Clean energy and visit to Temasek Poly

Clean energy = heat and electricity produced from renewable sources, generating little or no pollution or emissions 

e.g. wind energy, hydropower, solar electricity, biomass heating, organics-to-energy 

• Singapore’s key strategies in mitigating greenhouse gas emissions are to 1) switch to less carbon-intensive fuels (i.e. natural gas) and 2) to improve energy efficiency. 
• 60% of greenhouse gas emission comes from industry. 
• Energy Efficiency Promotion Centre provides industrial energy efficiency related resources 
• Legislation: understand mandatory energy management practices 
• incentives and grants 
• Energy Efficiency National Partnership that offers training programmes and workshops on energy efficiency and energy management 
• 7.6% of the total greenhouse gas emitted comes from household sector 
• 10% Energy Challenge launched in 2008 challenges households to reduce energy usage by 10% or more by practicing energy-saving habits such as switching off electrical appliances when not in use 
• Voluntary Agreement with retailers and suppliers to promote energy efficient air-conditioners, refrigerators and dryers 
• Mandatory Energy Labelling: registrable goods have to be labelled according to the Energy Conservation Act i.e. the more ticks, the more efficient the appliance is 
• roadshows, media publicity, brochures to raise public awareness on energy efficiency 

Green buildings in Singapore 

• Singapore Green Building Council: advocate green building design, practices and technology 
• Building and Construction Authority: BCA Green Mark helps facilitate reduction in water and energy usage, improve indoor environment quality, provide clear direction for continual improvement 

Temasek Polytechnic green features: 

• green roof 
• stack ventilation shaft creates convection current within the building 
• light shaft 
• design of windows to complement monsoon winds, aiding natural ventilation 
• membrane filtration system 
• monitoring devices at wind chimneys for raising sustainability awareness and educational purposes 
• vertical green 
• solar panels: converts 18% of 1kw from sun per 1m^2, install glass panels to reflect sunlight back onto panels
  —> solar panels on sea surface to maximise area

Fuel cell:

H atom separated into electron and proton, proton flows through membrane, electron flows through load (flow of electron opposite to current flow), recombines with oxygen —> water molecule (very little) 

No wastage —> clean energy 

Electrolytic cell: 

Electrolyse water into hydrogen gas and oxygen gas (ratio 1:2) 

Electricity input > electricity output: no point, commercialised process does not use electricity to obtain hydrogen gas 

Biodiesels

Petroleum diesels = a mixture of hydrocarbons (range from 8-21 carbon atoms) produced through the fractional distillation of crude oil 

Biodiesel = consists of fatty acid methyl or ethyl esters made from vegetable oil or animal fat (triglycerides) 

• transesterification reaction transforms one type of ester into a different type of ester. Biodiesel is made from vegetable oil or animal fat reacted with methanol/ethanol in presence of catalyst (KOH/NaOH) to give glycerol as the by-product 

Applications of biodiesel:

• Gasoline: fuel for vehicles is made form crude oil that takes millions of years to be formed, reserves are depleting 
• Faster harvest: as opposed to crude oil, biodiesel can be made from vegetable oil from plants, or use leftover vegetable oil 
• biodiesel produces less exhaust fumes due to its chemical structure with more oxygen atoms than crude oil 
• Airlines: Virgin Atlantic, Continental Airlines, Air New Zealand, Japan Airlines etc. A total of 8 US airlines that operate out of LAX have also signed a deal to use more than 1.5 million gallons of biodiesel a year for their ground vehicle 
• Commercial trucks, personal cars, SUVs, farm equipment 

Differences in properties between diesels and biodiesel 

The sizes of the molecules are about the same, but diesels and biodiesel have different chemical structure. Diesel consists of 95% hydrocarbon-saturated compounds and 5% aromatics, while biodiesel consists almost entirely of fatty acid methyl esters. As a result of the difference in chemical structure, in comparison to diesel, biodiesel: 

