The Best Way Forward?

Throughout this blog I have looked at the various methods that have been proposed by geo-engineering and renewable technologies.

Starting this blog I was very optimistic and in that perhaps short sighted in that I thought I would most definitely be able to find a solution to fix climate change through examining geo-engineering and renewable technologies. As my blog developed, my optimism slowly diminished and as the scale of the issue of climate change was further realised so too was the inability of technologies to scale up to provide a solution to climate change.

A number of other issues were also highlighted such as

• CDR methods addressed CO2 but not all emissions and as a result the threat of climate change was not fully resolved
• SRM methods in particular ignored the problem of CO2 in the atmosphere serving only to address and prevent incoming solar radiation
• a lack of research was often common in the technologies presented and as a result they were unable to be full implemented in the near future to begin addressing climate change 
• a lack of research was also common in identifying all the possible side effects - be they small or large scale further preventing immediate implementation
• a large number risks associated with the various technologies have been highlighted ranging from environmental hazards, food security issues, economic issues and social hazards 
• Vast amounts of space were often demanded by the technologies - more than what was available - and as a result the methods were limited in that space available was not enough for technologies to be able to mitigate climate change
• and finally vast amounts of investment were needed to implement many of the technologies and as a result they were not feasible options

If I were to decide between sustainable energy technologies vs geo-engineering technologies I think I would choose renewables over geo-engineering however there are a number of renewable technologies such as biogas production that simply cannot scale up to replace the use of fossil fuels and thus significantly address climate change. There are also some geo-engineering methods that deserve some merit and therefore I feel there are winner and losers in each category. In my opinion, future efforts to address climate change should focus on developing and refining those methods that are the most viable such as tidal technologies and offshore wind farms to name two of the most recent technologies covered in this blog. In addition to combining various strategies however I think there also needs to be a massive change in the way people consume as after all the planet is a finite resource and our excessive consumption is going to destruct it and as a result climate change needs to be addressed from all angles. The issue of climate change and the debates surrounding it need to be brought into the public sphere, scientific knowledge needs to develop the robustness of climate understandings and technologies to address this and international laws and policies need to be implemented to ensure the planet is prepared to adapt to change and capable of preventing further climate change and in this global emissions need to be heavily regulated so that global emissions are drastically reduced.

Most Promising for Tidal

The Delta Stream Turbine
This turbine device was developed by Tidal Energy Ltd based in the UK. The 1.2 MW turbine consists of three, three bladed, horizontal axis tidal turbines each with a 15m diameter, mounted on a triangular frame to produce a low centre of gravity for stability.

Evopod Tidal Turbine
The Evopod Tidal Turbine was developed by Ocean Flow Energy Ltd. based in the UK. The device is a five-bladed, horizontal axis, floating structure which is moored to the seafloor. The mooring system allows the device to maintain optimum heading into the tidal stream. A 1/10th scale model is currently being tested in Strangford Lough in Northern Ireland (Ocean Flow Energy Ltd).

Free Flow Turbines
The Free Flow Turbine was developed by Verdant Power Ltd. based in the USA and Canada. This three-bladed horizontal-axis turbine has a diameter of 4.68 m and a prototype is being tested in New York City’s East River, generating 1 MW h of electricity per day. Late in 2008 Verdant Power Ltd. were awarded a $1.15 million contract from Sustainable Development Technology Canada to develop phase one of the Cornwall Ontario River Energy Project.

Stingray Tidal Energy Converter
The Stingray Tidal Energy Generator converts tidal energy through transforming kinetic energy from moving water into the hydraulic power.  It consists of a parallel linkage holding several large hydroplanes. The 150 kW prototype was successfully deployed in September 2002, in Yell Sound, off Shetland in the UK. However the device was removed several weeks later and development has stalled.

Lunar Energy Tidal Turbine
The Lunar Energy Tidal Turbine is a horizontal axis tidal current turbine and was developed by Lunar Energy Ltd. based in the UK. The technology is made up with a gravity base, a 1 MW bi-directional turbine 11.5 m in diameter, a duct of length 19.2 m and diameter 15 m, and a hydraulic motor and generator. The ducting is included to maximise the energy extraction from the current water flow. Lunar Energy Ltd. has recently agreed a £500 million deal to install 300 tidal current turbines off the coast of Korea.

Tidal Power

Tides represent a large and benign source of renewable energy which can be converted to electricity using well-proven technology. Further to this, the constant rise and fall of the tides mean they are also a predictable source of energy (Baker, 1999).

Tidal energy has been exploited since the 12th Century however developments in the field have evolved and conventional and new technology for generating energy can be used. Sine the construction of the La Rance tidal barrage in France in 1967, tidal energy has been increasingly exploited (O' Rouke et al., 2010).Typically a barrage with turbines, but sometimes a barrage on its own (that look similar to a wind turbine) is built across an estuary or a bay and as the tide ebbs and rises water can flow through the turbines and drive generators (Jacobson and Delucci, 2011).

One benefit of Tidal Power is that it is an extremely predictable energy source, depending only on the gravitational pull of the moon and the sun and the centrifugal forces created by the rotation of the earth–moon system (O' Rouke et al., 2010) and despite opposition from environmental groups the potential energy of the tide has proven to be successful (see graph below).

