Opportunities for renewable bioenergy using microorganisms

May combine two claims.

In an MEC, the energy output is H2, not electricity; a small amount of electrical energy is consumed to boost the potential high enough to produce H2 at the cathode; the net energy conversion to H2 is around 80%.

“In an MEC, the energy output is H 2 , not electricity.In fact, a small amount of electrical energy is consumed to boost the potential high enough to produce H 2 at the cathode (Cheng and Logan, 2007).In the end, the net energy conversion to H 2 is around 80% (Cheng and Logan, 2007).”

• cites Cheng and Logan, 2007Not checked yet

  Not checked in the free run.

May combine two claims.

The highest current density to date is 12 A/m2 of anode area, which is more than 10 times larger than typical rates only 5 years ago.

“the highest current density to date, $12 A/m 2 of anode area”

• Also stated in: § Rittmann: Bioenergy Opportunities Using Microorganisms 207 · plain

  “is more than 10 times larger than typical rates only 5 years ago (Lee et al., 2008a;Rittmann et al., 2008).”

• cites Lee et al., 2008aNot checked yet

  Not checked in the free run.

• cites Rittmann et al., 2008Not checked yet

  Not checked in the free run.

May combine two claims.

Photosynthetic microorganisms (algae or cyanobacteria) offer many significant advantages over high-oil plants for producing lipids for biodiesel, the most important being a roughly 100-fold higher yield of lipids per hectare.

“While high-oil plants are a good source of lipids for conversion to biodiesel, photosynthetic microorganisms (algae or cyanobacteria) offer many significant advantages.The most important one is the last row in the table: a roughly 100-fold higher yield of lipids per hectare.”

• cites Huber et al., 2006Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

To make a dent in global warming, bioenergy must be generated at a very high rate, since the world today uses $10 TW of fossil-fuel energy.

“To make a dent in global warming, bioenergy must be generated at a very high rate, since the world today uses $10 TW of fossil-fuel energy.”

Probably not a substantial claim: may not pass S4 (based).

It is the third risk (global climate change) that will have the most long-lasting and profound impact.

“Although the portent of catastrophe may seem more immediate from the first two risks, it is the third risk that will have the most long-lasting and profound impact.”

Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

We have the potential to reduce, or perhaps even eliminate, the third risk by converting to renewable, carbon-neutral energy sources that provide the energy services now obtained from fossil fuels.

“Fortunately, we have the potential to reduce, or perhaps even eliminate, the third risk by converting to renewable, carbon-neutral energy sources that provide the energy services now obtained from fossil fuels.”

Probably not a substantial claim: may not pass S2 (checkable), S4 (based). May combine two claims.

Bioenergy must be generated without inflicting serious damage on the environment or disrupting our food supply.

“And, it must do so without inflicting serious damage on the environment or disrupting our food supply.”

Probably not a substantial claim: may not pass S4 (based).

Certain algae (eukaryotes) or cyanobacteria (prokaryotes) have high lipid contents.

“Certain algae (eukaryotes) or cyanobacteria (prokaryotes) have high lipid contents.”

May combine two claims.

All photosynthesis on earth today captures about 140 TW of energy as biomass, only about 10 times today's energy demand of human society.

“On the other hand, all photosynthesis on earth today captures about 140 TW of energy as biomass (Hall and Rosillo-Calle, 1998); this is only about 10 times today's energy demand of human society.”

• cites Hall and Rosillo-Calle, 1998Not checked yet

  Not checked in the free run.

May combine two claims.

Fossil fuel consumption will rise by 60% or so in the next 25 years unless we can replace it on a very large scale.

“The fossil fuel we consume today is a very large amount, and our consumption will rise by 60% or so in the next 25 years unless we can replace it on a very large scale (Energy Information Administration, 2005).”

• cites Energy Information Administration, 2005Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Combustion of fossil fuels is adding about 6 Gton of carbon per year to the atmosphere as CO2.

