All the energy that humans use comes directly or indirectly from the sun. In the beginning, humans used their own strength, which came from their food. That was the only energy source for hundreds of thousands of years, until fire was discovered 350,000 years ago, burning wood as fuel. They had discovered the biomass as energy source.

1. Alejo Etchart.
October 2008
A SUMMARY OF THE HISTORY OF ENERGY DEMAND
AND ITS DRIVERS. THE CASE OF PHOTOVOLTAICS
A brief summary of the history of the energy and its demand drivers
All the energy that humans use comes directly or indirectly from the sun. In the
beginning, humans used their own strength, which came from their food. That was the
only energy source for hundreds of thousands of years, until fire was discovered
350,000 years ago, burning wood as fuel. They had discovered the biomass as energy
source. Thanks to fire, humans gained supremacy over the rest of animals, as they
learned how to be always warm, scare the beasts and produce better arms. By 9,000
years B.C, animals’ strength started to be used to help humans in their daily activities.
The use of wind to move ships is also remote. The first mills to grind wheat using the
energy provided by water flows started to be used in the 1st Century B.C. Eight
centuries later, Persians started to use wind energy also to move mills.
These were the only ways of energy used until the 12th century, when coal, which has a
high calorific power, started to be used to improve metallic arms for wars and hunting.
Coal only becomes the source of energy par excellence with the advent of the Industrial
Revolution in England in the 18th century. After the invention of the steam engine, coal
was used to move locomotives and ships, and to extract minerals. The later need of
energy for electrified motors and illumination explained ulterior increases of coal
demand.
During the Second World War, coal started to be replaced by petroleum and natural
gas, relegating coal to the production of steel, and as a source for power-generating
plants. It was in 1859 when Edwin Drake bored the first oil well in Pennsylvania. The
invention of the engines made by Otto and Diesel in 1876 and 1892 allowed cars to be
powered by products derived from crude oil. Other uses of oil such as powering all
terrestrial, sea and air vehicles, producing plastics and tars, heating, producing
electricity and a wide list of other inventions, made the demand for petroleum increase
exponentially. Not until late fifties did natural gas - that can be found separately or
together with petroleum or coal reservoirs - gain commercial use, and becomes another
pillar of the economical growth of our society.
Together with the popularisation of vehicles and electricity, other drivers for the strong
energy demand increase between 1949 and 1973 were the low and stable price of oil,
and the population explosion from 2.5 to 4 billion.
Discoveries made during the late 19th and early 20th Centuries allowed Albert Einstein
to learn how to obtain fission nuclear energy, and later discoveries by Lise Meitner and
Otto Hahn made the process economically viable. By the late 1950s, the first nuclear
stations started to be used to produce electricity.

2. During the 1960s, consciousness of the ecologic problems arose, these problems being
seen as non-connected realities, and therefore to be tackled with specific end-of-the-pipe
policies. Only in the 1980s did the relationship between the big Earth problems (sea
pollution, ozone layer and forest destruction, drinkable water scarcity, etc.) and the
human action becomes evident. This fact, together with the growing scarcity of
petroleum and natural gas reservoirs, as well as the political consequences of being
dependent upon the petroleum exporting countries, encouraged the development of new
sources of energy to substitute fossil fuels (Bermejo, 2006), grouped under the name of
renewable energies.
What about the future?
According to the WEC (2007), the growth of 50% in energy demand since 1980 will
continue, at an annual rate of 1.6% between 2004 and 2030. Over 70% of this growth
will come from developing countries, where populations and economies are growing
considerably faster than in the OECD nations. China alone will account for some 30%
of the energy demand increase. Fossil fuels will continue to provide more than 80% of
the total energy demand well into the future, and coal will have double demand from
2004 to 2030. The 86% of the coal demand increase will be from developing Asia,
where reserves are large and low-cost.
Can our world hold this increase?
According to the IPCC (2007), human activities are the main responsible for increasing
concentrations of GHG in the atmosphere since 1970 to 2004 in a 70%. The WEC
(2007), states a universally recognized truth when they say that, “the greatest challenge
facing the energy sector today is how to meet rising demand for energy, whilst at the
same time reducing our emissions of greenhouse gases”.
All worldwide institutions call for renewable energies to become a major energy source.
In the EU, the Amsterdam Treaty fixed a goal of 12% for renewable energies share for
2010. The European Council targeted a 20% for 2020. As stated by the Worldwatch
Institute in State of the World 2003 (chapter 5) and recalled in all later yearly editions,
all renewable energies are needed and must be reinforced in order to achieve a
sustainable development.
The next sections are dedicated to the solar photovoltaic energy (PV) as one of the
highest potential renewable energies to move the world towards the desired scenario.
Solar photovoltaic energy (PV)
Solar photovoltaic energy was discovered in 1954, when silicon semiconductors doped
with certain impurities showed to be able to convert the light rays directly into

