Low Carbon Economy, 2011, 2, 173-191
doi:10.4236/lce.2011.23022 Published Online September 2011 (http://www.SciRP.org/journal/lce)
173
Opportunities for Sustainable Low Carbon Energy
Research Development and Applications
Abdeen Mustafa Omer
Energy Research Institute (ERI), Nottingham, United Kingdom.
Received March 1st, 2011; revised March 28th, 2011; accepted April 3rd, 2011.
ABSTRACT
People to rely upon oil for primary energy and this for a few more decades. Other conventional sources may be more
enduring, but are not without serious disadvantages. The renewable energy resources are particularly suited for the
provision of rural power supplies and a major advantage is that equipment such as flat plate solar driers, wind ma-
chines, etc., can be constructed using local resources and without the advantage results from the feasibility of local
maintenance and the general encouragement such local manufacture gives to the build up of small-scale rural based
industry. This article comprises a comprehensive review of energy sources, the environment and sustainable develop-
ment. It includes the renewable energy technologies, energy efficiency systems, energy conservation scenarios, energy
savings in greenhouses environment and other mitigation measures necessary to reduce climate change. This article
gives some examples of small-scale energy converters, nevertheless it should be noted that small conventional, i.e, en-
gines are currently the major source of power in rural areas and will continue to be so for a long time to come. There is
a need for some further development to suit local conditions, to minimise spares holdings, to maximise interchangeabil-
ity both of engine parts and of the engine application. Emphasis should be placed on full local manufacture. It is con-
cluded that renewable environmentally friendly energy must be encouraged, promoted, implemented and demonstrated
by full-scale plant especially for use in remote rural areas.
Keywords: Renewable Energy Technologies, Energy Efficiency, Sustainable Development, Emissions, Environment
1. Introduction
Power from natural resources has always had great ap-
peal. Coal is plentiful, though there is concern about de-
spoliation in winning it and pollution in burning it. Nu-
clear power has been developed with remarkable timeli-
ness, but is not universally welcomed, construction of the
plant is energy-intensive and there is concern about the
disposal of its long-lived active wastes. Barrels of oil,
lumps of coal, even uranium come from nature but the
possibilities of almost limitless power from the atmos-
phere and the oceans seem to have special attraction. The
wind machine provided an early way of developing mo-
tive power. The massive increases in fuel prices over the
last years have however, made any scheme not requiring
fuel appear to be more attractive and to be worth reinves-
tigation. In considering the atmosphere and the oceans as
energy sources the four main contenders are wind power,
wave power, tidal and power from ocean thermal gradi-
ents. The sources to alleviate the energy situation in the
world are sufficient to supply all foresee able needs.
Conservation of energy and rationing in some form will
however have to be practised by most countries, to re-
duce oil imports and redress balance of payments posi-
tions. Meanwhile development and application of nuclear
power and some of the traditional solar, wind and water
energy alternatives must be set in hand to supple- ment
what remains of the fossil fuels.
The encouragement of greater energy use is an essen-
tial component of development. In the short term, it re-
quires mechanisms to enable the rapid increase in en-
ergy/capita, while in the long term it may require the use
of energy efficiency without environmental and safety
concerns. Such programmes should as far as possible be
based on renewable energy resources. Large-scale, con-
ventional, power plant such as hydropower has an im-
portant part to play in development although it does not
provide a complete solution. There is however an impor-
tant complementary role for the greater use of small scale,
rural based, power plants. Such plants can be employed
to assist development since they can be made locally.
Renewable resources are particularly suitable for provid-

Opportunities for Sustainable Low Carbon Energy Research Development and Applications
174
ing the energy for such equipment and its use is also
compatible with the long-term aims.
In compiling energy consumption data one can catego-
rise usage according to a number of different schemes:
 Traditional sector—industrial, transportation, etc.
 End-use—space heating, process steam, etc.
 Final demand—total energy consumption related to
automobiles, to food, etc.
 Energy source—oil, coal, etc.
 Energy form at point of use—electric drive, low
temperature heat, etc.
2. Renewable Energy Potential
The increased availability of reliable and efficient energy
services stimulates new development alternatives [1].
This article discusses the potential for such integrated
systems in the stationary and portable power market in
response to the critical need for a cleaner energy tech-
nology. Anticipated patterns of future energy use and
consequent environmental impacts (acid precipitation,
ozone depletion and the greenhouse effect or global
warming) are comprehensively discussed in this paper.
Throughout the theme several issues relating to renew-
able energies, environment and sustainable development
are examined from both current and future perspectives.
It is concluded that renewable environmentally friendly
energy must be encouraged, promoted, implemented and
demonstrated by full-scale plant especially for use in re-
mote rural areas. Globally, buildings are responsible for
approximately 40% of the total world annual energy
consumption. Most of this energy is for the provision of
lighting, heating, cooling, and air conditioning. Increas-
ing awareness of the environmental impact of CO2 and
NOx and CFCs emissions triggered a renewed interest in
environmentally friendly cooling, and heating technolo-
gies. Under the 1997 Montreal Protocol, governments
agreed to phase out chemicals used as refrigerants that
have the potential to destroy stratospheric ozone. It was
therefore considered desirable to reduce energy con-
sumption and decrease the rate of depletion of world en-
ergy reserves and pollution of the environment. One way
of reducing building energy consumption is to design
buildings, which are more economical in their use of
energy for heating, lighting, cooling, ventilation and hot
water supply. Passive measures, particularly natural or
hybrid ventilation rather than air-conditioning, can dra-
matically reduce primary energy consumption. However,
exploitation of renewable energy in buildings and agri-
cultural greenhouses can, also, significantly contribute
towards reducing dependency on fossil fuels. Therefore,
promoting innovative renewable applications and rein-
forcing the renewable energy market will contribute to
preservation of the ecosystem by reducing emissions at
local and global levels. This will also contribute to the
amelioration of environmental conditions by replacing
conventional fuels with renewable energies that produce
no air pollution or greenhouse gases.
There is strong scientific evidence that the average
temperature of the earth’s surface is rising. This is a re-
sult of the increased concentration of carbon dioxide and
other GHGs in the atmosphere as released by burning
fossil fuels. This global warming will eventually lead to
substantial changes in the world’s climate, which will, in
turn, have a major impact on human life and the built
environment. Therefore, effort has to be made to reduce
fossil energy use and to promote green energies, particu-
larly in the building sector. Energy use reductions can be
achieved by minimising the energy demand, by rational
energy use, by recovering heat and the use of more green
energies. This study was a step towards achieving that
goal. The adoption of green or sustainable approaches to
the way in which society is run is seen as an important
strategy in finding a solution to the energy problem. The
key factors to reducing and controlling CO2, which is the
major contributor to global warming, are the use of al-
ternative approaches to energy generation and the explo-
ration of how these alternatives are used today and may
be used in the future as green energy sources [2]. Even
with modest assumptions about the availability of land,
comprehensive fuel-wood farming programmes offer
significant energy, economic and environmental benefits.
These benefits would be dispersed in rural areas where
they are greatly needed and can serve as linkages for
further rural economic development. The nations as a
whole would benefit from savings in foreign exchange,
improved energy security, and socio-economic im-
provements. With a nine-fold increase in forest – planta-
tion cover, a nation’s resource base would be greatly
improved. The international community would benefit
from pollution reduction, climate mitigation, and the in-
creased trading opportunities that arise from new income
sources. The non-technical issues, which have recently
gained attention, include: 1) Environmental and ecologi-
cal factors, e.g., carbon sequestration, reforestation and
revegetation; 2) Renewables as a CO2 neutral replace-
ment for fossil fuels; 3) Greater recognition of the im-
portance of renewable energy, particularly modern bio-
mass energy carriers, at the policy and planning levels; 4)
Greater recognition of the difficulties of gathering good
and reliable renewable energy data, and efforts to im-
prove it; 5) Studies on the detrimental health efforts of
biomass energy particularly from traditional energy users.
The renewable energy resources are particularly suited
for the provision of rural power supplies and a major
advantage is that equipment such as flat plate solar driers,
wind machines, etc., can be constructed using local re-

