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Monthly Archives: December 2012

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A new concept known as “hydraulic fracturing “ to enhance the recovery of land fill gas from new and existing land fill sites have been tested jointly by a Dutch and  Canadian companies. They claim it is now possible to recover such gas economically and liquefy them into Bio-LNG to be used as a fuel for vehicles and to generate power.

Most biofuels around the world are now made from energy crops like wheat, maize, palm oil, rapeseed oil etc and only  a minor part is  made from waste. But such a practice in not sustainable in the long run considering the anticipated food shortage due to climate changes.   The EU wants to ban biofuels that use too much agricultural land and encourage production of biofuels that do not use food material but waste materials. Therefore there is a need to collect methane gas that is emitted by land fill sites more efficiently and economically and to compete with fossil fuels.

There are about 150,000 landfills in Europe with about 3–5 trillion cubic meters of waste (Haskoning 2011). All landfills emit landfill gas; the contribution of methane emissions from landfills is estimated to be between 30 and 70 million tons each year. Landfills contributed an estimated 450 to 650 billion cubic feet of methane per year (in 2000) in the USA. One can either flare landfill gas or make electricity with landfill gas. But it is prudent to produce the cleanest and cheapest liquid biofuel namely “Bio-LNG”.

Landfill gas generation: how do these bugs do their work?

Researchers had a hard time figuring out why landfills do not start out as a friendly environment for the organisms that produce methane. Now new research from North Carolina State University points to one species of microbe that is paving the way for other methane producers. The starting bug has been found. That opens the door to engineer better landfills with better production management. One can imagine a landfill with real economic prospects other than getting the trash out of sight. The NCSU researchers found that an anaerobic bacterium called Methanosarcina barkeri appears to be the key microbe. The following steps are involved in the formation of landfill gas is shown in the diagram

Phase 1: oxygen disappears, and nitrogen

Phase 2: hydrogen is produced and CO2 production increases rapidly.

Phase 3: methane production rises and CO2 production decreases.

Phase 4: methane production can rise till 60%.

Phases 1-3 typically last for 5-7 years.

Phase 4 can continue for decades, rate of decline depending on content.

Installation of landfill gas collection system

A quantity of wells is drilled; the wells are (inter) connected with a pipeline system. Gas is guided from the wells to a facility, where it is flared or burnt to generate electricity. A biogas engine exhibits 30-40% efficiency. Landfills often lack access to the grid and there is usually no use for the heat.

The alternative: make bio-LNG instead and transport the bio-LNG for use in heavy-duty vehicles and ships or applications where you can use all electricity and heat.

Bio-LNG: what is it?

Bio-LNG is liquid bio-methane (also: LBM). It is made from biogas. Biogas is produced by anaerobic digestion. All organic waste can rot and can produce biogas, the bacteria does the work. Therefore biogas is the cheapest and cleanest biofuel  that can be generated without competing  with food or land use. For the first time there is a biofuel, bio-LNG, a better quality fuel than fossil fuel.

The bio-LNG production process

Landfill gas is produced by anaerobic fermentation in the landfill. The aim is to produce a constant flow of biogas with high methane content. The biogas must be upgraded, i.e. removal of H2S, CO2 and trace elements;

In landfills also siloxanes, nitrogen and Cl/F gases. The bio-methane must be purified (maximum 25/50ppm CO2, no water) to prepare for liquefaction. The cold box liquefies pure biomethane to bio-LNG

Small scale bio-LNG production using smarter methods.

•Use upgrading modules that do not cost much energy.

•Membranes which can upgrade to 98-99.5 % methane are suitable.

•Use a method for advanced upgrading that is low on energy demand.

•Use a fluid / solid that is allowed to be dumped at the site.

•Use cold boxes that are easy to install and low on power demand.

•Use LNG tank trucks as storage and distribution units.

•See if co-produced CO2 can be sold and used in greenhouses or elsewhere.

•Look carefully at the history and present status of the landfill.

What was holding back more projects?

Most flows of landfill gas are small (hundreds of Nm3/hour), so economy of scale is generally not favorable. Technology in upgrading and liquefaction has evolved, but the investments for small flows during decades cannot be paid back.