Major World Tidal Barrage Sites

In the UK tidal power is not used extensively. A key reason behind this is due to the inability of tidal power to be economically competitive with other traditional forms of energy. This disparity occurs as all the potential locations for tidal power in the UK have a mean tidal range of 5 metres which does not generate the energy desired (Baker, 1999). In addition to this, tidal power schemes run the risk of effected the environment due to the changes in salinity and salient regimes that they cause. Such changes could be hazardous as these components govern the primary conductivity of the water.

Current tidal current technology is currently not economically viable on a large scale as many technologies are in their early stages of development. Nevertheless, if developed these technologies offer a good way of generating renewable energy and if the environmental impacts were addressed then a positive path is paved for the future.

Photovoltaic-hydro energy system

Since the main problem of continuous energy supply from photovoltaic (PV) power plants is intermittence and inability to provide continuous energy supply (see previous blog posts), the idea to combine hydro energy with photovoltaic power has been proposed as for sustainable energy production. 

The combination of both these aspects creates a new type of sustainable hybrid power plant which can work continuously, using solar energy as primary energy source and water for energy storage. This type of hybrid electric power plant does not emit greenhouse gases, produce waste nor does it significantly exploit water resources while the risks to humans and the environment are far smaller than when using conventional technology.

As a result this sustainable idea proposed by Margeta and Glasnovic (2012) particularly interested me. For those wanting more detail on the nitty gritty of the method follow the embedded link.

Learning from the Romans

Diagram of Geothermal Engineering

Geothermal energy has been exploited since the years as the discovery of naturally occurring hot springs and aquifers was made in the Roman times.

Over the years the technology used to harness geothermal energy has developed and systems of up to 5km can now be engineered (RA, 2013). In such systems water is injected into the earths hot rock and extracted after it has been heated (see image). Although there are high levels of risk involved in the initial exploration and high capital requirements, geothermal energy systems are expected to provide energy for up to 50 years and as a result they provide what would seem to be a very reliable and cost effective source of on demand power, heat and cooling.

A major benefit of geothermal energy is that the estimated 99.9% of the earths mass estimated to have temperatures of over 100 degrees are continually maintained due to the presence of radio active decay in the Earths surface (RA, 2013).

In addition to this another key benefit is the fact that geothermal energy does not release any CO2 into the atmosphere nor does it produce any flue gas emissions such as soot particles and sulfur dioxide (Stober and Bucher, 2013)

The cost of drilling and engineering geothermal wells is estimated to be around US$1.5 to 3 million with a cost per drilled meter of US$800-1200/m and commerical and well depth is generally set at a maximum of 3km (Kingston Morrisson, 1996). The costs of drilling involve a degree of uncertainty if lost circulation zones are encountered and fluids are lost in rock fractures then the costs will increase (Barbier, 2002). Although these estimations are likely to have changed to some extent since they were made in 1996, the costs are nevertheless relatively low and and as a result geothermal energy presents itself as a cost effective method.


Worldwide

Image of a geo-engineering plant

Lund and Freeston (2001) estimate that in 2000, the global production of geothermal power was 15,145 MWt, utilising at least 52,746 kg/s of fluid and the thermal energy used is 190,699 TJ/yr. This thermal energy was used is a number of sectors such as swimming pool heating, space heating, geothermal heat pumps, greenhouse heating and industrial applications. For this, 1028 wells were drilled, 3362 people were employed to work on them and the total investment over 5 years on geothermal energy was 841 million US dollars.

The United Kingdom
In the UK, geothermal district heating is currently being used in Southhampton and Cornwall. According to DECC, Cornwall alone has the potential to supply 3GW of electricity from deep geothermal sources. The potential of geothermal energy to serve urban areas where there is a combined heat load is high and as a result a number of drilling rigs have been designed specifically for urban areas.  At present the market from geothermal heat in the United Kingdom is undeveloped and there is therefore a lot of potential to expand the drilling, geophysical, manufacturing and support sectors of geothermal energy in the UK.

Developing Countries
Geothermal Energy offers a viable energy method for developing countries as in addition to providing energy, it will also provide jobs (Ogola, 2012). Its low carbon footprint will ultimately serve to mitigate the impacts of future climate change which is particularly significant for developing countries in Africa as climate change's effects will be worse in these regions.

Is there really no trouble in a biofuelled sky?

Renewable Transport Fuels

Biomethane
In the previous post I discussed the renewable transport fuel bio-methane, produced through the purification of biogas after anaerobic digestion. In addition to bio-methane, other transport fuels include biodiesel and biomethanol.

Bio-methanol
Biomethanol is produced using plants such as wheat, sugar beet, maize and sugar cane through the process of fermentation, distillation and dehydration. The largest produced of biomethane is currently Brazil where almost half of the fuel used for transport is biomethane fuel. New EU regulations permit blends of up to 10% with biomethanol and 5% blends with petrol are permitted - engine modification may be required however.

Bio-diesel
Biodiesel is produced through the process of transesterification. Through the separation of glycerine from vegetable oil biodiesel is produced. The glycerine can be used in other products such as soap while biodiesel can be used as a straight fuel - alternatively it can be blended with mineral diesel to create a diesel blend - engine modification is not required for either type.

