Home Bio-Gas Digesters, and other Home Energy

Generating your own energy at home is becoming more popular. Mainly because it is becoming more economical, and provides a sense of energy independence that is otherwise lacking. Take the home biogas digester in the photo:

Sintex Industries, a plastics and textiles manufacturer in Gujarat, India, is betting it can find profit in human waste. Its new biogas digester turns human excrement, cow dung, or kitchen garbage into fuel that can be used for cooking or generating electricity, simultaneously addressing two of India's major needs: energy and sanitation.

Sintex's digester uses bacteria to break down waste into sludge, much like a septic tank. In the process, the bacteria emit gases, mostly methane. But instead of being vented into the air, they are piped into a storage canister.

A one-cubic-meter digester, primed with cow dung to provide bacteria, can convert the waste generated by a four-person family into enough gas to cook all its meals and provide sludge for fertilizer. A model this size costs about $425 but will pay for itself in energy savings in less than two years. That's still a high price for most Indians, even though the government recently agreed to subsidize about a third of the cost for these family-sized units. "We want to create a new industry for portable sanitation in India that's not available now," says S.B. Dangayach, Sintex's managing director. ___Source

The most popular current method of home energy generation is photovoltaics. Home wind turbines are also becoming popular in high-wind locations. Home biodiesel and biogas fermentation and synthesis are less common, but perhaps that is because no one has made them easy for homeowners.

Cattle farmers are more likely to begin finding ways to make energy and fertilizer from farm waste and animal manure. Expect ranchers to do the same. The name of the game is profitability, and that means using what you have, and making the most of it.

Biofuels: India and Canada Collaborate

The tremendous potential of biofuels and biomass are barely understood by policy-makers and planners. But technical experts from Canada and India are collaborating to bring biofuels out of the closet.

India says Saskatchewan University will help it in advanced research into second-generation technologies for biofuels...."Agri residues such as bagasse, wheat straw, sorghum and maize straws, leaf litter and various other plant biomass, which have not been adequately utilized for energy production, provide ample opportunities for use as biofuels," said S.A. Patil, director of the Indian institute.

"We have entered into an agreement with the Saskatchewan University in Canada for four specific projects on biofuels."...He said one project is for the conversion of biomass to ethanol using different technologies such as acid hydrolysis and supercritical carbon dioxide to produce fermentable sugars, which will be converted into ethanol via fermentation. Another project is production of biodiesel from jatropha and other oils using ultrasound technology.

Patil said the other two projects are for the conversion of waste biomass into biogas and fertilizers and for biomass conversion into hydrogen through supercritical water process.___Source__via biopact

Small-scale biorefinery projects promise to bring energy production down to a scale where ordinary entrepreneurs, businesspersons, and labourers can benefit--unlike megascale projects of big oil, big coal, and big nuclear.

“Biorefineries producing not just fuel, but also chemicals and energy can be built throughout the United States, utilizing locally available cellulosic biomass feedstocks. These small-scale projects will use a wide variety of feedstocks and test many different technologies for fuel and coproducts, providing experience and data that can be transferred to full-size, commercial-scale biorefineries....“A recent BIO report, ‘Achieving Sustainable Production of Agricultural Biomass for Biorefinery Feedstock,’ showed that through increased use of no-till agriculture farmers can produce and collect crop residues in an economically and environmentally sustainable way. The report identifies available techniques for sustainable harvesting of agricultural residues – such as corn stover and cereal straws – for use as feedstocks for advance biofuel biorefineries. The report is available at http://bio.org/ind/biofuel/SustainableBiomassReport.pdf.

The aspect of biomass and biofuels that seems to distress so many mega-scale energy analysts--its distributed, non-concentrated nature--is actually a good thing for small scale entrepreneurs, and small-town and small-village workers. Because biomass is so "spread out" over wide geographical areas, it lends itself far better to small-scale, local ventures. Faux environmentalists will fail to understand that feature, whereas true environmentalists who care about local economies, will seize sustainable biomass/biofuels as an important issue to promote.

Energy Briefs

ZeaChem and Coskata are promising high volume bio-ethanol at US $1 a gallon, by 2012. New Canadian startup Syntec promises even cheaper bio-ethanol--40 cents a gallon.

