Salinity gradient power rising as a realistic renewable energy source

Amazon River estuary
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Estuaries are the locations where river water mixes with seawater. They are found along coastlines throughout the world, but what most people don’t realize is the significant potential to produce clean energy from these mixing water streams. The salinity gradient between the two streams of water contains a large amount of osmotic power, which can be thought of as the available energy (or chemical potential) from the differences in salt concentration between the fresh water and seawater. The enormous amounts of energy released where freshwater and seawater meet “can be utilized for the generation of power through osmosis”, which is “defined as the transport of water through a semi-permeable membrane.” [1]

The idea of obtaining energy from osmosis, or salinity gradient power, has been studied for decades, but in early 2009 two teams were racing to be the first to build a working prototype power plant making salinity gradient power a feasible method for renewable energy generation. Both teams have been working on the development and implementation of a membrane based osmotic process, but their approaches for generating the electricity are very different [2]. Westus (The Centre for Sustainable Water Technology), located in the Netherlands, is focusing on the Reverse Electrodialysis (RED) method to produce electricity. They claim that they will utilize fresh water from the Rhine river and saltwater from the North Sea to construct a type of battery by employing two membranes permeable to ions, but not to water. Utilizing the saltwater, one membrane will allow the passage of positively charged sodium ions into a stream of fresh water and the other membrane will allow the passage of negatively charged chloride ions into another channel of freshwater. The separated charged particles with electrodes placed in both streams makes up the chemical battery, which directly produces electricity. [2] Statkraft, a leading renewable energy group located in Norway, is focusing on Pressure Retarded Osmosis (PRO) as their method to extract electricity from salinity gradients. This method utilizes a membrane, permeable to water, to draw fresh water into the concentrated salt water, thus increasing the pressure in the salt water chamber. The resulting pressure can then be used to drive a turbine to produce electricity. In November of 2009, Statkraft opened the world’s first prototype osmotic power plant in Tofte Norway. [3] This facility had a limited production capacity (of around 4 kW) and is mainly used for testing and validation of data, hopefully leading to the construction of a large commercial power plant by 2015.

Statkraft osmotic power prototype
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While the idea of harvesting free energy from estuaries and salinity gradients may seem like a flawless idea, it comes with both pros and cons. On one side, the technology is considered “as green as it gets”, with the only waste product being brackish water, which flows into the sea mixing with the sea water [2].  It is a constantly flowing source of renewable energy, unlike the intermittent energy provided by sources such as solar or wind power. It can also easily be combined with existing power plants and industries and can be built underground, thus reducing costs and visual pollution [2]. On the other side, the membrane technology still has a long way to go. The membranes are prone to bio-fouling from algae and silt, which reduce the membrane’s lifetime and efficiency. Salinity gradient power is mainly suitable only for places where there is an abundant supply of freshwater meeting saltwater, which clearly favors countries with a large coastline [2]. Also, the environmental impact and environmental policy should be considered for future plants of this type. First off, there are many species of aquatic life that are adapted to survive in waters with a specific range of salinity concentrations, and these power plants could affect the salinity of an area of water. It has been found that large salinity changes in aquatic environments can result in low densities of plants and animals [4]. Then one must consider the environmental policy and impact of structures that intake such large volumes of river water and sea water. These power plants must conform to strict construction permits and environmental regulations.

While many issues dealing with the viability of salinity gradient power as a renewable energy source are still being addressed, advancements in the technology are constantly being made. In June of 2012, Statkraft’s head of osmotic power said “We see that the development of technology is accelerating and that an industry is emerging. The membranes we are testing at Tofte this summer are ten times more efficient than the ones we installed during the opening of the prototype in the autumn of 2009” [5]. Earlier this year, researchers discovered a new more efficient way to harness osmotic power utilizing Boron nitride nano tubes [6]. They claim that a 1 meter-squared membrane using this technology could have the same 4 kW capacity as the whole Statkraft prototype power plant. This experimental device, which is three orders of magnitude more efficient than the current system, could significantly enhance the commercial viability of salinity gradient power as a realistic source of energy [6]. While the ultimate future of salinity gradient power is unknown, it has the potential to be one of the prominent renewable energy sources on the planet.

