Window Glazing

Approximately 18% of heat loss in a house is through windows. According to the Energy Saving Trust you could save £135 per year if you upgraded from single to double glazed windows.

To put technical figures on this, it is important to understand what certain values represent.

• U-Values represent the rate of heat transferred over an area. The lower this value the better a material is at not exchanging heat.
• R-Values represent the thermal resistance of a material, the larger the number, the better the materials effectiveness in insulating.

These two values look quite similar. They are. One is the reciprocal of the other. One or both values should be displayed as part of the information of a material that you are buying (whether its windows or loft insulation).

• ‘Low-e’, meaning low emissivity, shows that a material entitled with this on has a low e coating between glass layers. It is a coating of metal onto glass within a glass panes air space. This reflects thermal/heat radiation from the sun or inhibits its emission through the glass therefore reducing heat transfer through the glass.
• SHGC – stands for Solar Heat Gain Coefficient. This basically describes how a material allows heat through itself. In terms of building, such as a trombe wall, you may require a high SHGC to heat your home. In terms of glazing, you will require a low SHGC as this will mean that heat is not readily transferring between the interior and exterior of your house. In terms of windows, single glazing has the highest SHGC, and triple glazing the lowest.

Double or Triple Glazing is better than single glazing in terms of insulating your house, however double and triple are not necessarily better than each other. Triple is more costly for obvious reasons, however if you were to have double glazing with low-e coating in it then there would be only a little difference in U, R and SHGC values in comparison with normal triple glazing, and therefore still cheaper than triple glazing.

Cost

Double and Triple glazing is in the ‘high improvement’ section as it will cost a few thousand pounds to replace your existing single glazing. However, it is expected to last 20 years plus according to the Energy Saving Trust (EST). With this in mind and a quick calculation using the £135 saving per year and say 25 years, only gives you £3375 saved so far. It is recommended that you get quotes from a variety of double and triple glazing installers to get the cheapest. But at best for 10 to 15 windows plus doors you should be paying between £5000 and £6000.

So what are you getting for all this money? Well as for saving money, in the short space of time of 25 years, you’ll probably be in deficit by around £2000. However, you do save according to the EST, 720kg/CO₂, or 18 Tonnes (25 years) of CO₂ based on an average home! You also have the benefit of comfort and security in your home, and in theory a reduction in condensation. Retaining heat in the winter and keeping your house cool in the summer will mean your house is more comfortable to occupy.

So a further option could be of fitting the windows yourself, which may save you that couple of thousand pounds. Fingers crossed your windows will last for at least 44 years if you want to recuperate you money.

The cost figures I have given are based on my own guess/estimation from reading a vast number of blogs about double glazing installations over the internet. It has been useful as it has put into perspective not just the cost of double glazing, but also the companies that are out there and some genuine public opinions of them. This is why it is recommended to research heavily into replacing your windows before undertaking an installation.

Passive Solar Heating

You will have noticed that when you step inside a greenhouse, it tends to be a lot warmer than the outside. This is because of the sun’s ‘heat’ radiating through the glass and becoming trapped. Passive solar heating is all about this and can come within 3 general builds; direct gain, conservatories and trombe walls.

• Direct gain is what it says on the tin. The suns radiation travels through windows or is absorbed by a thermal mass such as a wall and heats the inside. This can be particularly helpful if the building is large, however, being small you will notice your dwelling overheating.
• Conservatories. It is in effect a greenhouse but with ventilation aspects built in. Air within the conservatory heats up, this warm air rises and travels through gaps and holes around your house, eventually leaking outside. This is designed to generally heat up the northern side of your dwelling.
• Trombe Walls. These are in effect a squashed conservatory. They have an air space which is enclosed by double glazing and a thermal mass (such as a specially designed wall in front of your house). When the sun is out, vents can be opened within the wall to allow warm air to circulate around the house. As heat rises the cooler air from your house is sucked into the trombe wall to be reheated. Obviously at night, when there is no chance of solar gain, these vents will be closed to retain heat.

These are useful builds to develop as they provide you with heating, reducing your day heating bill during winter months.

It is difficult to show a cost on conservatory and trombe wall builds as it will all depend on a builder’s quote and the design of your house.

Renewable Energy Technologies (RET)

The big ones! This is in essence, the final stage of cutting down your carbon emissions, saving energy and saving money. At present, no doubt you will have heard about renewable energy both globally and nationally. Buzz words such as sustainability have been used, sometimes in the wrong context. Sustainability or sustainable development means ‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs (United Nations 1987). Renewable Energy is defined as an energy resource that can never run out. Fossil fuels such as coal, gas and oil, are limited resources, and so are not renewable. In the case of biomass; as long as the fuel is ‘sustainably managed’ then this too, is a renewable resource.

Under the Climate Change Act, the UK has to reduce its CO₂ emissions by at least 26% by 2020. To do this, RET’s will form a substantial percentage of this 26%.

10% of the UK’s electricity generation is to come from Renewable sources by 2020. So, out of this 2% of UK electricity generation is intended to come from micro-scale RET’s, or in other words, from you the householder or small business. This is being done by incentives (such as the Feed-In-Tariff), the usual way of encouragement if the government want and need you to do something. Other percentages may come from the Renewable Heat Incentive, destined to be in place by April 2011 which will cover the thermal side of energy generation, and is expected to cover wood stoves and geothermal energy for example.

This section of the article will briefly outline most types of Renewable Energy Technologies with some food for thought on suitability, incentives and grants, and typical costing. Later articles will go into the overall types of RET’s on a macro (large) and micro (small) scale.

Photovoltaic (PV)

Photo comes from the Greek word for light and voltaic transpires from volt (the driving force in electricity). This is one of the types of solar panels available. This one generates electricity by radiation from the sun. This technology is the highest ‘earning’ in terms of the feed-in-tariff, basically the pence per kilowatt hour an energy company will pay you that you generate.

As the UK is in the Northern Hemisphere of the world then the sun is in a position south of the UK. This means, that to gain maximum radiation for a day, a panel must be installed, south facing. This is where suitability comes into it, and you will need to have a look if you have any space (normally on your roof as this is the least interrupted part of a dwelling as it is not blocked by trees and other buildings etc) available to you that you can install this on.

Also, is your roof built strongly enough? Certain roofs will not be able to hold a panel’s weight, so you may have to have the roof re-strengthened.

Cost – Typical installations range between £8,000 and £12,000. Larger arrays will obviously cost a lot more than this!

F-I-T – The feed- in-tariff, between Apr 2009 and Mar 2012 will give a price of 41.6p/kWh for an installation built onto an existing dwelling, or 36.1p/kWh for an installation built onto a new build. The lifespan however for PV feed-in-tariff is set to last until 2035!

The map shows average irradiation (or intensity of the sun) in Europe [1].

Solar Thermal

The other solar panel! This panel involves heating a fluid within the pipe workings of the panel which then in turn heat water or air. These tend to be cheaper than the PV panels. There are two types of solar thermal panels; evacuated tubes and flat plate collectors. There are also ‘point’ and ‘line’ focus collectors which involve dishes and curved troughs which aim the suns radiation to one focus point which then heats water; however the technologies are not so commonplace domestically.

Cost –Typical costs of a solar thermal panel are anywhere between £3,000 and £5,000, depending on the rating in kW.

F-I-T – The feed-in-tariff for solar thermal, between Apr 2009 and Mar 2012 is 18p/kWh, and is valid until 2030.

Biomass

Biomass is a collective term for materials that are or have been a living organism and are biodegradable. Biomass ranges from food waste to crops and wood. Biomass is generally used on a micro scale for heating purposes. However, on macro scale, both electricity and heat are generated. Biomass technologies on a macro scale range from straw fired power stations to anaerobic digesters. On a micro scale they are generally wood pellet stoves to wood burners.

