WHY RENEWABLE ENERGY?

Climate Change
In a recent report ‘Living Within a Carbon Budget’, the Tyndall Centre claims that a CO2 reduction of 90% from 1990 levels is necessary in order to stabilise atmospheric levels.
The last general glacial period, the ‘Wurm Glaciation’ took place from about 85,000 to 15,000 years ago.  There were peaks and troughs during that time, but at its peak sea levels are reckoned to have been 150m below those of the present day.  At that time glaciers covered over 30% of the land surface.  Now they cover 10%, and  contain 7% of the world’s fresh water.  If all the glacial ice that is left now were to melt it has been estimated that sea levels would rise by a further 70m and although a few are growing as a result of increased precipitation, the vast majority are melting faster than ever before.

The Causes
Carbon Emission patterns over the last 50 years or so
Global emissions and the Climate Change problem is a factor of population size, level of energy use and the technologies used to generate power. ‘…during the twentieth century, as world population increased by just under fourfold and as the average per-person consumption of fossil fuel ….. increased by over threefold, so the annual human-made emissions of carbon dioxide increased twelvefold.  Atmospheric carbon dioxide concentrations have duly increased by about a third’.
Even if population levels remained static, environmental pressure would increase if everyone lived in the style of the developed and consumerist western nations.  Equity of living standards may assist the stabilisation of populations in underdeveloped countries, but use of radical alternative technologies will be necessary to ‘achieve a smooth transition to an ecologically sustainable world.  Rich countries, as the main source of new knowledge, technologies and wealth, must lead this effort.’
Extracted from ‘Human frontiers, environments and disease’ by Tony McMichael  CUP 2001

Release of Methane from permafrost
The frozen permafrost of Siberia and Canada locks up vast quantities of methane which resulted from decomposition of organic material – mainly peat – 12,000 years ago.
The permafrost is now thawing and the methane captured beneath it is being released.  The effect in Western Siberia is being studied at Tomsk Sate University by Professor Sergei Kirpotin who has reported expanding lakes which exacerbate the effect by absorbing the sun’s heat to enhance the melting in a globally significant climate feedback.  The frozen Siberian peat bogs are bigger that the area of France and Germany put together and with the lakes appearing to ‘boil’ during the summer of 2006 it was estimated that the carbon emissions could be greater than those of the United States.  The strength of this feedback loop is still not certain, but Katey Walter of Alaska University published a study in Nature in September 2006 suggesting that emissions were significantly more than had previously estimated.

Living within Limits
‘For 2 million years, humans have mostly lived and consume within the limits set by local environments.  When natural limits were reached, hunter-gatherer bands occupied adjacent frontier land…..To survive long term a society (has) to live off nature’s ‘interest’, leaving natural ‘capital’ mostly intact…..
Today’s global population is no longer living predominantly on nature’s interest.  Many non-renewable resources are being depleted:….  Likewise my very slowly renewable resources are being depleted……..  These global environmental changes that we have set in train signify that we are living beyond Earth’s limits.  This has great implications for the sustainability of economies and urban societies, for creating political tensions and for human population health.’
Taken from ‘Human frontiers, environments and disease’  Tony McMichael C.U.P. 2001 p284-286

