The role of renewables in the energy crisis

Abstract

The recent progress of human kind has so far been strongly related to the use of fossil fuels. Nowadays, the uncontrolled growth of their use is producing a series of threats such as local pollution, global warming, and the unbalance between their growing demand and their progressive depletion is creating serious geopolitical frictions which may put at risk our civilization. While the nuclear option is seriously questioned in the Western world, the growth of renewable energy sources (RES) is creating the illusion that they may just replace fossil fuels and become a sort of panacea overcoming all aforementioned threats. Some of the shortcomings of this way of thinking are underlined in this paper. Actually, the correct answer is a combination of two factors: on one side the use of renewable energy sources, but on the other side the adoption of energy efficiency measures in order to rationalize the energy demand.

Full text

The role of renewables in the energy crisis
GianVincenzo Fracastoro
Energy Department, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10131 Torino (Italy)
Abstract. The recent progress of human kind has so far been strongly related to the use of fossil fuels.
Nowadays, the uncontrolled growth of their use is producing a series of threats such as local pollution, global
warming, and the unbalance between their growing demand and their progressive depletion is creating serious
geopolitical frictions which may put at risk our civilization. While the nuclear option is seriously questioned
in the Western world, the growth of renewable energy sources (RES) is creating the illusion that they may
just replace fossil fuels and become a sort of panacea overcoming all aforementioned threats. Some of the
shortcomings of this way of thinking are underlined in this paper. Actually, the correct answer is a
combination of two factors: on one side the use of renewable energy sources, but on the other side the
adoption of energy efficiency measures in order to rationalize the energy demand.
1. The “perfect storm”
1.1 Greenhouse Gases and energy
Thousands of papers have been probably written about the consequences of the increasing amount of CO2 and other
Green House Gases (GHG) on the Earth temperature. The last report from the Intergovernmental Panel for Climate
Change (IPCC), the most authoritative group of climate experts recently issued in 2013, does not leave many doubts
about this: if the increasing CO2 concentration trend will remain the same of today in the few next decades, temperature
increase at the end of the century may reach 3-5°C, with dramatic consequences.
While the entity of these effects is sometimes debated, it is well known where GHG emissions come from. Almost 2/3
of them are due to energy conversion of fossil fuels (coal, oil or natural gas), namely industry (14%), power plants
(24%), transport (14%), buildings (8%) and other energy related issues, as can be seen in Figure 1.
Figure 1 – World GHG emissions and its sources [1].
DOI: 10.1051/
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1.2 Local pollution
Beyond global effects on world climate, fossil energy conversion processes in buildings, factories, transportation are
responsible for local pollution, especially in urban and densely populated areas, leading to the release of million tons
per year of particulate matter, sulfur oxides, carbon monoxide and nitrous oxides (as shown in figure 2) in the air we
breath. Health consequences are nowadays fully acknowledged by medical science.
Figure 2 –NO2 concentrations around the world [2].
1.3 Unbalanced energy consumption
World per capita primary energy consumption (toe/person) differs by an order of magnitude between rich OECD
countries like USA, Canada or Norway and most of African, Asian, or South American countries (see figure 3). This
unbalance is in the long run going to be reduced.
Figure 3 - World per capita energy consumption [3].
Emerging economies (China, India, Indonesia, Brazil,…) are rapidly catching up, in a search for better quality of life for
their populations. As a result, if we observe energy consumption trends in the different World regions, we will notice
strong differences: from the constant and even declining slope of our old Europe to the slightly increasing trend of
North America to the high-rocketing tendency of Asia Pacific (see figure 4). If China alone should reach the same per
capita energy consumption of Italy it would more than double the Asia Pacific share, pushing world consumption to a
thrilling 17,000 Mtoe. As a consequence, CO2 emissions would increase even more so, due to the high share of poor
quality coal in China’s power mix.
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Figure 4 –World Energy consumption per Region [3].
1.4 Price of fossil fuels
Finally, looking at oil prices from 1861 onwards, we may see that prices above 100 $/barrel (in 2012 $) have already
been reached in the past (Figure 5), but are now steadily exceeded, and the price is not likely to decrease in the future,
with growing demand and progressively reducing “low hanging fruits”, or low-cost exploitable gas and oil reserves.
Figure 5 –Oil cost in $ of the year and present day $ (2012) [3].