“Combustion of fossil fuels is adding about 6 gigatons (Gton ¼ 10 9 tons) per year of C (in the form of CO 2 ) to the atmosphere each year (IPCC, 2007).”

• cites IPCC, 2007Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S4 (based).

Global warming can be slowed, and perhaps reversed, only when society replaces fossil fuels with renewable, carbon-neutral alternatives.

“Global warming can be slowed, and perhaps reversed, only when society replaces fossil fuels with renewable, carbon-neutral alternatives.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The ultimate source of energy in biomass is sunlight; photosynthesis captures the sun's energy and invests it in organic molecules.

“The second principle is that the ultimate source of energy is sunlight; photosynthesis captures the sun's energy and invests it in organic molecules, which are the carriers of the electrons and their energy.”

May combine two claims.

Total incident solar energy reaching the earth's surface is about 173,000 TW, which is 17,000 times what humans consume in fossil fuels.

“On the one hand, the total incident solar energy reaching the earth's surface is plentiful: $173,000 TW (Goldemberg and Johansson, 2004), which is 17,000 times what humans consume in fossil fuels.”

• cites Goldemberg and Johansson, 2004Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

If CO2 concentration continues to rise through 2100, average temperatures could rise by more than 3°C, ocean levels could rise up to 80 cm, most lake and reservoir levels will decline, extreme weather events will occur more frequently, and disease transmission may become more prevalent.

“Should the CO 2 concentration continue to rise through 2100, average temperatures could rise by more than 38C, ocean levels could rise up to 80 cm (nearly 3 feet), most lake and reservoir levels will decline, extreme weather events (e.g., hurricanes, drought, and flooding) will occur more frequently, and disease transmission may become more prevalent (IPCC, 2007).”

• cites IPCC, 2007Not checked yet

  Not checked in the free run.

May combine two claims.

Human society consumes about 13 TW of energy worldwide, and approximately 80% of that comes from burning fossil fuels.

“We now consume about 13 terrawatts (1 TW ¼ 10 12 W¼3.2EJ/year) of energy worldwide, and approximately 80% of that comes from burning fossil fuels (Goldemberg and Johansson, 2004).”

• cites Goldemberg and Johansson, 2004Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

Switching the source of biomass away from food crops to cellulosics, like switchgrass, could improve the energy output and lower the negative environmental costs.

“Switching the source of biomass away from food crops to cellulosics, like switchgrass, could improve the energy output and lower the negative environmental costs.”

May combine two claims.

H2 has the added benefit that it can be used as fuel for a conventional fuel cell, producing pollution-free electrical energy with an efficiency at least 50% higher than with a combustion-steam-turbine approach.

“However, H 2 has the very large added benefit that it can be used as the fuel for a conventional fuel cell, where electricity can be produced without combustion, producing pollution-free electrical energy with an efficiency at least 50% higher than with a combustion-steam-turbine approach.”

Classified as probably not a substantial claim. May combine two claims.

Today H2 gas is a large and mature industry, but virtually all hydrogen comes from reforming fossil fuels.

“Today, H 2 gas is a large and mature industry (about 10 8 m 3 /year in the United States), but virtually all of our hydrogen comes from reforming fossil fuels.”

May combine two claims.

An ideal technology for pretreatment is not yet at hand, and this places limits on what we can obtain from energy-conversion schemes.

“Hence, an ideal technology for pre-treatment is not yet at hand, and this places limits on the what we can obtain from energyconversion schemes.”

May combine two claims.

While direct contact of ARB with the anode may play a role, large-scale electron transfer uses soluble electron shuttles, conduction through the biofilm matrix, or a combination.

“While it is possible that direct contact of the ARB with the anode can play a role, large-scale electron transfer uses soluble electron shuttles, conduction through the biofilm matrix, or a combination (reviewed in Kato Marcus et al., 2007;Rabaey et al., 2005;Rittmann, 2006;Rittmann et al., 2008).”

• cites Kato Marcus et al., 2007Not checked yet

  Not checked in the free run.

• cites Rabaey et al., 2005Not checked yet

  Not checked in the free run.