Cost – A wood stove is likely to cost around £3,000, whereas a gravity or automatically fed wood pellet stove is around £8,500 -£9,500.S

F-I-T – There is no feed-in-tariff for Biomass. This is likely to come under the new Renewable Heat Incentive (RHI) to be implemented in 2011.

Wind

The UK has one of the best wind resources in the world. There has been much controversy surrounding wind generation, ranging from bird deaths to noise and the actual storage and supply of the electricity. This will be discussed in a later article. The name windmill and wind turbine often get confused. A wind mill uses wind to ‘mill’ a material, most notably corn and wheat to make flour. A wind turbine uses wind to generate electricity through a ‘turbine’ and generator.

There are many different sizes of wind turbine, on a micro scale, domestic roof mounted turbines tend to be rated at no larger than 2kW. Free standing micro scale turbines rate between 6 and 15kW and on a macro scale, usually built as a ‘wind farm’ turbines at present are rated 0.5 to 3MW. There are some turbines being developed that are rated as a whopping 6.5MW!

The suitability for a wind turbine depends on many things. Wind speed is of the most important. Turbines are generally built where an average wind speed for a year is around 5.5 metres per second and higher. Free standing turbines need to be above the ground in such a way that the surrounding area does not block or inhibit the wind causing turbulence. Therefore, a turbine should definitely not be sited near trees and buildings. The turbulence affects the turbines efficiency to generate electricity effectively.

Turbines can be built in conservational areas providing they meet the correct criteria. This can involve ensuring that the turbines do not suppress a view or inhibit the lives of endangered species.

Turbines should also be built as near as possible to the electricity grid due to the large cost that comes with building a connection.

Cost –Typical cost of a roof mounted turbine is around £1,500 to £2,000, whereas larger turbines are around £3,000 to £20,000, depending on the rating.

F-I-T –The feed-in-tariff between Apr 2009 and Mar 2012 is 34.5p/kWh for turbines rated below 1.5kW, and 26.7p/kWh for turbines rated between 1.5 and 15kW

Bio-fuels

Bio-fuels are not a relatively new idea. Rudolph Diesel invented the diesel engine originally to run on vegetable oil. Bio-fuels can be made from a variety of ‘energy crops’. There are two main types of bio-fuel, bio-diesel and bio-ethanol. Bio-diesel is manufactured to be the fuel in a diesel engine and is predominantly made from the oils of plants and other organisms. Bio-ethanol is the fuel substitute in a petrol engine and is made by turning plants sugars into alcohol.

You may see in fuel stations ‘blends’ of diesel and petrol. Such as E85 or E80, meaning 80 or 85% of the fuel volume is made up of the bio-fuel and the remaining 10 or 15% is the fossil fuel.

The cost of biodiesel at this present time (11^th June 2010) is around £1.04 – £1.05/litre for E100 biodiesel [2].

The cost of bio ethanol at this present time (11^th June 2010) is around £1.12 for E85 [3].

Hydro

‘Hydroelectricity’ in essence means ‘water electricity generation’. On a micro scale a hydro project could be built where there is a substantial enough flow of running water (that flows all year round). There are many variations of hydro turbines that are designed to work efficiently in a specific water condition. However, to get more power out of a body of water will really depend on how fast the water is flowing. The amount of energy that you could get out of a flow of water is quite amazing, which could mean a small payback period. I have visited a project that literally only took a couple of years for the owners to get their money back because they were selling what they didn’t use to the grid.

Some draw backs;

• The capital needed to be raised for the project is often quite large.
• You will need to consult the Environment Agency about the water course. Often there are fish or newts living in the water, and this may inhibit the project.

Cost – A micro hydro project could range anywhere between £20,000 and £40,000, depending on circumstances

F-I-T – The feed-in-tariff between Apr 2009 and Mar 2012 is 19.9p/kWh and lasts for 20 years.

Geothermal

‘Geothermal’, comes from the Greek Geo – meaning earth, and thermos – meaning heat. Geothermal technology is defined as a renewable resource.

Heat can be extracted from the ground anywhere in the world. However, for large scale needs a geothermal heat pump would have to be drilled to a deeper depth or be situated near a hot source. Hot springs, geysers and aquifers are examples of hot fluid sources. Drilling into deep rock where no fluid is present is known as ‘hot dry rock geothermal energy’. Fluid in this case is manually pumped down a bore hole to be heated up.

However, over extraction of heat from hot fluid sources too quickly can cause a cold spot.

Ground and Air Source Heat Pumps (GSHP and ASHP)

Ground and air source heat pumps are similar to air conditioning units. What ground source heat pumps do, is to extract heat from the ground during the winter, and put heat into the ground during the summer. It works because the earth remains at a pretty constant temperature during the entire year. Air source heat pumps work very similarly to this as well. Air and ground source heat pumps work like a refrigerator; however unlike a refrigerator, they can reverse between cooling and heating!

Cost- Anywhere between £7,000 and £13,000 for GSHP, and between £5,000 and £9,000 for ASHP.

F-I-T – Feed-in-tariff, from Apr-2009 to Mar 2012, around 7p/kWh. The lifespan for this particular price is until 2028 for ASHP and 2033 for GHSP.

For any more information on any large scale energy saving change you are considering for your home feel free to make an enquiry with Energy Saving Warehouse.

[1] http://re.jrc.ec.europa.eu/pvgis/cmaps/eu_opt/pvgis_Europe-solar_opt_presentation.png

[2] Taken from an online source; http://www.swbiofuels.co.uk/pricing.php

[3] Taken from a Taunton Morrison’s Fuel Station

A “low and no cost” improvement to your household is something that you can do to improve your living costs. Hopefully, in reading this, you are already making energy efficiency your No.1 priority in reducing your energy costs. You can be assured that you will see a reduction in your energy bills, but do not expect anything astronomical as of yet! This article will look at and give some examples of minor changes to either, your behaviour towards energy efficiency which you may not have yet considered, or low cost changes such as lighting and draught sealing.

It would be a good idea to record any changes that you have made, this then allows you to give yourself a well earned pat on the back when you can see the progress you have made. An example evaluation of a local pub has been provided at the bottom of this article on savings, investments and paybacks as an example of how you can do this to your own home or business.

Most households either have a gas or oil fuel supply, combined with an electricity connection.

Low and no cost solutions at this stage will only be applicable to the electrical consumption of a household. However, measures into making your home more insulated against outside temperatures can start with basic draught proofing including looking into space heating. Due to the necessity of using energy for cooking, it is difficult to reduce energy use and reduction of use is not as substantial as that for electrical appliance and space heating (See Diagram). Despite this there are ways of reducing energy use during cooking.

Lighting your home

Lighting forms 20% of a household’s average electricity bill. Presently there are many energy efficient light bulbs of all different shapes and sizes for you to replace your existing incandescent light bulbs. Despite the myths and people’s misconception (which are now proven to be incorrect), energy efficiency light bulbs are a must have if you want to begin cutting down your energy bills [2].

This is because energy efficient light bulbs use around 80% less energy than old incandescent ones, and it does not cost a fortune to replace all your old lights with them.

Draught Proofing

Dwellings require controlled ventilation in order to keep the air inside dry and fresh. Air should be free to circulate around the entire house in order to exchange stale air for fresh air, therefore minimising stagnant areas of the house where damp and mildew can form. Draughts, however, are uncontrollable, and this results in the house exchanging too much air with the outside. This is most noticeable in the winter, as cold air from the outside leaks in and reduces the temperature of your house, therefore you require more heating to keep your house warm and effectively “throwing money out of your windows”.