Opportunities for Sustainable Low Carbon Energy Research Development and Applications175
sources and without the advantage results from the feasi-
bility of local maintenance and the general encourage-
ment such local manufacture gives to the build up of
small scale rural based industry. This article gives some
examples of small-scale energy converters, nevertheless
it should be noted that small conventional, i.e, engines
are currently the major source of power in rural areas and
will continue to be so for a long time to come. There is a
need for some further development to suit local condi-
tions, to minimise spares holdings, to maximise inter-
changeability both of engine parts and of the engine ap-
plication. Emphasis should be placed on full local manu-
facture.
The renewable energy resources are particularly suited
for the provision of rural power supplies and a major
advantage is that equipment such as flat plate solar driers,
wind machines, etc., can be constructed using local re-
sources and without the high capital cost of more con-
ventional equipment. Further advantage results from the
feasibility of local maintenance and the general encour-
agement such local manufacture gives to the build up of
small scale rural based industry. Table 1 lists the energy
sources available.
Currently the ‘non-commercial’ fuels wood, crop resi-
dues and animal dung are used in large amounts in the
rural areas of developing countries, principally for heat-
ing and cooking; the method of use is highly inefficient.
Table 2 presented some renewable applications.
Table 3 lists the most important of energy needs.
Considerations when selecting power plant include the
following:
 Power level—whether continuous or discontinuous.
 Cost—initial cost, total running cost including fuel,
maintenance and capital amortised over life.
 Complexity of operation.
 Maintenance and availability of spares.
Table 1. Sources of energy [3].
Energy source Energy carrier Energy end-use
Vegetation Fuel-wood
Cooking
Water heating
Building materials
Animal fodder preparation
Oil Kerosene Lighting
Ignition fires
Dry cells Dry cell batteries Lighting
Small appliances
Muscle power Animal power
Transport
Land preparation for farming
Food preparation (threshing)
Muscle power Human power
Transport
Land preparation for farming
Food preparation (threshing)
Table 2. Renewable applications [4].
Systems Applications
Water supply
Wastes disposal
Cooking
Food
Electrical demands
Space heating
Water heating
Control system
Building fabric
Rain collection, purification, storage and
recycling
Anaerobic digestion (CH4)
Methane
Cultivate the 1 hectare plot and greenhouse
for four people
Wind generator
Solar collectors
Solar collectors and excess wind energy
Ultimately hardware
Integration of subsystems to cut costs
Table 3. Energy needs in rural areas [6].
Muscle power
Internal combustion engines
Reciprocating
Rotating
Heat engines
Vapour (Rankine)
Reciprocating
Rotating
Gas Stirling (Reciprocating)
Gas Brayton (Rotating)
Electron gas
Electromagnetic radiation
Hydraulic engines
Wind engines (wind machines)
Electrical/mechanical
Man, animals
Petrol-spark ignition
Diesel-compression ignition
Humphrey water piston
Gas turbines
Steam engine
Steam turbine
Steam engine
Steam turbine
Thermionic, thermoelectric
Photo devices
Wheels, screws, buckets, turbines
Vertical axis, horizontal axis
Dynamo/alternator, motor
 Life.
 Suitability for local manufacture.
Table 4 listed methods of energy conversion.
There is a need for greater attention to be devoted to
this field in the development of new designs, the dis-
semination of information and the encouragement of its
use. International and government bodies and independ-
ent organisations all have a role to play in renewable
energy technologies.
Table 4. Methods of energy conversion [7].
Transport, e.g., small vehicles and boats
Agricultural machinery, e.g., two-wheeled tractors
Crop processing, e.g., milling
Water pumping
Small industries, e.g., workshop equipment
Electricity generation, e.g., hospitals and schools
Domestic, e.g., cooking, heating, and lighting
Water supply, e.g., rain collection, purification, storage and reccling
Building fabric, e.g., integration of subsystems to cut costs
Wastes disposal, e.g., anaerobic digestion (CH4)

Opportunities for Sustainable Low Carbon Energy Research Development and Applications
176
The household wastes, i.e ., for family of four persons,
could provide 280 kWh/yr of methane, but with the addi-
tion of vegetable wastes from 0.2 ha or wastes from 1 ha
growing a complete diet, about 1500 kWh/yr may be
obtained by anaerobic digestion [5]. The sludge from the
digester may be returned to the land. In hotter climates,
this could be used to set up a more productive cycle
(Figure 1).
Society and industry in Europe and elsewhere are in-
creasingly dependent on the availability of electricity
supply and on the efficient operation of electricity sys-
tems. In the European Union (EU), the average rate of
growth of electricity demand has been about 1.8% per
year since 1990 and is projected to be at least 1.5%
yearly up to 2030 [8]. Currently, distribution networks
generally differ greatly from transmission networks,
mainly in terms of role, structure (radial against meshed)
and consequent planning and operation philosophies.
2.1. Energy Consumption
Over the last decades, natural energy resources such as
petroleum and coal have been consumed at high rates.
The heavy reliance of the modern economy on these fu-
els are bound to end, due to their environmental impact,
and the fact that conventional sources might eventually
run out. The increasing price of oil and instabilities in the
oil market led to search for energy substitutes.
In addition to the drain on resources, such an increase
in consumption consequences, together with the in-
creased hazards of pollution and the safety problems as-
sociated with a large nuclear fission programmes. This is
a disturbing prospect. It would be equally unacceptable
to suggest that the difference in energy between the de-
veloped and developing countries and prudent for the
developed countries to move towards a way of life which,
whilst maintaining or even increasing quality of life, re-
duce significantly the energy consumption per capita.
Such savings can be achieved in a number of ways:
Figure 1. Biomass energy utilisation cycle [9].
 Improved efficiency of energy use, for example
better thermal insulation, energy recovery, and total
energy.
 Conservation of energy resources by design for long
life and recycling rather than the short life throw-
away product.
 Systematic replanning of our way of life, for exam-
ple in the field of transport.
Energy ratio is defined as the ratio of:
Energy content of the food product/Energy input to
produce the food (1)
A review of the potential range of recyclables is pre-
sented in Table 5.
Currently the non-commercial fuelwood, crop residues
and animal dung are used in large amounts in the rural
areas of developing countries, principally for heating and
cooking, the method of use is highly inefficient. As in the
developed countries, the fossil fuels are currently of great
importance in the developing countries. Geothermal and
tidal energy are less important though, of course, will
have local significance where conditions are suitable.
Nuclear energy sources are included for completeness,
but are not likely to make any effective contribution in
the rural areas.
2.2. Biogas Production
Biogas is a generic term for gases generated from the
decomposition of organic material. As the material
breaks down, methane (CH4) is produced as shown in
Figure 2. Sources that generate biogas are numerous and
varied. These include landfill sites, wastewater treatment
plants and anaerobic digesters [11]. Landfills and waste-
water treatment plants emit biogas from decaying waste.
To date, the waste industry has focused on controlling
these emissions to our environment and in some cases,
tapping this potential source of fuel to power gas turbines,
thus generating electricity [12]. The primary components
of landfill gas are methane (CH4), carbon dioxide (CO2),
and nitrogen (N2). The average concentration of methane
is ~45%, CO2 is ~36% and nitrogen is ~18% [13]. Other
components in the gas are oxygen (O2), water vapour and
trace amounts of a wide range of non-methane organic
compounds (NMOCs). Landfill gas-to-cogeneration pro-
jects present a win-win-win situation. Emissions of par-
ticularly damaging pollutant are avoided, electricity is
generated from a free fuel and heat is available for use
locally.
2.3. Wave Power Conversion Devices
The patent literature is full of devices for extracting en-
ergy from waves, i.e, floats, ramps, and flaps, covering
channels [14]. Small generators driven from air trapped