Climate change evidence and predictions
Meteorological stations around the world using some of the most powerful computers and vast quantities of world-wide data on recorded temperatures, all demonstrate global warming at a rate that significantly exceeds the upper limits of natural variability.
These natural variations are caused by the eccentric path of the Earth around the Sun, and the tilt and ‘wobble’ of the Earth’s axis.  They produce general long and short term patterns which are known and predictable.  Similarly, Solar Flares and their effects although less predictable are known and recorded and can be directly related to recorded temperatures and weather patterns.
The climate change currently being experienced is greater and more rapid than has occurred in hundreds of thousands of years as well as being outside any probable range of natural patterns or causes.  World temperature increased by 0.4C in the 30 years from 1970, but at an ever accelerating rate that would lead to a further increase of 2-3C during the 21^st century.  As more and more research is undertaken in this area and more data is crunched evidence continues to emerge of additional feedback loops that are, and will increasingly, exaggerate the emerging trends, and could result in climate systems going through tipping points that cause the warming to become uncontrollable.
We also now know that due to the persistence of some greenhouse gasses in the atmosphere and the rate at which increasing temperatures permeate the ocean depths, even after greenhouse gas levels were stabilised, temperatures would still increase for hundreds of years, and sea levels for a thousand years or more.  Furthermore the effects of these changes would not be uniform.  For example, the Amazon rainforest would be especially likely to be affected by drought, and the Arctic could become warmer at a rate that was double the general average.  Disturbed and dramatic weather conditions will become the norm.
If a significant amount of the Antarctic ice sheet melted – as has occurred in the past but not in the last interglacial when temperatures were 1-2C higher than now – sea levels would rise by several metres.  If the same situation occurred in the Arctic, cold melt-water could slow, halt or reverse the Atlantic Gulf Stream and cause North West Europe to loose its 5C advantage over similar latitude countries, and experience cooling that outweighed any global warming effect at least for a century or so.
There is now better scientific consensus that man’s combustion of fossil fuels is the main cause of escalating carbon dioxide emissions which along with other greenhouse gasses are the main causes of Global Warming than of almost any other scientific issue.  In 2004 the respected journal Science undertook a random survey of 928 scientific papers that mentioned Climate Change, and found that not even one disagreed with the thesis.
The Greenhouse effect is well understood, and how it keeps our planet inhabitable, some 30C warmer than it would otherwise be.  It is essential to our existence on earth, but since the industrial revolution human induced emissions of the greenhouse gasses carbon dioxide (CO2), methane (CH4) and nitrous oxide (NO2) have been adding to natural levels.  At the same time as levels of these gasses increased, global temperatures increased in tandem and are now 0.7C higher.  Although there are natural undulations in yearly temperatures, partly caused by the energy output from sunspot activity, this is known, plotted, recorded and on average decreasing since around 1980.
So the predictions by the world’s top scientists working in this field are based, as they would have to be, on detailed analysis of data, and predictions based on the best evidence and most sophisticated computer models available.  As new research reveals new evidence so the predictions also change, but the thesis has stayed firm and consistent, and any new data has simply indicated the overly conservative nature of earlier suggestions.
Probably the most authoritative and globally accepted prognostications on climate change have come in reports from the Intergovernmental Panel on Climate Change (IPCC).  Their first report was published in 1990, and by their third report in 2001 they were concluding that most of the warming in the last 50 years has been due to human activities, and that a temperature increase of between 1.4 and 5.8C is likely by the end of the 21^st century (the figure depending on remedial measures introduced to limit energy use).  Suggested figures for the UK were 2 to 3.5C by 2080.  Since that time more sophisticated data have been produced, and new feedback loops evidenced.  A revised and updated IPCC report is due this Summer (2007