Draught proofing is a relatively low cost improvement that can be made to your home and, depending on the situation from house to house, could save you a few hundred pounds in your heating bill. It is important to remember not to attempt doing any higher cost improvements until you have done all you can on the lower cost improvements.

“Do it yourself” draught proofing materials should cost around £100, and to get a professional in you would probably be looking to double this figure.

Areas to look at draught proofing are:

• Chimneys & Fireplaces
• Doors
• Floorboards & Skirting
• Loft Hatches
• Pipeworking
• Wall Cracks
• Windows

As well as this, look at key holes and letter boxes. There are purpose built key flaps and draught proof letter boxes available from most DIY shops.

Play the Energy Companies

Energy companies (distribution) do not directly supply electricity and gas to your house. The national grid deals with the transportation of the electricity, whereas the distribution companies are the “go-betweeners” and instigate the selling of energy to a household. Like any business company of this size, they are all in competition with each other to get the highest profits. In order to do this they offer “amazing” deals to try and tempt more people to switch to them. Sometimes this can actually result as being the cheapest solution in the short-run, however, further down the line the prices are slowly increased, and this is why you should always take time to check what you’re currently paying for your energy. Often there is a company cheaper than all of the rest to provide you your energy. In doing this you are effectively “playing the energy companies at their own game”. Every 5-6 months have a look at one of the many price comparison websites and see if there is another energy company out there that will give you a better deal, after all, the energy ineffectively comes from the same pot!

However, when doing this be careful to look at what you are signing up to carefully, some companies in their small print state that you will have to pay a “get-out” fee so that you can switch. Others will give you money for joining their energy company, so it could work out that you do not actually lose money due to this.

Other websites, such as the ones below, will offer to do this and switch between the companies for you, for free. It is often the case that customers are on old tariffs (which they may be paying a lot more money than they could be) or just stick with the same energy company year on year.

Price comparison websites:

• www.uswitch.com
• www.moneysupermarket.com
• www.energyhelpline.com
• www.tescoenergy.com

Or why not use ESW’s own comparison tool to compare green energy providers in your area?

General tips and changes in attitude

• Is your cylinder thermostat set to 60⁰C?
• Can you turn down your heating by 1⁰C? If so that may cut your energy bills in heating by 10% Having your heating programmed at a low temperature throughout the day will also keep your heating as efficient as possible. Your main living area should really be set to 21⁰C and all other rooms at 18⁰C.
• Free heat when the sun retreats? Capture a few hours worth of free energy by closing all your windows just before dusk. Closing curtains on the north side of you house will act as insulation allowing the suns energy to come through the south side and not allowing much escaping through the south side!
• Turn your lights off when you’re not going to be in the room for a while.
• Standby is a big no. Some appliances can use around 20% of the energy when just on standby. Switch them off, the pennies add up. Other appliances may have internal clocks which may still draw out energy when not in use.
• No half measures with your washing machine…Fill it up! You will use less energy and water for one big load rather than two small ones. Also, try to use your tumble dryer as least as possible.
• Only boil as much water as you need in your kettle.
• Fix your dripping taps, especially hot ones.

[1] http://www.spacealtherma.com:8080/AlthermaSite/index_altherma.jsp?mt=882&taxonomy_id=882&lang=en&site=256

[2] 2. Lighting Brochure, Energy Saving Trust. Available [Online] at; http://www.energysavingtrust.org.uk/Media/node_1422/A-bright-idea-has-got-even-better

Mr Salmond launched the fund, which is being delivered through a partnership of Scottish Enterprise and Highlands & Islands Enterprise until 2015, at RenewableUK 2010, the wind and marine energy industry body’s annual conference & exhibition in Glasgow.

The First Minister also reiterated his call for the UK Government to remove the restrictions on immediate access to the £191m of Scotland’s Fossil Fuel Levy funds generated north of the border to invest in renewable industries.

He said: “I’m pleased to welcome the renewables industry to Scotland because we are a nation with considerable natural and human resources and the political will needed to deliver a green energy revolution that can build sustainable economic recovery and reduce Europe’s carbon emissions.

“The Scottish Parliament has condemned the UK Government’s refusal to give unrestricted access to Scotland’s £191 million Fossil Fuel Levy funds. Together with industry, we must and we will continue to press the Treasury to release these funds now due to Scotland. They remain vital for the development of offshore wind and marine power, for heat networks and technology to deliver our renewable heat targets; and vital too for our communities, so they can invest in and benefit from the green economy.

“However, the offshore wind industry is seeking leadership and immediate support from government and the Scottish Government is determined to provide that, as we have done for the last three years. Today I am delighted to announce – and open for business – Scotland’s £70 million National Renewables Infrastructure Fund. The fund covers infrastructure relating to manufacturing and test/demonstration facilities.

“Our National Renewables Infrastructure Plan has already established the most immediate needs. Together with Scottish Enterprise and Highlands & Islands Enterprise, we are determined to stimulate the market and act decisively to trigger vital capital investment and launch the next phase of Scotland’s renewables revolution.”

Scottish Enterprise Chief Executive Lena Wilson said: “Now is the time to build on Scotland’s position as the leader in global offshore wind development. We have more than a quarter of Europe’s natural wind resources and unrivalled offshore skills thanks to our decades of experience in oil and gas exploration. We now have a short window of opportunity to capitalise on our strengths and this fund will enable us to turn our offshore wind aspirations into reality.

“Companies from around the world already recognise the scale of the opportunity and Scotland’s competitive advantage. We need to build upon this by supporting the development of port and manufacturing locations with their owners and supply chain companies so that Scotland can reap the full rewards from this significant economic opportunity.”

Alex Paterson, Chief Executive of Highlands and Islands Enterprise (HIE), said: “Renewable energy is already playing a significant role in the Highlands and Islands economy, and HIE is determined to help the sector grow and flourish here.

“As well as the north and west of Scotland having significant planned offshore wind capacity, the Highlands and Islands are at the forefront of the development of marine renewables, both wave and tidal.

“The development of the Highlands and Islands port and harbour facilities and manufacturing capacity will underpin the commercialisation of the marine energy sector in Scotland.”

More than 7,000 offshore wind turbines are expected to be constructed off the UK’s coast over the next decade and the Scottish Government and its enterprise agencies are working to support offshore wind farm developers, including by ensuring the provision of Scottish ports and companies able to provide critical manufacturing, operations and maintenance services.

Scottish Enterprise and Highlands & Islands Enterprise will now to work with site owners and public sector partners to develop key locations to the required specification that will fortify Scotland’s position as a key offshore wind development location and attract the associated offshore wind inward investors.

Ground Source Heat Pumps (GSHP)

Depending on latitude, the ground remains at a relatively constant temperature all year, between 10⁰C and 16⁰C at a depth of 3m. By forcing water to flow in a pipe within this depth of 3m, heat from the ground can be transferred to the water. The pipework is normally looped creating a bigger surface area which enables the system to accept more heat quicker. Antifreeze is also added to the water for obvious reasons. Some homes may not have the advantage of space in their garden. If this is the case, a vertical single looped pipe can be installed within a drilled bore reaching 100m in depth.

This relatively constant temperature means that GSHP have an advantage opposed to other renewable technologies (such as solar thermal). It can provide heat for your home 24 hours a day for the entire year.

The heat produced from this system is much lower than what you would get from a normal central heating system. Radiators in your house would be warm to the touch as opposed to hot. However, as it is at a constant low temperature and not a few hours heating a day here and there, the efficiency as a system is high. To improve this efficiency further, larger surface area radiators or, even better, under floor heating could be installed.

