Global Policies

Picture by Andrea Zepeilli

Over the past weeks we have explored the range of alternative energy technologies that policy makers can adopt to lower greenhouse gas emissions. These technologies would also have to be complemented with effective climate-friendly policies to be undertaken by country governments committed to solving the climate change issue.

The Economist in Jun 2013 reported on some of the key policy decisions undertaken by countries to help combat climate change. China, which is the world's top greenhouse gas emitter, initiated a carbon-trading scheme in Shenzhen. The United States, which is the second largest emitter of CO2 (US Department of Energy, 2008) was reported by the Washington Post to have tightend pollution limits for gas-fired power plants and coal-fired power plants.

While some countries have reported positive steps towards CO2 emissions reduction, others have however downplayed the climate change issue. The New Scientist reported in Sep 2013 that following Australia's formation of a new government, it has abolished its emissions trading scheme, disbanded a climate advisory body and has a policy of a relatively low 5% CO2 reduction emission target.

The United Kingdom's energy policy focuses on the two key areas of climate change mitigation and energy security (Rogers-Hayden et al, 2013) . This has led to the UK government's support to construct more nuclear power plants for its future energy mix. On this aspect, Bang (2010) opined that climate change and energy security exhibit synergies that could help alleviate the climate change problem. Energy security has high relevance and immediate economic effects, which could help pull the climate change issue along as a matter of priority for policymakers. Meanwhile, countries like Russia may see less linakages between energy security and climate change as it is not reliant on gas imports (Sharples, 2013) 

Burck et al (2013) complied a Climate Change Performance Index (CCPI), which takes into account the renewable energy and energy efficiency actions of countries. European countries faired generally well, the US and China were in the poor range, and Australia was in the very poor range. The range of climate change responses explored above, seems aligned with the outcomes of the CCPI, perhaps serving as a reminder of how much more effort the global community would need to put in to slow the effects of climate change. 

Will You Accept Nuclear Power?

In my previous post, I touched on the critical aspect of public perception on the nuclear issue. Moving on, I believe it might be of some value to examine how the UK have viewed the adoption of atomic energy, and whether public opinion may have shifted following the catastrophic Fukushima incident in Mar 2012.  

Through a survey of 1822 UK citizens aged 15 and older, Corner et al (2011) observed that 71% of the respondents were concerned about climate change. Respondents in earlier surveys who had concerns about climate change and energy security earlier typically also harboured high ideals of environmental values and were not willing to accept nuclear power. Nonetheless, when the questions allowed for a ‘reluctant acceptance’ to allow respondents to express their dislike for nuclear power alongside their conditional support (if other energy options do not work out), this group of respondents were nudged towards support for nuclear.

Perception Survey Results
Source: Corner et al (2011)

Subsequently, Poortinga et al (2013) examined various survey results to consider how the Fukushima incident may have changed public perceptions of climate change and energy futures in Britain and Japan. While British attitudes have remained relatively stable, the Japanese public acceptance of nuclear power decreased, even if it would contribute to climate change mitigation. Poortinga et al (2013) surmised the lack of visible accidents in the UK and Europe may have made the British public less attentive to the risks of nuclear power. 

This may then lead to wonder how countries neighbouring Japan may feel about nuclear power after the Fukushima incident? A recent study conducted by Huang et al (2013) found that acceptance of nuclear power by China's public in a coastal city of Jiangsu province decreased significantly following the incident, in particular females, non-civil servants, people with lower income, and those residing close to a nuclear power plant. The interesting point is that 50% of the survey respondents considered it acceptable for nuclear incidents to occur once in 100 years. 

With Fukushima looming in the background, Wittneben (2012) noted that while the UK government remains adamant on the adoption of nuclear power, other EU countries such as Germany has taken a non-nuclear stance. Wittneben (2012) opined that various factors could be at work. Historical context, cultural influences, and the media could be some key reasons behind Germany's reluctance towards the nuclear option.

In my view, public acceptance would be key for any country looking to adopt atomic energy. Sailor et al (2000) cited the various challenges to be overcome when employing the nuclear option, which include enhancing nuclear reactor safety, proper radioactive waste disposal, and a rigorous safeguards regime to prevent nuclear weapon proliferation. These areas of concern still remains valid today, and any communication with the community would have to comprehensively address them.