NATIONAL CARBON EMISSIONS
The World Development Movement has undertaken valuable recent research and produced a report that compares the carbon emissions of average citizens of many countries, and demonstrate the inequity between those suffering, and likely to suffer most from Global Warming, and those causing the problem.
Only 20 countries have a larger carbon footprint than the UK, and 164 have smaller ones.  A Briton will produce 9.62 tonnes of CO2 annually, while an Afghan produces 0.02 tonnes, and a citizen of the United Arab Emirates produces 56 tonnes (the worst).
It is claimed by the WHO that 160,000 people die each year from climate change related diseases, and that a 2C rise in temperature could lead to 60 million more people being exposed to Malaria in Africa.
The average Briton is responsible for producing 26 kg of CO2 each day, (up 6% since 1997 - during the tenure of the Labour Government) which can be broken down as 7.4 electricity; 1.6 fuel production; 3.8 manufacturing and construction; 7.4 transport (5.2 road transport; 1.7 air travel; 0.1 railways; 0.4 shipping); 1.0 Office buildings; 3.8 residential heating; 1.0 other industrial processes, agriculture, military travel etc.  UK people emit more CO2 per person than the average EU citizen, and exceeded the sustainable global average in about 1830.  Overall, the UK produces over 2% of global emissions of CO2, but has less than 1% of world population.  The final official figures for CO2 emissions in 2005 were released on 1^st February and showed that the overall UK figure dropped by 0.1% from 2004 (household emissions fell by 4.6%, but aircraft emissions rose by 7%).
To keep the global temperature increase to around 2C, it is generally agreed that CO2 levels must not increase to more than about 450 ppm.  To do that, global emissions would have to reduce to about 70% of 1990 levels by 2050.  To sustain that situation, emission levels would have to be kept to around 6.5 billion tonnes p.a. which at current population levels would mean a carbon budget of 1.08 tonnes per person per year. For the average UK citizen producing 9.62 tonnes p.a. to be contributing no more than their fair share would mean reducing their emissions by 85-90%.
Already, the inhabitants of 68 countries produce less than 1.08 tonnes of CO2 annually, so have little or nothing more to give.  It really is down to everyone who produces more than the sustainable average to get their emissions down to that sustainable figure.  The current global average is 4.24 tonnes per person per year, less than half that of an average UK citizen.  The average UK citizen is worse even than the average EU citizen.
Among countries often blamed for being the principal cause of CO2 levels, the average emissions of a citizen of India is only 1.04 tonnes of CO2 per year, only about 11% of the average Briton.  India has 16.8% of the world’s population but emits only 4.1% of emissions.
China is not quite so innocent, but Chinese people still only produce 3.62 tonnes of CO2 each, less than half that of a UK person, and less than the global average.  China has 20.4% of the world’s population but is responsible for only 17.2% of emissions.
Turning to the biggest villain, the USA, it’s interesting to note that there are 7 other countries whose inhabitants are worse culprits, and running close behind the USA’s 20.18 tonnes per person comes Canada at 18.09, and Australia at an even closer 19.39.
For full report www.wdm.org.uk/resources/briefings/climate/climatecalander08012007 

EFFECTS OF CLIMATE CHANGE
Lake Qinghai
A report be the China Geological Survey Bureau predicts that despite a Chinese Government pledge of £442m to stop the holy lake shrinking, it will still disappear within the next 200 years.  Nearby glaciers on the Qinghai-tibet plateau have been shrinking by an average of 131sq km each year for the past 30 years, and at current rates a further 28% (13,000 sq km) will disappear by 2050.
Hedgehogs
Wildlife Centres are reporting large increases in the numbers of young Hedgehogs being handed in.  Confused by the milder weather Hedgehogs are continuing to breed rather than hibernate.  Finding adequate food is difficult, and the young can’t put on the weight necessary to see them through cold snaps, with the result that many are dying.
Eelpout
German scientists have warned that rising sea temperatures are killing of these fish, which live in the North and Baltic Seas.  While Oxygen levels in the oceans are decreasing, the warmer weather is increasing the fish’s requirements.
Britain’s average temperature
2006 was the warmest year in Britain since records began in1659
Global average temperature
2006 was the 6^th hottest year on record
Arctic Sea ice
In March 2006 Nasa satellites recorded record low levels of winter sea ice, contributing to a feedback loop that results in increased summer melt and less build up the following winter etc.  Many scientists believe that they are witnessing the fact that the climate tipping point has been reached.

UK Sea level rises
Over the last 100 years or so, UK sea levels have risen by approximately 1mm each year.  However, the UK land mass itself is rising in the North and sinking in the South, a response to the relief of the weight of the ice cap in the last ice age.  The net effect has been sea levels relative to the land rising by 0.6 mm annually in the North of Scotland, and 2 mm annually in South East England.
Global average sea levels have risen by 10 – 20 cm during the last century, but this situation is escalating and increases in the region of 50 cm or more are predicted in the 21^st century.