The system requires electricity to run its motor and pump. The approximate ratio of electricity to renewable heat generated is for every unit of electricity needed to run the system, 4 units of heat is generated.

Warm water from the ground loops passes through a heat exchanger. The heat is then transferred into a refrigerant fluid (refrigerant is also used in refrigerators and is used because of its thermodynamic properties suitable for heat exchange). The fluid is then compressed giving it a higher thermal energy content. This fluid then heats up the heating and water circuits in your house.

Spent water within the ground system is now cooler and goes back into the ground.

As a system, GSHP is continuously becoming more efficient. GHSP is a feasible Renewable Technology that can replace you existing heating system. It can save you several hundreds of pounds a year particularly if you are replacing an electricity fuelled system. Carbon savings are in the region of 5 tonnes a year for electricity replacement.

The table below is taken from the Energy Saving Trust and shows savings figures for carbon emissions and money.

Suitability and Costing

Primarily the most important suitability factor in installing a GHSP system is what fuel you are replacing it with. As you can see from the table above, not all conventional fuels are feasible. However, it does not take into account the Renewable Heat Incentive (RHI) due to be launched in April 2011. Electricity, Oil and Solid fuel types are beneficial to replace in terms of savings, however due to the cost of these fuels, the payback period will differ. Gas is a fuel which is relatively cheap, and as you can see from the table, at the moment it is not really feasible to replace it with a GSHP system.

According to the Energy Saving Trust, the typical cost for a GSHP system can be anywhere between £9,000 and £17,000, leaving you with a payback for an electricity replaced fuel of 18 to 34 years! Although figures for the RHI have not been published, the payback period is sure to be lessened greatly.

If the house is new build or going under refurbishment, this will reduce the cost further. GSHP works more effectively if its generated heat is distributed differently to conventional heating systems. Underfloor heating, low temperature fan convectors or larger radiators will distribute the heat more effectively than conventional radiators. These will be costly to install, however, as said before, if the house is going under refurbishment or a new build then these will be a credible alternative to installing conventional radiators.

As talked about in previous articles, ‘low and no cost improvements’ GSHP as with any Renewable Technology should only be installed if these improvements have been made, particularly with insulation improvements. GSHP will only be able to work efficiently and be more cost effective (reducing your payback) with your house being properly insulated. If you house isn’t properly insulated you may find that the GSHP system does not provide enough heat to meet your needs.

Do you have the garden space needed to install the pipework loops? This form tends to be cheaper than bore drilling.

Summary

In summary, GSHP is a credible alternative to common heating systems. It is improving in its efficiency and becoming cheaper. The RHI will reduce the cost further in years to come. GSHP will reduce your carbon emissions, on varying levels depending on what fuel is being replaced. Replacing electric heating is the most rewarding in terms of cost and CO₂ emissions, with natural gas being the least.

There is no maintenance (apart from service checks) involved with a GSHP system once it has been installed, and similar to certain other Renewable Technologies, it is a ‘plug and play’ technology. GSHP requires no fuel and also can provide space heating and hot water.

Air Source Heat Pumps (ASHP)

Air Source Heat Pumps work in a similar way to Ground Source Heat Pumps in that they extract a low grade heat from air rather than the ground. An ASHP system works again, similarly to a refrigerator, however what it can do is reverse itself, in the sense that it can provide heat but also be used to cool down a building. It does this my expanding or compressing a refrigerant. It can extract low grade heat from as low as -15⁰C!

Just like GSHP, it requires an electricity supply to run the system; however it is a much smaller system in terms of area that it needs, whereas GSHP often requires a large garden area.

Suitability and Costing

ASHP can work in two ways; air to air or air to water. Air to air uses fans to circulate warm air around your house, and air to water system a houses central heating system. Whereas air to water can be used for hot water and heating, air to air is used for heating only.

Like GSHP, ASHP is most efficient in under floor heating, large radiators as opposed to conventional radiator heating. However ASHP is less efficient generally as a system compared to GSHP.

The unit should be installed where it has access to warm air. Having it placed on a wall on the north facing side of a house will mean it will have to work harder, and so consumes more electrical energy. Whereas if you live in a warm climate, it should ideally be placed where it is cooler, in the UK this is obviously not the case.

ASHP has the added benefit of being able to be installed easier than GSHP and is also far cheaper, with installations costing between £6000 and £10,000 (Energy Saving Trust).

The table below is taken from the Energy Saving Trust website on Air Source Heat Pump savings.

The Renewable Heat Incentive (RHI)

As GSHP and ASHP won’t be producing electricity they are not eligible for the Feed-in-Tariff, but the government are currently in the process of finalising the Renewable Heat Incentive for technologies that produce heat and not electricity. This is due to be introduced in April 2011 and rather than measuring the heat generated by thermal technologies payment will be based on estimation. The estimation will be derived from the type of technology used, the age and size of the house – in essence the amount of heat needed to heat up your house.

Table 1. Energy Saving Trust, Ground Source Heat Pumps Savings Table. Available [Online] at: http://www.energysavingtrust.org.uk/Generate-your-own-energy/Ground-source-heat-pumps

Table 2. Energy Saving Trust, Air Source Heat Pumps Savings Table. Available [Online] at: http://www.energysavingtrust.org.uk/Generate-your-own-energy/Air-source-heat-pumps

There are two forms of Geothermal Energy: Hot Dry Rock and Conventional ‘Hydrothermal’ Geothermal.

Hot Dry Rock is a relatively new technology and is yet to become economically viable; an example of this is at Rosemanowes Quarry¹, Cornwall. The Hot Dry Rock project at Rosemanowes Quarry found that if they pushed water into the ground, they couldn’t get it to return to the surface. This was down to water percolating into the rock.

Hydrothermal has been used for decades, with Iceland being the pioneering country in using geothermal energy on a large scale. Today, the USA, closely followed by the Philippines, are the largest generators of Geothermal Energy within the world.

Within hydrothermal energy plants, there are four ways of generating energy.

The first is an ‘open system’. It is known as an ‘open’ system because fluid from a geothermal resource is used directly within the generating process. The system is made up of two wells. Hot steam is extracted from one well and passed through a turbine which in turn is attached to a generator, generating electricity. The steam is then passed through a condenser thus cooling into a hot water form which is then injected into the other well, back into the ground.

The second is a ‘closed system’. Instead of using the geothermal fluid directly from the wells into a turbine, the fluid transfers its heat to another fluid through a heat exchanger (much like a refrigerator). This heated fluid then drives the turbine and generator much like before.

The last two are a mix of a closed and open system. The geothermal fluid being extracted from the well will produce steam, but as itself, will not completely turn into steam. This is known as a ‘flash evaporation’. This steam is then used through a turbine as before. The difference between these two is that the first system uses one turbine and one flash evaporation, whereas the second system uses two flashes and two turbines. With the second system, the geothermal fluid unused within the first flashing process is used in the second flashing process.

Advantages and Disadvantages of Geothermal Energy

The process of generating energy from geothermal sources should produce no by-products. Heat or waste water is often recycled by pumping it back into the earth or used to heat other industrial processes. However, fluids drawn up from the earth will contain a mixture of gases, such as CO_2, Methane, Sulphides and Ammonia. Yet, in comparison to fossil fuels, geothermal fluid extraction will emit a lot less pollutants and therefore could be used as a mitigation tool in reducing CO₂ emissions.

Conventional ‘Hydrothermal’ Geothermal plants are site specific. To harness heat from the earth the plant will need to be built close to a heat hot spot close to the earth’s surface, i.e. close to a contact between tectonic plates. However, the ratio of a geothermal plant to its energy output is much better than most plants. For example, for a geothermal plant to generate a GW of energy it will require 3.5km², compared with a wind farm which will need 12km², or coal at 32km².