• has higher lubricity - reduces engine wear 
• contain practically no sulfur - reduce pollution by emission 
• has 10-12% higher oxygen content - reduce pollution 
• tend to more viscous at low temperatures - becomes problem during cold winters 
• more likely to oxidise to form solid gel-like mass 
• more chemically active as a solvent - more aggressive when used on material considered safe for diesel fuel 
• much less toxic - beneficial for spill clean ups 

Advantages of biodiesel

• Cost 
• cost the same as diesel in the market, but the overall cost benefit of using biodiesel is much higher. Biodiesel has higher lubricity, keeping the engine running for longer, requires less maintenance. With increasing market demands for biodiesel, there is the potential for the price to be driven down. 
• Renewable 
• diesel is refined from non-renewable crude oil. Biodiesel is made from different sources including manure, wastes from crops and specific plants e.g. sugar cane 
• Lower pollution levels 
• diesel produces large amounts of carbon dioxide gas when burnt, contributing to the greenhouse gas in the atmosphere. Studies suggest that biodiesel reduces greenhouse gas emission up to 65%. Though carbon dioxide is created as by-product of the synthesis, it is frequently used to grow the plants that will then be converted into the fuel, allowing it to become a self-sustaining system where the carbon dioxide is recycled.  
• Reduced dependency on foreign oil 
• make biodiesel from local crops 

Disadvantages of biodiesel 

• High cost of production 
• Monoculture 
• growing the same crop may deprive the soil of nutrients that are usually put back into the soil through crop rotation e.g. Malaysia's palm plantations 
• Use of fertilisers and water for irrigation 
• fertilisers may cause water pollution
• Use of food source to make fuel 
• ethical issue 
• take up agricultural space for other crops, put pressure on the current growth of crops, may mean a rise in food prices 

Sources:

http://pubs.cas.psu.edu/FreePubs/pdfs/uc205.pdf

http://www.conserve-energy-future.com/advantages-and-disadvantages-of-biofuels.php

Bioplastics

Synthetic plastics
- 80% of polymers are produced from non-renewable fossil resources. Mass consumption of products with short lifespan (e.g. disposal utensils). Disposed items are transported to landfills; in Singapore, the landfill is currently Pulau Semakau.
- However, this creates garbage patches in the sea, where the plastic breaks up into tiny pieces too small to be scooped up, and forms patches of plastics floating at the surface of the water. Ingestion of these tiny pieces of plastic by the marine animals is detrimental to their health. There is little we can do to clean up the patches. The only solution is to prevent throwing plastic waste into the sea.
- Not all plastics can be recycled.

Bioplastic (made from starch and protein)
- Bioplastics consists of biodegradable plastics and plastics from renewable resources. Hence, not all bioplastics are biodegradable; it depends on the chemical structure
- Natural polymers: produced in growth cycles of cells of living organisms. E.g. proteins, fats, nucleic acids, cellulose, starch, polyesters. Materials created by nature can also be degraded by nature.

- Amino acids: Plastics are formed by polymerisation (addition polymerisation or condensation polymerisation). 2 amino acids can form a peptide bond through condensation polymerisation, with water being the by-product. The OH comes from the carboxyl group, while the H atom comes from the amino group of the 2nd amino acid. In this way, bioplastics can be made from proteins. 

• 80% of 2% cow's milk is made up of the polymer casein, a protein. This protein can go through polymerisation to create a natural plastic, as the casein molecules are condensed into long chains. 
• Addition of acid (vinegar) causes casein to denature and unfold, to rearrange into the chains of a polymer. 
• Straining the curds using a cheesecloth causes casein to precipitate, discard the clear watery substance (whey). Repeat straining process 3 times. 
• Shape casein into desirable shape before letting it dry into a bioplastic 

- Starch: consists of amylose (linear) and amylopectin (branched). After starch is dried from an aqueous solution, it forms a film due to hydrogen bonding between the chains of polymers. Amylopectin inhibits the formation of film, add acid to break down amylopectin. 