Opportunities for Sustainable Low Carbon Energy Research Development and Applications177
Table 5. Summary of material recycling practices in the
construction sector [10].
Construction and
demolition material
Recycling technology
options Recycling product
Asphalt
Cold recycling: heat
generation; Minnesota
process; parallel drum
process; elongated
drum; microwave as-
phalt recycling sys-
tem; finfalt; surface
regeneration
Recycling asphalt;
asphalt aggregate
Brick Burn to ash, crush
into aggregate
Slime burn ash; filling
material; hardcore
Concrete Crush into aggregate
Recycling aggregate;
cement replacement;
protection of levee;
backfilling; filter
Ferrous metal Melt; reuse directly Recycled steel scrap
Glass
Reuse directly; grind
to powder; polishing;
crush into aggregate;
burn to ash
Recycled window
unit; glass fibre; fill-
ing material; tile;
paving block; asphalt;
recycled aggregate;
cement replacement;
manmade soil
Masonry Crush into aggregate;
heat to 900˚C to ash
Thermal insulating
concrete; traditional
clay
Non-ferrous metal Melt Recycled metal
Paper and cardboard Purification Recycled paper
Plastic
Convert to powder by
cryogenic milling;
clopping; crush into
aggregate; burn to ash
Panel; recycled plas-
tic; plastic lumber;
recycled aggregate;
landfill drainage; as-
phalt; manmade soil
Timber
Reuse directly; cut
into aggregate; blast
furnace deoxidisation;
gasification or pyro-
lysis; chipping;
moulding by pressur-
ising timber chip un-
der steam and water
Whole timber; furni-
ture and kitchen uten-
sils; lightweight recy-
cled aggregate; source
of energy; chemical
production;
wood-based panel;
plastic lumber; geofi-
bre; insulation board
by the rising and falling water in the chamber of a buoy
are in use around the world [15]. Wave power is one
possibility that has been selected Figure 3 shows the
many other aspects that will need to be covered. A wave
power programme would make a significant contribution
to energy resources within a relatively short time and
with existing technology.
Wave energy has also been in the news recently. There
is about 140 megawatts per mile available round British
coasts. It could make a useful contribution people needs
in the UK. Although very large amounts of power are
Figure 2. Biogas production process [14].
available in the waves, it is important to consider how
much power can be extracted. A few years ago only a
few percent efficiency had been achieved. Recently,
however, several devices have been studied which have
very high efficiencies. Some form of storage will be es-
sential on a second-to-second and minute-to-minute basis
to smooth the fluctuations of individual waves and
wave’s packets but storage from one day to the next will
certainly not be economical. This is why provision must
be made for adequate standby capacity.
The increased availability of reliable and efficient en-
ergy services stimulates new development alternatives.
This article discusses the potential for such integrated
systems in the stationary and portable power market in
response to the critical need for a cleaner energy tech-
nology. Anticipated patterns of future energy use and
consequent environmental impacts (acid precipitation,
ozone depletion and the greenhouse effect or global
warming) are comprehensively discussed in this paper.
hroughout the theme several issues relating to renew- T

Opportunities for Sustainable Low Carbon Energy Research Development and Applications
178
Figure 3. Possible systems for exploiting wave power, each element represents an essential link in the chain from sea waves to
consumer [15].
able energies, environment and sustainable development
are examined from both current and future perspectives.
It is concluded that renewable environmentally friendly
energy must be encouraged, promoted, implemented and
demonstrated by full-scale plant especially for use in re-
mote rural areas. Globally, buildings are responsible for
approximately 40% of the total world annual energy
consumption. Most of this energy is for the provision of
lighting, heating, cooling, and air conditioning. Increas-
ing awareness of the environmental impact of CO2 and
NOx emissions and CFCs triggered a renewed interest in
environmentally friendly cooling, and heating technolo-
gies. Under the 1997 Montreal Protocol, governments
agreed to phase out chemicals used as refrigerants that
have the potential to destroy stratospheric ozone. It was
therefore considered desirable to reduce energy con-
sumption and decrease the rate of depletion of world en-
ergy reserves and pollution of the environment. One way
of reducing building energy consumption is to design
buildings, which are more economical in their use of
energy for heating, lighting, cooling, ventilation and hot
water supply. Passive measures, particularly natural or
hybrid ventilation rather than air-conditioning, can dra-
matically reduce primary energy consumption. However,
exploitation of renewable energy in buildings and agri-
cultural greenhouses can, also, significantly contribute
towards reducing dependency on fossil fuels. Therefore,
promoting innovative renewable applications and rein-
forcing the renewable energy market will contribute to
preservation of the ecosystem by reducing emissions at
local and global levels. This will also contribute to the
amelioration of environmental conditions by replacing

Opportunities for Sustainable Low Carbon Energy Research Development and Applications179
conventional fuels with renewable energies that produce
no air pollution or greenhouse gases. The provision of
good indoor environmental quality while achieving en-
ergy and cost efficient operation of the heating, ventilat-
ing and air-conditioning (HVAC) plants in buildings
represents a multi variant problem. The comfort of
building occupants is dependent on many environmental
parameters including air speed, temperature, relative hu-
midity and quality in addition to lighting and noise. The
overall objective is to provide a high level of building
performance (BP), which can be defined as indoor envi-
ronmental quality (IEQ), energy efficiency (EE) and cost
efficiency (CE).
2.4. Ethanol Production
Alternative fuels were defined as methanol, ethanol,
natural gas, propane, hydrogen, coal-derived liquids,
biological material and electricity production [8]. The
fuel pathways currently under development for alcohol
fuels are shown in Figure 4. The production of agricul-
tural biomass and its exploitation for energy purposes
can contribute to alleviate several problems, such as the
dependence on import of energy products, the production
of food surpluses, the pollution provoked by the use of
fossil fuels, the abandonment of land by farmers and the
connected urbanisation. Biomass is not at the moment
competitive with mineral oil, but, taking into account
also indirect costs and giving a value to the aforemen-
tioned advantages, public authorities at national and in-
ternational level can spur its production and use by in-
centives of different nature. In order to address the prob-
lem of inefficiency, research centres around the world
have investigated the viability of converting the resource
to a more useful form, namely solid briquettes and fuel
gas [1] (Figure 5).
The main advantages are related to energy, agriculture
and environment problems, are foreseeable both at re-
gional level and at worldwide level and can be summa-
rised as follows:
 Reduction of dependence on import of energy and
related products.
 Reduction of environmental impact of energy pro-
duction (greenhouse effect, air pollution, and waste
degradation).
 Substitution of food crops and reduction of food
surpluses and of related economic burdens, utilisa-
tion of marginal lands and of set aside lands.
 Reduction of related socio-economic and environ-
mental problems (soil erosion, urbanisation, land-
scape deterioration, etc.).
 Development of new know-how and production of
technological innovation.
Biomass resources play a significant role in energy
supply in all developing countries. Biomass resources
should be divided into residues or dedicated resources,
the latter including firewood and charcoal can also be
produced from forest residues. Ozone (O3) is a naturally
occurring molecule that consists of three oxygen atoms
held together by the bonding of the oxygen atoms to each
other. The effects of the chlorofluorocarbons (CFCs)
molecule can last for over a century. This reaction is
shown in Figure 6.
It is a common misconception that the reason for recy-
cling old fridge is to recover the liquid from the cooling
circuit at the back of the unit. The insulating foams used
inside some fridges act as sinks of CFCs- the gases hav-
ing been used as blowing agents to expand the foam dur-
ing fridge manufacture. Although the use of ozone de-
pleting chemicals in the foam in fridges has declined in
the West, recyclers must consider which strategy to adopt
Figure 4. Schematic process flowsheet [4].

