Principles of Renewable Energy sources

1. SAI GOUTHAM GOLIVE
EEE DEPARTMENT, BAPATLA ENGINEERING
COLLEGE, BAPATLA
PRINCIPLES OF RENEWABLE
ENERGY SOURCES

2. Unit – 1
1) what is renewable energy?
Renewable energy. ‘Energy obtained from natural and persistent flows of energy occurring in the
immediate environment’. An obvious example is solar (sunshine) energy, where ‘repetitive’ refers to the 24-
hour major period. Note that the energy is already passing through the environment as a current or flow,
irrespective of there being a device to intercept and harness this power. Such energy may also be called
Green Energy or Sustainable Energy.
2) What is non-renewable energy?
Non-renewable energy. ‘Energy obtained from static stores of energy that remain underground unless
released by human interaction’. Examples are nuclear fuels and fossil fuels of coal, oil and natural gas.
Note that the energy is initially an isolated energy potential, and external action is required to initiate the
supply of energy for practical purposes. To avoid using the ungainly word ‘non-renewable’, such energy
supplies are called finite supplies or Brown Energy.
3) List the differences between renewable and non renewable energy sources?
4) What are the ultimate energy sources?
There are five ultimate primary sources of useful energy:
1 The Sun.
2 The motion and gravitational potential of the Sun, Moon and Earth.
3 Geothermal energy from cooling, chemical reactions and radioactive
decay in the Earth.

3. 4 Human-induced nuclear reactions.
5 Chemical reactions from mineral sources.
Renewable energy derives continuously from sources 1, 2 and 3 (aquifers). Finite energy derives from
sources 1 (fossil fuels), 3 (hot rocks), 4 and 5. The sources of most significance for global energy supplies
are 1 and 4. The fifth category is relatively minor, but useful for primary batteries, e.g. dry cells.
5) What are the natural energy currents on earth?
The flows of energy passing continuously as renewable energy through the Earth are shown in Figure 1.2.
For instance, total solar flux absorbed at sea level is about 1_2×1017W. Thus the solar flux reaching the
Earth’s surface is ∼20MW per person; 20MW is the power of ten very largediesel electric generators,
enough to supply all the energy needs of a town of about 50 000 people. The maximum solar flux density
(irradiance) perpendicular to the solar beam is about 1kWm− 2; a very useful and easy number to
remember. In general terms, a human being is able to intercept such an energy flux without harm, but any
increase begins to cause stress and difficulty. Interestingly, power flux densities of ∼1kWm−2 begin to cause
physical difficulty to an adult in wind, water currents or waves. However, the global data of Figure 1.2 are of
little value for practical engineering applications, since particular sites can have remarkably different
environments and possibilities for harnessing renewable energy. Obviously flat regions, such as Denmark,
have little opportunity for hydro-power but may have wind power. Yet neighbouring regions, for example
Norway, may have vast hydro potential. Tropical rain forests may have biomass energy sources, but
deserts at the same latitude have none (moreover, forests must not be destroyed so making more deserts).
Thus practical renewable energy systems have to be matched to particular local environmental energy
flows occurring in a particular region.

4. 6) Define spaghetti and pie diagrams?
All energy systems can be visualised as a series of pipes or circuits through which the energy currents are
channelled and transformed to become useful in domestic, industrial and agricultural circumstances. Figure
1.3(a) is a Sankey diagram of energy supply, which shows the energy flows through a national energy
system (sometimes called a ‘spaghetti diagram’ because of its appearance). Sections across such a
diagram can be drawn as pie charts showing primary energy supply and energy supply to end-use