SNOWDON
Countryside Council for Wales and the University of Wales in Bangor have undertaken research which shows that snow levels on Snowdon have decreased by 35% in the last 10 years, causing the snow line to move up by 560m.  The 2006/07 winter accumulation is by far the lowest recorded since records began 14 years ago.
The Spring temperature has increased by 2.5C in the last 30 years, and from this information it has been concluded that at the current rate of change  Snowdon would loose its winter snow cover by 2020.  The warning comes just three months after Scottish scientists predicted that ice-capped highland peaks would soon also become a thing of the past.  The prediction is based on average January and February temperatures which have been rising by 0.3C every 10 years for the past 30 years.

Global Carbon Sinks
About half of all man-made emissions of carbon dioxide is locked up by the oceans and the land.  In July 2006 an international team of climatologists published a report in the Journal of Climate about the effect that a warmer world would have on these sinks.  Applying the changes to 11 of the world’s most powerful computer models of the carbon/climate cycle the found that as the climate became hotter so the ability of the oceans and the land to absorb CO2 decreased to the point that they could become net emitters. 
Guy Kirk of the National Soil Resources Institute has found that the land is a greater emitter of CO2 now than it was 20 years ago, and that this is due to higher temperatures speeding up the decay of organic matter.  Since 1978, an extra 13million tonnes of CO2 have been released each year from Britain’s soil, slightly more than has been saved during that period by cleaning up industrial processes.
At  sea the picture is similar.  As more CO2 dissolves in sea water, it becomes more acid, and is capable of dissolving less and less.  The sea is currently becoming more acid at a rate which is 100 times more rapid than for millions of years.  In addition, many small organisms use dissolved carbon to help form their shells, but find this increasingly difficult in more acidic seas, thus again decreasing carbon capture in the global oceans.
In December 2006, Nasa satellites showed that phytoplankton, plants that form the basis of the entire marine food chain, were decreasing their photosynthetic productivity, and absorbing less CO2 by up to 30% in some places.
All these feedbacks are pushing the earth’s climate system towards unknown tipping points that could have a sudden and dramatic effect.  We know this can happen because it has occurred before.  55 million years ago when global temperatures rose by 10C resulting in a mass species extinction, and 14,500 years ago when melting ice sheets and warmer weather caused sea levels to rise by 20 metres.
But this time it is us that are pushing the climate towards the brink.
Extracted from The Independent 29^th December 2006, ‘The Year in Review 2006’

EU Climate Change Policy
On the 10^th January 2007, the EU released a scientific report that detailed how continental Europe would be devastated by Climate Change.  The lifestyles of its people, its ecosystem and fertility would not survive the changes predicted for the 21^st century.
The EU hopes that the increase in global temperature can be capped at 2C above pre-industrial levels (currently 0.6C) and in order to do that proposes that member states cut their CO2 emission levels to 30% below 1990 levels by 2020.  The report presents a powerful view of how essential elements of modern civilised life depend on natural ecosystems, and identifies the consequences if they are disrupted.  The report predicts that initially Northern Europe would benefit from improved agricultural yields, fewer deaths from adverse winter weather, and a vibrant tourist industry.  But, increased deaths in the overheating south would run into tens of thousands and far outweigh the northern gains.  The current popularity of the Mediterranean area is the focus of about 100 million tourists each year – the largest human annual migration in the world – and loss of visitor numbers added to diminished crop yields, would be devastating.  Threats to North Sea fish stocks, coping with sea level rises along with extreme weather events would be financially crippling.