Now there is a solution: enhanced gas recovery by hydraulic fracturing. Holland Innovation Team and Fracrite Environmental Ltd. (Canada) has developed a method to increase gas extraction from landfill 3-5 times.

Hydraulic fracturing increases landfill gas yield and therefore economy of scale for bio-LNG production

The method consists of a set of drilling from which at certain dept the landfill is hydraulically broken. This means a set of circular horizontal fractures are created from the well at preferred depths. Sand or other materials are injected into the fractures. Gas gathers from below in the created interlayer and flows into the drilled well. In this way a “guiding” circuit for landfill gas is created. With a 3-5 fold quantity of gas, economy of scale for bio-LNG production will be reached rapidly. Considering the multitude of landfills worldwide this hydraulic fracturing method in combination with containerized upgrading and liquefaction units offers huge potential. The method is cost effective, especially at virgin landfills, but also at landfill with decreasing amounts of landfill gas.

Landfill gas fracturing pilot (2009).

• Landfill operational from 1961-2005

• 3 gas turbines, only 1 or 2 in operation at any time due to low gas extraction rates

• Only 12 of 60 landfill gas extraction wells still producing methane

• Objective of pilot was to assess whether fracturing would enhance methane extraction rates

Field program and preliminary result

Two new wells drilled into municipal wastes and fractured (FW60, FW61). Sand Fractures at 6, 8, 10, 12 m depth in wastes with a fracture radius of 6 m. Balance gases believed to be due to oxygenation effects during leachate and

Groundwater pumping.

Note: this is entirely different from deep fracking in case of shale gas!

Conceptual Bioreactor Design

 The conceptual design is shown in the figures.There are anaerobic conditions below the groundwater table, but permeability decreases because of compaction of the waste. Permeability increases after fracking and so does the quantity of landfill gas and leachate.

Using the leachate by injecting this above the groundwater table will introduce anaerobic conditions in an area where up till then oxygen prevailed and so prevented landfill gas formation

It can also be done in such a systematic way, that all leachate which is extracted, will be disposed off in the shallow surrounding wells above the groundwater table.

One well below the groundwater table is fracked, the leachate is injected at the corners of a square around the deeper well. Sewage sludge and bacteria can be added to increase yield further

Improving the business case further

A 3-5 fold increased biogas flow will improve the business case due to increasing

Economy of scale. The method will also improve landfill quality and prepare the landfill for other uses.

When the landfill gas stream dries up after 5 years or so, the next landfill can be served by relocating the containerized modules (cold boxes and upgrading modules). The company is upgrading with a new method developed in-house, and improving landfill gas yield by fracking with smart materials. EC recommendations to count land fill gas quadrupled for renewable fuels target and the superior footprint of bio-LNG production from landfills are beneficial for immediate start-ups

Conclusions and recommendations

Landfills emit landfill gas. Landfill gas is a good source for production of bio-LNG. Upgrading and liquefaction techniques are developing fast and decreasing in price. Hydraulic fracturing can improve landfill gas yield such that economy of scale is reached sooner. Hydraulic fracturing can also introduce anaerobic conditions by injecting leachate, sewage sludge and bacteria above the groundwater table. The concept is optimized to extract most of the landfill gas in a period of five years and upgrade and liquefy this to bio-LNG in containerized modules.

Holland Innovation Team and Fracrite aim at a production price of less than €0.40 per kilo (€400/ton) of bio-LNG, which is now equivalent to LNG fossil prices in Europe and considerably lower than LNG prices in Asia, with a payback time of only a few years.

(Source:Holland Innovation Team)

 

Seawater desalination is a technology that provides drinking water for millions of people around the world. With increasing industrialization and water usage and lack of recycling or reuse, the demand for fresh water is increasing at the fastest rate. Industries such as power plants use bulk of water for cooling purpose and chemical industries use water for their processing. Agriculture is also a major user of water and   countries like India exploit ground water for this purpose. To supplement fresh water, Governments and industries in many parts of the world are now turning to desalinated seawater as a potential source of fresh water. However, desalination of seawater to generate fresh water is an expensive option, due to its large energy usage. However, due to frequent failure of monsoon rains and uncertainties and changing weather pattern due to global warming, seawater desalination is becoming a potential source of fresh water, despite its cost and environmental issues.