3. electricity, by turning photons arriving from sunlight and knocking onto electrons, into
a higher state of energy. The most efficient location of photovoltaic panels are
building’s roofs and solar plants.
Approximately 90% of the generated electricity is sent to the general grid, using an
inverter to convert DC into AC. There are smaller installations for remote uses, like
road lightings or telephones, detectors, cathodic protection of pipelines and many
others.
Photovoltaic electricity production has multiplied by 16 in the last 6 years. Well-
designed and mounted installations require minimum maintenance and have a lifespan
of up to thirty years.
EPIA and Greenpeace (2008) advanced scenario says by 2030, PV systems could
generate around 2,600 TWh of electricity worldwide, which means almost 14% of the
world population’s needs.
Advantages of PV
- The 89 petawatts of light arriving to the earth's surface is almost 6,000
times the 15 terawatts of power consumption.
- Solar power use is non-polluting. The net emissions of PV are highly
favorable, compensating the emissions made during fabrication and
transportation with the CO2 savings in a 1 to 5 years term out of the 20-
30 year of their lifespan (J. Pearce at al., 2002).
- Solar electric generation is economically more viable than other
renewable energy sources for local powering.
- Operational costs of solar power plants are very low.
- There is a large way for technologic improvement in materials, processes
and whole efficiency, which are currently improving rapidly (The Energy
Daily, 2007). Expected new materials and technologies to substitute
silicon, like carbon-based polymers and molecules upon thin films,
amorphous or microcrystalline silicon, continuous printing process,
silver cells, concentrator modules and others (AZnanotechnologies,
2008; Saneyuki, 2003). Higher economies of scale will be reached
following the market trend.
- The 120,000 people worldwide employment in PV related jobs may
grow to almost 3,7 million in 2030 under a moderate scenario (EPIA,
2008)
- Under the same scenario, accumulated CO2 savings 2006-2030 can reach
over 5,300 Mt.
Disadvantages of PV
- The cost of the panels and installation is still expensive, delaying the
return on investment period. At the current price of electricity in most of
the countries, unless subsidizing tariffs are offered by the grid network,
the incomes from selling power to the grid do not cover the investment
made.
- The sunlight received depends on the season, time of the day, weather
conditions and location, so it is not stable and its viability varies
worldwide.

4. - As solar light is not available at night and is dependent on weather
conditions and location, a storage system is needed for local use,
increasing the total cost.
- A toxic material (cadmium) is used for panels’ fabrication. Even if it is
properly isolated inside the panel, a special treatment is needed at the end
of its lifespan.
Subsidizing PV: FITs versus quota?
Therefore, one of the most important problems for the rapid expansion of large scale PV
infrastructure seems to be its economical viability in a short term.
The 2nd European Photovoltaic Industry Association (EPIA) round table, (July 2007,
Brussels) debated on the future of support mechanisms for PV electricity in Europe.
Germany’s model through a feed-in tariff (FIT) is recognized worldwide as the most
efficient way to promote grip-tied PV systems, and most of the industrialized countries
are following this model. FITs stimulates the PV sector in two ways:
- Security
It guarantees a price paid by electric companies to PV electricity
producers for 20 years, without depending on the State budget. This price
is higher than the one at which electricity retailers sell the standard
electricity, but it is easily absorbed into the average cost of electricity for
distributors because the amount of subsidized energy is not significant in
their portfolio. This way, customers indirectly pay for PV and promote it
through the monthly bill.
- Stimulates improvement
It encourages cost reduction, through a yearly cut of the FIT for new
systems connected to the grid starting from 2009. This way, pressure is
put on the PV-industry to reduce production costs and improve
performance. Customers will opt for systems with highest or fastest
investment return.
The monthly extra-cost per consumer in Germany is only about 1,25€ (EPIA and
Greenpeace, 2008). Germany is the major market in the world, and also the fastest
growing in 2005, 2006 and 2007. Eighteen other EU countries had already adopted this
model by July 2007. South-European countries, especially Spain, are also becoming key
players in PV (BMU, 2007). USA failed to regulate federally the incentives for
renewable energies, so that the State Tax incentives remain the main drivers for PV’s
expansion. Nevertheless, many states are adopting individual FIT programs, and the
expiring of Investment Tax Credits (ITC) at the end of 2008 could lead to extend the
FIT program in all the country. The Canadian situation is similar to the USA. Japan’s
policy (the second world’s largest producer), mixes FITs with other policies.
The other current way to promote PV is the “quota model”, which regulates the quantity
instead of the price, by forcing the electric companies to have a certain percentage of
their portfolio filled with renewable energies (IEEP, 2006). It is currently followed
mainly in the USA (although some states are shifting to FIT), UK and Sweden. In the