Opportunities for Sustainable Low Carbon Energy Research Development and Applications
180
Figure 5. Biomass resources from several sources are converted into a range of products for use by transport, industry and
building sectors [3].
to deal with the disposal problem they still present each
year. It is common practice to dispose of this waste wood
in landfill where it slowly degraded and takes up valu-
able void space. This wood is a good source of energy
and is an alternative to energy crops. Agricultural wastes
are abundantly available globally and can be converted to
energy and useful chemicals by a number of microorgan-
isms. The success of promoting any technology depends
on careful planning, management, implementation, trai-
ning and monitoring. Main features of gasification pro-
ject are:
 Networking and institutional development/streng-
thening.
 Promotion and extension.
 Construction of demonstration projects.
 Research and development, and training and moni-
toring.
2.5. Biomass CHP
Combined heat and power (CHP) installations are quite
common in greenhouses, which grow high-energy, input
crops (e.g., salad vegetables, pot plants, etc.). Scientific
assumptions for a short-term energy strategy suggest that
the most economically efficient way to replace the ther-
mal plants is to modernise existing power plants to in-
crease their energy efficiency and to improve their envi-
ronmental performance. However, utilisation of wind
power and the conversion of gas-fired CHP plants to
biomass would significantly reduce the dependence on
imported fossil fuels. Although a lack of generating ca-
pacity is forecast in the long-term, utilisation of the ex-
isting renewable energy potential and the huge possibili-
ties for increasing energy efficiency are sufficient to
meet future energy demands in the short-term.

Opportunities for Sustainable Low Carbon Energy Research Development and Applications181
Figure 6. The process of ozone depletion [5].
A total shift towards a sustainable energy system is a
complex and long process, but is one that can be
achieved within a period of about 20 years. Implementa-
tion will require initial investment, long-term national
strategies and action plans. However, the changes will
have a number of benefits including: a more stable en-
ergy supply than at present, and major improvement in
the environmental performance of the energy sector, and
certain social benefits. A national vision [12] used a
methodology and calculations based on computer model-
ling that utilised:
 Data from existing governmental programmes.
 Potential renewable energy sources and energy effi-
ciency improvements.
 Assumptions for future economy growth.
 Information from studies and surveys on the recent
situation in the energy sector.
In addition to realising the economic potential identi-
fied by the National Energy Savings Programme, a long-
term effort leading to a 3% reduction in specific electric-
ity demand per year after 2020 is proposed. This will
require: further improvements in building codes, and
continued information on energy efficiency.
The environmental Non Governmental Organisations
(NGOs) are urging the government to adopt sustainable
development of the energy sector by:
 Diversifying of primary energy sources to increase
the contribution of renewable and local energy re-
sources in the total energy balance.
 Implementing measures for energy efficiency in-
crease at the demand side and in the energy trans-
formation sector.
The price of natural gas is set by a number of market
and regulatory factors that include:
Supply and demand balance and market fundamentals,
weather, pipeline availability and deliverability, storage
inventory, new supply sources, prices of other energy
alternatives and regulatory issues and uncertainty.
Classic management approaches to risk are well docu-
mented and used in many industries. This includes the
following four broad approaches to risk:
 Avoidance includes not performing an activity that
could carry risk. Avoidance may seem the answer to
all risks, but avoiding risks also means losing out on
potential gain.
 Mitigation/reduction involves methods that reduce
the severity of potential loss.
 Retention/acceptance involves accepting the loss
when it occurs. Risk retention is a viable strategy
for small risks. All risks that are not avoided or
transferred are retained by default.
 Transfer means causing another party to accept the
risk, typically by contract.
Methane is a primary constituent of landfill gas (LFG)
and a potent greenhouse gas (GHG) when released into
the atmosphere. Globally, landfills are the third largest
anthropogenic emission source, accounting for about
13% of methane emissions or over 818 million tones of
carbon dioxide equivalent (MMTCO2e) [13] as shown in
Figures 7-9.
2.6. Geothermal Energy
Geothermal steam has been used in volcanic regions in
many countries to generate electricity. The use of geo-
thermal energy involves the extraction of heat from rocks
in the outer part of the earth. It is relatively unusual for
the rocks to be sufficiently hot at shallow depth for this
to be economically attractive. Virtually all the areas of
present geothermal interest are concentrated along the
margins of the major tectonic plates, which form the sur-
Figure 7. Global CHP trends from 1992-2003 [17].

Opportunities for Sustainable Low Carbon Energy Research Development and Applications
182
Figure 8. Distribution of industrial CHP capacity in the EU
and USA [17]. 1 Food, 2 Textile, 3 Pulp & paper, 4 Chemi-
cals, 5 Refining, 6 Minerals, 7 Primary metals, and 8 Oth-
ers.
Figure 9. World landfill methane emissions (MMTCO2e)
[17].
face of the earth. The forced or natural circulation of wa-
ter through permeable hot rock conventionally extracts
heat.
There are various practical difficulties and disadvan-
tages associated with the use of geothermal power:
Transmission: geothermal power has to be used where
it is found. In Iceland it has proved feasible to pipe hot
water 20 km in insulated pipes but much shorter dis-
tances are preferred.
Environmental problems: these are somewhat variable
and are usually not great. Perhaps the most serious is the
disposal of warm high salinity water where it cannot be
reinjected or purified. Dry steam plants tend to be very
noisy and there are releases of small amounts of methane,
hydrogen, nitrogen, amonia and hydrogen sulphide and
of these the latter presents the main problem.
The geothermal fluid is often highly chemically corro-
sive or physically abrassive as the result of the entrained
solid matter it carries. This may entail special plant de-
sign problems and unusually short operational lives for
both the holes and the installations they serve.
Because the useful rate of heat extraction from a geo-
thermal field is in nearly all cases much higher than the
rate of conduction into the field from the underlying
rocks, the mean temperatures of the field is likely to fall
during exploitation. In some low rainfall areas there may
also be a problem of fluid depletion. Ideally, as much as
possible of the geothermal fluid should be reinjected into
the field. However, this may involve the heavy capital
costs of large condensation installations. Occasionally,
the salinity of the fluid available for reinjection may be
so high (as a result of concentration by boiling) that is
unsuitable for reinjection into ground. Ocasionally, the
impurities can be precipitated and used but this has not
generally proved commercially attractive.
World capacity of geothermal energy is growing at a
rate of 2.5% per year from a 2005 level of 28.3 GW [13].
The GSHPs account for approximately 54% of this ca-
pacity almost all of it in the North America and Europe
[13]. The involvement of the UK is minimal with less
than 0.04% of world capacity and yet is committed to
substantial reduction in carbon emission beyond the
12.5% Kyoto obligation to be achieved by 2012. The
GSHPs offer a significant potential for carbon reduction
and it is therefore expected that the market for these sys-
tems will rise sharply in the UK in the immediate years
ahead given to low capacity base at present.
There are numerous ways of harnessing low-grade
heat from the ground for use as a heat pump source or air
conditioning sink. For small applications (residences and
small commercial buildings) horizontal ground loop heat
exchangers buried typically at between 1 m and 1.8 m
below the surface can be used provided that a significant
availability of land surrounding the building can be ex-
ploited which tends to limit these applications to rural
settings.
Heat generation within the earth is approximately 2700
GW, roughly an order of magnitude greater than the en-
ergy associated with the tides but about four orders less
than that received by the earth from the sun [7].
Temperature distributions within the earth depend on:
 The abundance and distribution of heat producing
elements within the earth.
 The mean surface temperature (which is controlled