The transportation and energy sectors are major anthropogenic sources of greenhouse gas emissions (GHG). Agriculture is also a large source, representing about 9% of total GHG  emissions, the most important being nitrous oxide and methane (Mata et al, 2010). With future growth inevitable, the global consumption of energy thus poses a serious threat in terms of environmental change - affecting the atmosphere and thus global warming but also the oceans too.

Finding clean and renewable energy sources is thus one of the most important but also the most challenging problems facing mankind. Biofuels offer new oppotunities to diversify income and fuel supply sources, they promote employment in rural areas, offer of long term replacement of fossil fuels, reduce GHG emissions, boost the decarbonisation of transportation fuels and increase the security of energy supplies (Mata et al., 2010). In this regard, they undoubtedly offer promise for the future and sequentially the production of biofuels has increased.

The global production of biofuels is estimated to be over 35 billion litres and this figure is expected to grow due to policy measures and biofuel production targets (COM, 2003). In the EU the main alternative to diesel is biofuel and as a result it represents 82% of the total production of biofuels. In Brazil and the United States political and economic objectives are encouraging a growth in biofuel production.

Unfortunately, however, a number of potential limitations of renewable transport fuels have been highlighted by academics and as a result the potential of biofuels is hindered.

Firstly, the price of biofuels in comparison to diesel has been highlighted as a key set backs. Biodiesel, for example, is produced from vegetable oils and animal fats and as the former can also be used for human consumption the production of biodiesel poses a major threat in terms of increasing the price of food-grade oils and biodiesel. In such a case, despite its advantages, the cost of biodiesel would prevent its usage. Thus in order for biodiesel to become an alternative, it must compete economically with other fuels and not compete with edible vegetable oils. Economically, biodiesel prices depend heavily upon the cost of feedstocks used to produce the fuel as these account for 65-70% of the total price (Canakci and Sanil, 2008). Thus to be low cost and profitable the feedstocks must have low costs. In addition to this, the must be produced from non-edible oils, animal fats, soap stocks and greases to not affect the price of edible oils. Additionally, biodiesel and thus biofuels need to have lower environmental impacts whilst ensuring the same level of performance of existing fuels (Reinhardt et al., 2008).

Before the latter is even assessed, the feasibility of biofuel production presents a hurdle that would be difficult to overcome in that the quantities of waste oils and animal fats available today are not enough to meet the demands for biodiesel, nor are there enough feedstocks for the production of biomethane and bioethanol to meet demands.

In addition to this, the total land required for biofuel production exceeds the amount of available arable land for bio-energy crops. In order to meet demands more land for bio-fuel production would therefore be needed (Scarlet et al., 2008). This poses a possible threat as pressures for land use change and increases of cultivated land will lead to land competition and biodiversity loss through deforestation and the use of ecologically important areas (RFA, 2008). Moreover, biofuel production presents a threat to food security when it involves replacing crops used for human consumption.

The sustainability of renewable transport fuels are thus complicated by issues of feasibility in the face of current energy demands. On balance, they present the opportunity to diversify sources of energy and in doing so the threats towards energy security are relieved, however, in terms of being an option to be adopted in the future to address climate change, renewable transport fuels simply do not have the capacity to fully meet demands and thus replace the use of fossil fuels. Increasing the capacity of biofuels to meet demands entails social and economic issues such as price increases and food security.

A Solar Powered Car

In the news today was an article about Ford as they revealed their plans for a solar powered car at the Las Vegas electronics convention. To listen to Mike Tinskey, Ford's leading executive for the car discuss their plans follow this link .... http://www.bbc.co.uk/news/business-25588679

Biomass and Biogas

Biomass
Biomass refers to the substances that have grown from animal or vegetable matter and can be used as a renewable fuel. Biomass is regarded as being a carbon neutral fuel as it returns a similar amount of energy to the atmosphere that was taken out by the biomass. Trees for example absorb CO2, they are then chopped and used for energy and the carbon is returned back into the atmosphere. The trees that are cut down are replenished and as a result biomass is part of a closed carbon cycle with no net CO2 emissions that contribute to global warming (REA, 2013).

Biogas
Biogas is the gas that is formed by the natural breakdown of organic waste and matter - biomass - in the absence of oxygen. It makes use of wet wastes and manure and hence plays an important role in reducing greenhouse gases (GHGs). More specifically, in the EU, biogas will play an increasingly important role in the future as new EU policies concerning renewable energy systems (RES) have set the goal of supplying 20% of European energy demands with RES by 2020. A large part of this renewable energy will originate from European farming and forestry and in particular biogas as 'at least 25% of bioenergy in the future can originate from biogas' (Nielson et al., 2009).

Thus let's have a closer look at the process ... 

The renewable technology with which biogas is formed is Anaerobic Digestion (AD). AD harnesses natural biological processes, using available biomass to produce renewable methane. This methane in turn can be used to produce electricity and heat or alternatively it can be upgraded for vehicle fuel and injection to the gas grid (Weiland, 2010). 

The biomass that is used in biogas production has a wide range - farm manures, crops, stage sludge and catering/food wastes can all be used as feedstock. The only requisite is that the foods have a high moisture content as this makes them more suitable for the AD process (REA, 2013). Many AD technologies involve a process of treatment for the feedstock - this usually takes the form of maceration which reduces the particle size to around 12mm. The process ensures that all of the feedstock is fluid enough to be pumped through the process and also it increases the surface area of the material stimulating bacterial activity. 