International Policy
Kyoto Protocol
Under the Kyoto Protocol the pre-2004 EU member states (EU-15) agreed a target to reduce greenhouse gas emissions, from a range of greenhouse gasses, by an overall average of 8% below 1990 levels by 2008-2012.  By 2004 EU-15 emissions were 0.6% below 1990 levels.
Individual countries have their own targets to contribute to the overall aim.  The UK has an overall reduction target of 12.5% of the ‘basket’ of gasses.  By 2004 the reduction of the 6 designated gasses was 15% overall.  However, by the same date emissions of the main greenhouse gas, carbon dioxide, had been reduced by 5% against a UK target for this particular gas of a 20% reduction by 2008-2012, and annual emissions have been increasing slightly since 2000 (and were essentially static in 2005 with household emissions of CO2 reducing by 4.6%, but aircraft emissions increasing by 7%).  The main factor responsible for the UK’s flattering overall reductions was a decrease in methane emissions from landfill sites of around 60%.
The Kyoto Protocol is an amendment to the United Nations Framework Convention on Climate Change.  It was opened for signature on 11^th December 1997, and came into force on 16^th February 2005.  Parties to The Protocol include169 countries and other government entities

Fuel Security
Nuclear Power

Nuclear Power is neither a sustainable or cheap means of electrical production, neither will it save CO2 emissions to any significant extent.  At the end of December it was announced by British Energy that outages of power production will be greater than predicted, and will wipe £100m off their profits. 
All power stations have to be regularly taken out of production for maintenance.  Think of the standby capacity required to compensate for a Nuclear Power Station, when you hear claims that the intermittency of Wind Turbine power production means that spare generating capacity has to be on standby at all times, with the result that there is little or no CO2 savings from this kind of power generation, and no saving in other kinds of fuels.
Two of British Energy’s units at Hunterston B and at Hinkley Point will not be back on-line until March 2007, after cracks were found in boiler tailpipes, and represents the worst case option that was envisaged when cracks were first found in November 2006.  Even after March the units will be only operating at 70% output, and the 30% reduction will require more reserve capacity than half a dozen or more good sized Wind Farms all completely ceasing production at the same time, and staying that way for months on end.
Lets look at the cost of Nuclear Power in environmental and financial terms.  It is very difficult to get a realistic impression of the meaning of the £70b that the British taxpayer is paying to decommission existing ageing plants.  Well, try imagining the combined annual sales of all the UK’s Garden Centres.  That would have to be some pretty massive amount, but apparently it is a mere £1.3b, only about one fiftieth of the money we will spend on the power stations.  Can any rational person still believe that that nuclear electricity is economical and cheap, or that decommissioning alone doesn’t result in massive CO2 emissions.  The Nuclear Decommissioning Authority which is responsible for the clean-up at 20 sites normally gets part of its funding from  Central Government and partly from the power generating industry.  Apparently it is facing a shortfall at present, which the Government refuses to fund, and as a result of which decommissioning may have to be halted.
Another example of the hidden cost of Nuclear Power is the cost of security.  It is generally accepted that nuclear fuel poses significant risks both in use and potential abuse.  Take waste transportation, although the DTI are convinced of the robustness of security measures, this has involved a no-fly zone over Sellafield for instance, and an in-house police force which costs in the region of a mere £50m p.a.
In the event of an accident, of course, the effect can be horrendous.  The IAEA/WHO concluded that some 4,000 premature deaths were likely to be caused by the fallout, but more recent by TORC H, the International Agency for Research on Cancer, and by Greenpeace have challenged some of the original assumptions and estimated 30-60,000 deaths; 6,700 – 38,000 deaths and 93,000 deaths respectively.
Uranium is not a renewable resource, reserves are finite, and mining it is not sustainable.  Conventional Uranium that can be mined economically is reckoned to amount to about 4.7m tonnes, which is enough to last for another 85 years are current rates of use.  With expected expansion of Nuclear power these reserves would run out by 2025, but of course diminishing supply would cause prices to rise and enable more to be mined economically (although this would inevitably mean significant increases in the cost of energy generation in an industry that has made it clear that it needs and expects a favourable price for its electricity, and enhanced environmental impacts).  This kind of search becomes ever more desperate and expensive.  Better to admit sooner rather than later that we should be totally dedicated to a sustainable energy supply.