All these factors (global environmental aspects, pollution problems in high population density and urban areas, expected
rapid increase of energy demand by emerging economies, progressive depletion and increasing cost of fossil energy
sources) add up creating a threatening scenario that has been dubbed “the perfect storm” by Bob Armstrong, vice
President of MIT-Energy I nitiative.
Furthermore, ominous “monsters” [4] are behind the door:
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a 1-3-meter rise in sea level by the end of this century
major alterations of the global hydrological cycle
major changes in forest cover
major emissions of greenhouse gases from the tundra.
All these phenomena may have strong feedbacks in a world “out of control”, and “today’s science cannot predict how
much atmospheric change would let these monsters in, nor how quickly they could enter” [5].
2. Will Renewable Energy Sources be the solution?
Apart from the climate change sceptical people (more numerous than expected within the political class and among
technicians and economists), those who take seriously these threats may be divided in two categories: those who think
that the problem cannot be easily solved and those who think that the solution is already at hand. These last (a
decreasing cohort of nuclear fission fans or fusion-devotees, and an increasing army of Renewable Energy Sources
followers) think that just replacing fossil fuels with carbon-free ones will solve any problem, and make monsters and
storms suddenly vanish. Actually, this is not the correct solution, and maybe not even a feasible one.
2.1 Advantages of RES
Advantages of RES are well known: they are perennial and free (except biomass), non-polluting during conversion
process (except biomass), and fairly distributed in practically every country: there are areas rich with running rivers or
mountain water basins, sunny areas, regions which are swept by strong and regular winds, or covered by thick forests or
with coastal areas washed by waves, or tides, or ocean streams… Renewable energy is really everywhere!
Devices for RES exploitation are becoming cheaper and cheaper. Moreover, the different structure of the cost of RES
with respect to fossil fuels should be stressed: while energy produced from fossil fuels is mainly paid for the extraction
and depletion of matter which would take million years to be recreated, cost of energy produced by RES actually
derives from labour costs required to fabricate the energy conversion devices (solar collectors, photovoltaic panels,
wind turbines, etc.). Since most of the materials required to build these devices can be recycled (most PV installers
guarantee for free final decommissioning and recycling of installations), what we are actually paying for is good jobs in
high-tech sectors.
2.2 Disadvantages of RES
However, RES also have a number of shortcomings.
They are diluted, with energy densities ranging between a few W/m2 to less than 1 kW/m2, compared to the
MW/m2 scale of fossil fuel power plants. This inherently leads to large and costly installations and to extensive
land use.
They are discontinuous and not exploitable at will or readily storable (except biomass, hydro and geothermal
power). Discontinuous often goes along with unpredictable or at least partially predictable, except with short
notice, and always with arbitrary. These two drawbacks reduce “de facto” the value of the energy produced by
RES, and inherently create the need for costly back-up, or storage systems which are rather inefficient,
expensive and often make use of environmentally unfriendly materials (just think of lead and cadmium of
electric batteries).
Another issue concerns the Life-Cycle balance of energy production from RES. While it’s certainly true that
energy is produced without any primary energy use by RES, on a Life-Cycle approach this is no longer true, as
all RES conversion devices require energy for their construction. Usually, the energy required by construction
of RES conversion devices is orders of magnitude smaller than the energy produced during their lifetime. To
make an example, energy produced by a wind turbine during its lifetime is 50-60 times larger than the energy
required for its construction. On the contrary, the high energy intensity of PV production makes this analysis
more uncertain.
The same should apply when a CO2 life cycle analysis is carried on. Avoided CO2 emissions should outpace
CO2 emissions during RES conversion devices fabrication. This analysis partially goes along with that on
primary energy use LCA, with some differences which should not be neglected.
2.3 CO2 emissions by PV panels
This paragraph will analyse the issue of PV life cycle CO2 emissions. The CO2 avoided will depend on the energy
produced and the CO2 emitted on the energy required by construction. Energy and CO2 consumption/emission and
production/avoided emission will respectively depend on where and how is the PV panel produced, and where and how
is the PV panel installed. A PV panel produced in China ( most ly with low quality coal-made electricity) and installed in
Switzerland (with 1200 kWh/m2 solar irradiation) will hardly have a positive CO2 balance in its lifet ime (see fig. 6),
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while a PV panel fabricated in Europe and installed in Sicily (almost 2000 kWh/m2 solar irradiation) will start having a
positive CO2 emissions balance after less than 7 years.