Seawater desalination technology has not undergone any major changes during the past three decades. Reverse osmosis is currently the most sought after technology for desalination due to increasing efficiencies of the membranes and energy-saving devices. In spite of all these improvements the biggest problem with desalination technologies is still the rate of recovery of fresh water. The best recovery in SWRO plants is about 50% of the input water. Higher recoveries create other problems such as scaling, higher energy requirements and O&M issues and many suppliers would like to restrict the recoveries to 35%, especially when they have to guarantee the life of membranes and the plant.

Seawater is nothing but fresh water with large quantities of dissolved salts. The concentration of total dissolved salts in seawater is about 35,000mgs/lit. Chemical industries such as Caustic soda and Soda ash plants use salt as the basic raw material. Salt is the backbone of chemical industries and number of downstream chemicals are manufactured from salt. Seawater is the major source of salt and most of these chemical industries make their own salt using solar evaporation of seawater using traditional methods with salt pans. Large area of land is required for this purpose and solar evaporation is a slow process and it takes months together to convert seawater into salt. It is also labor intensive under harsh conditions.

The author of this article has developed an innovative technology to generate fresh water as well as salt brine suitable for Caustic soda and Soda ash production. By using this novel process, one is able to recover almost 70% fresh water against only 40% fresh water recovered using conventional SWRO process, and also recover about 7- 9% saturated brine simultaneously. Chemical industries currently producing salt using solar evaporation are unable to meet their demand or expand their production due to lack of salt. The price of salt is steadily increasing due to supply demand gap and also due to uncertainties in weather pattern due to global warming. This result in increased cost of production and many small and medium producers of these chemicals are unable to compete with large industries. Moreover, countries like Australia who have vast arid land can produce large quantities of salt   with mechanized process  competitively; Australia is currently exporting salt to countries like Japan, while countries like India and China are unable to compete in the international market with their age-old salt pans using  manual labor. In solar evaporation the water is simply evaporated.

Currently these chemical industries use the solar salt which has a number of impurities, and it requires an elaborate purification process. Moreover the salt can be used as a raw material only in the form of saturated brine without any impurities. Any impurity is detrimental to the Electrolytic process where the salt brine is converted into Caustic soda and Soda ash. Chemical industries use deionized water to dissolve solar salt to make saturated brine and then purify them using number of chemicals before it can be used as a raw material for the production of Caustic soda or Soda ash. The cost of such purified brine is many times costlier than the raw salt. This in turn increase the cost of chemicals produced.

In this new process, seawater is pumped into the system where it is separated into 70% fresh water meeting WHO specifications for drinking purpose, and 7-10% saturated pure brine suitable for production of caustic soda and Soda ash. These chemical industries also use large quantities of process water for various purposes and they can use the above 70% water in their process. Only 15-20% of unutilized seawater is discharged back into the sea in this process, compared to 65% toxic discharge from convention desalination plants. This new technology is efficient and environmentally friendly and generates value added brine as a by-product. It is a win situation for the industries and the environment. The technology has been recently patented and is available for licensing on a non-exclusive or exclusive basis. The advantage of this technology is any Caustic soda or Soda ash plant located near the seashore can produce their salt brine directly from seawater without stock piling solar salt for months together or transporting over a long distance or importing from overseas.

Government and industries can join together to set up such plants where Governments can buy water for distribution and industries can use salt brine as raw material for their chemical production. Setting up a desalination plants only for supplying drinking water to the public is not a smart way to cut the cost of drinking water. For example, the Victorian Government in Australia has set up a large desalination plant to supply drinking water. This plant was set up by a foreign company on BOOT (build, own and operate basis) and water is sold to the Government on ‘take or pay’ basis. Currently the water storage level at catchment area is nearly 80% of its capacity and the Government is unlikely to use desalinated water for some years to come. However, the Government is legally bound by a contract to buy water or pay the contracted value, even if Government does not need water. Such contracts can be avoided in the future by Governments by joining with industries who require salt brine 24×7  throughout the year, thus mitigating the risk involved by  expensive legal contracts.