Opportunities for Sustainable Low Carbon Energy Research Development and Applications183
by the ocean/atmosphere system).
 The thermal properties of the earth’s interior and
their lateral and radial variation.
 Any movements of fluid or solid rock materials
occurring at rates of more than a few millimetres
per year.
Of these four factors the first two are of less impor-
tance from the point of view of geothermal energy. Mean
surface temperatures range between 0˚C - 30˚C and this
variation has a small effect on the useable enthalpy of
any flows of hot water. Although radiogenic heat pro-
duction in rocks may vary by three orders of magnitude,
there is much less variation from place to place in the
integrated heat production with depth. The latter factors,
however, are of great importance and show a wide range
of variation. Their importance is clear from the relation-
ship:
β = q/k (2)
where:
β is the thermal gradient for a steady state (˚C/km), q
is the heat flux (10–6 cal·cm–2·sec–1) and k is the thermal
conductivity (cal·cm–1·sec–1·˚C –1).
The first requirement of any potential geothermal
source region is that β being large, i.e., that high rock
temperatures occur at shallow depth. Beta will be large if
either q is large or k is small or both. By comparison with
most everyday materials, rocks are poor conductors of
heat and values of conductivity may vary from 2 × 10–3
to 10–2 cal·cm–1·sec–1·˚C–1. The mean surface heat flux
from the earth is about 1.5 heat flow units (1 HFU = 10–6
cal·cm–2·sec–1) [7]. Rocks are also very slow respond to
any temperature change to which they are exposed, i.e.,
they have a low thermal diffusivity:
K = k/ρ·Cp (3)
where:
K is thermal diffusivity; ρ and Cp are density and spe-
cific heat respectively.
These values are simple intended to give a general idea
of the normal range of geothermal parameters (Table 6).
In volcanic regions, in particular, both q and β can vary
considerably and the upper values given are somewhat
nominal.
2.7. Landfill Gap
Landfill gas (LFG) is currently extracted at over 1200
Table 6. Values of geothermal parameters [16].
Parameter Lower Average Upper
q (HFU)
k = cal·cm–2·sec–1·℃–1
β = ˚C/km
0.8
2 × 10–3
8
1.5
6 × 10–3
20
3.0 (non volcanic) ≈ 100
(volcanic)
12 × 10–3
60 (non volcanic) ≈ 300
(volcanic)
landfills worldwide for a variety of energy purposes
(Table 7), such as:
 Creating pipeline quality gas or an alternative fuel
for vehicles.
 Processing the LFG to make it available as an al-
ternative fuel to local industrial or commercial cus-
tomers.
 Generation of electricity with engines, turbines,
micro-turbines and other emerging technologies.
In terms of solid waste management policy, many
NGOs have changed drastically in the past ten years from
a mass production and mass consumption society to
‘material-cycle society’. In addition to national legisla-
tion, municipalities are legally obliged to develop a plan
for handling the municipal solid waste (MSW) generated
in administrative areas. Such plans contain:
 Estimates of future waste volume.
 Measures to reduce waste.
 Measures to encourage source separation.
 A framework for solid waste disposal and the con-
struction and management of solid waste manage-
ment facilities.
Landfilling is in the least referred tier of the hierarchy
of waste management options: Waste minimisation, reuse
and recycling, incineration with energy recovery, and
optimised final disposal. The key elements are as follows:
construction impacts, atmospheric emissions, noise, water
quality, landscape, visual impacts, socio economics,
ecological impacts, traffic, solid waste disposal and cul-
tural heritage.
3. Energy Efficiency
Energy efficiency is the most cost-effective way of cut-
ting carbon dioxide emissions and improvements to
households and businesses. It can also have many other
additional social, economic and health benefits, such as
warmer and healthier homes, lower fuel bills and com-
pany running costs and, indirectly, jobs. Britain wastes
20 per cent of its fossil fuel and electricity use. This im-
Table 7. Types of LFG implemented recently worldwide.
Landsill caps Electricity generation Fuel production
Soil caps Reciprocating Medium BTU gas
Clay caps engines High BTU gas
Geo-membrane capsCombustion turbines Liquefied methane
Micro-turbines
LFG destruction Steam turbines Thermal generation
Flares Fuel cells Boilers
Candlestick Kilns
Enclosed CHP Greenhouse heaters
Turbines Leachate evaporators
Engines

Opportunities for Sustainable Low Carbon Energy Research Development and Applications
184
plies that it would be cost-effective to cut £10 billion a
year off the collective fuel bill and reduce CO2 emissions
by some 120 million tones. Yet, due to lack of good in-
formation and advice on energy saving, along with the
capital to finance energy efficiency improvements, this
huge potential for reducing energy demand is not being
realised. Traditionally, energy utilities have been essen-
tially fuel providers and the industry has pursued profits
from increased volume of sales. Institutional and market
arrangements have favoured energy consumption rather
than conservation. However, energy is at the centre of the
sustainable development paradigm as few activities af-
fect the environment as much as the continually increas-
ing use of energy. Most of the used energy depends on
finite resources, such as coal, oil, gas and uranium. In
addition, more than three quarters of the world’s con-
sumption of these fuels is used, often inefficiently, by
only one quarter of the world’s population. Without even
addressing these inequities or the precious, finite nature
of these resources, the scale of environmental damage
will force the reduction of the usage of these fuels long
before they run out.
Throughout the energy generation process, there are
impacts on the environment on local, national and inter-
national levels, from opencast mining and oil exploration
to emissions of the potent greenhouse gas carbon dioxide
in ever increasing concentration. Recently, the world’s
leading climate scientists reached an agreement that hu-
man activities, such as burning fossil fuels for energy and
transport, are causing the world’s temperature to rise.
The Intergovernmental Panel on Climate Change has
concluded that “the balance of evidence suggests a dis-
cernible human influence on global climate”. It predicts a
rate of warming greater than any one had seen in the last
10,000 years, in other words, throughout human history.
The exact impact of climate change is difficult to predict
and will vary regionally. It could, however, include sea
level rise, disrupted agriculture and food supplies and the
possibility of more freak weather events such as hurri-
canes and droughts. Indeed, people already are waking
up to the financial and social, as well as the environ-
mental, risks of unsustainable energy generation methods
that represent the costs of the impacts of climate change,
acid rain and oil spills. The insurance industry, for ex-
ample, concerned about the billion dollar costs of hurri-
canes and floods, has joined sides with environmentalists
to lobby for greenhouse gas emissions reduction. Friends
of the earth are campaigning for a more sustainable en-
ergy policy, guided by the principal of environmental
protection and with the objectives of sound natural re-
source management and long-term energy security. The
key priorities of such an energy policy must be to reduce
fossil fuel use, move away from nuclear power, improve
the efficiency with which energy is used and increase the
amount of energy obtainable from sustainable and re-
newable energy sources. Efficient energy use has never
been more crucial than it is today, particularly with the
prospect of the imminent introduction of the climate
change levy (CCL). Establishing an energy use action
plan is the essential foundation to the elimination of en-
ergy waste. A logical starting point is to carry out an en-
ergy audit that enables the assessment of the energy use
and determine what actions to take. The actions are best
categorised by splitting measures into the following three
general groups:
1) High Priority/Low Cost
These are normally measures, which require minimal
investment and can be implemented quickly. The fol-
lowings are some examples of such measures:
 Good housekeeping, monitoring energy use and tar-
geting waste-fuel practices.
 Adjusting controls to match requirements.
 Improved greenhouse space utilisation.
 Small capital item time switches, thermostats, etc.
 Carrying out minor maintenance and repairs.
 Staff education and training.
 Ensuring that energy is being purchased through the
most suitable tariff or contract arrangements.
2) Medium Priority/Medium Cost
Measures, which, although involve little or no design,
involve greater expenditure and can take longer to im-
plement. Examples of such measures are listed below:
 New or replacement controls.
 Greenhouse component alteration, e.g., insulation, seal-
ing glass joints, etc.
 Alternative equipment components, e.g., energy effi-
cient lamps in light fittings, etc.
3) Long Term/High Cost
These measures require detailed study and design.
They can be best represented by the followings:
 Replacing or upgrading of plant and equipment.
 Fundamental redesign of systems, e.g., combined heat
and power CHP installations.
This process can often be a complex experience and
therefore the most cost-effective approach is to employ
an energy specialist to help.
3.1. Policy Recommendations for a Sustainable
Energy Future
Sustainability is regarded as a major consideration for
both urban and rural development. People have been ex-
ploiting the natural resources with no consideration to the
effects, both short-term (environmental) and long-term
(resources crunch). It is also felt that knowledge and
technology have not been used effectively in utilising
energy resources. Energy is the vital input for economic