• cites Rittmann, 2006Not checked yet

  Not checked in the free run.

May combine two claims.

Converting high-lipid plants to biodiesel has a higher net energy yield than converting crops to ethanol or butanol, because the long-chain aliphatics that comprise biodiesel are naturally immiscible in water.

“The net energy yield is higher this way than when converting crops to ethanol or butanol, since the long-chain aliphatics that comprise biodiesel are naturally immiscible in water.”

May combine two claims.

Methanogenesis constitutes a mature technology that can be adapted to most forms of residual biomass.

“It constitutes a mature technology that can be adapted to most forms of residual biomass.”

May combine two claims.

When combined with the fact that photosynthetic microorganisms do not require arable land and need not compete with food production, the ~100-fold higher yield means that microbial biodiesel has the potential to displace large amounts of fossil fuel for powering automobiles, trucks, airplanes, and power plants.

“When combined with the fact that photosynthetic microorganisms do not require arable land and need not compete with food production, the factor of $100-fold higher yield means that microbial biodiesel has the potential to displace large amounts of fossil fuel for powering automobiles, trucks, airplanes, and power plants.”

• AssumptionRests on an assumption: Photosynthetic microorganisms do not require arable land and need not compete with food production.

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Biodiesel directly replaces petroleum-based diesel fuel for transportation and other uses that demand a very high-density fuel.

“Biodiesel directly replaces petroleum-based diesel fuel for transportation and other uses that demand a very highdensity fuel.”

Probably not a substantial claim: may not pass S4 (based).

A conversion process today may capture 50% of the energy value from most residues.

“A conversion process today may capture 50% of the energy value from most residues.”

May combine two claims.

The concept of the MFC is proven, and making bioelectricity from organic fuel is not difficult.

“Thus, the concept of the MFC is proven, and making bioelectricity from organic fuel is not difficult.”

May combine two claims.

Sunflowers can produce up to about 1 m3 of lipids per hectare-year, but land cultivable in high-lipid plants is limited.

“Sunflowers can produce up to about 1 m 3 of lipids per hectare-year (Huber et al., 2006), but land cultivable in highlipid plants is limited.”

• cites Huber et al., 2006Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S4 (based).

Even if the technological barriers to cellulosic ethanol or bioethanol are overcome, they still will have only a small impact on reducing fossil-fuel consumption.

“Even if the technological barriers to cellulosic ethanol or bioethanol are overcome, they still will have only a small impact on reducing fossil-fuel consumption”

Probably not a substantial claim: may not pass S4 (based).

Once organic matter is bioavailable, a good conversion process captures almost 100% of the electrons in a useful energy output.

“Once the organic matter is bioavailable, a good conversion process captures almost 100% of the electrons in a useful energy output.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

An MFC is a special form of a fuel cell in which bacteria grow as a biofilm on the anode, catalyze the oxidation of organic compounds in or derived from biomass, and transfer electrons to the anode.

“As illustrated in Figure 2, an MFC is a special form of a fuel cell in which bacteria grow as a biofilm on the anode.The bacteria catalyze the oxidation of organic compounds either in or derived from biomass (after it has gone through fermentation), and the bacteria then transfer the electrons to the anode.”

May combine two claims.

Energy yield must increase by orders of magnitude over corn-to-ethanol to meet the goal of replacing petroleum use; a factor of 3 or 10 is too little.

“Clearly, energy yield must increase by orders of magnitude over corn-to-ethanol if we are to meet the goal of replacing petroleum use; a factor of 3 or 10 is simply too little.”

May combine two claims.

Changing the electron acceptor at the cathode from O2 to H+ allows H2 to be generated at the cathode, and this form of an MFC is called a microbial electrolytic cell (MEC).

“Among the most interesting opportunities is to change the electron acceptor at the cathode from O 2 to H þ .As is illustrated in Figure 3, this change allows H 2 to be generated at the cathode (Cheng and Logan, 2007;Lee et al., 2008a;Torres et al., 2007), and this form of an MFC is called a microbial electrolytic cell, or MEC.”

