Friday, July 10, 2020

Plant- Microbial fuel cell: Generating electricity from green, living plants

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Charvi Trivedi

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Plant- Microbial fuel cell: Generating electricity from green, living plants

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Global Views 360

Publication Date

July 10, 2020

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Marshland near Blythburgh. View over the tidal River Blyth

Marshland near Blythburgh. View over the tidal River Blyth  | Source:  Eileen Henderson via Wikimedia

Humans are capable of discovering and creating great things with the help of science and one such impressive discovery is that green, living plants can generate electricity. It may seem unbelievable, but not impossible.

One must be wondering how this technology works. Well, the answer is quite simple; photosynthesis. Plants excrete organic matter into the soil as a result of photosynthesis. Only some of the organic matter is used by plants and the rest is released in the soil. This released organic matter is broken down by bacteria. In the breakdown process, electrons are released as a waste product. Since the movement of electrons produces electricity, these electrons, which are of no use to the plant, can be harvested. The best part about this innovation is that the plants from which energy is being generated are not affected in any way.

This idea was first put into use by a Dutch start-up called Plant-e. This company was launched in September 2009 and is successful in launching and selling many environment- friendly products like DIY kits to the public for experimentation purposes and modular systems which could be easily installed on green roofs for abundant electricity production. Plant-e is involved in various projects, within The Netherlands, like automatic lighting systems in gardens and many more.

This technology works with the plants which thrive in moist soils and where the water is present in abundance. Therefore marshlands, paddy fields and deltas are some of the most suitable places for setting up plant batteries as a huge amount of water is present in those areas. Hence, the use of this technology is limited to certain geographic areas containing moist soils and cannot be used in arid regions. It may, however, promote the growth of more trees and plants which will gradually reverse the malicious effects of global warming.

Another obstacle in widespread adoption of this technology in today’s time is the high cost of installation of the system. The initial adopters of this technology are those who are attracted by the efficiency and eco-friendly nature of the plant batteries and willing to pay a premium for it.

The concept of plant batteries can be further taken into rural areas where most of the population still does not have access to adequate electricity. It is estimated that plant-MFC technology can cover upto 20% of European Union’s primary future electricity needs. Also, plants are almost 100% efficient at converting photons from sunlight into electrons which indicates a bright future for this technology. However, more research needs to be done in this field.

Another innovation in the field of green electricity is using algae , which often grows in ponds and rivers, for generating electricity. The basic concept which explains the working is similar to the way plants are able to produce electricity; photosynthesis.

Various other ventures in the field of renewable energy also include vegetable batteries, meaning, electric power generated from fruits and vegetables like lemons, tomatoes and potatoes, have been investigated. According to experiments, at least 3 to 4 vegetables are required just to light a small LED bulb. Moreover, it leads to poisoning of the vegetables and those food products need to be thrown away, without being useful for consumption purposes. It is therefore not a viable option for energy production.

Plant based electricity generation is still an evolving technology which has immense potential for producing energy in an environmentally sustainable way. It will realise full potential when the installation cost is attractive enough for the farmers to prefer it over the electricity grids or fossil fuel based personal electricity generator sets.

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February 4, 2021 4:52 PM

Randomised Control Trials and the Alleviation of Poverty in India

Abhijit Banerjee and Esther Duflo won the 2019 Nobel Prize in Economics for their “experimental approach in alleviating global poverty”. Their experimental approach encompassed a variety of novel methods to understand and analyse interventions and Randomised Control Trials (RCTs). Their research has been used by policy makers to make informed policy decisions to best help the marginalised.

What are RCTs?

To understand the effect of a policy, intervention, or medicine, decision makers try to measure the efficacy of the treatment. Do deworming pills given to children improve test scores? Does providing chlorinated water improve the health and economic outcomes of villages? These are some causal (read causal, i.e. caused by, not casual) questions researchers are interested in. The best way to analyse causal effects is to randomise the selection of people in the treatment and the control group (for example: children who are given deworming pills versus children who are not given the pills). This random selection of the two groups removes many statistical biases that might affect the results.

RCTs in India:

Many of the RCTs performed by Banerjee and Duflo were in India. They involved short- and long-term impact assessments of various interventions, policies, models, and treatments. We look at a few RCTs implemented in India:

Teacher absenteeism rates:

Troubled by the low attendance rates (or high absence rates) of public-school teachers in India, Duflo assessed the impact of financial incentives on the absence rates of teachers in Rajasthan. The study monitored teacher attendance by cameras, which was tied to a financial incentive if the attendance was high. From a baseline absence rate of 44%, teacher absenteeism in the treatment group fell by 21%, relative to the control group. High teacher attendance caused child test scores to improve too.

COVID-19 and health-seeking behaviour:

In the context of COVID-19, Banerjee tested the effect of sending messages via SMS that promoted health preserving behaviour. The results were very positive. By sending a short, 2.5-minute clip to 25 million randomly selected individuals in West Bengal, the intervention i) found a two-fold increase in symptom reporting to village health workers, ii) increased hand washing rates by 7%, and iii) increased mask-wearing by 2%. While mask-wearing rates increased only marginally, the spillover effects (wearing a mask stops the virus from infecting more people) were moderately high and positive.

Asset Transfers and the Notion of Poverty:

An RCT by Banerjee in West Bengal involving a productive asset transfer accompanied with training found large and persistent effects on monthly consumption and other variables. The treatment group reported 25% higher consumption levels relative to the control group, who did not receive the asset transfer and training. Implications of such RCTs are huge. The notion that the poor are lazy and unwilling to perform strenuous labour is falsified by this RCT. Often, what the poor lack are opportunities that are hard to come by, given their financial status. A small nudge, like the asset transfer, can cause large and positive effects on their well-being.  

Salt fortification to reduce anaemia:

RCTs also help rule out less cost-effective interventions. Duflo and Banerjee evaluated an RCT which distributed fortified salt in 400 villages of Bihar, to reduce the prevalence of anaemia. However, this intervention found no statistically significant impact on health outcomes like anaemia, hemoglobin, etc.  Thus, while RCTs help introduce novel methods of impacting the lives of the poor, they also help in ruling out in-effective measures. A policy maker might try other alternatives to reduce the prevalence of anaemia.

Are RCTs the gold standard?

Maybe. Extrapolating results from a regional RCT to national policies could present problems. Contextuality matters. A study that indicates positive gains for one region might present different, and rather adverse effects for another region. Nation wide effects might not be as prominent as regional results of a single RCT. The good part is that Banerjee and Duflo have a solution. Just perform more RCTs!

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