Opportunities for Sustainable Low Carbon Energy Research Development and Applications185
and social development of any country. Its sustainability
is an important factor to be considered. The urban areas
depend, largely, on commercial energy sources. The rural
areas use non-commercial sources like firewood and ag-
ricultural wastes. With the present day trends for im-
proving the quality of life and sustenance of humankind,
environmental issues are considered highly important. In
this context, the term energy loss has no significant tech-
nical meaning. Instead, the exergy loss has to be consid-
ered, as destruction of exergy is possible. Hence, exergy
loss minimisation will help in sustainability.
The development of a renewable energy in a country
depends on many factors. Those important to success are
listed below:
3.1.1. Motivation of the P op u l ation
The population should be motivated towards awareness
of high environmental issues, and rational use of energy
in order to reduce cost. Subsidy programme should be
implemented as incentives to install biomass energy
plants. In addition, image campaigns to raise awareness
of renewable technology.
3.1.2. Technical Product Development
To achieve technical development of biomass energy
technologies the following should be addressed:
 Increasing the longevity and reliability of renewable
technology.
 Adapting renewable technology to household tech-
nology (hot water supply).
 Integration of renewable technology in heating
technology.
 Integration of renewable technology in architecture,
e.g., in the roof or façade.
 Development of new applications, e.g., solar cool-
ing.
 Cost reduction.
3.1.3. Distribution and Sales
Commercialisation of biomass energy technology re-
quires:
 Inclusion of renewable technology in the product
range of heating trades at all levels of the distribu-
tion process (wholesale, and retail).
 Building distribution nets for renewable technology.
 Training of personnel in distribution and sales.
 Training of field sales force.
3.1.4. Consumer Consultation and Installation
To encourage all sectors of the population to participate
in adoption of biomass energy technologies, the follow-
ing has to be realised:
 Acceptance by craftspeople, and marketing by them.
 Technical training of craftspeople, initial and fol-
low-up training programmes.
 Sales training for craftspeople.
 Information material to be made available to crafts-
people for consumer consultation.
3.1.5. Projecti ng and Planning
Successful application of biomass technologies also re-
quire:
 Acceptance by decision makers in the building sec-
tor (architects, house technology planners, etc.).
 Integration of renewable technology in training.
 Demonstration projects/architecture competitions.
 Biomass energy project developers should prepare
to participate in the carbon market by:
1) Ensuring that renewable energy projects comply
with Kyoto Protocol requirements.
2) Quantifying the expected avoided emissions.
3) Registering the project with the required offices.
4) Contractually allocating the right to this revenue
stream.
 Other ecological measures employed on the devel-
opment include:
1) Simplified building details.
2) Reduced number of materials.
3) Materials that can be recycled or reused.
4) Materials easily maintained and repaired.
5) Materials that do not have a bad influence on the
indoor climate (i.e., non-toxic).
6) Local cleaning of grey water.
7) Collecting and use of rainwater for outdoor pur-
poses and park elements.
8) Building volumes designed to give maximum ac-
cess to neighbouring park areas.
9) All apartments have visual access to both backyard
and park.
3.1.6. Energy Saving Measures
The following energy saving measures should also be
considered:
 Building integrated solar PV system.
 Day-lighting.
 Ecological insulation materials.
 Natural/hybrid ventilation.
 Passive cooling.
 Passive solar heating.
 Solar heating of domestic hot water.
 Utilisation of rainwater for flushing.
Improving access for rural and urban low-income ar-
eas in developing countries must be through energy effi-
ciency and renewable energies. Sustainable energy is a
prerequisite for development. Energy-based living stan-
dards in developing countries, however, are clearly be-
low standards in developed countries. Low levels of ac-
cess to affordable and environmentally sound energy in
both rural and urban low-income areas are therefore a

Opportunities for Sustainable Low Carbon Energy Research Development and Applications
186
predominant issue in developing countries. In recent
years many programmes for development aid or technical
assistance have been focusing on improving access to
sustainable energy, many of them with impressive re-
sults.
Apart from success stories, however, experience also
shows that positive appraisals of many projects evaporate
after completion and vanishing of the implementation
expert team. Altogether, the diffusion of sustainable tech-
nologies such as energy efficiency and renewable ener-
gies for cooking, heating, lighting, electrical appliances
and building insulation in developing countries has been
slow.
Energy efficiency and renewable energy programmes
could be more sustainable and pilot studies more effec-
tive and pulse releasing if the entire policy and imple-
mentation process was considered and redesigned from
the outset. New financing and implementation processes
are needed, which allow reallocating financial resources
and thus enabling countries themselves to achieve a sus-
tainable energy infrastructure. The links between the
energy policy framework, financing and implementation
of renewable energy and energy efficiency projects have
to be strengthened and capacity building efforts are re-
quired.
3.2. Environmental Aspects of Energy
Conversion and Use
Environment has no precise limits because it is in fact a
part of everything. Indeed, environment is, as anyone
probably already knows, not only flowers blossoming or
birds singing in the spring, or a lake surrounded by
beautiful mountains. It is also human settlements, the
places where people live, work, rest, the quality of the
food they eat, the noise or silence of the street they live
in. Environment is not only the fact that our cars
consume a good deal of energy and pollute the air, but
also, that we often need them to go to work and for
holidays. Obviously man uses energy just as plants,
bacteria, mushrooms, bees, fish and rats do. Man largely
uses solar energy-food, hydropower, wood- and thus
participates harmoniously in the natural flow of energy
through the environment. But man also uses oil, gas, coal
and nuclear power. By using such sources of energy, man
is thus modifying his environment.
The atmospheric emissions of fossil fuelled installa-
tions are mosty aldehydes, carbon monoxide, nitrogen
oxides, sulpher oxides and particles (i.e., ash) as well as
carbon dioxide. Table 8 shows estimates include not
only the releases occuring at the power plant itself but
also cover fuel extraction and treatment, as well as the
storage of wastes and the aea of land required for
operations. Table 9 shows energy consumption in diffe-
Table 8. Annual greenhouse emissions from different sour-
ces of power plants.
Emissions
Primary source
of energy Atmosphere Water
Waste (× 103
metric tons) Area (km2)
Coal
Oil
Gas
Nuclear
380
70 - 160
24
6
7 - 41
3 - 6
1
21
60 - 3000
negligible
-
2600
120
70 - 84
84
77
rent regions of the world.
3.3. Greenhouses Environment
Greenhouse cultivation is one of the most absorbing and
rewarding forms of gardening for anyone who enjoys
growing plants. The enthusiastic gardener can adapt the
greenhouse climate to suit a particular group of plants, or
raise flowers, fruit and vegetables out of their natural
season. The greenhouse can also be used as an essential
garden tool, enabling the keen amateur to expand the
scope of plants grown in the garden, as well as save
money by raising their own plants and vegetables. There
was a decline in large private greenhouses during the two
world wars due to a shortage of materials for their con-
struction and fuel to heat them. However, in the 1950s
mass-produced, small greenhouses became widely avail-
able at affordable prices and were used mainly for raising
plants [18]. Also, in recent years, the popularity of con-
servatories attached to the house has soared. Modern
double-glazing panels can provide as much insulation as
a brick wall to create a comfortable living space, as well
as provide an ideal environment in which to grow and
display tender plants.
The comfort in a greenhouse depends on many envi-
ronmental parameters. These include temperature, rela-
tive humidity, air quality and lighting. Although green-
house and conservatory originally both meant a place to
house or conserve greens (variegated hollies, cirrus, myr-
tles and oleanders), a greenhouse today implies a place in
which plants are raised while conservatory usually de-
scribes a glazed room where plants may or may not play
a significant role. Indeed, a greenhouse can be used for
so many different purposes. It is, therefore, difficult to
Table 9. Energy consumption in different continents.
Region Population (millions) Energy (Watt/m2)
Africa
Asia
Central America
North America
South America
Western Europe
Eastern Europe
Oceania
Russia
820
3780
180
335
475
445
130
35
330
0.54
2.74
1.44
0.34
0.52
2.24
2.57
0.08
0.29