Local Empowerment
A critical barrier to the development of RE at a local level is that social responsibility is currently at a relatively low ebb.  We are living through an era that puts a he emphasis on individualism, and individual rights at the expense of community and social responsibilities.  If I am fortunate in having a view that I enjoy, nothing should be permitted to intrude on it, and if pain and inconvenience are all that is immanently on offer for tackling a problem that is a decade or two away, one can hardly expect people to be falling over themselves to be taking immediate action.
A recent report commissioned by the Energy Savings Trust predicts that by 2010 UK householders will double the amount of energy they use on electronic equipment.  Overall, energy consumption by UK households has decreased slightly from 17.9 MWh in 2000 to 17.7 MWh in 2005.  By far the greatest energy use in the home is for heating (81%), and this has reduced from 14.6 to 14.4 MWh/y, probably mainly due to increased use of more efficient gas central heating, and a couple of mild winters.  Slightly less energy is used to power fridges and freezers than 6 years ago, but interestingly, greater efficiency in lighting has been compensated by greater use.  The prospects for dramatic reduction in energy use by households is not good.  It will need all the incentives we can come up with to keep household emissions stable.
Source – DTI Environmental Statistics and Market Transformation Programme

Visual Impact

The visual impact of technologies is often a contentious issue, after all “ beauty is in the eye of the beholder.” While some may find the sight of a wind turbine majestic another may think it objectionable. Some may feel the acid yellow filled fields of oil seed rape plants unnatural others may find it simply part of the ‘patchwork’ of diversity within the landscape. So the question really is whether the visual impact of a technology outweighs its benefits.

Nuclear power stations are large-scale industrial plants with associated sub-stations and power transmission lines, the mining of Uranium Oxide also has a visual impact in the countries where it is sourced.
Oil’s impacts range from huge oil refineries to small domestic oil tanks.
Gas power stations are generally smaller than coal fired because gas can be easily transported in underground pipes so power stations can be more local to where the energy is to be used.
Coal mines may be either ‘open cast’ or deep mine. Open cast are highly visible. Deep mine is also visible because of associated pit head works and slag heaps. Power stations are highly visible with cooling towers, chimneys, and electricity sub stations.
Anaerobic Digestion’s visual impact is directly proportional to scale. AD plant can be small and located within existing buildings so have no visual impact at all. Conversely can be large scale with dedicated plants and so will be visible.  
Oil Seed Rape is an ‘annual’ plant sown and harvested within a single year. However when in flower the crop is a bright (highly visible) yellow. It is a matter of opinion whether this is visually acceptable.
Short Rotation Coppice (usually a Willow cultivar) can grow to 4 – 5 m in height. Because the crop grows over a three-year period the visual impact is that of a semi-permanent scrub woodland.
Miscanthus can grow up to 3m in height. The crop is visible but may be considered as part of the landscape.
Wind 6kW: This size of turbine is most frequently used for small off grid sites. Typically on a 9m tower with a blade diameter of 5m.
Wind 1.3MW The 1.3MW wind turbine is the ‘second generation’ industry standard. Standing 65m to hub height with blades of 45m blades, the blade tip can reach 110 m above ground. There can be no question this size of wind turbine is highly visible particularly since to be economic they need to stand in a good wind stream (average wind speed at hub height 7.5m/s), which normally means on hilltops or high ground.
Solar Hot Water can be integrated into a roof structure but more likely to be retrofitted to a roof so stand proud of the surface. There are two main types; flat plate which as the name suggests comprises a glazed large flat plate of black material with water pipes attached to the rear surface, and evacuated tube consisting of a row of cylindrical glass tubes and a header tank.
Solar Hot Air A new technology but usually flat plate in style.
Photovoltaics can be integrated into the roof structure and be almost indistinguishable from the roofing tiles. On the other hand PV can be retrofitted to a roof and stand proud of and possibly be a different colour from the roofing slates and hence stand out.