Freshwater consumption is also minimal and means that geothermal plants will require 50 times less freshwater than that of nuclear or fossil fuel power plants per MW generated.

It has been known that some plants may over extract heat from the earth. Thus leaving the area redundant of heat for many years -much the same way as over extracting water from aquifers).

Geothermal energy requires no other fuel. It is therefore unaffected by rises in other types of fuel cost. Incidentally in some pioneering countries, geothermal energy was developed as a response to the oil crisis of 1973.

Geothermal Energy in the UK

As a resource, geothermal energy is not as prolific in the UK as other countries such as Iceland and the USA. This is due to the UK not being situated near areas of volcanic activity or tectonic plate boundaries. The potential in the UK for geothermal projects must therefore come from Hot Dry Rock schemes, which as a technology is still within infancy, or underground reservoirs – aquifers.

Geothermal feasibility was first looked at within the UK as a response to the 1973 oil crisis but was not continued as oil prices fell after. The first geothermal ‘scheme’ in the UK was built in Southampton² in 1987. The scheme extracts heat from an aquifer which feeds a local district heating system.

Eastgate in County Durham has a hot dry rocks project in planning which will be built on an old cement works.

A commercial sized geothermal project is also in its planning stage which will be built near Redruth in Cornwall on the United Downs industrial estate.

There is potential for geothermal projects in the North Sea³ using spent oil reservoirs.

For more information on other renewable technologies visit our informative pages

1. Rosemanowes Quarry. http://en.academic.ru/dic.nsf/enwiki/4979917

2. Southampton District Heating Scheme, Southampton County Council. http://www.southampton.gov.uk/s-environment/energy/Geothermal/default.aspx

3. North Sea Geothermal Energy, Healer George. Accessed [Online] 22 Oct 2010. Available at: http://www.healergeorge.com/geothermal/index.html

Current Worldwide Tidal Power

Tidal Barrages

Although tidal barrage power is not a completely new idea, only a few barrage plants are in operation. The first began operating in 1966 at the Rance river, St Malo in France. The plant produces 240MW. There are only four other tidal power generation plants in the world:

• Annapolis in Canada – built in 1984 producing 20MW.
• Jiangxia in China – built in 1980 producing 3.2MW.
• Kispaya Guba in Russia – built in 1968 producing 1.7MW.
• Uldolmok in South Korea – built in 2009 producing 1MW.

A 254MW plant being built on the Sihwa Lake, South Korea and due to be completed during 2010.¹

There have been numerous proposals for a barrage scheme across the Bristol Channel in the UK, however none have been built to date. The latest proposal is known as the Severn Barrage and would house 216 turbines, generating 8,640MW combined, and producing 5% of the UK’s energy demand (based on 2002).

How it works

In terms of a Tidal barrage, the tidal power harnesses the kinetic energy of a flow of water in three ways:

• Ebb generation involves allowing an incoming tide to flow through opened sluice gates of a barrage. When at high tide the gates are closed. After a period of time, when the tide lowers, a head is created. This acts the same way as a dam. The head of water is released through the turbines and therefore generates electricity.
• Flood generation involves generating electrical energy from the incoming tide.
• Two-way operation maximises the use of both the ebb and flood generation techniques. More expensive turbines will be needed that can generate power in both directions.

Although generation can occur for a relatively long period throughout the day, it is not possible for continuous generation (24/7) to occur using a tidal barrage. For example, there will need to be a period of time for a head to be created for ebb generation to work. Two-way generation will result in four short bursts of electrical generation, accounting for each change in tide during the day. Also, as the tides change (due to the moons cycle of 24.8hr periods), tidal generation will continuously change day by day. This causes a problem, when generation is at its maximum during a tide of a particular day, it may not match the demand.

Advantages of Tidal Barrages

• Aside from construction and maintenance costs, tidal power generates electricity for free (as it does not need any fuel).
• It will be able to produce electricity reliably due to predictable tides.
• It may provide transport connections (saving the motorist time and fuel consumption).
• The tidal range limits may be reduced and therefore water activities such as water-skiing and fishing could benefit from this.

Disadvantages of Tidal Barrages

• Environmental consequences of affecting the natural tidal flow will have devastating consequences on natural habitats upstream of the barrage. Mudflats are one such area of particular conservational importance. Tidal flows may not retract from mudflats as they once did. A mitigating circumstance to overcome these environmental consequences may be to ‘re-home’ the wildlife by artificially creating mudflats elsewhere.
• Maintenance issues arise, particularly if a turbine or sluice gate is in need of repairs. The barrage would have to be temporarily switched off and therefore would not be producing power for a turbine to be repaired.
• There are only a few sites suitable for the construction of barrages.
• Migrating fish would have to be considered. This could possibly be mitigated by building ‘fish ladders’ through the barrage.
• The ecosystem of saline/freshwater may be affected.
• Tidal resonance will be affected, the tidal range will reduce, and such phenomenon’s as the Severn Bore (If the Severn Barrage were to be built) would disappear.

‘Underwater Tidal Farms’, Tidal Fences and Tidal Reef’s

Tidal barrages are not the only way of harnessing energy from incoming and outgoing tides. Three other ideas are currently being researched presently; Underwater Tidal Farms, Tidal Fences and Tidal Reefs.

Underwater Tidal Farms are in essence an underwater ‘wind’ farm. Water is around 800 times denser than air. It is therefore possible to extract the same amount of energy from a tidal machine that is much smaller in size than a wind turbine, and therefore much cheaper to build (in terms of construction to energy generation).

Recently, in the summer of 2010, the world’s largest and most powerful tidal turbine was unveiled in Scotland. It had been developed by ‘Atlantis Resources’ and is known as the AK1000. It has two 18m diameter rotors and its column stands at 22.5m.²

Tidal Fences are an underwater partial barrier that would be much friendlier to the environment. It would still harness the ingoing and outgoing tides but would not be able to generate as much electricity as a tidal barrage would.

A tidal reef would use reversible turbines that are fixed to an estuary’s floor and would harness the incoming and outgoing tides. This would have minimal impact on fish that swim up the estuary as it would be completely submerged allowing fish to swim over it.

Wave Power Devices

Wave power is the transportation of energy through ocean surface waves Waves are generated by friction created by wind. The further a wind is allowed to impact on the surface of water, the more energy the waves will have. The distance of open ocean that is allowed to be affected is known as the ‘fetch’. The UK (particularly on the South West, West and North) has the advantage of having a large fetch and therefore more energy is available that may be harnessed by a wave power device. Proximity to the coastline is important if a wave power device is to be installed. Waves will increase in amplitude (height) as it travels over shallower water and wave power devices harness this movement. More important though are the grid connection costs, as the further a device is away from the land, the higher the cost involved with transmitting electricity.

A group of wave power devices is known as an ‘array’.

The limitations of wave devices are not just for offshore generation but also for coastal generation. The ‘Limpet³’ is one such wave device installed in 2000 on the coast of western Scotland. It is rated at 500kW and generates energy through harnessing a wave to fill and empty a contained structure. This contained structure houses air and a ‘Wells’ contra-rotating turbine. The drawing in and out of air within this container through the turbine generates electricity.

There is a great potential for harnessing energy from waves. There are many innovative and different wave power devices being researched and tested although some are better than others. One of the first promising wave devices was the ‘Salter’s Duck⁴’ and was developed as a solution to the 1970’s oil crisis. The Duck was hugely efficient, generating 81% of a wave’s energy. However, famously it was never developed any further due to some miscalculations by a factor of 10 of an estimation cost of its energy production. The miscalculation was only discovered a few years ago and so is expected to be redeveloped. The Duck works by bobbing up and down every time a wave travels underneath it.  A pendulum connected to a generator inside the Duck’s shell moves backwards and forwards and this generates electricity.