Picture by:
Watashiwani on Flickr

Picture by: 
http://nuclearpoweryesplease.org/en/

Is Nuclear Energy the Answer?

Photo by Michael Kappel on Flickr

In the wake of the Fukushima incident, the UK government recently announced its intention to develop Britain's next generation of nuclear energy via a deal with state-owned French and Chinese companies. This would be in line with its policy to have the first new nuclear power stations generating electricity from around 2019.

The UK has a relatively long history in its reliance on nuclear power. Nonetheless in the 1990s, the UK government committed itself to shun the nuclear option. The first nuclear power plants that came into operation in the 1950s, recently passed the international peer review for its decommissioning conducted by the International Atomic Nuclear Agency (IAEA). 

Circumstances have since changed. Greenhalgh and Azapagic (2009) explained that the UK government has committed to an 80% reduction below 1990 levels of carbon dioxide emissions by 2050 through the Climate Change Act 2008. Under the auspices of the EU, a target of 15% of energy consumption to be met by renewable energy. Given the latest climate change targets and need for energy security, the UK government has made a dramatic change and proceeded to adopt the nuclear option as part of its energy mix and to meet its obligations in mitigating carbon emissions.

According to the government's white paper on nuclear energy released in 2008, UK’s CO2 emissions would have been some 29 to 59 MtCO2 higher if there had been no nuclear power stations.  If we apply the CO2 emission statistics by the Department of Energy and Climate Change (DECC), this would represent 14-28% of the CO2 emissions arising from the energy supply sector in 2008, which appears rather significant. 

UK carbon dioxide emissions, 1990-2012

Source: DECC Statistics

Sovacool (2008) considered 103 lifecycle studies and calculated a mean value of GHG emissions for a nuclear reactor as 66 g CO2e/kWh. While the nuclear power plant does not emit GHG directly, the plant still requires fossil-fuel during the construction, decommissioning, and uranium mining and enrichment phases. Nontheless the rate of GHG is better than coal (960 g CO2e/kWh) and oil (778 g CO2e/kWh) electricity generators, but worse off than renewable sources such as wind (9 g CO2e/kWh) and solar (32 g CO2e/kWh). 

From a scientific perspective, the nuclear option does present itself as a potential solution towards the mitigation of CO2 emissions while meeting mankind's growing energy needs. Nonetheless, regulators would need to ensure that stringent policies on nuclear safety and safeguards would need to be in place. Last but not least, public perception would likely be a key deciding factor on whether a country would consider nuclear energy as an option. 

For those of us who may be curious, here is a video that illustrates how a nuclear power plant typically functions. 

                              

Pursuit of Happiness

 Bhutan Haa Valley by Wikimedia

An interesting opinion piece titled "Can Bhutan Achieve Hydropowered Happiness?" in the New York Times caught my eye recently. It appears that Bhutan plans to build an array of new dams and ramp up hydropower capacity from 1,480MW to 10,000 MW by 2020

Famed for its pursuit of Gross National Happiness (GNH), this set me wondering how Bhutan approaches the issue of energy use and climate change. 

Picture by Samir Mahta

Uddin et al (2007) explains that Bhutan is one of the world's least-urbanized countries. Apart from relying on agriculture and tourism, Bhutan gains much revenue from its sale of hydro-electricity to neighbouring India. Bhutan does not have much fossil energy resources and imports petroleum, while relying on its water and forest resources for most of its energy needs. The hydro-electricity sale also represents an important facet of Bhutan-India relations as Bhutan depends heavily on India for its economy and security (Nyaupane and Timothy, 2010). 

Meanwhile in November 2013, Bhutanese prime minister was reported by the Financial Times  to have announced that government vehicles will be replaced with electric cars, followed by the gradual replacement of taxis and family cars with locally assembled electric vehicles. The government realises that while Bhutan obtain proceeds from the sale of hydro-electricity to India, the majority of these gains are channeled towards importing fossil fuels for transport. Such a venture is believed to be highly suited for Bhutan as electricity is cheap, and most road trips are short.