Opportunities for Sustainable Low Carbon Energy Research Development and Applications187
decide how to group the information about the plants that
can be grown inside it.
Throughout the world, urban areas have increased in
size during recent decades. About 50% of the world’s
population and approximately 76% in the more devel-
oped countries are urban dwellers [18]. Even though
there is an evidence to suggest that in many ‘advanced’
industrialised countries there has been a reversal in the
rural-to-urban shift of populations, virtually all popula-
tion growth expected between 2000 and 2030 will be
concentrated in urban areas of the world. With an ex-
pected annual growth of 1.8%, the world’s urban popula-
tion will double in 38 years [18]. This represents a seri-
ous contributing to the potential problem of maintaining
the required food supply. Inappropriate land use and
management, often driven by intensification resulting
from high population pressure and market forces, is also
a threat to food availability for domestic, livestock and
wildlife use. Conversion to cropland and urban-industrial
establishments is threatening their integrity. Improved
productivity of peri-urban agriculture can, therefore,
make a very large contribution to meeting food security
needs of cities as well as providing income to the peri-
urban farmers. Hence, greenhouses agriculture can be-
come an engine of pro-poor ‘trickle-up’ growth because
of the synergistic effects of agricultural growth such as
[18]:
 Increased productivity increases wealth.
 Intensification by small farmers raises the demand
for wage labour more than by larger farmers.
 Intensification drives rural non-farm enterprise and
employment.
 Alleviation of rural and peri-urban poverty is likely
to have a knock-on decrease of urban poverty.
Despite arguments for continued large-scale collective
schemes, there is now an increasingly compelling argu-
ment in favour of individual technologies for the devel-
opment of controlled greenhouses. The main points con-
stituting this argument are summarised by [18] as fol-
lows:
 Individual technologies enable the poorest of the
poor to engage in intensified agricultural production
and to reduce their vulnerability.
 Development is encouraged where it is needed most
and reaches many more poor households more
quickly and at a lower cost.
 Farmer-controlled greenhouses enable farmers to
avoid the difficulties of joint management.
Such development brings the following challenges
[19]:
 The need to provide farmers with ready access to
these individual technologies, repair services and
technical assistance.
 Access to markets with worthwhile commodity
prices, so that sufficient profitability is realised.
 This type of technology could be a solution to food
security problems. For example, in greenhouses,
advances in biotechnology like the genetic engi-
neering, tissue culture and market-aided selection
have the potential to be applied for raising yields,
reducing pesticide excesses and increasing the nu-
trient value of basic foods.
However, the overall goal is to improve the cities in
accordance with the Brundtland Report [19] and the in-
vestigation into how urban green could be protected. In-
deed, greenhouses can improve the urban environment in
multitude of ways. They shape the character of the town
and its neighbourhoods, provide places for outdoor rec-
reation, and have important environmental functions such
as mitigating the heat island effect, reduce surface water
runoff, and creating habitats for wildlife. Following
analysis of social, cultural and ecological values of urban
green, six criteria in order to evaluate the role of green
urban in towns and cities were prescribed [19]. These are
as follows:
 Recreation, everyday life and public health.
 Maintenance of biodiversity—preserving diversity
within species, between species, ecosystems, and of
landscape types in the surrounding countryside.
 City structure—as an important element of urban
structure and urban life.
 Cultural identity—enhancing awareness of the his-
tory of the city and its cultural traditions.
 Environmental quality of the urban sites—impro-
vement of the local climate, air quality and noise
reduction.
 Biological solutions to technical problems in urban
areas—establishing close links between technical
infrastructure and green-spaces of a city.
The main reasons why it is vital for greenhouses plan-
ners and designers to develop a better understanding of
greenhouses in high-density housing can be summarised
as follows [20]:
 Pressures to return to a higher density form of hous-
ing.
 The requirement to provide more sustainable food.
 The urgent need to regenerate the existing, and of-
ten decaying, houses built in the higher density,
high-rise form, much of which is now suffering
from technical problems.
The connection between technical change, economic
policies and the environment is of primary importance as
observed by most governments in developing countries,
whose attempts to attain food self-sufficiency have led
them to take the measures that provide incentives for
adoption of the Green Revolution Technology [20].

