, and 4.2 grams/mile, respectively, for all vehicles tested, with one exception. The flex-fuel Chevrolet Impala exceeded the NMOG standard for the FTP-75 on E20 and Tier 2 gasoline.

It should be noted that it will take time to deploy E85 pumps in significant numbers throughout the U.S. During that time, the automobile manufacturers will be working not only on hybrid vehicles which improve MPG by sharing the load with plug-in and battery charges, but they will also be working on improving flex-fuel and ethanol combustion technology.

The automobile industry has had 100 years to fine tune their engines to work on cheap gasoline. Now that there is a mandate in the Energy Bill of 2007 to increase gasoline MPG significantly there will be significant research invested in improving performance on all kinds of fuels and configurations. Perhaps the relative energy content of the fuel will cause less concern to the driving public as the frequency of fuel fill-ups declines.

As far as emissions are concerned, that will be an area of focus for car manufacturers as well. They have innovated catalytic converters and carburetor designs in the past. There is no reason to expect less from them in the future as public demands turns to competitive environmental performance.

We will doubtless see many breakthroughs as thinking outside the fossil fuel paradigm box explodes.

technorati , , , ,