The Syntec B2A technology, initially developed at the University of British Columbia, is focused on second-generation cellulosic ethanol production. The Syntec process parallels the low-pressure catalytic synthesis process used by methanol producers. Syntec's innovative technology uses any renewable waste biomass such as hard or soft wood, sawdust or bark, organic waste, agricultural waste (including sugar cane bagasse and corn stover), and switch-grass to produce syngas. This syngas, comprised of carbon monoxide and hydrogen, is then scrubbed and passed through a fixed bed reactor containing the Syntec catalysts to produce ethanol, methanol and higher order alcohols. The Syntec technology can also produce alcohols from biogas (sourced from anaerobic digestion of manure and effluent), landfill gas or stranded methane.__NextEnergy

Better information regarding the efficiencies of biofuels indicates that recent articles published in Science that were extremely critical of biofuels efficiencies, were highly misleading. The category of "biofuels" is too wide, varied, and inclusive to be susceptible to simplistic analyses such as were presented in the articles referred to by the link above.

The waste heat from internal combustion engines used in passenger and freight vehicles could be put to better use than heating the atmosphere. Honda is looking to put heat-mining technology in its hybrid vehicles.

Honda is exploring the use of a Rankine cycle co-generation unit to improve the overall efficiency of a hybrid vehicle by recapturing waste exhaust heat from the internal combustion engine and converting it to electricity to recharge the battery pack. Honda engineer Kensaku Yamamoto presented an overview of the work in a paper at the 2008 SAE Hybrid Vehicle Technology Symposium in San Diego.

Test results showed that in 100 kph (62 miles/hour) constant-speed driving, the use of the Rankine cycle improved the thermal efficiency of the engine by 3.8%. In the US highway cycle, the Rankine cycle system regenerated three times as much energy as the vehicle’s regenerative braking system.___GCC __via_Ecogeek

Hopeful discoveries in gas storage technology may make gas-phase powered vehicles more feasible.

In the case of gas storage, MOFs offer the crucial advantage of soaking up some of the gas pressure exerted by the molecules. This makes hydrogen derived from non-fossil energy sources such as biomass, or even genetically engineered plants, potentially viable as a fuel for cars while the alternative of pressurised canisters is not, says Ferey. The key difference is that the amount of gas stored in a conventional cylinder at say 200 atmospheres pressure could be accommodated in an MOF vessel of the same size at just 30 atmospheres, which is much safer...The porous nature of MOFs enables them to be exploited in quite another way as catalysts to accelerate chemical reactions for a wide variety of materials production and pharmaceutical applications, although this field, as Ferey noted, is still in its infancy. ____Source

This technology will likely require another ten or more years to become available for production model vehicles. By then, it is likely that series hybrids powered by bio:fuel cells will be common, incorporating a number of different ways of capturing waste heat to re-charge auxiliary batteries and super-capacitors.

Passive Cooling--Ancient and Modern

The ancients used passive cooling to maintain internal comfort when outside temperatures soared--long before the invention of air conditioning. Now an an Indian Engineer-Designer team wants to bring back passive solar cooling on a larger scale.

Jyotirmay Mathur of the Mechanical Engineering Department, at the Malaviya National Institute of Technology, in Jaipur, together with architect and urban designer Rajeev Kathpalia of Vastu Shilpa Consultants, in Ahmedabad, point out that the development of energy-efficient, and even passive, cooling systems for buildings is essential in the light of environmental pressures and costs. In the past, they point out, building designers had to rely on natural ways and means for maximising comfort inside buildings.

The team has now reasoned that two distinct technologies - the so-called solar chimney for roof-based based ventilation and a wind tower that provides a draft of air could be combined simply and effectively into a passive cooling system.

They have designed a building that incorporates a multi-storey wind tower clad with heavy stone panels which produces an upward draft of air drawn into the building passively and cooled by the massive tonnage of the stone classing. The air flows through the rooms and corridors and accumulates heat as it does so. This is then carried to the top of the building and vented with large black, thermally conducting, panels providing a way to shed the heat quickly from the top of the building. The result is a reduction in internal temperature of several degrees. The resulting temperature drop would be sufficient to improve the comfort of people in the building without the need for powered air conditioning that is both expensive to install, maintain and operate.___Source

Passive solar building design is part of the Sustainable Building approach to Green Building that has been followed loosely and sporadically for decades by a few builders. These practises are much more effective in a dry climate

Nuclear Power News

Russian energy company Gazprom is proposing using both floating nuclear power plants and submerged nuclear reactors, to provide power for undersea oil and gas field development.

Russia recently inked a deal with Bulgaria to build a couple of new nuclear power reactors, investors in Alberta have been looking hard at using nuclear power in the oil sands region, and this morning I came across two stories about floating or submerged nuclear power plants for both Norway and the Gulf Cooperation Council (GCC) states.____Source

Meanwhile, China is slowly adding nuclear power capacity to its overall power ensemble--which is incredibly top-heavy with coal at this time.