Simple Diagram of Salter’s Duck

The ‘Pelamis⁵’ or ‘Wave Dragon’ is a wave device that sits semi-submerged on the ocean surface. It has tubes hinged together (like a column) which move freely with the amplitude of a wave. The movement of these joints causes a hydraulic ram to push fluid into a hydraulic motor generating electricity. Each device is currently rated at 750kW and is 180m long 4m diameter in size.

The ‘Wave Hub⁶’ is a research project that was due to be installed in the summer of 2010 16km off of Hayle, Cornwall. It will be a fixed to the sea bed. The best way to describe the wave hub is as a ‘socket’ accepting energy generated from wave power arrays. As it stands, four different technologies will be allowed to connect to the hub in order to do tests. The hub will measure the strength of the waves and also enter into a PPA (Power Purchase Agreement) on behalf of the developers. The wave hub also provides planning consent for wave arrays, reducing the lengthy task of getting planning permission for each technologies research. The wave hub is connected to the grid through an onshore substation at Hayle by an underwater cable that then is built within the sand dunes running up to the substation.

Environmental Impacts

• Could create safe havens for sea life as shipping and fishing would not be permitted in an area where a wave power array is sited.
• Tests have been carried out and are ongoing into whether an array of wave power devices affects the sonar of cetaceans.
• Some devices are noisy (i.e. the Limpet). Noise is created by air rushing through the turbine, however the sound created by the waves in the first place will most likely drown this noise out.
• There has been speculation about the affect that an array has on surfing. Computer modelling helps to determine a suitable site so that an array can be far enough from the coast not to affect the surfing industry.

Other Problems

Shipping: As wave power devices are based out at sea it is obvious that an array of them will create a hazard to shipping and fishing areas. Just like rocky coastal areas are defined on a map, wave power arrays will also have to be included.

Storm Surges: A wave power device would have to undergo occasional great stress as a result of storm surge. A storm surge would almost indefinitely create a fault with the device. To militate against this, it may be possible to temporarily sink a device until the storm surge has passed or tow it back into a harbour where it could be sheltered.

Renewable Obligation Certificate

Wave power is classed as an ‘emerging renewable technology’, and therefore under the Renewable Obligation Certificate will receive 2 ROC’s per MWH that it generates. In comparison, an ‘established’ technology such as energy from Landfill Gas receives 0.25 ROC’s per MWH that is generates. Incidentally, wave power is deemed to be a ‘large generator’ and so does not fall under the Feed-In-Tariff within the UK.

If you would like to find out more about renewable technologies then take a look at our informative pages.

References

1. Korean Tidal Barrage; http://www.newsworld.co.kr/cont/article2009/0909-52.htm

2. Atlantis Resources Homepage; http://www.atlantisresourcescorporation.com/about-atlantis/history.html

3. Limpet, WaveGen Homepage; http://www.wavegen.co.uk/what_we_offer_limpet_islay_wavecam.htm

4. How Salter’s Duck Works; http://science.howstuffworks.com/environmental/green-science/salters-duck1.htm

5. Pelamis, Ocean Power Delivery; http://www.pelamiswave.com/index.php

6.Wave Hub South West Research and Development; http://www.southwestrda.org.uk/working_for_the_region/key_sw_projects/cornwall__the_isles_of_scilly/wave_hub.aspx

Hydroelectricity

How It Works

Hydroelectricity involves transferring energy from water by allowing it to flow through a turbine. The turbine revolves and electrical energy is generated. We can increase the amount of energy content water has by effectively adding gravitational energy into it. By storing water at a height and then releasing it, the water in essence has now gained a vast amount of additional energy. The velocity of the water is increased and will therefore cause the turbine which it is flowing through, to revolve much faster, and thus create more energy.

Advantages

• In comparison to other power plant generations (such as Nuclear and Coal), Hydroelectric Dams can be turned on or off very quickly – beneficial for supplying energy when demand is high.
• Apart from the initial construction, Hydroelectric Dams produce no carbon emissions.
• Hydroelectric Dams (unlike wind or solar power) are not intermittent. They can produce electrical energy continuously and at a constant rate.
• The reservoir that stores the electricity can be used for water sports and other water activities.
• The water can also be used for irrigation.
• It can be used as a renewable intermittent power resource. For example, when demand is low and wind turbines are generating an excess amount of electricity that is not needed; this energy can be used to pump up water into the reservoir. When demand is high, and there is an intermittent period, the hydroelectric dam can be turned on and uses the water which was stored by the wind turbines electricity.
• Once initial costs of construction have been paid back, hydroelectricity is very cheap to generate (in comparison to other renewable and fossil fuel generation plants).
• Modern hydroelectric power plants generate 90% of the water’s energy. In comparison to coal which at best generates 50% of its fuel.

Disadvantages

• The local ecosystem around the area a dam is built will be permanently changed as well as the ecosystems downstream.
• The risk of flooding is greatly increased. If a dam were to burst, settlements downstream would be affected.
• A dam may cause earthquakes. An increase in pressure due to the mass of stored water can trigger this to happen.
• Dams that are built on a long distance river may affect other countries that also rely on the same river. I.e. the Ganges. When the dam’s water has been released in India it upsets the naturally occurring flooding in Bangladesh.
• Fish migratory courses may be affected.
• Its construction may cause drought further downstream.

Micro Hydropower

How It Works

Water is siphoned off from the river or stream by a dam or a weir. This enables a smooth collection of water into the canal and forebay. Usually, within the canal and forebay system a screen collects debris, as this will damage the turbine system. The forebay houses water which is then fed into, and through a penstock. The penstock will be only a few inches in diameter, and creates a jet of water through a nozzle onto the turbine. The turbine is housed inside a ‘powerhouse’. The powerhouse is enclosed to protect the alternator/generator/inverter from the elements, and also to act as a barrier to noise that is produced through generation. The tail race feeds the water back into the river or stream.

To estimate the maximum power that a river could produce, you will need to take an average (not maximum) flow rate for the year –measured in metres cube per second. I.e. an average sized stream is likely to have anywhere between 0.25 and 1 m³/s. You will also need to find out the head (height of the water from the top to the bottom), measured in metres. This is only a rough calculation:

Power (estimation) = Flow rate x Head x 5

The 5, denotes gravity divided by frictional losses within a system, and again, is a rough, rounded number.

Advantages

• It is very efficient and reliable.
• In winter months, when demand for energy is highest, a hydro powers resource is at its highest.
• It is a good power source for developing countries. Many places may not have a grid system supplying them with electricity. Hydro offers a cheap and reliable source of energy.
• It will often generate enough electricity for personal needs, and will often produce a large excess, which can be sold to the grid.
• Unlike hydroelectric dams, a big reservoir isn’t required as it works off of the run of the river and therefore has a minimal impact on the local ecology.

Disadvantages

• It is limited to the ‘power’ of the river.
• Feasibility is extremely site specific.
• Whereas demand is expected to be highest during the winter months, generation requirements are hindered during the summer months when the river does not produce such a large capacity of water.
• Fish migratory paths may be hindered, and therefore careful planning will be needed which still allows fish to migrate whilst temporarily extracting water for electrical generation.
• Freezing temperatures (particularly for the penstock) will need to be addressed, such as burying or insulating.

UK Micro Hydro Schemes

The UK’s feed-in-tariff levels for Micro Hydro Schemes start at 19.9p/kWh for projects under 5kW, and 17.8p/kWh for projects between 15 and 100kW. Both have a lifespan of 20 years. So, if a project is installed this year (2010/2011) the generator for a 5kW system will earn 19.9p/kWh every year for 20 years for the total that is generated, whether consumed or exported to the grid. For every 1kWh that is exported to the grid, the generator will also receive 3p/kWh.