It is heartening to learn that despite having low per-capita annual emissions of CO2, Bhutan chooses to pursue climate friendly measures, rather than continue with its reliance on fossil fuels. Hopefully more developing economies can consider similar approaches as part of their growth plans. 

Tidal Power

Fig 1: Tidal Stream Generator schematic from Flickr

In Sep 2013, BBC reported that Scottish Energy Minister Fergus Ewing consented to the development of the largest tidal turbine array in Europe as a step towards generating renewable energy to combat climate change. This represents a major step towards tidal energy generation that may have the potential to meet 20% of the UK's electricity demand.

There are various methods of harnessing tidal power, such as the tidal stream generator (TSG) in Fig 1 and the tidal barrage in Fig 2. These have been undertaken by various countries such as China, France, Korea, the UK, and the USA (Rourke et al, 2010). Tidal barrages can be constructed in an estuary or a bay in high tide areas (Grabbe et al, 2009). In comparison, TSGs would have lesser impact on the environment than tidal barrages due to the avoidance of dam construction, and tidal barrages have a higher cost of construction compared to TSGs. 

Fig 2: Tidal Barrage Schematic by Andy Darvill

Tidal energy has the key advantage of having greater predictability on its availability compared to other renewable energy sources such as solar and wind, however it still suffers from the problem of being intermittent (Griffin and Hemer, 2010). In comparison to wind turbines, tidal current turbines generate a much larger thrust due to the density of seawater, and thus requires use of a stronger material which results in greater capital costs. (Rourke et al, 2010). 

Meanwhile, Ward et al (2012) suggests that future sea-level rise can have significant impacts on the tidal dynamics of the area, which is further enhanced when the effects from tidal power plants are incorporated. Impacts to tidal amplitudes, currents and associated tidal dissipation and bed shear stresses may be observed.

In terms of CO2 emissions savings, Denny (2009) conducted a study based on Ireland which found that with 560 MW of installed tidal generation, CO2 emissions can be reduced by 501 kiloton, which translates to 2% of the total Irish system's CO2 emissions. Grabbe et al, (2009) also cited that life cycle assessment for a marine current turbine compares well with offshore wind turbines in the areas of carbon intensity and energy payback period.

From the angle of public perception, Devine-Wright (2011) conducted a survey which found general public support for tidal energy in Ireland. He suggests that by capturing the symbolic meanings associated with places proposed for development, the public may be better able to accept project proposals for renewal energy.

In conclusion, tidal power plants have the advantage of providing a predictable, but intermittent electricity supply, and there are challenges in terms of cost. More studies would also be needed to determine the marine environment impact arising from tidal power plant construction and operation.

Mauna Loa

Mauna Loa Observatory. 
Photo by Wikimedia Commons

As I was pondering over the many technologies reviewed so far on energy use and its effect on climate change, I began to wonder how the first scientific measurements of CO2 came about.

Up till the 1950s, scientists had largely believed that anthropogenic CO2 emissions would be absorbed by vegetation of the ocean, and would hardly have a measurable impact on climate change (NY Times, 2005). It was due to the dedicated work pioneered by Dr Charles Keeling (1928-2005) from the Scripps Institution of Oceanography in San Diego that the effect of CO2 on earth's climate has come to grab the world's attention.

Dr Charles Keeling receiving the Medal of Science from President Bush

Photo by Wikimedia Commons

Dr Keeling, in an essay titled "Energy and the Environment" published in 1998, meticulously recorded how he had engaged a glass-blower to customise the apparatus he needed, the long drive to Big Sur State Park in California where he took the first CO2 measurements, and the subsequent initiation of the historical CO2 time-series measurement at Mauna Loa in Hawaii in 1958, which we have come to know today as the Keeling Curve

Keeling Curve from Wikimedia Commons

Dr Keeling's work on CO2 measurements was fraught with challenges, ranging from technical issues on the sampling equipment to funding cuts from the government. His research nonetheless continued unfaltered. In a paper titled "Industrial production of carbon dioxide from fossil fuelsand limestone" published in 1972, Dr Keeling reported that the cumulative increase in anthropogenic carbon from mankind's industrial and domestic activities was about 18 % of the amount of CO2 in the atmosphere during the late nineteenth century.