[1] http://www.statkraft.com/energy-sources/osmotic-power/

[2] http://www.gizmag.com/salinity-power-renewable-energy-osmosis/11206/

[3] http://www.gizmag.com/statkraft-osmotic-power/13451/

[4] Montague, C., Ley, J. A Possible Effect of Salinity Fluctuation on Abundance of Benthic Vegetation and Associated Fauna in Northeastern Florida Bay. Estuaries and Coasts. 1993. Springer New York. Vol. 15 No. 4. Pg. 703-717

[5] http://www.statkraft.com/presscentre/news/statkraft-considering-osmotic-power-pilot-facility-at%20sunndalsora.aspx

[6] http://www.gizmag.com/osmotic-salinity-gradient-power-nanotubes/26623/

A Look at Carbon Capture and Storage

Global warming has become an accepted phenomenon in the scientific community.  The consensus is that anthropogenic activities are dominant factors in this rapid climate change.  An increase in violent storms and severe droughts are becoming a normal occurrence on a global scale.  The impacts of one species have never before induced global changes in climate.  Limiting global temperature rise to 2 °C above preindustrial temperatures has become an accepted broad political consensus worldwide (1, 3).  The combustion of fossil fuels has been identified as the major contributor to climate change (1, 5, and 7).  Climate change predictions set a deadline of 2020 to significantly reduce greenhouse gases in order to mitigate anthropogenic effects on global warming (3).  Urgent action is needed.

Carbon capture and storage (CCS) has the potential to play a significant role in limiting climate change.  Future global emissions from the combustion of fossil fuels can potentially be reduced by 20% with the implementation of CCS (4).   Currently 3 megatons of CO2 (MtCO2) per year by pilot plants is already being captured from the emissions caused by natural gas cleanup and power plants.  The CO2 is then being stored in geologic formations (3).  Unfortunately, at the present there is a serious lack of funding to provide for new construction of CCS.  This fact will push the learning from these first pilot projects well beyond the year 2020 (3).  Additionally, another drawback to CCS will be the inevitable incremental costs incurred.  For example in the U.K., additional costs per year per household may be increased as much as 10% as a result of CCS implementation (3).

There are three methods of CCS currently under investigation.  Pre combustion capture is a process that chemically strips off the carbon leaving only hydrogen to burn.  Oxyfuel combustion burns coal or gas in the presence of denitrified air to yield only CO2 and water.  Post combustion uses chemical solvents to capture the CO2 from the flue gases (1, 2, and 3).   Captured CO2 is then fluidized by pressurizing to 70 bars.  This liquefied CO2 is next transported to a storage site where it can be injected to depths greater than 800m (2, 3).  The selection of storage sites is critical and will require monitoring for leakage for many decades to come.  Additionally, methods to re-mediate deficient storage will need to be readily put into place (1, 2, and 3).  Many of the techniques already being practiced by the oil and gas industry will function quite well as modeling and monitoring tools for CO2 storage.  However, as learning progresses these techniques will need to be evaluated for strengths and weaknesses.  Some examples of these techniques are: horizontal drilling to provide for cost effective storage, modeling techniques to predict groundwater displacement, CO2 migration, CO2 distribution and immobilization, seismic monitoring to image location of underground CO2, and borehole monitoring to heed early warnings of seepage (2, 3).   Teng et. al (2005) have analyzed some theoretical outcomes to physical and economic outcomes of carbon storage with leaking.  Their research highlights the need for critically essential decisions in reservoir selection, project design, and plant operation to avoid project failure (6).

At the moment the largest barrier to deployment of more CCS pilot plants is not a technological barrier but a market barrier.  Current demonstration coal plants have required additional capital in the range of $1.5 billion to complete construction.  Demonstration plants also have the barrier of recovering the operational costs of producing decarbonized electricity (3).  Critical commercial help and subsidies are needed for large scale up of CCS.  Haszeldine (2009) points out that price supports currently used to support renewables are actually supporting a more expensive option per energy unit than it would if it supported the deployment of CCS.  Rapid deployment of CCS is needed to promote learning.  Additionally, the sharing of detailed commercial information instead of tightly controlled company secrets commonly associated with competitive development will be help to straighten the learning curve of a much needed technology (3).