Some AD plants also include a screening and/or pasteurisation process to ensure all unwanted material are removed and all harmful pathogens such as E.Coli are killed. When animal by products are being used pasteurisation is often however a requirement. Treated organic material is then placed in sealed tanks to allow the break down of naturally occurring micro-organisms and the release of gas (Weiland, 2010). The gas formed by AD is around 60% methane and 40% carbon dioxide. The methane produced can be used to generate renewable electricity and heat. The left over organic material itself, the digestate, is rich in nutrients and as a result it can be used instead of chemical based fertilisers. Methane rich biogas, biomethane, can also replace natural gas as a feedstock for producing materials and chemicals. 

An illustration of the process of anaerobic digestion (Al Seadi, 2002)

The biogas process, as illustrated above, is defined by an integrated system of renewable energy production, resource utilization, organic waste treatment, nutrient recycling and the finally redistribution. A number of intertwined agricultural and environmental benefits are subsequently generated, these include 

• Renewable energy production 
• Lower greenhouse gas emissions 
• Pathogen reduction through sanitation 
• Cheap and environmentally healthy organic waste recycling 
• Improved fertilization efficiency (Holm-Nielsen et al., 1997)
• Economic advantages for farmers
• Less disruption from odours and flies (Birkmose, 2007)

The energy from biogas can thus be utilizated in various ways -

• Heat production
• Electricity production 
• Combined power and heat production 
• Biomethane 
• Injected into the main gas or electricity grid after conversion
• Converted into transport fuels 

A exemplary case study for the conversion of biogas into transport fuel is Sweden. Here the market for the upgrade of biogas to transport fuels has grown rapidly over the last decade. Around 15,000 vehicles now drive on upgraded biogas and this figure was expected to have reached 70,000 by 2012 (Persson et al., 2006)

As animal production units in developed countries are intensifying so is the amount of waste that is being generated by these livestock (Holm-Nielson et al., 2009). This presents a considerable threat to the environment due to the increased air and water pollution and over fertilisation of the land an excess of animal manure entails. Nutrient leaching, mainly nitrogen and phosphorous, ammonia evaporation and pathogen contamination are key threats (Holm-Nielson et al., 2009). 

Animal production is responsible for 18% of overall GHG emissions of CO2 and 37% of anthropogenic methane generation which is has 23 times the potential of CO2 in causing global warming. It should also be noted that 65% of anthropogenic nitrous oxide and 64% of anthropogenic ammonia emission originates from the world-wide animal production sector (Steinfeld et al., 2006). 

In light of this, the production of biogas presents a viable approach for addressing not only the manure management problems that will result from increased animal production but also for addressing climate change as GHG emissions are reduced and the amount of fossil fuels used can be reduced.

Happy New Year!!!

For those of you who might be feeling a little worse for wear today, here is a video for you to take a break with, enjoy!

Wishing you all a great year!

Get wind of this ....

Energy is an essential component of global socio-economic development and economic growth. The demands for energy are therefore not going to disappear at any point, in fact, they are likely to grow and as a result the viability of renewable energy methods in reducing the use of fossil fuels and ultimately reducing anthropogenic climate change is a key consideration.

Wind Energy is another form of solar energy whereby sunlight that hits the ocean, warms sections of the ocean causing the air to warm up and rise which, in turn, generates surface winds. It's potential to supply energy is large and subsequently it is one of the main renewable energy methods. It has also been one of the fastest growing energy technologies of the past decade (AWEA, 2002) and as the industry has grown, so has the size of individual wind turbines and the size of group developments. As wind is significantly affected by topography, weather conditions and land use patterns (Ramachandra and Shruthi, 2005), developers are beginning to look further offshore to harness maximum amounts of energy. In doing so, greater economies of scale will likely push the rating of individual wind turbines into the 3–5 MW range with maximum wind farm capacity potentially reaching 1000 MW (Milborrow, 2003). Wind farms of this scale have the potential to provide a sizeable percentage of local power demand and generation capacity, particularly when their output is fed into small or transmission constrained power grids.

Advantages 
Both onshore and offshore wind have the same benefits with regards to conventional power sources. Most notably, wind power has very low carbon emissions over its lifecycle and it has negligible emisssions of mercury, nitrous oxides and sulfur oxides. Another benefit of wind power is that it does not use fuel and is therefore freed from the price volatility associated with electricity generated from oil, natural gas, biomass, nuclear and coal (Snyder and Kaiser, 2009). Wind power does not rely on large sources of freshwater as conventional sources of power do (DOA, 2008).