Dr Keeling cited a three-fold increase in global fossil fuel consumption since he began measuring CO2, which essentially increased almost six-fold over his lifetime. He came to know Dr Harrison Brown at Caltech. Brown (1954) wrote that "should a great catastrophe strike mankind. the agrarian cultures which exist at the time will clearly stand the greatest chance of survival and will probably inherit the earth. Indeed. the less a given society has been influenced machine civilization. the greater will be the probability of its survival". 

Dr Keeling subscribed to Dr Brown's view that mankind should conserve fossil fuel use as a most prudent approach, regardless of whether dire environmental consequences would result from rapid fossil fuel use, given that the danger of global warming would be reduced as well.

As I read Dr Keeling's recollection of his journey, what struck me most was the passion that he held for science. Perhaps serving as a gentle reminder to put aside the controversies behind the climate change issue, and enjoy the pursuit of scientific knowledge in its purest form.

 "Why did I devise such an elaborate sampling strategy when my experiment didn't really require it? The reason was simply that I was having fun. I liked designing and assembling equipment. I didn't feel under any pressure to produce a final result in a short time. It didn't occur to me that my activities and progress might soon have to be justified to the sponsoring Atomic Energy Commission. At the age of 27, the prospect of spending more time at Big Sur State Park to take suites of air and water samples instead of just a few didn't seem objectionable, even if I had to get out of a sleeping bag several times in the night. I saw myself carving out a new career in geochemistry." (Keeling, 1998)

Geothermal

Geothermal electrical power generation schematic from Canadian Energy Commission

Geothermal has been used by some countries for the warming of buildings and electricity generation, and has been promoted as a key alternative energy technology that can help mitigate climate change impacts. 

The US Department of Energy (DOE) lists several benefits of geothermal power, including the following:

• 24-hour continuous production of geothermal electrical power regardless of weather conditions.
• Geothermal has a small footprint that use only 1,046 GWh/km2, as compared with coal (9433 GWh/km2). wind (3458 GWh/km2) and solar (8384 GWh/km2)
• Life cycle greenhouse gas emissions are 4 times less than solar, and 6-20 times lower than natural gas. 

Iceland leads the world in use of geothermal energy. 54% of the country’s total energy use is supplied by direct heat and electrical energy from geothermal sources, and more than 89% of the population have geothermal heating in their homes. (Lund, 2010)

Most geothermal heat pumps (GHPs) operate within 6 metres of the Earth’s surface that maintains a stable temperature of 10 to 16 °C (EncyclopaediaBritannica, 2013). The efficiency of a geothermal technology is typically expressed by its Coefficient of Performance (CoP), which measures the thermal energy generated as a ratio of the the electrical power consumed. CoPs typically range around 2-6. (Tong et al, 2010, Ozcan and Ozgener, 2011). GHPs could present an average savings in GHG emissions of above 50% in comparison to conventional heating systems. (Saner, 2010)

Heat from depths of around 2-6km has also been extracted for generating electricity, using steam with temperatures ranging from 120 to 370 °C. (Zaigham and Nayyar, 2010). In terms of costing, electrical energy generation costs 2–10 US¢/kWh for geothermal and hydro, 5–13 US¢/kWh for wind, 5–15 US¢/kWh for biomass and 25–125 US¢/kWh for solar photovoltaic (Fridleifsson, 2001).

Geothermal fluids may contain traces of chemicals such as hydrogen sulfide, ammonia and mercury which are largely reinjected into drillholes and not released into the environment. Thus far, national and legally binding regulations for geothermal technology only exist in few countries such as Denmark or Sweden. Haehnlein (2010) suggests that to avoid detrimental environmental impacts, it is necessary to define groundwater temperature limits for heating and cooling and minimum distances between such geothermal systems.  

Geothermal electricity generation has been made available commercially since 1913 but so far the focus has been largely on hydropower (Fridleifsson, 2001). For developing countries like Kenya, Ogola (2012) argues that the use of geothermal energy will improve food security, mitigate the impact of climate change, and provide employment opportunities. 

With a small footprint and limited greenhouse gas emissions, the arguments so far gives support to the potential of geothermal energy as a cost-effective and viable alternative energy source. There is however a need to strengthen national legislation to ensure minimal environmental impact arising from geothermal energy use.