Figure 6 –CO2 emissions during PV fabrication and avoided emissions during their lifetime [6].
2.4 Limitations imposed to RES by the grid
Another even more limiting important factor is related to the grid, and to the mix of power production installations
available in the country where renewable energy is produced. If it’s not possible to count on the possibility to export or
store excess power, solar power should not exceed a certain fraction of total installed capacity, otherwise it will results
in a waste of energy. As an example, in Spain, a power mix with: 55% Base load (with 30% elasticity), 20% Wind, 15%
Solar and 10-15% Gas Turbines will result in the month of August in a non-negligible waste of energy, emphasized in
Figure 7 by yellow peaks going beyond the red curve representing the energy demand [7].
Figure 7 –Power production and demand profiles in August on the Spanish Grid with 20% wind and 15% PV [7].
A generalization of these results is shown in Figure 8 with a 50% base load and 20% wind share. For example, with
20% base load elasticity a 10% PV share will generate an energy excess (waste) below 0.5%, while with 20% PV the
waste energy will grow by a factor of 10 above 5%.
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Figure 8 –Energy excess for different combinations of base load elasticity and PV share for Spain [7].
3. Demand side management
The drawbacks previously shown clarify the fact that simple replacement of fossil fuels with RES will not solve the
problem, and lead us to understand why we need to accompany RES growth with other important and complex
measures, the most important of which is certainly demand side management.
Let’s start from the beginning… We don’t need coal, oil, gas, or uranium, nor PV panels or wind turbines. What we
really need is heat to keep our houses warm or for industrial production, electricity to run electrical equipment, and
mechanical energy to move around and transport goods! If we look at the EU energy breakdown (Figure 9), these end
uses amount to 37 Exajoules1 (EJ), or 883 Mtoe: transportation covers 6% of total end uses, electricity has a 27% share,
while heat is the dominant end use with the remaining 67% share. However, the final energy (electricity, heat and fossil
fuels for our cars and boilers) needed to produce this amount is about 58 EJ, with 21 EJ lost mainly in the transportation
sector, where only about 10% of the fuel heat content is converted by internal combustion engines into mechanical
energy transferred to the wheels. Going further upstream, the primary energy supply exceeds 80 EJ, with another 22 EJ
lost in power generation.
More than 50% of primary energy is therefore lost in the process which transforms it into final energy and from this to
end uses. All of this waste is released as heat to the environment. If the heat demand could be at least partially covered
by heat lost in energy conversion processes (and maybe internal combustion engines replaced by more efficient
mechanical energy generators), a tremendous amount of primary energy could be saved (and CO2 emissions avoided).
1 One exajoule (EJ) is equal to 1018 J, or 23.86 million tons of oil equivalent (Mtoe).
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Figure 9–Total primary Energy supply, final consumption and end use in Europe [8].
In other words, less energy can be used for the same service (i.e., without changing the lifestyle of people) increasing
energy efficiency: the energy demand of most users may be reduced, the efficiency of traditional energy conversion
systems can be easily improved, and strong actions should be aimed at users to let them understand the value and not
only the price of energy. In a systemic approach, incentives should also be considered by governments as effective
policies to foster the start-up of new technologies until they become competitive.
In a word, one kWh saved is often better than one kWh produced by whatsoever source…
4. The EU solution
The EU answer to storms and monsters has been the so-called “20-20-20”, duly taking into account the previous issues.
By 2020 the EU should in fact achieve:
a reduction in EU greenhouse gas emissions of at least 20% below 1990 levels
20% of EU energy consumption to come from renewable resources
a 20% reduction in primary energy use compared with projected levels, to be achieved by improving energy
efficiency.
Goals reached so far since the baseline year 2005 are quite promising. In 2011 RES have covered 13% of final energy
consumption (20.6% of electricity is renewable) in Europe, up by 4.5% in 6 years, and GHG emissions are 16% below
1990 levels.
What about Italy? Engagements assumed by Directive 2009/28/EC required RES to grow from 5.2% in 2005 to 17% in
2020. More specifically, for the three sectors (electricity, heat and transportation) the situation in 2005 and the goals for
2020 are described in Figure 10.
Figure 10 –Italy: “20-20-20” engagements: situation in 2005 and expectations for 2020.
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Figure 11 –Electricity consumption (% and TWh) in Italy (2000-2012).