5. 7) Briefly describe about energy planning?
Currently, energy planning in India is not an integrated
activity. Since there are many energy sources and end uses,
many organisations and agencies deal with different aspects
of energy. The plans for electricity, coal, oil and fuel wood
are done by respective organisations mainly based on the
projection of energy demand. The primary goal of this
approach is to go in for energy supply expansions on the
assumption that there is a correlation between energy use and
gross domestic product. With this approach energy becomes an
end in itself, and the focus shifts on meeting increased
energy consumption through energy supply expansion alone.
This supply and demand based planning approach for each
individual energy form has resulted in problems like more
losses, more conversions and low efficiencies. This is
evident from the disappearance of forests, village wood lots,
road side trees, construction of giant hydroelectric dams,
fossil fuel based power plants and controversial nuclear
plants. This conflict between the energy demand and
environmental quality goals can be solved by having an
integrated approach to the problem of energy planning, with a
view to minimise consumption of non-renewable resources of
energy and maximise efficiency of energy usage and harnessing
of renewable sources of energy in an ecologically sound way.
Another aspect that has to be considered in the planning

6. process is that of matching energy resources and end uses.
Because of convenience, current usage of high quality energy,
such as, electricity for low quality activities like bath
water heating is to be discouraged. Hence, strategies for
integrated energy planning should include (a) improvements in
efficiencies of end use devices and/or conversion equipments,
(b) optimising energy source -end use matching, (c)organised
approach towards optimal use of renewable resources, (d)
proper exploitation of biomass energy resources, and (e)
discourage use of depletable resources (by penalising).
Ecologically sound development of the region is possible when
energy needs are integrated with environmental concerns at
the local and global levels, for which an integrated planning
framework would be necessary. The central theme of the
integrated energy plan would be to prepare and implement the
area based decentralised energy plans for meeting energy
needs for subsistence , development of alternate energy
sources (renewable, non-renewable) at the least cost to the
economy and environment, and linking the micro level plans
with national economic planning and development programs,
including those for energy, agriculture and rural development
sectors.
Towards the goal of implementing analytical methods for
integrated energy planning, computerised Decision Support
System (DSS) is used. This provides useful assistance in the
analyses of available information, optimal allocation of
resources for various end uses, the projection of future
scenarios and the evaluation of alternative scenarios.
The energy plan development exercise consists of the
following components:
(i) Database Development: Energy planning depends on the
availability and quality of data , and gaps and
deficiencies in the database can be identified as a
result from planning. The database serve as input to
demand and supply analyses. The objective of the
database is to identify , generate and assemble
information required for energy analyses. It is part
of the iterative and continuous process of energy
planning.
(ii) Sectorwise energy demand: This involves the survey of
the present energy consumption in different sectors for
various end uses covering the type, magnitude and
composition of fuel, trends, seasonal constraints and
preferences in consumption; and estimation of energy
demand based on the sample survey data.
(iii) Assessment of the supply situation: This involves
analysis of present energy supply system; assessment of
woody and other bioresources; assessment of renewable
sources potential, such as, solar, wind and hydro; and
study of supply system of commercial energy.
(iv) Development of an energy plan for the district: Based
on the estimated supply and demand, an energy plan to
meet the energy demand would be worked out in
accordance with the development priorities. Techno-
economic analyses of various energy technologies would
be carried out to find out the technical and economic
viability of the system. An energy plan at district
level would be proposed based on the Decision Support

7. System approach. Analyses of the importance of
community participation in energy conservation,planning
and identification of measures that will enhance the
level of participation.
(v) Implementation and management: With the knowledge of
administrative structure at district level and agencies
implementing the energy development program, a suitable
institutional structure would be suggested for
implementing and managing the energy plan.
District is taken as the unit of energy planning since (i)
district is the basic administrative unit for implementing
all developmental programs and (ii) district level planning
will facilitate integration between national planning
exercises and planning at lower levels.
8) Briefly describe about energy management?
Energy management is the art and science of optimum use of energy to maximise profits (minimise costs)
and thereby improve the economic competiveness. The energy should be used efficiently, economically
and optimally. Energy management can also be defined as the science involving planning, directing, con-
trolling the supply and consumption of energy to maximise productivity and comforts and minimise the
energy costs and pollution with conscious, judicious and effective use of energy. The energy management
involves strategy, policy, organisational changes, energy audit, energy conservation measures,
administrative actions, training and awareness programmes, monitoring of energy conservation efforts etc.
Energy management is an important management function of every organisation (like production, finance,
marketing, planning, and design). Energy organisation must have a written energy management policy
document and the top management must be committed to implement the energy policy. The energy
objectives must be known to energy executive and supervisor. The energy must be monitored via the
production.
Steps for Energy Management:
Energy management involves the following basic steps:
1. Energy management as Policy and Commitment.
2. Selection of energy manager and defining his responsibilities;
i. Energy planning,
ii. Monitoring energy consumption,
iii. Planning energy conservation,
iv. Implementing energy conservation measures,
v. Achieve energy conservation objectives.
3. Formulation energy strategy and energy conservation plan.
4. Bring awareness and involvement at various levels by means of training programmes, workshops,
communication, in-house journals.
5. Introduce suggestion scheme and award scheme.