Counting the Cost

Source: Flickr

Bloomberg recently reported on an Asian Development Bank (ADB) study which suggested that regional mean temperatures in 2090 for East Asia (China, Japan, South Korea and Mongolia) could be 3.8 to 5.2 degrees Celsius higher than the 1961-1990 average. As a result, the region could be vulnerable to floods that could threaten $864 billion in assets.

Adapting infrastructure to climate change would cost the region $22.9 billion a year in 2005 dollars in areas such as coastal protection. Climate-related natural disasters since 1970 have cost $259 billion to China, $64 billion to Japan, $15 billion to South Korea and $2 billion to Mongolia. It may thus make economic sense for the region to embark on more adaptation measures.

An interesting study was conducted by Rojelj et al (2013) to determine the probablistic cost estimates for climate change mitigation. At present global carbon prices of less than US$1 / tCO2e, the likelihood of limiting warming to less than 2 degrees Celsius is almost zero. However, imposing a carbon price of about US$20/ tCO2e would increase the probability of staying below 2 degrees Celsius to about 50%.

Source: Rojelj et al (2013)

The same paper also found that carbon price would be highly sensitive to political inaction. Should governmental action be delayed till 2030, the probability of global mean temperatures staying below 2 degrees Celsius dropped dramatically from 50% to 15%

Source: Rojelj et al (2013)

In conclusion, whichever energy mix that a country selects, it would be important that adaptive measures are also put in place by policy makers early. It makes economic sense to do so, as illustrated above. 

Wind Power Contributes to Climate Change?

Source: Wikipedia

Amongst the various energy options such as nuclear and fossil fuels, most would likely consider wind power as a relatively climate-friendly technologies. The New York Times in Oct 2013 reported that 12 miles off the coast of Fukushima nuclear power plant site, a giant floating wind turbine has been installed that can generate enough electricity to power 1,700 homes. Japan aims to have 140 of such wind turbines that would generate one gigawatt of electricity. This is equivalent to the power generated by one nuclear reactor.However, the perception of wind power being climate-friendly is now being challenged.

The Telegraph in Apr 2012 reported on a study which postulated that wind farms could result in localised climate changes. The paper by Zhou et al (2012) presented observational evidence for the period of 2003–2011 over a region in west-central Texas, where four of the world’s largest wind farms are located. The analysis revealed a significant warming trend of up to 0:72 degrees Celsius per decade over wind farms. Interestingly, the spatial pattern of the land surface temperature increase (red areas) correlates well with the geographic distribution of wind turbines, as shown in the chart below. 

Source: Zhou et al (2012) 

Most of the wind farms were built around 2005-2008, so the temperature difference depicted is for the years before (2003) and after (2010) the wind farms were constructed.

On a separate note, the US EPA has cited other concerns on the use of wind power. Modern wind towers can be between 60-120m in height and are typically sited on atop ridgelines or in the sea. Wind facilities may sometimes face opposition from local communities due to aesthetics considerations, as well as its impact on wildlife such as birds. Recently, the Washington Post reported that the US government fined a wind farm in Wyoming a hefty sum of S1 million for the deaths of eagles in turbines under the Migratory Bird Treaty Act.

Wind farms are also subject to availability of the wind resource, and consumers have to fall back on conventional sources of power that may contribute GHG when there are no winds*, The latest finding by Zhou et al (2012)  would further trigger the need to rethink the modes by which some of our climate-friendly technologies could create localised impact on the regional climate. 


*Updated on 28 Nov 2013

Fossil Fuel Divestment

Photo by London Commodity Markets

The Guardian recently reported on an Oxford University study that recommended for investors to divest funds away from the fossil fuel sector. While the direct impact of divestment campaigns on share prices and company financing may be small, the study suggests that the reputational pressure could still influence transformative change in the fossil fuel industry.

The researchers nonetheless acknowledged that even with the maximum possible capital divested by university endowments and public pension funds, the total was relatively small compared to the market capitalisation of traded fossil fuel companies and size of state-owned enterprises.