In 2005 (see fig. 11), with a total gross electricity consumption of 352 TWh (1 Mtoe = 11.63 TWh), 50 TWh (or 14% of
total consumption) came from renewable energy sources (96% from hydro and geothermal), 253 TWh (72%) were
produced by thermal power plants burning fossil fuels, and the remaining 49 TWh (13.9%) were imported.
In 2012, with more or less the same total gross consumption as in 2005 (349 TWh) renewable energy reached 82 TWh
(23.5%), almost doubled respect to 2005, thanks to wind and PV which increased by a factor 16 in only 7 years. 43
TWh (12.3%) were imported, and 218 TWh (down by 10 points to 62.5%) were produced by power plants burning
fossil fuels. Further progress is forecasted for 2013, meaning that the goals for 2020 are, on the electrical side, almost
already reached. On the other hand, heat and transportation are still far from the target.
5. Final considerations
The extraordinary effort produced by the EU has to be acknowledged, and its results in terms of CO2 emissions is
clearly visible (see figure 12). However, it’s quite evident from the same figure that the situation with the rest of the
world is completely different. While the EU CO2 emissions in the period 2005-12 decreased from 7.5 to 7 billion tons,
those of the rest of the World increased them from 21.5 to 27.5 billion tons (+28%), making the whole balance grow
from 29 to 34.5 billion tons (+19%).
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Figure 12 - CO2 emissions in Europe and in the World.
What else can we do if we want to stabilize CO2 emissions to 450 ppm, and limit the effects of global warming?
In front of us we have a difficult choice between two alternative ways of thinking.
The first alternative would aim at fueling the increasing economic development of most world countries with “large
size” and high impact carbon-free measures, such as:
increase RES installations, if necessary covering square kilometres of fertile land for intensely exploiting RES
increase the number of nuclear installations
adopt Carbon Capture and Sequestration (CCS) techniques requiring, for a 1000 MW coal plant, the injection
of 6 Mt (9 million cubic meters) of CO2 every year
imitate volcanoes by geoengineering techniques requiring the injection of million tons of sulfur into the
stratosphere in order to counteract the warming effect of CO2 concentration increase.
Some scientists strongly support these ideas, claiming that a negative opinion would reveal a “watermelon” (green skin
but with a red heart) way of thinking.
The other alternative would be to understand that people’s welfare may be separated by energy – whatever energy –
consumption.
In order to decarbonise our economy we should not only think of replacing fossil fuels with RES, but rather to adopt a
new paradigm accommodating them in a completely different energy system where energy demand has been
minimised, and heat, gas and power networks should become able to:
host any clean energy source available
handle two-directional energy flows (from centre to periphery and vice versa) so that the traditional difference
between consumers and producers fades away and users become “prosumers”
shave the demand power peaks using centralized and local storage facilities (water basins, clean and efficient
batteries...),
automatically switch among different energy networks (power to gas to heat…..) in order to satisfy the demand
so that energy networks become intermodal like transportation networks.
In a few words, smart grid systems should be created, where demand is reduced, residual demand is always met with the
cleanest available fuel and waste of energy is reduced to a minimum: not impossible, but a hard job in front of us!
6. References
1 World Resources Institute, http://www.wri.org/publication/navigating-numbers, 2005.
2 IUP, Institute für Umweltphysik, http://www.flickr.com/photos/41766005@N06/4042373874/
3 BP Statistical review of World Energy, http://www.bp.com/en/global/corporate/about-bp/statistical-review-of-
world-energy-2013.html, 2013.
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4 Steve Pacala, Princeton University Centre for Energy and Environmental Studies (PU-CEES), as reported by
Robert Socolow at CLAIRE Convention, Politecnico di Torino, Pra Catinat, May 2013.
5 Robert Socolow, Princeton University Centre for Energy and Environmental Studies (PU-CEES), CLAIRE
Convention, Politecnico di Torino, Pra Catinat, May 2013.
6 Trovò E., Moduli fotovoltaici ed emissioni di gas serra, Tesi di laurea, Politecnico di Torino, 2013.
7 Zubi, G., Future of Distributed Grid-Connected PV in South Europe. PhD Thesis, University of Zaragoza and
Politecnico di Torino, 2010.
8 Ecoheatcool, WP1 - The European Heat Market, Final Report,
http://www.euroheat.org/Files/Filer/ecoheatcool/documents/Ecoheatcool_WP1_Web.pdf , Bruxelles, 2006.
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