Alternative Sources Of Energy

2960 words (12 pages) Essay

19th May 2017 Environmental Sciences Reference this

Tags:

Disclaimer: This work has been submitted by a university student. This is not an example of the work produced by our Essay Writing Service. You can view samples of our professional work here.

Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of UKEssays.com.

Bio-fuels are formed from biomass, normally plants seeds, and liquid bio fuels can be use for transportation. We are one of the world’s leading distributors of bio fuels and we are developing enhanced bio fuels that could see CO2 reductions and a sustainable alternative fuel source.

The two main forms of bio fuel today are ethanol and FAME (Fatty Acid Methyl Esters), which have largely relied on food crops such as wheat or sugar cane as their source. We are working to find a source material that does not compete with food crops, to develop a conversion process that will produce low CO2, and to produce efficient fuels.

Our bio fuels research includes finding alternative feedstocks. We are looking into finding tough new enzymes to break down the cellulose in plants such as straw.

Algae have potential as a sustainable source of vegetable oil that could be used for the production of bio fuel for diesel engines. It is early days but algae hold promise, as they grow rapidly and can be cultivated in ponds of seawater and minimise the use of fertile land and fresh water.

Alternative Energy

The world has plenty of potential renewable energy sources, but each has its own technical challenges. Scientists are working to develop alternative energy sources that are sustainable, clean and convenient.

Fossil fuels are expected to remain the world’s main source of energy for decades to come but sustainable, clean and convenient energy sources will also be needed in the mix.

Today’s most widespread biofuel, ethanol, is commonly made from starchy or sugary plants.

Hydrogen is seen by many as “the fuel of the future”, but it still has a long way to go. It is an energy carrier, in the same way as electricity, and so must be produced from another substance. Most commonly, hydrogen is produced using steam that reacts with methane and converts it into hydrogen and carbon. It can also be produced from water through electrolysis. The hydrogen can then be stored and converted to energy via hydrogen fuel cells, now available for cars. In hydrogen fuel cell vehicles a chemical reaction inside the fuel cell – usually between hydrogen and oxygen – creates electricity for the motor and the only resulting exhaust pipe emission is water vapour.

We are learning as much as possible about hydrogen refuelling and how to meet future customer needs. We are involved in research and demonstration projects and have already opened a cluster of commercial hydrogen filling stations.

biomass

Biomass is any plant derived organic matter available on a renewable basis,

including dedicated energy crops and trees, agricultural food and feed crops,

agricultural crop wastes and residues, wood wastes and residues, aquatic plants

etc. The energy in biomass can be harnessed in waste-to-energy plants or

cogeneration plants.

Waste-to-Energy Plants

All incinerable waste not recovered, reused or recycled is sent for incineration at

the waste-to-energy plants operated by the National Environment Agency. The

combustion of municipal waste including renewables in the waste produce heat,

which is recovered to generate electricity. The electricity generated is fed into the

electricity grid. The biomass in Singapore’s municipal waste are mainly wood

waste, horticultural waste, food waste and waste paper.

Waste-To-Energy Plants Turbine Capacity (MW)

Ulu Pandan Incineration Plant 16

Tuas Incineration Plant 46

Senoko Incineration Plant 56

Tuas South Incineration Plant 80

Biomass Cogeneration Plants

Cogeneration is the simultaneous production of electricity and heat, both of which

are used. Through the utilisation of the heat, the efficiency of cogeneration plant

can reach 80% or more. Cogeneration therefore offers energy savings ranging

between 15-40% when compared to the supply of electricity and heat from

conventional power stations and boilers. Cogeneration plants that use biomass

fuel are carbon-neutral compared to those using fossil fuels.

Two companies, M/s ECO-IEE Pte Ltd and M/s Bee Joo Industries Pte Ltd have

biomass cogeneration plants. The ECO cogeneration plant has a turbine capacity

of 0.53 MW and uses wood waste as fuel. The Bee Joo cogeneration plant has

turbine capacity of 1.0 MW and uses wood waste and horticulture waste as fuel.

Alkaline fuel cells (AFC)

Alkaline fuel cells use compressed hydrogen and oxygen to produce electricity.

They normally operate at 70-90°C, with 300-5000 W of power at about 25-30%

system efficiency.

The Apollo astronauts used alkaline fuel cells to provide both electricity and

drinking water. However, pure hydrogen fuel was used.

More information on AFCs may be found here.

TOP

Phosphoric acid fuel cells (PAFC)

Phosphoric acid fuel cells use phosphoric acid as the electrolyte to produce

electricity. Types of fuel that PAFCs can use include anaerobic digester gas,

natural gas, gasoline, etc. They operate at 190-215°C, generating up to 200 kW

of power at about 35-40% efficiency.

The internal parts of the fuel cell must be able to withstand the corrosive acid.

More information on PAFCs may be found here.