8. 6. Appoint energy audit team/consultants.
7. Obtain report on energy conservation measures.
8. Establish practice of monitoring energy consumption and effectiveness of energy conservation
measures.
9. Adopt new technology measures.
10. Adopt recycling of scrap, avoid wastage etc.
11. Carry out modifications, retrofitting or replacement of existing plant/machinery so as to save energy.
Objectives of Energy Management:
1. Objectives of supply side:
To formulate energy strategies, plan energy supply on short term, mid-term and long term basis and to
ensure adequate supply of various forms of secondary (usable) energy to various consumers in the
allocated geographical zone with minimum cost and minimum environmental pollution, to regulate energy
flow.
2. Objectives of End-user side:
To select optimum energy forms for consumption and to optimize energy consumption of each form of
energy for reducing energy costs and for improving productivity, standard of living and environment. In
accordance with this generic objective, every end-user organisation should have an energy objective
statement in written form as a management policy statement. This is an obligatory function for every
organisation on supply side and demand side in individual and national interest.
9) Briefly describe about energy efficiency?
Energy efficiency simply means using less energy to perform the same task – that is, eliminating energy
waste. Energy efficiency brings a variety of benefits: reducing greenhouse gas emissions, reducing
demand for energy imports, and lowering our costs on a household and economy-wide level.
While renewable energy technologies also help accomplish these objectives, improving energy efficiency is
the cheapest – and often the most immediate – way to reduce the use of fossil fuels. There are enormous
opportunities for efficiency improvements in every sector of the economy, whether it is buildings,
transportation, industry, or energy generation.
Buildings
Building designers are looking to optimize building efficiency and then incorporate renewable energy
technologies, leading to the creation of zero-energy buildings. Changes in existing buildings can also be
made to reduce energy usage and costs. These may include small steps, such as choosing LED light bulbs
and energy efficient appliances, or larger efforts such as upgrading insulation and weatherization.

9. Energy Generation and Distribution
Combined heat and power systems capture the "waste" heat from power plants and use it to provide
heating, cooling, and/or hot water to nearby buildings and facilities. This increases the energy efficiency of
power generation from approximately 33 percent to up to 80 percent. The smart grid is another system that
will improve the efficiency of electric generation, distribution, and consumption.
Community Design
Neighborhoods that are designed with mixed use developments and safe, accessible options for walking,
biking, and public transportation are key to reducing the need for personal vehicle travel.
Vehicles
More energy efficient vehicles require less fuel to cover a given distance. This generates fewer emissions,
and makes them significantly less expensive to operate. Plug-in hybrids and fully electric vehicles are
particularly fuel efficient.
Freight
Freight can be moved more efficiently by improving the efficiency of rail and truck transportation and by
shifting long-distance freight transport from trucks to rail.
Human Behavior
The four strategies above improve energy efficiency primarily through technology and design. However, the
way people use these technologies will significantly impact their effectiveness. What impact can a highly
efficient technology have if households and businesses are not motivated to buy, install, and/or activate it?
How does driving behavior and unnecessary idling impact gas mileage? How many people will use public
transportation if there is a cultural stigma against it? Research has shown that 30 percent of the potential
energy savings of high efficiency technologies is lost due to a variety of social, cultural, and economic
factors. Addressing these factors is also an important component of making our economy more energy
efficient.