Debates on divestment of university endowments has been on-going within the academic community. For example, Hendey (2012) wrote an article in the Harvard Political Review expressing his view that divestment from fossil fuel companies would deliver a strong signal to the energy industry that the academia takes a serious view of the climate-energy challenge. 

On the other hand, Harvard's President Drew Faust released a statement in Oct 2013 that divestment of its investment in fossil fuel industry may not be warranted. She argued that there are more effective ways for Harvard to address both climate change and to enhance its commitment to sustainable investment.

While we continue to ponder upon the efficacy of such fossil fuel divestment campaigns, I believe that tracking developments in this area would be interesting to see how academic institutions and the industry would respond to mounting pressure from such campaigns.

How Reliable is Solar?

Photo from Flickr

According to the US Environmental Protection Agency (EPA), mankind started using the magnifying glass to concentrate sun’s rays and create fire since the 7th century BC. For the modern photovoltaic technology, one may trace its origins to 1954 when Bell Labs based in the US developed the silicon photovoltaic (PV) cell that was capable of converting sufficient solar energy to run everyday electrical equipment 

While solar technology has since progressed much, challenges remain in terms of efficiency, cost and variability. 

An article by Shaheen et al (2011) cited that PV cell production has been dominated by crystalline silicon modules representing 94% of the market. Limited by thermodynamic considerations, PV cells can likely achieve maximum efficiency of 31%. To this end, Zhou et al (2010) proposed that hybrid solar–wind energy systems could help improve system efficiency and power reliability

In the area of cost, the potential of organic PV cells has been actively researched. Organic molecules and polymer materials are typically inexpensive to manufacture and could offer substantive cost reductions that would make it economically viable for large-scale power generation. The chart below illustrates the cost gap that would need to be covered in order to meet the US Department of Energy's cost goal of $0.33/W for the PV cell. 

Historical and projected costs for wafer c-Si and film c-Si photovoltaic modules
Chart from Shaheen et al (2011)

There is also an added aspect of environment justice (EJ) proposed by Mulvaney (2013).The paper contends that PV technologies use materials and processes that rely on toxic materials and generate waste flows similar to those in the electronics and semiconductor industries which may impact on workers and communities. Enormous land resources to harvest solar energy would also be required that may result in conflicts with other ecological and cultural resources.

It would thus appear that solar energy from a life cycle perspective may not be as environmentally friendly as one would expect. Nonetheless, with on-going research into organic PV cells, hopefully we can one day witness a major breakthrough in PV technology in the areas of cost, efficiency and reliability.

The Irony of Hydropower

Photo from Wikipedia

Hydropower is considered by many to be a strong candidate in the fight against climate change. This is notwithstanding the potential social impacts and habitat destruction that is commonly associated with such mega damming projects. Here is an illustration of how a typical hydropower plant works.

Illustration from Wikipedia Commons

Hydropower will likely continue to play a key role in future energy production. A study by Lehner et al (2005) correlated the potential of hydropower plants to produce electricity to changes in river discharge. Based on findings from their models, the authors proposed the following scenarios for the 2070s in Europe.

• Scandinavia and northern Russia could see an increase in developed hydropower potential (15–30% and above)
• Portugal and Spain in southwestern Europe, as well as Ukraine, Bulgaria and Turkey in the southeast, could see a decrease of developed hydropower (20–50% and more).
• The United Kingdom and Germany's developed hydropower potential would likely remain stable

This leads one to wonder if hydropower may have its limitations going forward? 

There has thus far been a notion that removing trees along streams would increase surface runoff going directly into streams, and thereby benefit hydropower generation. Challenging this notion, New York Times recently reported on a study by Stickler et al (2013) that considered “indirect” rainfall effects resulting from deforestation generation potential for the Belo Monte energy complex under construction on the Xingu River in the eastern Amazon. Deforestation of the Amazon region inhibited rainfall within the Xingu Basin and simulated power generation declined to only 25% of maximum plant output. 

Apart from rainfall effects, Simoes and Barros (2007) also observed that increased temperatures could lead to increased evapotranspiration rates, which would result in reduced power generation for hydropower plants. In 2001, due to an upward trend in temperature, rainfall fell behind evapotranspiration rates, and reservoir levels dropped to 20% of total capacity. The situation was so severe that the federal government announced a national rationing plan to avoid blackouts. 