In the near term, offshore wind power will be more expensive than onshore wind power, however, there are several benefits of offshore wind power that are not shared by onshore wind; these benefits may or may not justify the additional costs. These benefits include

• Offshore locations can be preferable to onshore locations - in the US, for example, offshore wind power is physically close to the major population centers of the coastal United States, thereby removing the need for expensive high voltage transmission (NREL, 2008)
• Offshore winds are also generally stronger and more constant than onshore winds. As a result, turbines can operate at their maximum capacity for a larger amount of time and the constancy of wind reduces wear on turbines and provides a more constant source of power reducing the need for backup sources (Snyder and Kaiser, 2009). Increases in wind speed can lead to a 150% increase in electricity production for offshore wind turbines and an increase in the capacity factor of the wind farm from about 25 to 40% (Junginger et al., 2004).
• Turbine noise is an oft-cited criticism made by opponents to onshore wind power (Pederson and Wey, 2004). The offshore wind power industry does not have to be as concerned about turbine noise as does the onshore industry.
• As a result, the offshore industry can also use far larger turbines. These larger turbines should make offshore wind power more economically attractive due to scale economies (Snyder and Keiser, 2009).

Disadvantages
One of the most substantive criticisms of wind power is that it is unable to provide constant, predictable power to the grid. Electricity grids are designed to send a constant electricity to consumers and as a result they rely on power plants to produce predictable and steady electricity. Wind energy is not steady and varies on the scale of minutes, hours, days and months and the changes in wind power output are difficult to predict ahead of time (Snyder and Keiser, 2009). As a result, integrating wind power into the electricity grid requires back up systems for when production on wind farm changes and is too low to produce electricity (Lund, 2005). This however increases the total national cost of electricity. The DOE has estimated that the supply up to 20% of the nation's electrical use from wind power would cost up to $5/MW h in integration costs.

Other disadvantages regard the aesthetics of wind farms and the noise that turbines make. In Denmark, Ladeenburg and Dubgaard (2007) examined the willingness of the population to pay to move turbines further from the shoreline. With an 8km baseline, to move turbines a further 12, 18 and 50km away, respondents were willing to pay 46, 96 and 122 Euros per year per household in order to move the farm farther afield.

While with regards to offshore wind turbines the risks and costs associated are assumed to be higher due to the offshore environment being significantly more uncertain and difficult than an onshore one. As such, the offshore environment would increase the maintenance of wind farms - which for onshore farms is quite low- as they would involve personnel traveling to and from offshore turbines; this increases equipment and time costs as well as insurance costs due to increased risks (Snyder and Keiser, 2009).

Could we count on Solar Energy?

After reviewed the various geo-engineering methods this blog is now going to review the option of renewable energy as a way to reduce fossil fuel combustion and ultimately climate change. First up is Solar Energy.

Solar Energy
Solar Photovoltaics (PVs) are arrays of cells containing that contain a material such as silicon that converts incoming solar radiation into electricity. Today, solar PVs are used in a number of applications from mediums scale utility level power generation to small scale residential roof top power generation (Trainer, 2013).  
Concentrated Solar Power (CSP) systems use mirrors or reflective lenses to focus sunlight on a fluid to heat it to a high temperature. The heated fluid flows from the collector to a heat engine where a portion of that heat is converted into electricity. Some CSP systems can store heat for a longer period of time so that electricity can be produced at night (Jacobson and Delucchi, 2011).

Distribution of solar energy at the Earth's surface (Jacobson, 2010)

The map above shows the average downward surface solar radiation at the Earth's surface. Globally, there would be 6500 TW of solar energy available from the world's land and ocean surfaces if all sunlight was used to power PVs; however, the deliverable solar power over land in locations where solar PV could practically be developed is about 340 TW.

CSP is estimated as being able to provide about 240 TW of the world's power output, which is less than PV as the land area required for CSP without storage is about one-third greater than is that for PV, however, the figure is still high. With thermal storage, however, the land area for CSP increases more as more solar collectors are needed to provide energy for storage, but energy output does not change and the energy can be used at night.

In cases where water-cooled CSP plants are being used the energy output may differ as plants can require water for cooling during operation (about 8 gal/kWh—much more than PVs and wind (∼0 gal/kWh), but the figure is still much less than nuclear and coal (∼40 gal/kWh) (Sovacool and Sovacool, 2009). Water-cooled plants therefore might be a constraint in some areas and air-cooled plants would have to be used. An advantage of this is that air-cooled CSP plants use >90% less water than water-cooled plants do, at the cost of only about 5% less electric power and with 2–9% higher electricity rates (USDOE, 2008b). As a result, air-cooled plants suggest a viable alternative to water-cooled plants for those constrained regions that may not have access to the water needed for cooling. 

Material Resources
Solar PVs use amorphous silicon, polycrystalline silicon, micro-crystalline silicon, cadmium telluride, copper indium selenide/sulfide, and other materials. As for the supply of material, the power production of silicon PV technologies is not limited by crystalline silicon however it is limited by reserves of silver which is used as an electrode (Feltrin and Freundlick, 2008) thus if silver as top electrode can be reduced in the future the supply of materials for solar PV systems will pose no problems for the development of a large global PV system.

Issues

One of the main issues facing the viability of solar (and wind) power today is whether these methods, that produce variable outputs, could provide reliable sources of electric power all day, every day, seasonally and yearly.  

An electricity system is therefore expected to be able to respond to changes in demand in a matter of seconds. Addressing this therefore, our current electricity system uses 'automatic generation control' (AGC) to respond to variations in the order of seconds to minutes, it used spinning reserves to respond to variations of minutes to an hour and peak power generation to respond to hourly variations (DeCarolis and Keith, 2005; Kempton and Tornic 2005). 