The Local Planning Authority will need to be consulted on building a powerhouse and pipe work. The Environment Agency is in charge of watercourses in the UK, and you will need permission prior to installation and an abstraction of water licence. You will also need to assess the affects on river ecology and flooding.

There are many examples of Micro Hydro Schemes within the UK. Old water mill sites are also commonly used. Gants Mill in Somerset is one such example.

‘Old Walls’ Dartmoor, Devon: http://www.re4d.org/images/stories/pdf/re4d%20cs%20old%20walls.pdf

‘Gants Mill’ Bruton, Somerset: http://www.gantsmill.co.uk/hydropower.htm#tour

World Hydroelectricity

‘The International Energy Outlook 2000 predicts that the global consumption of electricity will be 76% higher in 2020 than it was in 1997. Electricity consumption will increase from 12,000TWh (1997) to 22,000TWh (2020).The worlds total feasible hydropower potential has been estimated at 14,370TWh/yr of which 8082TWh/yr is considered economically viable for development. In 2000, 2600TWh/yr was already in operation.’ (Hydropower and Dams, World Atlas and Industry Guide 2000)

China, India, Iran and Turkey are developing large scale hydro projects².’

More recently, the ‘Key World Energy Statistics 2007’ wrote that Hydroelectricity combined had a capacity of 836GW producing 2994 TWh of energy generation in 2005. With China being the highest contributor (13.3% – 397 TWh).

References

1. Boyle, G. 2004. Renewable Energy, Power for a Sustainable Future. 2^nd Ed. Oxford: Oxford University Press. Chapter 5. Hydroelectricity, The Galloway Hydros.

2. World Hydroelectricity. Information taken from: http://www.ieahydro.org/reports/Hydrofut.pdf

Sometimes, energy from water may come naturally through the flow of a river or waves. Other times, energy comes from the force of water as it is released at height from a dam or other container. We are in essence ‘giving’ energy to the water here by gravity.

Hydropower produces no CO₂. It can also be far less expensive as a form of electrical generation than fossil fuel powered plants and nuclear power plants. Once the hydropower system has been built, all it will require is maintenance and operation (much like any other power plant) as the ‘fuel’ is water which is naturally replenished for free, by the water cycle.

• Hydropower can be generated using four different methods:
• Hydroelectric Dams
• Rivers (Micro and Macro Schemes)
• Tidal Barrages
• Wave Power

Hydroelectric Dams have been around for over a century. They used to be, and in some cases still are, the main source of electrical generation for many countries. Nowadays, they tend not to be used as much as a primary source of energy (as fossil fuels tend to be). They are however generally used for generating electricity at peak demand, as they are quick to turn on and off (unlike a nuclear power plant). It is unlikely that more will be built in any large number, as any suitable sites often already have a dam built. It is more likely that refurbishments of existing dams will occur. The biggest dam construction in the world is in China on the Yangtze River, named the 3 gorges dam. It is not only the biggest hydroelectric energy generator but also the biggest energy generator in the world.

There are many rivers that are suitable for micro or larger scaled hydropower schemes. Water wheels have been around for centuries, and used initially to power an industry, such as textile or wheat. By temporarily siphoning off water from rivers and sending it through a turbine, electricity can be generated. There are different turbines, specifically designed for a certain nature of a water flow. Some are designed for fast flowing rivers with a small head, others, low flow with a high head.

Tidal Barrages work with turbines that can turn in both rotational directions. Water flows inland on a high tide and seaward on a low tide. As the water flows through a series of turbines, electrical energy is generated.

There are many different forms of Wave Power Devices still being researched and tested. Some are now being built in ‘arrays’ (groups of wave power devices). The ‘Pelamis’¹ or ‘Wave Dragon’ is one such wave power device currently within its final stages of generating power as an array off of the coasts of Portugal and west coasts of Scotland. Wave power devices use the movement of the water in a variety of different ways. The ‘Pelamis’ works by generating energy through the movement between segments of its body. As one segment rises another one dips. The ‘forces’ created by hydraulic pressures between these segments generates the electricity through a hydraulic motor.

The following two articles on Hydropower will go into these concepts in more detail:

• Hydropower 1. Introduction
• Hydropower 2. Hydroelectricity and Micro Hydro Schemes
• Hydropower 3. Tidal Barrages and Wave Power Devices

Specific terminology useful for these three articles is below.

Terminology

h, Head

Example;

The hydraulic head here in the example is the distance between the water’s surface below (i.e. a river) and the outlet of the water from the reservoir.

Penstock

Is a water channel that nowadays leads into a turbine, transporting water through it.

Weir

A weir is a sort of dam that allows a river to ‘overflow’ over itself. The same terminology is used for large scale dams, where the crest of the dam allows water to overflow over itself, therefore maintaining a maximum water level within the reservoir.

Turbine

A turbine is a rotating mechanism (usually in the form of a series of blades) that extracts energy from a flowing fluid that is allowed to pass through the turbines path, and thus creates useful energy from the moving fluid.

Reservoir

An artificial lake used to store a quantity of water.

Ρ, Fluid Density

In Physics, this means Mass divided by Volume. All that is needed to be considered here is that freshwater and seawater have different densities. Sea water is 1025 kg/m³, whereas freshwater is 1000kg/m³.

Φ, Fluid Flow

Fluid flow is a volume of fluid that passes through a given area per unit of time, e.g. m³ per second.

G, Gravity

Measured as 9.81 m/s²

1. Pelamis Website. Available [Online] at: http://www.pelamiswave.com/

Overall the report shows that there has been a 15% increase in the UK’s entire energy consumption since 1970 to 2001, and of this, there has been a 10% increase since 1990 (taking into account the cold winters or hot summers)¹. Interestingly, transport has increased 95% between 1970 and 2001. In 2001, 54,932,000 tonnes of oil equivalent (toe) was consumed by the transport sector, of which, approximately three quarters was consumed by road transport.²

Today, the rate at which we consume oil is not only a concern, but the amount of carbon emissions being emitted from our day to day usage is also an issue. By finding an economical alternative to oil, oil consumption and carbon emissions can simultaneously be reduced.

Alternatives for diesel and petroleum fuels that are fast becoming economical to the user are ‘Biodiesel’ and ‘Bioethanol’. With some slight engine modifications, these fuels may be used to replace or offset fossil fuel consumption and carbon emissions.

World Ethanol fuel production currently (2009) stands at 4,067 million (UK) gallons, the USA producing over half and Brazil a third of this total.

How Biodiesel  and Bioethanol is made

Biodiesel

Biodiesel is made from natural fats, a typical source is vegetable oil which occurs naturally in seeds from many plants. Crushing these seeds is the basis of extracting these oils. Vegetable oil is made up of triglycerides which are compounds made up of three strands of fatty acids and a strand of glycerol. By processing these triglycerides with an alcohol (methanol) and a catalyst (sodium hydroxide or potassium hydroxide), two products can be made: crude biodiesel and crude glycerol. Later refining of the products and recovery of methanol will leave methyl ester (which is a pure biodiesel) and a purer glycerol. So let’s now look at the process in more detail. The diagram below illustrates the biodiesel process.

The first stage is to mix the alcohol and catalyst together. The raw vegetable oil is added to the mixture and heated. This is known as the ‘transesterification’ process. There is always a surplus of an alcohol added to ensure that all of the vegetable oil has the chance to react.