Traffic

Most renewable energy systems once installed require no further traffic movements in relation to power generation or transmission. Fossil Fuels vary in how much transport is required and fuel crops also require transportation from where they are grown to centralised power stations.


Miscanthus once planted requires only a single pass to harvest each year. However if used in a large biomass power station there may be many lorry movements converging to deliver the required amount of feedstock.
Short Rotation Coppice once established the crop is harvested on a three year rotation so tractor movements are less than other forms of farming. If the coppice is used to fire a biomass power station there could be lorry movements close to the station.
Oil Seed Rape’s traffic impact at present is confined to tractor movements on the land to plough, sow, fertilise, spray and harvest the crop plus lorries to remove crop for processing.
Coal power stations are generally built close to mines to minimise traffic but due to large quantities, transport is often by train.
Gas is less of a problem because the fuel is brought in by pipeline.
Oil is usually transported by road tanker and/or used as a road transport fuel so massive traffic implications.
Nuclear power station traffic movements are usually confined to staff going to and from work.

Noise, Smoke & Odour

Noise, Smoke & odour are issues that affect those who live and work within the local vicinity of some power producing technologies.

Coal: Noise – associated with industrial nature of the process. Smell – sulphurous smells from combustion.  Smoke – from power station chimneys. 
Gas: Noise - is less of a problem due to reduced vehicle movements. Smell – is not normally an issue.  Smoke – gas is clean burning so not normally an issue.
Oil: Noise – that associated with industrial plant. Smell – can give off sulphurous fumes. Smoke – not usually an issue but diesel engines can give off particulates.

Figure 3. Fossil Fuel Combustion Power Station

Anaerobic Digestion  - Smell – A possibility due to the fact the feedstock is of organic nature so rotting may be in process, odour is only an issue when it escapes, in an anaerobic digestion plant it is highly contained. Animal slurries and Municipal waste can smell so it is strictly regulated to avoid disruption and disturbance.
Wind 1.3MW: Noise was a concern with ‘first generation’ turbines. Noise used to emanate from two sources; gearboxes and blade tips. Second generation turbines either have no gearboxes or better engineered (quieter) gearboxes and blade rotational speeds have been reduced to eliminate tip noise. As each blade sweeps passes the tower, occasionally a “whooshing” sound may be heard in certain directions from the blade. In higher wind speeds the sound of the wind in the trees drowns out any turbine noise and rarely is noise a problem more than 400 m from the tower. There is a suggestion that ‘infrasound’ (low frequency sound – below the threshold of human hearing) is a problem. Research to date suggests that this is not a problem, but investigations are ongoing.
Wind 6kW: Noise may be an issue, generally smaller turbines rotate at higher speeds so generating tip noise. However since this size of turbine is generally chosen for remote sites the only people likely to be disturbed are the owners themselves.
Wind72w: There may be concerns about noise vibration within the building to which the appliance is attached.
Micro- hydro : Noise may be an issue but appropriate sound insulation should mitigate this.

Figure 4. Typical site with low head potential

Transmission

This is the transportation of electricity from where it is produced via overhead or underground cables.

Wind 1.3 MW: Transmission – A grid connection power line is possible if the turbine is part of a wind farm.
Micro-hydro: Transmission – A grid connection power line is possible depending the circumstance.
Tidal & Wave: Transmission for ‘at sea’ installations, an undersea cable will need to be laid. Once ashore, the power is likely to be connected into the grid system so overhead power lines are likely.
Anaerobic Digestion (AD) Transmission – depends on end use; being a gas can be compressed into tanks and taken away by road. Could be used on site to power a CHP plant so there could be local transmission lines. 
Coal, Gas & Nuclear: Transmission – National Grid across the country
Oil: Transmission – can be used for large power stations so can be grid connected so associated power lines.  Can be used independently at domestic scale for heating purposes so no transmission lines. 