• Potato or cornstarch 

- Results of experiment: Cornstarch plastic most durable, hard but brittle. Potato plastic too thin layer, could not peel out of petri dish. Casein plastic very brittle

Benefits of bioplastics: 

• most plastics are made from crude oil and the process produces pollutants such as carbon dioxide which contribute to climate change. Crude oil is also in great demand throughout the world
• bioplastics circumvent these issues by involving the use of plants as the raw material instead of crude oil
• by converting the sugar present in plants into plastic, bioplastics are renewable 

Limitations of bioplastics: 

• hidden environment costs, such as toxic pesticides sprayed on the crops and carbon dioxide emissions from harvesting vehicles
• although fossil fuels are not used to make many bioplastic products, they are typically used to power manufacturing plants
• production requires nearly as much energy as producing conventional plastics 
• a number of bioplastics are compostable. With suitable conditions, microbes will break down the bioplastic into plant material, water, and carbon dioxide. This carbon dioxide goes back into the atmosphere as greenhouse gas emissions 
• might decompose in landfill, giving off methane, a greenhouse gas 20 times more potent than carbon dioxide 
• ineffective labeling keeps many compostable plastics out of the composting mix 
• recycling a mixture of plastics is not possible because different plastics have different melting points 

Personal reflection: 

I support the use of bioplastics because even though it might not seem like a much better alternative than normal plastic or may even be worse in the case of methane gas emission, but bioplastics have the potential to be further improved upon. For example, companies can invest in research to move from food source such as corn to abundant non-food crops such as switchgrass. There is the potential to leave less environmental impact than the current bioplastics because there might be a possibility of manufacturing bioplastics without using fuel, but using wind power and other renewable energy sources. 

Introduction to green chemistry

Why should anyone know about green chemistry? 
Our world population is expanding exponentially at an unprecedented rate, and as a result the amount of resources we require is much more than what the Earth's natural resources can sustain us for. For example, UK's reserves of oil, coal and gas is expected to run out in a little more than 5 years (http://www.bbc.com/news/science-environment-27435624). Therefore, in order to sustain our growth, we need to experiment and come up with ways which we can harness forms of energy to convert them into useful products. Green chemistry also reduces waste produced in the manufacturing process.
- legislation
- local authority and neighbourhood pressures
- waste disposal
- hazard evaluation
- health and safety
- increasing supply chain pressures
- inefficient use of raw materials

What is green chemistry? 
It is the design of chemical processes and products that eliminate or reduces the the use of and/or generation of hazardous substances.
- sustainable chemistry
- chemistry that is benign by design
- pollution prevention at molecular level

12 principles of green chemistry

1. Prevention - better to prevent waste rather than clean up after it has been produced 
2. Atom economy - a measure of amount of starting materials that go into the final product. % of atom economy = mass of desired product / total mass of reactants x 100% --> high or low atom economy. The higher the atom economy, means more atoms/molecules of reactants incorporated into product, greener product produced. NOT the same as percentage yield (gives no indication of waste produced)! 
3. Safer chemical synthesis and design - synthetic methodologies to use and generate substances that possess little or no toxicity to human health and environment. Chemical products to preserve efficacy of function while reducing toxicity. E.g. BPA in water bottles linked to health complications 
4. Safer solvents and auxiliaries - to be made unnecessary whenever possible and innocuous if needed
5. Design for energy efficiency - renewable energy and conservation of energy. Creating products in highly efficient manner while reducing energy requirements 
6. Use of renewable feedstocks - 90-95% of products we use in our daily lives are made from petroleum. Seeks to shift our reliance on petroleum to renewable materials that can be gathered/harvested locally. E.g. biodiesel. BUT there is the debate regarding if it is ethical to use food to synthesise products, taking into consideration that there are people all over the world with insufficient food. 
7. Catalysis 
8. Design for degradation -  degrade into safe, innocuous by-products when disposed of 
9. Reduce derivatives 
10. Real time analysis for pollution prevention 
11. Inherently safer chemistry for accident prevention