Opportunities for Sustainable Low Carbon Energy Research Development and Applications
188
Since, the Green Revolution Technologies were introdu-
ced in many countries actively supported by irrigation
development, subsidised credit, and fertiliser programm-
es, self-sufficiency was found to be not economically
efficient and often adopted for political reasons creating
excessive damage to natural resources. Also, many deve-
loping countries governments provided direct assistance
to farmers to adopt soil conservation measures. They
found that high costs of establishment and maintenance
and the loss of land to hedgerows are the major
constraints to adoption [20]. The soil erosion problem in
developing countries reveals that a dynamic view of the
problem is necessary to ensure that the important ele-
ments of the problem are understood for any remedial
measures to be undertaken. The policy environment has,
in the past, encouraged unsustainable use of land [20]. In
many regions, government policies such as provision of
credit facilities, subsidies, price support for certain crops,
subsidies for erosion control and tariff protection, have
exacerbated the erosion problem. This is because techno-
logical approaches to control soil erosion have often been
promoted to the exclusion of other effective approaches.
However, adoption of conservation measures and the
return to conservation depend on the specific agro-
ecological conditions, the technologies used and the
prices of inputs and outputs of production.
3.3.1. Types of Greenhouses
Choosing a greenhouse and setting it up are important,
and often expensive, steps to take. Greenhouses are ei-
ther freestanding or lean-to, that is, built against an ex-
isting wall. A freestanding greenhouse can be placed in
the open, and, hence, take advantage of receiving the full
sun throughout the day. It is, therefore, suitable for a
wide range of plants. However, its main disadvantage
when compared to a lean-to type is that more heat is lost
through its larger surface area. This is mainly why lean-
to greenhouses have long been used in the walled gar-
dens of large country houses to grow Lapageria rosea and
other plants requiring cool, constant temperature, such as
half-hardly ferns. However, generally, good ventilation
and shading in the spring and summer to prevent over-
heating are essential for any greenhouse. The high day-
time temperatures will warm the back wall, which acts as
a heat battery, releasing its accumulated heat at night.
Therefore, plants in a greenhouse with this orientation
will need the most attention, as they will dry out rapidly.
Also, greenhouses vary considerably in their shapes
and internal dimensions. Traditional greenhouses have
straight sides, which allow the maximum use of internal
space, and are ideal for climbers [21]. On the other hand,
greenhouses with sloping sides have the advantage of
allowing the greatest penetration of sunlight, even during
winter [21]. The low winter sun striking the glass at 90˚C
lets in the maximum amount of light. Where the sun
strikes the glass at a greater or lesser angle, a proportion
of the light is reflected away from greenhouse. Sloping
sides, also, offer less wind resistance than straight sides
and therefore, less likely to be damaged during windy
weather. This type of greenhouse is most suitable for
short winter crops, such as early spring lettuce, and flow-
ering annuals from seed, which do not require much
headroom.
A typical greenhouse is shown schematically in Fig-
ure 10. However, there are several designs of green-
houses, based on dimensions, orientation and function.
The following three options are the most widely used:
 A ready-made design.
 A designed, which is constructed from a number of
prefabricated modules.
 A bespoke design.
Of these, the prefabricated ready-made design, which
is utilised to fit the site, is the cheapest greenhouses and
gives flexibility. It is, also, the most popular option [22].
Specific examples of commercially available designs
are numerous. Dutch light greenhouses, for example,
have large panes of glass, which cast little shade on the
plants inside. They are simple to erect, consisting of
frames bolted together, which are supported on a steel
framework for all but the smallest models. They are easy
to move and extra sections can be added on to them, a
useful attraction [22]. Curvilinear greenhouses, on the
other hand, are designed primarily to let in the maximum
amount of light throughout the year by presenting at least
one side perpendicular to the sun. This attractive style of
greenhouse tends to be expensive because of the number
of different angles, which require more engineering [22].
Likewise, the uneven span greenhouses are designed for
maximum light transmission on one side. These are gen-
erally taller than traditional greenhouses, making them
suitable for tall, early season crops, such as cucumbers
Figure 10. Greenhouse and base wi th hor t ic ultur a l glass.

Opportunities for Sustainable Low Carbon Energy Research Development and Applications189
[21]. In addition, the polygonal greenhouses are designed
more as garden features than as practical growing houses,
and consequently, are expensive. Their internal space is
somewhat limited and on smaller models over-heading
can be a problem because of their small roof ventilations.
They are suitable for growing smaller pot plants, such as
pelargoniums and cacti [23]. Another example is the so-
lar greenhouses. These are designed primarily for areas
with very cold winters and poor winter light. They take
the form of lean-to structures facing the sun, are well
insulated to conserve heat and are sometimes partially
sunk into the ground. They are suitable for winter vege-
table crops and early-sown bedding plants, such as bego-
nias and pelargoniums [23]. Mini lean-to greenhouses are
suitable for small gardens where space is limited. They
can, also, be used to create a separate environment within
larger greenhouses. The space inside is large enough to
grow two tomato or melon plants in growing bags, or can
install shelves to provide a multi-layered growing envi-
ronment, ideal for many small potted plants and raising
summer bedding plants [23].
3.3.2. Cons truction Materials
Different materials are used for the different parts. How-
ever, wood and aluminium are the two most popular ma-
terials used for small greenhouses. Steel is used for larger
structures and rigid polyvinyl chloride, UPVC for con-
servatories, which is used mainly in conservatory building,
does not decay or rust and is, therefore, maintenance-free
[24]. However, after a period of time it can become
abraded by dirt in the atmosphere and lose its smart finish.
Greenhouses clothed in plastic or glass. Plastic offers the
cheapest form of protection, while glass is the most aes-
thetically pleasing of the two materials.
3.3.3. Ground Radiation
Reflection of sunrays is mostly used for concentrating
them onto reactors of solar power plants. Enhancing the
insolation for other purposes has, so far, scarcely been
used. Several years ago, application of this principle for
increasing the ground irradiance in greenhouses, glass
covered extensions in buildings, and for illuminating
northward facing walls of buildings was proposed [25].
Application of reflection of sun’s rays was motivated by
the fact that ground illuminance/irradiance from direct
sunlight is of very low intensity in winter months, even
when skies are clear, due to the low incident angle of
incoming radiation during most of the day. This is even
more pronounced at greater latitudes. As can be seen in
Figure 11, which depicts a sunbeam split into its vertical
and horizontal components, nearly all of the radiation
passes through a greenhouse during most of the day.
The primary objective of greenhouses is to produce
agricultural products outside the cultivation season. They
Figure 11. Relative horizontal and vertical components of
solar radiation.
offer a suitable microclimate for plants and make possi-
ble growth and fruiting, where it is not possible in open
fields. This is why a greenhouse is also known as a “con-
trolled environment greenhouse”. Through a controlled
environment, greenhouse production is advanced and can
be continued for longer duration, and finally, production
is increased [26]. The off-season production of flowers
and vegetables is the unique feature of the controlled
environment greenhouse. Hence, greenhouse technology
has evolved to create the favourable environment, or
maintaining the climate, in order to cultivate the desir-
able crop the year round. The use of “maintaining the
climate” concept may be extended for crop drying, dis-
tillation, biogas plant heating and space conditioning.
4. Conclusions
Two of the most essential natural resources for all life on
the earth and for man’s survival are sunlight and water.
Sunlight is the driving force behind many of the renew-
able energy technologies. The worldwide potential for
utilising this resource, both directly by means of the solar
technologies and indirectly by means of biofuels, wind
and hydro technologies is vast. During the last decade,
interest has been refocused on renewable energy sources
due to the increasing prices and fore-seeable exhaustion of
presently used commercial energy sources. Thermal
comfort is an important aspect of human life. Buildings
where people work require more light than buildings
where people live. In buildings where people live the
energy is used for maintaining both the temperature and
lighting. Hence, natural ventilation is rapidly becoming a
significant part in the design strategy for non-domestic
buildings because of its potential to reduce the environ-
mental impact of building operation, due to lower energy
demand for cooling. A traditional, naturally ventilated
building can readily provide a high ventilation rate. On the
other hand, the mechanical ventilation systems are very
expensive. However, a comprehensive ecological concept
can be developed to achieve a reduction of electrical and
heating energy consumption, optimise natural air condi-

Opportunities for Sustainable Low Carbon Energy Research Development and Applications
190
tion and ventilation, improve the use of daylight and
choose environmentally adequate building materials.
Plants, like human beings, need tender loving care in the
form of optimum settings of light, sunshine, nourishment,
and water. Hence, the control of sunlight, air humidity and
temperatures in greenhouses are the key to successful
greenhouse gardening. The mop fan is a simple and novel
air humidifier; which is capable of removing particulate
and gaseous pollutants while providing ventilation. It is a
device ideally suited to greenhouse applications, which
require robustness, low cost, minimum maintenance and
high efficiency. A device meeting these requirements is
not yet available to the farming community. Hence, im-
plementing mop fans aides sustainable development
through using a clean, environmentally friendly device
that decreases load in the greenhouse and reduces energy
consumption.
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Current Distortion Evaluation in Traction 4Q Constant Switching Frequency Converters 191
Nomenclature
a: annum
ha: hectares
HFU: heat flow unit
l: litre
MSW: municipal sewage waste