TOP

Proton exchange membrane fuel cells (PEMFC)

Proton exchange membrane fuel cells (also known as polymer electrolyte fuel

cells) use a polymer-based electrolyte, typically in a thin, permeable sheet. This

membrane must not leak or crack, while a platinum catalyst must also be coated

on both sides of the membrane.

The operating temperature is about 70-90°C, with outputs of between 1W and 20

http://www.nccc.gov.sg/renewables/fct.shtm (1 of 2) [17/7/2010 2:07:03 AM]

Fuel Cell Technologies

kW of power. System efficiency is about 30-35%. The low temperature makes

PEMFCs suitable for use in homes and cars. The fuel (typically hydrogen) must

also be highly purified. Natural gas can also be reformed to produce hydrogen for

fuel cells.

More information on PEMFCs may be found here.

TOP

Molten carbonate fuel cells (MCFC)

Molten carbonate fuel cells use high-temperature carbonates (of sodium or

magnesium) as the electrolyte for generating electricity. Hence, the normal

operating temperature is around 600-650°C, producing 250 kW – 2 MW of power

at about 45-50% efficiency.

Waste heat produced by the reaction can be utilized to maximize system

efficiency. This also means that MCFCs would be too hot for home applications.

More information on MCFCs may be found here.

TOP

Solid oxide fuel cells (SOFC)

Solid oxide fuel cells use a hard, ceramic compound of metallic oxides (of calcium

or zirconium) as the electrolyte. They normally operate at about 700-1,000°C,

producing up to 100 kW of power. System efficiency is around 50-55%. At such

temperatures, reformers are not necessary for producing hydrogen from fuels, eg

natural gas.

Waste heat from SOFCs can also be recovered for use in other applications, eg

making more electricity. However, SOFCs are large in size, hence limiting its

applications.

More information on SOFCs may be found here.

Introduction

The tide moves a huge amount of water twice each day, and harnessing it could provide a great deal of energy – around 20% of Britain’s needs.

Although the energy supply is reliable and plentiful, converting it into useful electrical power is not easy.

There are eight main sites around Britain where tidal power stations could usefully be built, including the Severn, Dee, Solway and Humber estuaries. Only around 20 sites in the world have been identified as possible tidal power stations.

A few years ago, “tidal power”meant “tidal barrage”.

But these days there are other options as well.

How it works: Tidal Barrages

These work rather like a hydro-electricscheme, except that the dam is muchbigger.

A huge dam (called a “barrage”) is built across a river estuary. When the tide goes in and out, the water flows through tunnels in the dam.

The ebb and flow of the tides can be used to turn a turbine, or it can be used to push air through a pipe, which then turns a turbine. Large lock gates, like the ones used on canals, allow ships to pass.

If one was built across the Severn Estuary, the tides at Weston-super-Mare would not go out nearly as far – there’d be water to play in for most of the time.

But the Severn Estuary carries sewage and other wastes from many places (e.g. Bristol &Gloucester) out to sea. A tidal barrage would mean that this stuff would hang around Weston-super-Mare an awful lot longer!

Also, if you’re one of the 80,000+ birds that feeds on the exposed mud flats when the tide goes out, then you have a problem, because the tide won’t be going out properly any more.

Advantages

Once you’ve built it, tidal power is free.

It produces no greenhouse gases or other waste.

It needs no fuel.

It produces electricity reliably.

Not expensive to maintain.

Tides are totally predictable.

Offshore turbines and vertical-axis turbines are not ruinously expensive to build and do not have a large environmental impact.

Disadvantages

A barrage across an estuary is very expensive to build, and affects a very wide area – the environment is changed for many miles upstream and downstream. Many birds rely on the tide uncovering the mud flats so that they can feed. Fish can’t migrate, unless “fish ladders” are installed.

Only provides power for around 10 hours each day, when the tide is actually moving in or out.

There are few suitable sites for tidal barrages

Is it renewable?

Tidal energy is renewable. The tides will continue to ebb and flow, and the energy is there for the taking.

Can tidal energy work in Singapore?

Windmill under the sea

The New Paper 11 Nov 08;

This week, Singapore hosted the International Energy Week where policy makers from all over the world met academics and industry players to talk about energy options and strategies for the future.

CHNG CHOON HIONG looks at tidal energy as it is used in the UK while TEH JEN LEE asks whether it could work here.

PICTURE a 37m-tall, 1,000-tonne windmill that is submerged under the sea and you get a good idea of what the SeaGen Tidal Energy generator is.

11 November 2008

PICTURE a 37m-tall, 1,000-tonne windmill that is submerged under the sea and you get a good idea of what the SeaGen Tidal Energy generator is.

Situated in Strangford Narrows, off the coast of Northen Ireland, the SeaGen is the world’s first commercial-scale tidal energy turbine, harnessing the virtually inexhaustible energy carried by tidal currents.

Tidal currents are caused by the gravitational interaction between the earth and the moon arising from their relative motion.

As such, the tidal cycle is perfectly predictable, an advantage over power generated by wind and sunlight.