Figure 5. Transmission lines

Scale

Some technologies can operate on all three scales and still be productive, whether this be an individual home or a large scale scheme generating energy for thousands of houses.

Photovoltaics can operate across all three scales, being modular PV panels can be fitted in any size array.
Solar Hot Water & Solar Hot Air generally between 2 and 4 sq metres in size.
Wind 1.3MW wind turbine is the ‘second generation’ industry standard used in larger scale schemes.

Figure 6. Wind Turbine

Wind 6Kw & Wind – 72w: These sizes of turbines are most frequently used for small off grid sites.
Tidal & Wave: Tide mills used to be part of the pre-Industrial Revolution landscape so can be done at small scale. However given the technical nature and difficult installation requirements of larger installations tidal & wave power are likely to be very large scale in order to be economic.
Miscanthus: At present, scale is dictated by economics. Large scale offers economies of scale so are likely.

Short Rotation Coppice: It is unlikely that any one farm will have the land area available to develop a completely viable system. It is more likely that a number of farms within a region will each grow some SRC and supply a central power station. Therefore there is likely to be a large number of small patches of SRC across the landscape.  
Oil Seed Rape: generally individual farms confine planting as part of a crop rotation scheme so may be a few acres to tens of acres.

Economics

This is an assessment of the economics associated with each of the technologies at the present time, but often the economic success is dependant on the uptake and with greater popularity comes competitive pricing and the lowing of initial outlays.

Hidden cost
Nuclear: Originally marketed as supplying energy so cheaply it won’t need to be metered, this has proved to be not the case. No account having been taken of the huge costs associated with de-commissioning. Economics continue to be a concern. (large government loans to keep the operating companies in business). 

Costly
Fuel Cells: High initial capital cost but low running costs so long term economic benefit.
Wave & Tidal: Wave & Tidal technology given the technical nature and difficult installation requirements of larger installations wave & tidal power is likely to be very large scale to be economic.
Photovoltaics: the manufacturing process is complex and PV remains an expensive technology, although there is a belief that costs are being maintained artificially high due to vested interested in the oil industry. There is hope that a completely new solar cell based on ‘Die-sensitised cells’ will emerge in the near future.

Medium
Wind 6kW: The economics are less attractive than larger turbines (costs about £25,000).
Wind – 72w: The economics are less attractive than larger turbines
Micro-hydro: Costs are very site specific. A new site may require civil engineering works that will add to the cost. Renovating an old mill site can be a very cost effective option. Micro-hydro is capital intensive initially but if well designed will offer many years (70+) of operation. Pay back should be possible in under 10 years.
Solar Hot Air: A new technology so costs have yet to settle down

Marginal
Miscanthus: The crop has a number of other uses (animal bedding, fibre boards) some of which are more remunerative than growing as an energy crop. However Miscanthus could be used more than once in a ‘circular’ process i.e. first as animal bedding then as a feedstock for anaerobic digestion to produce methane
Oil Seed Rape: As an energy crop, at present it is economically marginal. Crop needs several passes with tractor. Hence research to improve return on crop so may be more economic in future. As a ‘second use’ crop (waste vegetable oil) the economics are good
Anaerobic Digestion: Research continues to enable the process to be economically viable in an increasing variety of systems and situations. 

Viable
Solar Hot Water: A well established technology with a good supply chain so costs are very competitive.
Wind 1.3MW: The economics are good. They can pay back, in energy terms, their cost of manufacture in about 6 months.
Short Rotation Coppice: It is difficult to assess at this time, Needs a co-ordinated approach to put growing and using infrastructure in place.
Ground source heat pumps: High initial capital cost but low running costs so mean a long-term benefit.
Coal: It is clearly viable as this is still a significant means of energy generation at present.
Oil:  Its