 

Energy storage systemsFlow batteryReversible fuelcell

The share of renewable energy is steadily increasing around the world. But storing such intermittent energy source and utilizing it when needed has been a challenge. In fact energy storage makes up a significant part of the cost in any renewable energy technology. Many storage technologies are now available in the commercial market, but choosing a right type of technology has always been a difficult choice. In this article we will consider four types of storage technologies. The California Energy Commission conducted economic and environmental analyses of four energy storage options for a wind energy project: (1) lead acid batteries, (2) zinc bromine (flow) batteries, (3) a hydrogen electrolyzer and fuel cell storage system, and (4) a Hydrogen storage option where the hydrogen was used for fueling hydrogen powered vehicle. Their conclusions were:

”Analysis with NREL’s (National Renewable Energy laboratory)  HOMER model showed that, in most cases, energy storage systems were not well used until higher levels of wind penetration were modeled (i.e., 18% penetration in Southern California in 2020). In our scenarios, hydrogen storage became more cost-effective than battery storage at higher levels of wind power production, and using the hydrogen to refuel vehicles was more economically attractive than converting the hydrogen to electricity. The overall value proposition for energy storage used in conjunction with intermittent renewable power sources depends on multiple factors. Our initial qualitative assessment found the various energy storage systems to be environmentally benign, except for emissions from the manufacture of some battery materials.

However, energy storage entails varying economic costs and environmental impacts depending on the specific location and type of generation involved, the energy storage technology used, and the other potential benefits that energy storage systems can provide (e.g., helping to optimize

Transmission and distribution systems, local power quality support, potential provision of spinning reserves and grid frequency regulation, etc.)”.

Key Assumptions

 

Key assumptions guiding this analysis include the following:

Wind power will expand in California under the statewide RPS program to a level of

approximately 10% of total energy provided in 2010 and 20% by 2020, with most of

this expansion in Southern California.

• Costs of flow battery systems are assumed to decline somewhat through 2020 and

costs of hydrogen technologies (electrolyzers, fuel cell systems, and storage systems)

are assumed to decline significantly through 2020.

• In the case where hydrogen is produced, stored, and then reconverted to electricity

using fuel cell systems, we assume that the hydrogen can be safely stored in

modified wind turbine towers at relatively low pressure at lower costs than more

conventional and higher-pressure storage.

• In the case where hydrogen is produced and sold into transportation markets, we

assume that there is demand for hydrogen for vehicles in 2010 and 2020, and that the

Hydrogen is produced at the refueling station using the electricity produced from

wind farms (in other words, we assume that transmission capacity is available for

this when needed)?

Key Project Findings

 

Key findings from the HOMER model projections and analysis include the following:

Energy storage systems deployed in the context of greater wind power development

were not particularly well utilized (based on the availability of “excess” off-peak

electricity from wind power), especially in the 2010 time frame (which assumed 10%

wind penetration statewide), but were better utilized–up to 1,600 hours of operation per

year in some cases–with the greater (20%) wind penetration levels assumed for 2020.

• The levelized costs of electricity from these energy storage systems ranged from a low of

$0.41 per kWh—or near the marginal cost of generation during peak demand times—to

many dollars per kWh (in cases where the storage was not well utilized). This suggests

that in order for these systems to be economically attractive, it may be necessary to

optimize their output to coincide with peak demand periods, and to identify additional

value streams from their use (e.g., transmission and distribution system optimization,

provision of power quality and grid ancillary services, etc.)

• At low levels of wind penetration (1%–2%), the electrolyzer/fuel cell system was either

inoperable or uneconomical (i.e., either no electricity was supplied by the energy storage

system or the electricity provided carried a high cost per MWh).

• In the 2010 scenarios, the flow battery system delivered the lowest cost per energy

stored and delivered.

• At higher levels of wind penetration, the hydrogen storage systems became more

economical such that with the wind penetration levels in 2020 (18% from Southern

California), the hydrogen systems delivered the least costly energy storage.

• Projected decreases in capital costs and maintenance requirements along with a more

durable fuel cell allowed the electrolyzer/fuel cell to gain a significant cost advantage

over the battery systems in 2020.