The country's nuclear power plants generated 62.9 billion kWh last year, representing an increase of 14.6 percent compared with a year earlier, according to the Commission of Science Technology and Industry for National Defense.

"China's nuclear power industry has experienced a transition from appropriate development to accelerated development," Han Wenke, deputy director of the Energy Research Institute under the National Development and Reform Commission (NDRC), said.

At present, nuclear power accounts for less than 2 percent in the country's total power generation.

The authorities plan to increase the country's nuclear power capacity to 40,000 mW by 2020, which would take the sector's share of the total power industry to 4 percent.___Source

Nuclear fusion is the long term goal. Nuclear fission will be an important part of the energy mix for the next century, until fusion and geothermal achieve widespread utility.

Biomass can easily be turned to "bio-coal" carbon. Now, that biomass carbon can be used to drive fuel cells. The only output is pure CO2--the favoured food for plants!

Last year, the director of the Department of Colloid Chemistry at the Max Planck Institute of Colloids and Interfaces, Prof Dr Markus Antonietti, developed an innovative technique with which any type of biomass can be converted into renewable and climate friendly 'designer coal'. Uses for the carbon are plenty, but professor Antonietti confessed that he and his researchers are part of a growing group of scientists who dream of a Direct Carbon Fuel Cell (DCFC) and a green carbon economy. As its name implies, a DCFC converts elemental carbon into electricity directly, and in a hyper-efficient way - the cells have almost twice the efficiency of most other types of fuel cells and double that of fossil fuel power plants.

...The reaction yields 80 percent of the carbon–oxygen combustion energy as electricity, yet no burning of the carbon takes place. DCFCs for stationary applications provide up to 1 kilowatt of power per square meter of cell surface area — a rate sufficiently high for practical applications. Some developers are designing DCFCs for mobile applications that can deliver energy densities in the range of 1,000–2,000 Wh/kg, far higher than any advanced battery.

...DCFC technology has several potential benefits over other fuel cells. First, it can use a wide variety of very abundant low cost carbonaceous fuels including coal, coke, tar, biomass and organic waste. Conventional fuel cells typically operate on gaseous fuels. The fuel (natural gas, propane, ethanol, etc.) is reformed to a hydrogen syngas, which is fed into the fuel cell stack. The DCFC, however, can operate directly on solid carbon fuel, which is stable, easy to store, handle and transport. DCFCs don't require the construction of an entirely new and expensive infrastructure - which is the case for hydrogen - nor do they lose the energy needed to turn fuel into gas.

Secondly, unlike hydrogen or methanol fuel cells, DCFC use no catalyst or costly noble metals like platinum. This cuts costs, and should increase reliability.___Biopact

This development has all the makings of a fuel cell revolution. Hydrogen has always been a bad bet for mobile and de-centralised fuel cell applications. It is time to grow out of that childish hydrogen fantasy.

Cross-posted from Al Fin

France, Japan, US Collaborate on Reactor Design

Japan, France, and the US are expanding cooperation on the Sodium Cooled Fast Reactor Prototype (SFR). The SCFR is among the projects in the Gen IV Reactor Forum.

The sodium-cooled fast reactor uses liquid sodium to transfer heat to a working fluid for power generation. The SFR is designed for management of high-level wastes and, in particular, management of plutonium and other actinides (the radioactive elements that lie between actinium and lawrencium on the periodic table, with atomic numbers 89 - 103).

Important safety features of the system include a long thermal response time, a large margin to coolant boiling, a primary system that operates near atmospheric pressure, and intermediate sodium system between the radioactive sodium in the primary system and the power conversion system. Water/steam and carbon-dioxide are being considered as the working fluids for the power conversion system in order to achieve high-level performances in thermal efficiency, safety and reliability.

...The SFR’s fast spectrum makes it possible to use available fissile and fertile materials (including depleted uranium) considerably more efficiently than thermal spectrum reactors with once-through fuel cycles.

The envisaged SFR capability to efficiently and nearly completely consume trans-uranium as fuel would reduce the actinide loadings in the high-level radioactive waste it produces, according to a summary of the technology by the GIF. Such reductions would bring benefits in the radioactive waste disposal requirements associated with the system and enhance its non-proliferation attributes. Reducing the capital cost and improving passive safety, especially under transient conditions, are the major challenges for the SFR system.___Green Car Congress

Gen-IV reactors will be safer and more reliable--and produce less dangerous waste products--than conventional nuclear fission generators currently used. The SFR appears to have important advantages over other Gen-IV designs.

The three nation collaboration aims to standardise reactor and power plant design, and to facilitate conversion of older facilities to newer SFR plants.