• cites Cheng and Logan, 2007Not checked yet

  Not checked in the free run.

• cites Lee et al., 2008aNot checked yet

  Not checked in the free run.

• cites Torres et al., 2007Not checked yet

  Not checked in the free run.

May combine two claims.

The challenge is to make bioelectricity at a fast enough rate that the capital costs of the MFC are offset by the value of the energy output; today's MFCs are far from fast enough to be commercially viable.

“The challenge is to make bioelectricity at a fast enough rate that the capital costs of the MFC are offset by the value of the energy output.Today's MFCs are far from fast enough to be commercially viable.”

May combine two claims.

The biggest advantage of an MFC is that it can generate combustion-less, pollution-free bioelectricity directly from the organic matter in biomass, eliminating the intermediate step of generating H2 for a conventional fuel cell.

“The biggest advantage of an MFC is that it can generate combustion-less, pollution-free bioelectricity directly from the organic matter in biomass.The intermediate step of generating H 2 for a conventional fuel cell is eliminated.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The most common approach for converting biomass to H2 is a bacterial fermentation process that is essentially a truncated version of methanogenesis.

“The most common approach for converting biomass to H 2 is a bacterial fermentation process that is essentially a truncated version of methanogenesis.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

The cost of methane production is still relatively high compared to the cost of natural gas from fossil-fuel deposits, but this situation should change as natural-gas costs rise and methanogenesis and pre-treatment technologies improve.

“The cost of methane production is still relatively high compared to the cost of natural gas from fossil-fuel deposits, but this situation should change as natural-gas costs rise and methanogenesis and pre-treatment technologies improve.”

May combine two claims.

Oils extracted from plants and photosynthetic microorganisms have the potential to produce much more significant quantities of biodiesel and are where serious attention must be directed.

“Oils extracted from plants and photosynthetic microorganisms have the potential to produce much more significant quantities of biodiesel and are where the serious attention must be directed.”

May combine two claims.

All approaches that rely on diverting food crops to biofuels will fail to meet the criteria because they compete with food production for high-grade arable land and because their bioenergy output is limited.

“All approaches that rely on diverting food crops to biofuels will fail to meet the criteria because they compete with food production for high-grade arable land and because their bioenergy output is limited.”

Probably not a substantial claim: may not pass S4 (based).

The technology for cellulosic ethanol or bioethanol is not close to being ready.

“However, the technology is not close to being ready.”

May combine two claims.

The simplest systems for growing photosynthetic microorganisms are large, open ponds or raceways; they keep down capital costs but offer limited control over growth conditions, evaporative water loss, and invasion of non-desired species.

“The simplest systems for growing photosynthetic microorganisms are large, open ponds or raceways (e.g., Borowitzka, 1999;Christi, 2007;Pulz, 2001).They keep down the capital costs, but offer limited control over the growth conditions, evaporative water loss, and invasion of non-desired species.”

• cites Borowitzka, 1999Not checked yet

  Not checked in the free run.

• cites Christi, 2007 sourceNot checked yet

  Not checked in the free run.

• cites Pulz, 2001Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Successful bioenergy faces two serious challenges: producing enough biomass-derived fuel to replace a significant fraction of the ~10 TW of energy generated today from fossil fuels, and producing the bioenergy without incurring serious damage to the environment and to the food-supply system.

“Successful bioenergy faces two serious challenges.The first is producing enough biomass-derived fuel to replace a significant fraction of the $10 TW of energy generated today from fossil fuels.The second challenge is producing the bioenergy without incurring serious damage to the environment and to the food-supply system.”

May combine two claims.

Arid and semi-arid regions seem to be the most favorable for locating production facilities for microbial biodiesel, and they can have the added benefit of not taking high-grade arable land out of service.

“Arid and semi-arid regions seem to be the most favorable, and they can have the added benefit of not taking out of service highgrade arable land.”

May combine two claims.

The non-lipid biomass can be converted to methane, hydrogen, or electricity by the microbial conversion processes.