My colleagues seem to have mixed views on the practice of CCS.   The reliability of CO2 available to inject for enhanced oil recovery is a serious dilemma.  How can we implement CCS on a grand scale without the Co2 delivery infrastructure in place?  It is my opinion that this is only a reality because we have not been able to convince investors or the public that CCS is a reliable and safe science for us to be practicing.   It is true.  Until a CO2 distribution network is constructed, a reliable source of CO2 will be a pressing concern.  The practice of CO2 injection for enhanced oil recovery (EOR) has been going on for decades.  EOR is being practiced in areas where we have already disturbed the natural development of the earth.  It seems to me that one of the biggest fears for my colleagues is what will be the consequences of this CO2 injection?  This is also a concern of mine.  It perplexes me that some are so willing to accept similar risks with hydraulic fracturing, but they are not willing to trust the science behind CCS.

Another fascinating topic raised by one of my colleagues was the idea of pore space ownership.  Just like many battles have been fought over the ownership of groundwater, I foresee the same thing happening with CO2 sequestration.  Who will really own the pore space underground?  On the borders of conflicting countries it’s not so simple.  If you use Texas as an example, the wise governing bodies of Texas legislature have given the landowners the right to the resources below them, unless they have sold them off.

¹Environmental Non-Government Organisation (ENGO) perspectives on Carbon Capture and Storage (CCS)., 2012.  http://cdn.globalccsinstitute.com/sites/default/files/publications/55041/engo-perspectives-carbon-capture-storage.pdf

²Gibbins, J., and Chalmers, H., 2008, Carbon capture and storage: Energy Policy, v. 36, p. 4317–4322.

³Haszeldine, S.R., 2009, Carbon capture and storage: how green can black be?: Science, v. 325, p. 1647–1652.

⁴International Energy Agency, 2010, Energy Technology Perspectives: , p. 458.

⁵Metz, B., Davidson, O., Coninck, H. de, Loos, M., and Meyer Leo, 2005, IPCC special report on carbon capture and storage: Cambridge University Press,, p. 443.

⁶Teng, F., and Tondeur, D., 2007, Efficiency of carbon storage with leakage: physical and economical approaches: Energy, v. 32, p. 540–548.

⁷U.S. Energy Information Administration; International Energy Outlook, 2011.  Pg. 6

Click to access 0484%282011%29.pdf

Europe’s emerging wind energy markets

In Europe, wind energy generation was initiated by a few countries more than 20 years ago. Since the early 2000s, and stimulated by energy and climate policies from the newly formed European Union, it has spread across much of western Europe. Now the EU turns its attention to emerging markets in central and eastern Europe, the new frontier for Europe’s wind energy generation. While wind energy in these emerging markets is important for their own economy’s, it is also important in that it is hoped to offset the predicted future declines in Europe’s more mature markets.[1] At the European Wind Energy Association (EWEA) annual event, Robert Clover of MAKE consulting said that by 2050, wind energy will be at the center of Europe’s power needs, producing 50% of Europe’s electricity demands, and “after 2020 wind is the cheapest technology, it is scaleable and it has minimal water requirements.”[2] He also added that in Europe by 2015, onshore wind generation will become equal to the other electricity generating technologies feeding the grid.

On Sept. 27 of 2001, the EU adopted a directive on the promotion of electricity produced from renewable energy sources to meet 22% of the EU’s total electricity consumption from renewable energies in a decade.[1] This directive gave every Member State a specific target. Eight eastern and central European countries joined the EU in 2004 and a few more in 2007.  These newer added countries, which adopted the EU’s energy policies, were more reliant on coal and nuclear and had less developed renewable energy technologies than the 15 western European Member States. This addition caused the EU’s overall renewable energy target to be reduced to 21% of electricity consumption, considering the starting point of these added countries.[1] The adopted EU directive stimulated investments in wind energy and other renewables.

[1]

From 2005 to 2011 in the EU, there has been a substantial rise in the amount of electricity produced from wind power. In 2005, the EU-15 (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, Netherlands, Portugal, Spain, Sweden, UK) produced 40,500MW of wind power capacity, more than 200 times the capacity of the EU-12 (Bulgaria, Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Romania, Slovakia, Slovenia), which produced only 208MW of wind power capacity.[1] By 2011, the gap was reduced by ten fold, where the EU-12 installed 4,197MW of wind capacity compared to the 89,997MW installed in the EU-15.[1] It can be clearly seen that the emerging EU countries (EU-12) have a much faster growing renewable energy capacity compared to the early EU members (EU-15). From 2005 to 2011, the total installed wind capacity in the EU-12 increased by 4 GW (around 665MW/year) for an increase of over 1900%, while the total installed EU-15 wind capacity increased from 40GW to almost 90GW during the same period (around 8,330MW/year) for an increase of 122%.[1]