The main challenge facing the electricity system today is the daily and yearly variations in electric demand in comparison the the constant supply of nuclear, coal and geothermal energy. In addition to this, unexpected and extreme events can cause disruptions to plants - unplanned maintenance for example can shut down coal plants while extreme heat could cause nuclear plants to shut down. 

The down time of current electric technologies and systems is therefore important - in America coal plants on average were shut down for 6.5% of the year for unscheduled maintenance and for 6% of the year for scheduled maintenance (North American Electric Reliability Corporation, 2009). In comparison to this, solar prove more beneficial as they have an average down time of 1% although some projects have had no downtime, while others have had 10% (Banke, 2010). Moreover, when solar (and wind) project are down only a small portion of electrical production is affected, whereas when a plant is down a large fraction of the electricity grid feels the impacts - if a centralised plant is affected the WHOLE grid can be down! 

The main new issue facing solar (and wind) power is that the availability of energy at a single location varies and this variation does not match patterns of demand (North American Electric Reliability Corporation, 2009). As a result there are times when solar power systems can not meet demands and times when they exceed them and are left with a surplus of ultimately wasted energy. Having said that, there are other renewable technologies other than wind and power that do not vary as much. These other methods include tidal power, geothermal energy and hydroelectricity and will be the subject of my blog after solar and wind power have been discussed. In addition to this Delucchi and Jacobson (2010) put forward seven ways to design and operate renewable energy systems so that they can satisfy demands and minimise the production of energy that is not used. 

Playing with nature ...

The ability of plants to uptake CO2 from the atmosphere produced a focus on the potential of nature to geo-engineer the climate and mitigate future environmental change. The terrestrial biomass that have been examined specifically for geo-enigineering purposes are afforestation, reforestation and biochar.

Reforestation: refers to the establishment of forest on land that had recent tree cover
Afforestation: refers to land that hasn't had tree cover or forest for a longer period of time

Anthropogenic deforestation has been recognised as a major contributor to global warming both due to the loss of future CO2 uptake and the release of sequestered CO2 that occurs when trees are cut down. Afforestation and reforestation processes are considered to be cheap and safe techniques, that ultimately achieve the end goal of CO2 uptake from the atmosphere. Globally deforestation is decreasing and reforestation and afforestation are increasing in some regions (see fig 1). Despite this, the impacts of deforestation remain, with large losses having taken place in tropical regions (FAO, 2013).

Effectiveness
Candall and Raupach (2008) state that reforestation has the potential to reduce atmospheric CO2 by 70-100ppm by 2100. This high figure offers promise, particularly when compared to the predicted reduction of 130ppm that would be caused by ocean iron fertilisation (discussed in my previous blog post). Unfortunately, a close inspection of the methods of the paper reveals this figure is deceiving as it assumes that complete reforestation is possible when actually it is not. Moreover, a reduction of 70-100ppm by 2100, be as it may a reduction of atmospheric CO2, is not a large enough reduction to reverse the effects of anthopogenic climate change.

Impacts
It has been demonstrated that only 9% of land surface would be biophysically suitable for reforestation and afforestation. However, more than half of this available land is used for agriculture and as a result not only food security would be compromised, there would be a high socioeconomic cost to afforestation and reforestation as farmers would lose labour as their are replaced by low labour forestry management (Zomer et al., 2008).

Afforestation and reforestation processes could also have hydrological impacts as runoff would be reduced and 'green vapour' flows would increase. In 2008 Trabucco et al., concluded that afforestation on 27% of suitable land would be affected by a 80-100% decrease in runoff, while 50% of suitable land could experience a reduction of 60%. In particular decreases were prevalent in drier, semi arid areas and in conversions from grasslands to subsistence agriculture. Consequently, reforestation and afforestation could potentially effect water resources and water management which is particularly significant given rising concerns over water scarcity. Moreover, the characteristics of suitable land also need to be considered as many areas deemed as suitable land may exhibit problems i.e. the human activities prior to and the mode of establishment for new trees.

Decreases in runoff in areas that are deemed suitable for reforestation and afforestation 

Increases in green vapour flows in areas deemed suitable for afforestation and reforestation 

A key factor that is overlooked in research on reforestation and afforestation is whether the processes are likely to be adopted. A study by Schirmer and Bull (2013) examined this in Australia and showed that widespread adoption requires designing afforestation so it (i) provides a range of socio-economic benefits that go beyond provision of income; (ii) minimises disruption to land management flexibility; and (iii) is compatible with landholder beliefs about appropriate use of agricultural land. 

Further to this, economic markets are also an important aspect to consider. In 2012, during the recovery from economic downturn, the market for industrial roundwood and sawnwood production increased by 6%, while wood panel production increased by 2% compared to 2011 in North America. The Asia-Pacific also increased its prominance as a producer and consumer of forest products, with China taking the lead. Sawnwood production in the region climbed by 11 percent and panels by 6 percent compared to 2011.

The importance of considering the range of perceptions of stakeholders involved in both the implementation of methods and also in the wider market is thus highlighted. Perhaps more significant is the suggestion that without changing perceptions towards a realization of the danger of deforestation and the benefits and ultimately adoption of reforestation and afforestation, research of the effectiveness of the methods is a futile task. Thus, if the method is adopted in the future to combat climate change then efforts to change perceptions will also be needed. 