The authors therefore cautioned that such climatic variability typically do not capture media attention, but the subtle changes over long periods would accumulate and invalidate assumptions on water availability for hydropower stations, thereby affecting electricity generation.

Therein lies the irony. Although hydropower is viewed by many as a potential solution to global warming, the viability of hydropower itself is at the mercy of climate change. Relevant stakeholders should therefore consider undertaking more holistic analysis that factor in climate change impacts as part of their environmental impact assessments for future hydropower projects. 

Dynamic Life Cycle Analysis

Photo by: Wikipedia

Over the past few posts, I have made some references to the use of Life Cycle Analysis (LCA) in determining the viability of the various Alternative Energy Technologies (AETs) that were discussed. For example, Sovacool (2008) compiled the life-cycle GHG emissions from various AETs as shown in Table 1 below. 

Table 1 - Sovacool (2008) : GHG Life-cycle Estimates for Electricity Generators

Meanwhile, Kenny et al (2010) suggested that a more advanced form of analysis called the dynamic LCA should be used as a gauge on the suitability of AETs to drive the optimization of electricity generation for effective climate change mitigation. 

The interesting feature of the dynamic LCA, is that it takes into account the growth rate of the technology, in addition to other critical factors such as emissions arising from plant operations as well as its construction phase. Table 2 below summarises their findings:

Table 2 - Kenny et al (2010) : Rankings of current technologies according to carbon-neutral growth rates

Electric energy technology	Carbon-neutral growth rate (%)
Geothermal	24
Wind	91
Biomass	50
Concentrating solar thermal	43
Small Hydro	43
Solar photovoltaic	41
Nuclear	22
Hydro	5
Natural gas combined cycle	−5*
Oil	−20*

The “carbon-neutral growth rate” is defined as the rate at which the aggregate carbon mitigation of an energy technology as a whole (eg, all wind power projects in the world) is offset by the carbon emitted in the construction of new plants. Negative carbon growth rates imply that adding capacity of that technology to the grid will result in an increase in GHG emissions per unit energy. 

It does not come as a surprise that fossil fuel technologies fare badly in the rankings. The results suggest that wind, biomass and solar AETs could be promising. 

Nonetheless, the authors have also acknowledged that further refinements could be made to their methodology such as the inclusion of economic principles. With these refinements, the new methodology could be of interest to potential investors and policy makers, and could potentially reshape future evaluations of AETs. 

Algae

Photo by: Wikipedia

Since biomass cultivation on land poses competition to food security, perhaps we can consider using other forms of biomass from the sea? Can algae be a promising source of biomass energy, since they generally do not compete with food crops for resources and land?

It appears that there has already been strong interest in algae biofuel development. A recent Time article mentioned that while technology to make cellulosic ethanol or biofuel from algae is available, there are high costs and challenges associated with scaling the production up sufficiently to compete with oil.

Liu et al (2013)'s life cycle analysis (LCA) on  algae-to-energy systems with hydrothermal liquefaction (HTL) showed that substantively lower GHG emissions can be achieved compared to gasoline as depicted by the chart below for various scenarios. Nonetheless, conventional fossil fuels such as gasoline maintain the upper edge as they enjoy a higher Energy Return on Investment (EROI).

Source: Liu et al (2013) 

HTL is of particular commercial interest because it is able to seamlessly integrates with existing petroleum refining infrastructure. During hydrothermal liquefaction, high moisture biomass is subjected to elevated temperatures and pressures, similar to the natural geological processes that has produced existing stocks of fossil fuel.

Apart from cost considerations, one should also consider the CO2 mitigation potential of algae biofuels through a life cycle analysis. Andres et al (2010) compared the environmental impact from algae production with various biofuel crops such as switchgrass, canola, and corn farming. The results indicate that conventional crops have lower environmental impacts than algae in energy use and GHG emissions. It appears that the large environmental footprint of algae cultivation is driven predominantly by upstream impacts, such as the demand for CO2 and fertilizer. To reduce these impacts, wastewater could be used to offset most of the environmental burdens associated with algae.

Looks like it will still be some way to go before algae biomass can become a marketable and truly climate-friendly alternative energy technology.