After a reaction has taken place, there will be two products, crude biodiesel and crude glycerine with other impurities from the reaction. The glycerine mixture has a higher density than that of the crude biodiesel and so rests on the bottom. Tapping this off from the bottom will leave the crude biodiesel remaining. This is the separation step.

Both products of the transesterification process will contain excess amounts of alcohol (as it was used in excess!). This will be taken out by distilling, or flash evaporation, and reused within the process again.

Catalyst that hasn’t been used during the process, as well as any soaps and water, are removed from the crude glycerine. This can now be sold on as crude glycerine or purified further by distillation. The glycerol is a useful by-product as it can be sold to pharmaceutical or cosmetic industries.

The crude biodiesel is also purified (if it needs to be) to take out impurities. Biodiesel essentially is produced from a renewable resource. It is biodegradable and is not toxic to the environment. Therefore, the impact from a biodiesel spillage is relatively low in comparison to that of fossil fuel diesel. Biodiesel also has a higher flash point than fossil fuel diesel and is safer in the event of a car crash due to the nature of its flammability.

Waste vegetable oil is often used as opposed to pure oil as this is a cheaper supply. However, as a result it will more often require filtration in order to take out impurities. Impurities are not just remnants of fish and chips, but also will include water which will need to be taken out of the raw vegetable oil. Water is unhelpful in the process as it combines with the fatty acids producing soaps.

Bioethanol

Ethanol (ethyl alcohol) is the same alcohol found in alcoholic drinks! Bioethanol is simply ethanol made from biomass. The feedstock for bioethanol can come from any crop that can be used as a carbohydrate source. Common crops are sugar beet, sugar cane, miscanthus, maize, sorghum, potato, wheat and corn. In brief, the feedstock is converted into sugars. These sugars are then fermented which forms a by-product, ethanol. The process of making Bioethanol is outline in the diagram below.

Bioethanol differs from biodiesels in regard to the fact that bioethanol requires the feedstock to be grown, whereas biodiesel can be made from used vegetable oils.

Milling is required as this creates a greater surface area for the third stage, hydrolysis, to take place.

The hydrolysis process breaks down carbohydrates, i.e. starch, into simple sugars such as glucose

The fermentation process breaks down the sugars using yeast. The ethanol is a by-product of the fermentation process, and is toxic to the yeast if it exceeds 15% of the total volume. Therefore, the ethanol must be continually siphoned off so that the yeast can continue to work. As the siphoned ethanol has high moisture content, the water will need to be removed.

This purification stage involves distilling the liquid. By heating the liquid up, the ethanol boils before water (as it has a lower boiling point than water) and so can be allowed to vaporise, condense and be collected.

Work is being done on using the waste products of the milling process to make Bioethanol. This involves breaking down biomass slowly using enzymes (much like cattle digestion), to form glucose. This is production of ethanol from cellulose, and is still being researched.

Advantages and Disadvantages of Biodiesel and Bioethanol over Fossil Fuel Diesel and Petroleum

Advantages of Biodiesel

• A Renewable Source (N.B. tends to use ‘waste’ oil as opposed to growing ‘new’ vegetable oil for economic reasons).
• Environmentally friendly: 78% less Carbon emissions than fossil fuel diesel³.
• Non-toxic: It is up to 98% biodegradable within 3 weeks, and is immiscible (does not mix) with water.
• Often only a slight engine modification is needed due to the nature of the biodiesel that eats away at plastic seals within the engine. Older diesel engines tend not to have any plastic within the engine!
• Prolongs the life of an engine: it has better lubrication properties than normal diesel, this reduces system wear.
• Combusts more completely: fuel economy is up 8% over diesel.
• High flash point, making it safer to transport and safer in case of a road traffic incident.
• Generally cheaper by 20p/litre than diesel.

As you can see it is much more environmentally friendly than diesel! It has no Sulphur Dioxide content, around 50% reduction in soot and other particulates, anywhere between 10 and 50% reduction in Carbon Monoxide, and a reduction in Poly Aromatic Hydrocarbons (PAH’S). PAH’s’ are organic pollutants and also, more crucially, are also formed from incomplete combustion of fossil fuels.

Disadvantages of Biodiesel

• Has a lower energy content (around 8-9% lower) than diesel. However it makes up some of this by the lubrication properties and its more complete combustion than diesel.
• Few outlets sell biodiesel, and there are only a small number of manufacturers.
• If the biodiesel is poorly made (i.e. its water content is higher than it should be) then it could cause engine problems.
• Some manufacturers now account for blends of biodiesel in modern cars.  This will need to be checked when purchasing a new car.

Advantages of Bioethanol

• Is a Renewable source, providing it is sustainably managed.
• Exhaust gases are much cleaner than fossil petrol.
• Almost any plant can be used, as long as it contains starch and can be converted into sugar.
• Has a lower taxation in the UK. This reduced fuel duty offsets the higher production costs.

Disadvantages of Bioethanol

• During the processes of making Bioethanol, the amount of CO₂ released almost matches that which has been taken in during the feedstock growth, making little ecological difference as an entity. However, the production of petrol will release much more CO₂ than Bioethanol production.
• Sustainability issues: Brazil is a good example of the environmental impact caused from growing fuel crops. Huge amounts of rainforest were destroyed in order to grow sugarcane for Bioethanol production.
• Energy content is much lower than Bioethanol. Weight for weight, it could contain up to a third less energy than petrol-all dependent on the feedstock used, and quality of the process and fuel.
• Older cars will struggle to accept even a 10% Bioethanol mix (B90).

Implementation of Biofuels for the UK

Distribution within the UK of biofuels is extremely limited in comparison to other countries. Unlike many other countries that have been incentivised to produce and distribute biofuels, the UK has been in a more comfortable situation in the past few decades, and as a result biofuels have not been needed. However, since the UK has gone from being a net exporter to a net importer of oil (from the North Sea), transport fuel is now an issue.

Biofuel implementation is going to be a gradual process unless a sudden incentive to produce and distribute biofuels happens. It is also a ‘chicken and egg’ situation: do you build the infrastructure needed to distribute and consume the biofuels, or grow the crops first and hope that the demand for them becomes apparent? As it stands at the moment, the Government has a target for biofuels that it wants to achieve and this comes under the ‘Renewable Transport Fuels Obligation’ (RTFO). The RTFO denotes that all transport fuel suppliers ensures that 5% of all road vehicle fuel is supplied from renewable sources by 2010.

The UK is at a disadvantage in comparison to the USA due to the lack of space available for, or land able to be converted into growing biofuels. Biofuels are not only used for transport fuel but also for combustion in biomass plants (generating electricity). Miscanthus is a suitable crop to be grown in the UK, but there is competition here for who will use the fuel, do we use it for transport fuel, or burn it in a biomass plant? Cereal crops could also be used for biofuels. The total area that is used to grow crops within the UK in 2009⁴ equated to 4,695,000 hectares. Cereals constituted 3,133,000 of these hectares. There are many uses for these crops (such as beer!), but would anybody be happy to accept a straight swap for beer crops to biofuel crops?

1. Department for Business, Enterprise and Regulatory Reform [BERR]. Energy Consumption within the UK. [2001]. Introduction. Available [Online] at: http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/files/file11250.pdf

2. Department for Business, Enterprise and Regulatory Reform [BERR]. Energy Consumption within the UK. [2001]. Section 2.1. Available [Online] at: http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/files/file11250.pdf

3. USA Biodiesel Board. Available [Online] at: http://www.biodiesel.org/resources/faqs/

4. Department for Environment Food and Rural Affairs, DEFRA. DEFRA Economics and Statistics –Agriculture in the UK 2009. Table 3.1. http://www.defra.gov.uk/evidence/statistics/foodfarm/general/auk/latest/excel/index.htm

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