A sea of uncertainty

In 1999 when John Martin infamously asserted 'Give me half a tanker of Iron and I will give you an ice age' the world, perhaps, thought for a second that the problem of ocean acidification could be solved.

Phytoplankton absorb CO2 and sunlight to produce
energy and photosynthesis

His statement was made in response to his hypothesis that an increase in the primary production of planktonic communities found in high nutrient, low chlorophyll (HNLC) areas of the surface ocean would increase the amount of carbon sequestration from the atmosphere. This hypothesis arises as during the glacial period the interactions between iron availability and silicon usage by diatoms in the Southern Ocean are thought to explain, in part, the reduction in atmospheric CO2 concentrations (Siegenthaler, 2005). Iron rich conditions are therefore thought to have caused the long term sequestration of atmospheric CO2 that occurred during the glacial intervals.

Primary productivity in 30–40% of the world's oceans is limited by the availability of iron, particularly in the open-ocean regions of the Southern Ocean, equatorial Pacific Ocean and north Pacific Ocean (Moore et al., 2002). Increasing the amount of iron in these regions has thus been explored due to the potential of added iron to reproduce the interactions that occurred in the oceans during glacial period. 

Phytoplankton are nutrient limited and as a result an increase in the nutrients iron (Fe), nitrogen (N) or phosphorus (P), would increase their primary production, producing large 'blooms' of photosynthesising algae. The hope of studies that research iron fertilisation is that the ocean, with added iron, will sequester CO2 and thus slow the rising levels of warming caused by climate change (Armbrust, 2009) however most studies so far have shown increased productivity (see fig above) however this is limited to consumption and recycling in the surface - there is little deep water sequestration. 

Studies have focused on the use of iron due it being both the most efficient out of the three by 2 and 5 orders of magnitude (respectively) and the cheapest out of the three (The Royal Geographical Society, 2009).

Green patches in the sea are phytoplankton communities 

The IPCC have predicted that by 2100, mean surface ocean pH will be at a level of 0.44 units lower than pre-industrial levels while atmospheric CO2 will measure 965ppm (IPCC, 2000). Using these predictions, Cao and Caldeira (2010) measure the extent to which iron fertilisation could be used to reverse the effects of climate change by bringing us back to pre-industrial temperatures - or as John Martin asserts give us 'an ice age'. Their study found that iron fertilization could only reduce mean surface ocean pH to 0.38 units lower than pre-industrial levels while atmospheric concentrations of CO2 could only be reduced to 833ppm (Cao and Caldeira, 2010). 

Focusing more specifically on the Southern ocean, Zarharlev et al., (2008) concluded that even if there was continuous fertilisation, the uptake of CO2 would only reach a maximum of 1Gt - which is less than 11% of our annual emissions. More recently, Martin et al., (2013) have shown that iron fertilization enhanced net community production but not downward particle flux in the Southern Ocean due to the ability of zooplankton communities to reprocess sinking particles and alter particle size distribution - both of which prevent the export and sequestration of CO2.

Iron fertilisation is therefore limited as a method to address climate change as it can not bring about large scale reductions in surface ocean pH or atmospheric CO2. Further to this, it does not necessarily stimulate the particulate organic carbon (POC) export and sequestration desired under limited Si concentrations. 

In addition to this, there are a number of potential environmental impacts that could result from such large scale fertilisation such as - 

1. Ocean oxygen depletion - anoxia, caused by eutrophication in lakes and coastal regions, can have huge negative impacts on bethnic communities and thus the whole food web of the ocean and as oxygen depletion is an outcome of iron fertilisation the risk of anoxia is high, particularly in the Indian Ocean - the implication of this could be catastrophic. 
2. Nutrient depletion in surrounding waters 
3. Harmful algae blooms could develop
4. The size of the phytoplankton species may change and become larger which would have implications for the food web of the ocean
5. Increased greenhouse gases as a result of increased methanogenesis that occurs in the digestion of phytoplankton

According to the IPCC, ocean iron fertilisation offers a potential method for removing CO2 from the atmosphere due to the potential of phytoplankton to sequester carbon dioxide in the form of particulate organic carbon. Having said that, they also state that ocean iron fertilisation remains largely speculative and many of the environmental side effects need to be assessed. Large scale iron fertilisation could have negative impacts on marine life and human health.

Despite this, however, there are rumblings that a commercialisation of iron fertilisation will occur in order to sell carbon offsets in a future where the price of carbon has increased due to climate treaties having mandated even stricter caps on emissions and governments having issued higher taxes.

As iron fertilisation would likely occur beyond a countries 200 mile exclusive economic zone, regulation would fall under international law. At present, the London Convention treaty that concerns the sea promotes the effective control of all sources of marine pollution and governs the deliberate disposal of waste or other matter at sea for its 82 treaty members. The updated London Protocol agreement specifies that all dumping is prohibited except for some specified wastes such as carbon dioxide from industrial carbon capture processes into sub-seabed geology. Under these two agreements iron fertilisation is not specifically dumping however even if it were it is not unusual for entities seeking to skirt a treaty to register their ships in a nation that is not part of the treaty or does not enforce is very strictly (Powell, 2008).