[1]

The rate of development of wind energy has been diverse and uneven in the 12 newer Member States. From 2005-2011, while some countries in the EU-12 (Malta, Slovenia, and Slovakia) did not install any wind power, others like Poland, Romania, Bulgaria, and Hungary had a monumental increase in the total wind capacity installed. Both Poland and Hungary’s wind power capacity grew by over 1800%, with Poland’s capacity reaching 1,616MW.[1] Of the 12 newer Member States, 88% of the total wind capacity installed (3,690MW of 4,197MW) is located in only five countries, Poland, Romania, Hungary, Czech Republic, and Bulgaria.[1]  By the end of 2012, Poland had 2.5GW, Romania 1.9GW, and Bulgaria 0.7GW of wind power capacity installed.[3] The EU-12 plans to increase wind power capacity from the current 6.4GW to 16GW by 2020, which would be enough electricity to power 9 million households.[3] It is clear that for the future of the European wind energy industry, it’s important that these newly emerged and emerging markets are helped to achieve their full potential.[1]

Works cited:

[1] Eastern winds-Emerging European wind power markets. A report by the European Wind Energy Association – February 2013 <http://www.ewea.org/fileadmin/files/library/publications/reports/Eastern_Winds_emerging_markets.pdf&gt;

[2] <http://www.ewea.org/blog/2013/02/wind-will-be-cheapest-electricity-generating-technology-by-2020/&gt;

[3] <http://www.ewea.org/press-releases/detail/?tx_ttnews%5Btt_news%5D=2022&cHash=8038d5b6fd3f880c51b099ae3f4e5f54&gt;

Composting and the Environment

An example of compost dirt

When it comes to protecting the environment and stopping climate change, most people view it as a large scale problem that can only be solved on a large scale.  Such as limiting the greenhouse gas emissions of power plants, and improving the emissions on our vehicles.  These strategies can be greatly effective, but there are ways that individuals can take action to lower the amount of greenhouse gases that are emitted by their waste by composting.  Composting is a simple process in which you can use wasted food scraps and basically anything that is biodegradable to create a nutrient rich soil that can be used for gardening.  Technically, composting is the process of aerobic decomposition of organic materials into a black soil that is beneficial as a soil conditioner, and a fertilizer. For composting to work effectively it requires four components, carbon, oxygen, nitrogen, and water.  By composting, there is less waste going into landfills, which produce high levels of methane (a powerful greenhouse gas) through anaerobic decomposition.  In addition, since this process creates useful soil and fertilizer, it reduces the need for individuals with gardens to buy energy intensive fertilizers.

Example of a closed container compost

Example of an open compost bin

Composting can be done on a large or small scale with equal effectiveness, whether in a backyard or an apartment.  For homeowners with a backyard, a compost pile can be created by simply sectioning off part of the yard with chicken wire.  To begin a simple compost pile, start by layering between dry leaves and grass clippings, also known as “brown matter,” and food scraps.  This will help speed up the decomposition process.  Finally, the compost needs to be turned and raked with some sort of rake or pitch fork periodically, and in a few months there should be usable compost soil.  This describes an open bin composting method.  Closed containers can also be used for creating compost.  A popular variety is a rotating drum compost container.  It effectively works the same as the open bin concept except water has to be added to the container, and instead of raking the pile it just needs to be turned periodically.  An advantage of using a closed container method is that it can be used in an apartment setting where there is no yard space available.  Therefore, anyone can compost no matter the size of their home.

As can be seen, it is possible for everyone to compost their leftover food and waste into a useful product, but there is also great potential for composting on an industrial scale.  Inevitably there is always going to be people who aren’t willing to put forth the time and effort it takes to manage a compost pile.  Therefore, composting on a large industrial scale would allow the waste created by all of society, including those who are uninterested in composting at home, to be composted into something useful.  There are several well established methods for composting on large scales, and it is a great alternative to allowing biodegradable waste to decompose into methane in landfills.  For this to be effective, waste management companies could offer a composting service similar to the recycling services that exist already, and all the customers would have to do is keep their food scraps and other biodegradable waste in a separate container and place it outside on the designated pickup days.  It would be the same as separating the recyclables from the trash, and would take a minimal amount of effort on the consumer end.  As a result, everyone could be a part of  composting their waste to help lower the levels of greenhouse gas emissions and create a useful byproduct, whether they want to do it on their own or not.