• Sizing the electrolyzer/fuel cell system to match the flow battery system’s relatively

high instantaneous power output was found to increase the competitiveness of this

system in low energy storage scenarios (2010 and Northern California in 2020), but in

scenarios with higher levels of energy storage (Southern California in 2020), the

Electrolyzer/fuel cell system sized to match the flow battery output became less

competitive.

• In our scenarios, the hydrogen production case was more economical than the

Electrolyzer/fuel cell case with the same amount of electricity consumed (i.e., hydrogen

production delivered greater revenue from hydrogen sales than the electrolyzer/fuel

cell avoided the cost of electricity, once the process efficiencies are considered).

• Furthermore, the hydrogen production system with a higher-capacity power converter

and electrolyzer (sized to match the flow battery converter) was more cost-effective than

the lower-capacity system that was sized to match the output of the solid-state battery.

This is due to economies of scale found to produce lower-cost hydrogen in all cases.

• In general, the energy storage systems themselves are fairly benign from an

environmental perspective, with the exception of emissions from the manufacture of

certain components (such as nickel, lead, cadmium, and vanadium for batteries). This is

particularly true outside of the U.S., where battery plant emissions are less tightly

controlled and potential contamination from improper disposal of these and other

materials are more likely. The overall value proposition for energy storage systems used in conjunction with intermittent renewable energy systems depends on diverse factors.

• The interaction of generation and storage system characteristics and grid and energy

resource conditions at a particular location.

• The potential use of energy storage for multiple purposes in addition to improving the

dependability of intermittent renewable (e.g., peak/off-peak power price arbitrage,

helping to optimize the transmission and distribution infrastructure, load-leveling the

grid in general, helping to mitigate power quality issues, etc.)

• The degree of future progress in improving forecasting techniques and reducing

prediction errors for intermittent renewable energy systems

• Electricity market design and rules for compensating renewable energy systems for their

output

Conclusions

 

“This study was intended to compare the characteristics of several technologies for providing

Energy storage for utility grids—in a general sense and also specifically for battery and

Hydrogen storage systems—in the context of greater wind power development in California.

While more detailed site-specific studies will be required to draw firm conclusions, we believe

those energy storage systems have relatively limited application potential at present but may

become of greater interest over the next several years, particularly for California and other areas

that is experiencing significant growth in wind power and other intermittent renewable.

Based on this study and others in the technical literature, we see a larger potential need for

energy storage system services in the 2015–2020 time frames, when growth in renewable produced electricity is expected to reach levels of 20%–30% of electrical energy supplied.

Depending on the success in improved wind forecasting techniques and electricity market

designs, the role for energy storage in the modern electricity grids of the future may be

significant. We suggest further and more comprehensive assessments of multiple energy

storage technologies for comparison purposes, and additional site- and technology-specific

project assessments to gain a better sense of the actual value propositions for these technologies

in the California energy system.

 

This project has helped to meet program objectives and to benefit California in the

Following ways:

Providing environmentally sound electricity. Energy storage systems have the

Potential to make environmentally attractive renewable energy systems more

competitive by improving their performance and mitigating some of the technical issues

associated with renewable energy/utility grid integration. This project has identified the

potential costs associated with the use of various energy storage technologies as a step

toward understanding the overall value proposition for energy storage as a means to

help enable further development of wind power (and potentially other intermittent

renewable resources as well).

Providing reliable electricity. The integration of energy storage with renewable energy

sources can help to maintain grid stability and adequate reserve margins, thereby

contributing to the overall reliability of the electricity grid. This study identified the

potential costs of integrating various types of energy storage with wind power, against

which the value of greater reliability can be assessed along with other potential benefits.

Providing affordable electricity. Upward pressure on natural gas prices, partly as a

function of increased demand, has significantly contributed to higher electricity prices in

California and other states. Diversification of electricity supplies with relatively low-cost

sources, such as wind power, can provide a hedge against further natural gas price

increases. Higher penetration of these other (non-natural-gas-based) electricity sources,

Potentially enabled by the use of energy storage, can reduce the risks of future electricity.”

(Source: California Energy Commission prepared by University of Berkeley).

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