5. first two, the quota refers to the quantity of the portfolio to be filled-in with all the
renewable energies altogether.
Establishing a quota comprising all the renewable energies altogether can be to the
detriment of the least developed ones, as is the case of PV compared to wind or
hydroelectric. Further, the FIT encourages innovation by giving higher profit to the
most efficient production, while the quota model does not. Facts prove indeed, that
much greater progress has been made through FITs (BMU, 2007). UK’s House of
Commons (2007, paragraph 51) recommend the FIT system.
The future of PV
Apart from the technological advances and the political approaches discussed above, the
popularization of PV imperatively needs the development of Smart Grids that,
minimally, allow individual producers to send the power generated to the grid; ideally,
it permits the choice of which type of energy is received and completely monitors it.
Only Germany has implemented a Smart Grid. The EPIA (2007) strongly urges all its
members to follow the same path.
Finally, social environmental awareness needs to be spread. What consumers buy
against a price is performance, value, safety and reliability ahead of environment, so
price signals should be sent to the market in order to guide them in their purchasing
decisions. (WBCSD, 2002)
©
BIBLIOGRAPHY
- AZnanotechnologies (2008) New Materials Making Photovoltaic Devices Cost
Efficient”, http://www.azonano.com/News.asp?NewsID=7272 [Accessed 19/10/08]
- Bermejo, R. (2005), “La gran transición hacia la sostenibilidad”. Ed. Los Libros de la
Catarata, Madrid
- (BMU) Federal Ministry for the Environment, Nature Conservation and Nuclear
Safety (2007), “EEG– The Renewable Energy Sources act”, Berlin
- Energy Information Administration (EIA) (2008), “International Energy Outlook
2008”, http://www.eia.doe.gov/oiaf/ieo/world.html [Accessed 18/10/08]
- European Photovoltaic Industry Association (EPIA) (2007), “Access to the grid: A
precondition for the solar photovoltaic market to take-off”, Press release
http://www.epia.org/fileadmin/EPIA_docs/documents/RoundTable/RT03_070913_Pres
s_Release.pdf [Accessed 20/10/08]
- European Photovoltaic Industry Association (EPIA) and Greenpeace (Solar
Generation IV (2008), “Solar Generation V – 2008”,
www.epia.org/fileadmin/EPIA_docs/documents/EPIA_SG_V_ENGLISH_FULL_Sept2
008.pdf [Accessed 17/10/08]
- House of Commons, Trade and Industry Committee (2007), “Local energy- turning
consumers into producers” First Report of Session 2006–07.
- Institute for European Environmental Policy (IEEP) (2006), “Innovation Case Study:
Photovoltaics”, http://ec.europa.eu/environment/enveco/pdf/paper4.pdf [Accessed
18/10/08]

6. - Intergovernmental Panel for Climate Change (IPCC) (2007), “Climate Change 2007:
Synthesis Report”, IPCC, Geneva
- Pearce J, Lau A. (2002) “Energy analysis for sustainable energy production…” In:
Proceedings of American Society of Mechanical Engineers Solar 2002: Sunrise on the
Reliable Energy Economy. 2002.
- Saneyuki et al. (2003), “Development of Amorphous silicon/ Microcrystalline Silicon
Tandem Solar Cells” available at
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01306227 [Accessed 19/10/08]
- The Energy Daily (2007), “Study Sees Solar Cost-Competitive In Europe By 2015”,
Vol. 35, No. 173.
- University of Cambridge, Department of Applied Economics- MIT Center for Energy
and Environmental Policy Research (2004), “Cambridge Working Papers in Economics
0503”, http://www.econ.cam.ac.uk/electricity/publications/wp/ep70.pdf [Accessed
20/10/08]
- World Business Council for SD (WBCSD) (2002), “The Business Case for SD”.
WBCSD, Geneva.
- World Energy Council (WEC) (2003), “Drivers on the Energy Scene”, published by
WEC, London.
- World Energy Council (WEC) (2007) Survey of Energy Resources 2007, published by
WEC, London.
- Worldwide Watch ( 2003) “State of the World 2003” Norton & Company, New York,
NY.