These weaknesses in International law may be countered by economic markets and the strict regulations imposed on the trading of carbon credits by the Kyoto Protocol and the European Union Emissions Trading Scheme. In an attempt to console, Powell (2008) highlights these regulations mean that carbon credits from iron fertilisation can, at present, only be sold on the voluntary carbon market. 

In my opinion, this isn't consoling at all as, despite it currently being much smaller than other segments of the carbon market, the voluntary market is growing and in addition to this it is not regulated strictly like Kyoto and EU projects - this could be dangerous as improper and inaccurate accounting and dumping of iron could occur. Buesseler et al., (2008) argue that it would be premature to start selling carbon offsets from commercial iron fertilization due to uncertainty over how effectively CO2 is removed from the atmosphere and retained in the ocean for a significant amount of time. In addition to this there are numerous environmental impacts and risks of unregulated dumping.

Buesseler et al., (2008) later wrote "moving forward on OIF should only be done if society is willing to acknowledge explicitly that it will result in alteration of ocean ecosystems and that some of the consequences may be unforeseen". In my opinion I am not sure if gaining societies acknowledgement is enough to permit iron fertilisation (is acknowledgement approval?), nor do I feel that societal acknowledgement is the direction that should be taken 'moving forward'. If the method is ineffective and the risks are too great than the method cannot be used to fix climate change.

Lets take a News Break ....

'Reducing sunlight unlikely to cool earth' 

Listed above is the title of an article published on 7th December by the Climate News Network which asserts that geo-engineering whereby, the planets thermostat is controlled by blocking, absorbing or reflecting some of the sunlight hitting the Earth, would not work to fix climate change. 

This conclusion is made in response to two recently published papers that both arrive at the same result - that you cannot fix climate change by reducing solar radiation due to the effects this would have on rainfall patterns. The first paper to make this conclusion was published by a US led group of scientists while the more recent paper was published by Axel Kleidon and Maik Renner of the Plank Institute for Biogeochemistry in Jena, Germany. 

The papers arrive at this assertion by highlighting the different responses of sunlight and surface warming on the hydrologic cycle and on vertical transport within the atmosphere. As such SRM geo-engineering that compensates for 2 degrees of warming causes the water cycle to weaken by 2% and vertical transport by almost 8%. 

This research on SRM leaves me particularly skeptical about the viability of the various methods I have discussed thus far in this blog, particularly as much of the research on the various methods puts forward impacts upon precepitation as a possible side effect. Thus it is with skepticism that I embark on the second part of my geo-engineering journey which looks at the various Carbon Dioxide Removal techniques that have been proposed as a solution to fix climate change.  

The last SRM Method …. Spaced Based

The idea of putting sunshades in space was first proposed by James Early in 1989 and since then the idea has been developed and proposed as a solution to climate change.

Space Based SRM would work to reduce the amount of solar energy entering the Earth by placing reflective materials such as dust particles or discs into orbit around the earth. The effectiveness of space based SRM is pretty much indisputable and unlike other SRM methods there is no physical limit of the extent of solar radiation reduction.

Issues arise when the logistics of space based SRM methods are taken into consideration as both the costs and magnitude of the methods are very high.

Image 1

The first proposal by James Early mentioned above consisted of one single sun shield situated at the Sun Earth Lagrangrian point 1 (See image 1). The shield would measure 2000km in width and be 10μ thick in order to block 2% of the Sun’s solar radiation. The cost of implementing this method is between $1-10 trillion – not only is this range huge and therefore vague, the minimum cost of $1 trillion dollars is also huge and as a result other methods are likely to be considered over a space based shield. Moreover, the method becomes less feasible when the amount of work that would be needed to construct the shield in space is factored into the equation alongside the very high costs.

Addressing this issue is the developments of sunshields that are smaller in size but reflect the same amount of solar radiation (McInnes, 2010)– these highly engineered refractors are however significantly more expensive to produce thus although the magnitude of the space mirror may be reduced the costs would be even higher.

Alternatively and probably a more likely scenario would be the use of a large number of smaller sized discs with the same total surface area as that of one single disc (McInnes, 2010). The smaller sized discs could be free flying independent elements or they could form a large occulting disc (see image 2 below). An absorbing occulter uses lunar or near Earth asteroid material and the total occulting area grows over a period of 50-100 years to match the required reductions in solar insolation as carbon emissions rise.

Image 2 - Occulting Disc 

Roger Angel’s (2006) research proposes a cloud of free flying spacecraft, 100,000km in length, that consists of transparent material that deflects the path of radiation in order to reduce the suns heat by 1.8%. A total of 20million sunshades and launches would be required at the again very high cost of $600 billion.  In addition to this a further $30 billion would be required to build a launcher and $150 billion would be needed to cover the energy costs to use it.

Although space based methods are located outside the Earth, there are still environmental effects caused as a result of the methods. Lunt et al.’s (2008) study shows that the SRM world would be significantly different to a pre industrial world in a number of ways. Firstly Arctic sea ice would be lower, the ENSO would have a reduced amplification, the Atlantic Ocean overturning would be stronger and the hydrological cycle’s intensity would be less intense, most notably in the tropics. Such changes could have significant repercussions, ecologically and on societies, however these changes would be less catastrophic than those that would occur from global warming left unaddressed