“In addition, the non-lipid biomass can be converted to methane, hydrogen, or electricity by the microbial conversion processes.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Microbial methane production is well established, but can be improved; the other energy outlets (hydrogen and electricity) are very promising but still at the research stage.

“Microbial methane production is well established, but can be improved.The other energy outlets are very promising, but still at the research stage.”

• AssumptionRests on an assumption: Microbial methane production is well established.

May combine two claims.

Enclosed photobioreactor systems can overcome the limitations of open ponds but incur increased capital costs.

“Enclosed photobioreactor systems (e.g., Borowitzka, 1999;Christi, 2007;Hai et al., 2000;Morita et al., 2001;Pulz, 2001) can overcome the limitations of the open ponds, but incur increased capital costs.”

• cites Borowitzka, 1999Not checked yet

  Not checked in the free run.

• cites Christi, 2007 sourceNot checked yet

  Not checked in the free run.

• cites Hai et al., 2000Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S4 (based).

Fossil-fuel use will decline only when society comes up with renewable, C-neutral alternatives in very large quantity.

“Fossil-fuel use will decline only when society comes up with renewable, C-neutral alternatives in very large quantity.”

Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

One of the best options in the long term is bioenergy, in which the sun's energy is captured as biomass and converted to useful energy forms.

“One of the best options in the long term is bioenergy, in which the sun's energy is captured as biomass and converted to useful energy forms.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Of the many bioenergy options on the table today, most fail on both counts; however, several microorganism-based bioenergy options have the potential to produce renewable energy on a large scale, without disrupting the environment or human activities.

“Of the many bioenergy options on the table today, most fail on both counts.However, several microorganism-based bioenergy options have the potential to produce renewable energy on a large scale, without disrupting the environment or human activities.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Society generates biomass residuals from agricultural, animal, and industrial operations, as well as from human wastes; these residuals have large energy value and can replace a significant portion of our use of fossil fuel.

“Society generates biomass residuals from agricultural, animal, and a variety of industrial operations, as well as from human wastes.These residuals have large energy value and can replace a significant portion of our use of fossil fuel.”

Probably not a substantial claim: may not pass S2 (checkable). May combine two claims.

Even if 50% of the biomass is lipids captured for biodiesel, the other 50% of the biomass should be converted to useful products, most obviously to CH4, H2, or electricity by microbial conversion processes.

“Even if 50% of the biomass is lipids that are captured for biodiesel, the other 50% of the biomass should be converted to useful products.The most obvious use for the carbohydrate and protein fractions of the microbial biomass is conversion to CH 4 , H 2 , or electricity by the microbial conversion processes described earlier.”

May combine two claims.

Uncontrolled evaporative losses are not allowable, leading to the use of closed photobioreactor systems.

“Clearly, uncontrolled evaporative losses are not allowable, and this leads to the use of closed photobioreactor systems.”

Probably not a substantial claim: may not pass S4 (based).

The only hope for achieving a major slowing and ultimately a reversal in net CO2 accumulation is greatly reducing the combustion of fossil fuels.

“The only hope for achieving a major slowing and ultimately a reversal in net CO 2 accumulation is greatly reducing the combustion of fossil fuels.”

Classified as probably not a substantial claim.

On top of producing biodiesel, photosynthetic microorganisms produce a lot more energy value when they become a major feedstock for the other microbial energy-conversion processes.

“On top of producing biodiesel, photosynthetic microorganisms produce a lot more energy value when they become a major feedstock for the other microbial energy-conversion processes.”

May combine two claims.

Growth rates of photosynthetic microorganisms will be higher if a concentrated stream of CO2 is available, so colocation of photobioreactors near a power plant is desirable.

“While it is possible to obtain CO 2 from the atmosphere, growth rates will be higher if a concentrated stream of CO 2 is available.Therefore, colocation of the photobioreactors near a power plant is desirable.”

• AssumptionRests on an assumption: Growth rates of photosynthetic microorganisms will be higher if a concentrated stream of CO2 is available.