There are, however, some drawbacks in harnessing tidal power.

It has some prerequisites which limit its use to just a few regions in the world.

There are also worries such as the possible disruption of marine life and the ecosystem. However, the concerns about damaging the ecosystem are yet to be firmly established.

Costing more than £8.5 million ($20 million) in development, the SeaGen is commissioned for operation till 2013. During this time, it will generate 1,200kW of clean renewable power, enough to provide for the electrical needs of 1,000 UK households.

Can this work in Singapore?

USING current technology, Singapore cannot harness tidal energy because our mean tidal range of about 1.7m is too low.

The New Paper 11 Nov 08

USING current technology, Singapore cannot harness tidal energy because our mean tidal range of about 1.7m is too low.

Mean tidal range is the difference in height between mean low water and mean high water levels during spring tides, which occur during new moon and full moon, when there is greatest variation in tides.

The tidal range is low all around South-east Asia because of the configuration of the land – fairly straight coastlines which are surrounded by seas.

In contrast, there are beaches in some countries elsewhere with a tidal range of more than 10m.

For example, in the Bay of Fundy on the Atlantic coast of North America, home to the world’s highest tides, the tidal range has been measured in excess of 15m.

These high tides produce swift-flowing currents when the tide is coming in and going out.

In Singapore, because of the low tidal range, the tidal currents are not strong enough to generate electricity. It would be like trying to get power from water flowing through a monsoon drain.

Professor Teh Tiong Sa, visiting senior fellow at the Tropical Marine Science Institute, said: ‘To have viable energy from tides, the higher the tidal range the better.

‘For Singapore, it’s too low to even think about it now, unless technology changes and things become more efficient.’

Singapore, August 12 – Somewhere off the coast of Invergordon in Scotland on Thursday, the world’s largest tidal turbine will be unveiled, marking a turning point in the global renewable tidal energy industry.

This turbine, which can generate consistent electricity to power 1,000 British homes, may be located thousands of miles from Singapore but it represents a key moment for the city-state’s growing clean technology or “cleantech” industry.

This is because the AK1000 turbine, as it is called, was tested in Singapore waters and designed on Singapore’s shores during key periods of its 10-year research history.

Chief executive Timothy Cornelius of Atlantis Resources Corporation – the firm behind the turbine – said the unveiling and installation of the one megawatt turbine was the “culmination of 10 years of hard work and belief from all partners and staff”.

It is an important milestone not only for Atlantis, which has invested S$100 million of private investors’ funds into developing the turbine to date, but for the global marine power industry, he said. “This is when ocean power generation goes from being in the research space to the commercial space.”

The company, which originated in Australia before moving its headquarters to Singapore five years ago, is now looking at possible locations to build a manufacturing plant that will mass produce its turbines for commercial application.

Dwindling fossil fuel resources and growing concern on its negative impact on global climate change has resulted in a global race for clean energy in recent years. Tidal energy has potential to be a key energy source for a world grappling with rapid urbanisation.

Apart from Scotland, countries such as Japan and India have vast untapped tidal energy resources that could be converted into renewable energy, thus reducing the country’s reliance on fossil fuels, said Mr Cornelius. If all goes well, the firm will begin looking to list on an Asian bourse – possibly in Singapore – next year, he added.

He credited the company’s success to its move to Singapore, where the firm had access to a highly-skilled labour workforce and research collaborations with institutions such as Nanyang Technological University. It now has a local staff of 15. “Singapore has strong intellectual property laws too, which was a key pull factor for us,” he said.

The turbine was also tested in the southern waters of Singapore near the Raffles lighthouse in 2008 to collect key data. Its waters are however too busy due to shipping routes for tidal energy to be tapped, added Mr Cornelius.

When installed, the AK1000 turbine weighing 150 tonnes and at a height of 22.5 metres, will sit at a dedicated berth at the European Marine Energy Centre, located in Scotland’s Orkney. It costs about US$3 million for one turbine and the payback period is five to 10 years depending on the flow rate of the waves, he added.

Cleantech director Goh Chee Kiong of the Economic Development Board said yesterday that Atlantis’s presence in Singapore will “increase the vibrancy of the fast-growing cleantech industry” here.

“This project affirms Singapore’s attractiveness as a global home for cleantech businesses,” said Mr Goh, who also highlighted that Atlantis benefitted from Singapore’s strengths in existing industry clusters such as precision engineering, offshore and marine.

Atlantis said it is now actively pursuing projects in the Asia Pacific region, especially to ‘power hungry’ markets. “We are confident of developing tidal power as a credible new renewable asset class in Asia,” said Mr Cornelius.

Source: The Straits Times

Cite This Work

To export a reference to this article please select a referencing stye below:

Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.

Related Services

View all

DMCA / Removal Request

If you are the original writer of this essay and no longer wish to have your work published on the UKDiss.com website then please:

Related Lectures

Study for free with our range of university lectures!