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!