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"Sapienza" Università degli Studi di Roma
Ingegneria Astronautica, Elettrica ed Energetica
Impianti Elettronucleari
Seminari del Prof. Agostino Mathis – Anno 2018
ENERGIA NUCLEARE
PER LA SOSTENIBILITA’ A LUNGO TERMINE
Secondo Seminario - 5 dicembre 2018
5. Esempi di utilizzo degli Small Modular Reactors
6. L’integrazione degli impianti nucleari con fonti
intermittenti e non-programmabili
7. La sovraproduzione degli impianti nucleari integrati con le
fonti intermittenti
8. Produzione di bio- ed eco-carburanti
Prof. Agostino Mathis – Via Bertero, 61 – 00156 ROMA (Italy)
Cell. 338-1901198; E-mail: amathisit@yahoo.com 1
Due modi tipici di usare gli SMR
Nelle tavole seguenti, si descrivono alcuni esempi di utilizzo
degli SMR, raggruppabili nelle due seguenti modalità:
Centrali costituite da più reattori modulari:
• Cluster di reattori HTR-PM a Shidaowan (Cina)
• Cluster di reattori NuScale in Utah (USA)
• Cluster di reattori SMR off-shore su isole artificiali (UK)
Generazione distribuita:
• Teleriscaldamento (district heating): NHR200-II della CGN e
DHR-400 Yanlong della CNNC (Cina)
• Completa decarbonizzazione: elettricità, calore per processi
industriali e riscaldamento, acqua calda, ed anche carburanti
liquidi, per l’area metropolitana di Helsinki (Finlandia), di 1,5
milioni di abitanti
Centrali costituite da più reattori modulari: • Cluster di reattori HTR-PM a Shidaowan (Cina) • Cluster di reattori NuScale in Idaho e Utah (USA) • Cluster di reattori SMR off-shore su isole artificiali (UK)
Cina all’avanguardia: a Shidaowan la prima centrale modulare basata sul reattore HTR-PM Si tratta di un reattore ad alta temperatura “pebble bed” (a letto di sfere) refrigerato ad elio in grado di produrre vapore alle stesse condizioni di un moderno impianto alimentato a carbone. Sono in costruzione 2 reattori HTR-PM da 250 MWth, che alimentano un turboalternatore da 210 MWe, a cui se ne potranno aggiungere altri, del medesimo tipo e potenza. Se l’impianto si comporterà nel modo sperato, la Cina farà partire un piano per rimpiazzare con questo reattore, entro il 2040, 300- 400 caldaie a carbone, a partire dalle zone popolate ad alto inquinamento atmosferico. Da: «NUCLEARE A FISSIONE: STATO ATTUALE E PROSPETTIVE PER UN MONDO A BASSE EMISSIONI» Tesi di Stefano Costa – Sapienza università di Roma – 2017.
Il reattore ad alta temperatura HTR-PM (1/3) Poiché questi reattori dovranno funzionare vicino a zone densamente abitate, si è investito molto sulla sicurezza: si prevede che le sfere di combustibile (con diametro di 60 mm, e composte da migliaia di particelle TRISO, da 0,5 mm di diametro) possano resistere ad una perdita del refrigerante, dato che la temperatura massima che si raggiungerebbe all’interno del vessel sarebbe comunque più bassa della massima sopportabile, pari a 1600°C. La taglia base dovrebbe essere di 600 MWe, suddivisi su 3 moduli, aventi ciascuno 2 reattori, collegati ad una turbina a vapore. Il costo previsto per la costruzione è di 5000 $/kW, ma gli studiosi cinesi si aspettano che in futuro potrà scendere fino a 2000 $/kW. Da: «NUCLEARE A FISSIONE: STATO ATTUALE E PROSPETTIVE PER UN MONDO A BASSE EMISSIONI» Tesi di Stefano Costa – Sapienza università di Roma – 2017.
Impianto nucleare HTR-PM standard da 2 x 600 MWe [fonte: Tsinghua University] Da: «NUCLEARE A FISSIONE: STATO ATTUALE E PROSPETTIVE PER UN MONDO A BASSE EMISSIONI» Tesi di Stefano Costa – Sapienza università di Roma – 2017.
Il reattore ad alta temperatura HTR-PM (2/3) Il modulo base dell’impianto HTR-PM dimostrativo consiste in due reattori collegati ad una turbina a vapore da 210 MWe; ogni reattore ha un generatore di vapore e un circolatore principale dell’elio, oltre a tutti gli internals di grafite, carbonio e altri metalli. La potenza termica di ogni reattore è di 250 MWth (megawatt termici); l’elio viene riscaldato da 250 °C a 750 °C; il vapore inviato alla turbina ha una temperatura di 567 °C e una pressione di 13,25 MPa. Il rendimento complessivo dovrebbe essere elevato, pari al 42%. Il combustibile, contenuto nella particella TRISO, è diossido di uranio con un arricchimento del 8,6%. Da: «NUCLEARE A FISSIONE: STATO ATTUALE E PROSPETTIVE PER UN MONDO A BASSE EMISSIONI» Tesi di Stefano Costa – Sapienza università di Roma – 2017.
Caratteristiche principali del reattore HTR-PM [fonte: Tsinghua University] Da: «NUCLEARE A FISSIONE: STATO ATTUALE E PROSPETTIVE PER UN MONDO A BASSE EMISSIONI» Tesi di Stefano Costa – Sapienza università di Roma – 2017.
Il reattore ad alta temperatura HTR-PM (3/3) Il punto di forza di questo impianto sta nella sua sicurezza. Il rischio di una fusione del nocciolo è ridotto al minimo: la particella TRISO ha una temperatura limite di 1600-1800 °C, la densità volumetrica di potenza è relativamente bassa e la potenza è distribuita in più moduli, ognuno con il suo sistema di emergenza. Andamento della temperatura del combustibile in caso di mancata refrigerazione [fonte: Tsinghua University] Da: «NUCLEARE A FISSIONE: STATO ATTUALE E PROSPETTIVE PER UN MONDO A BASSE EMISSIONI» Tesi di Stefano Costa – Sapienza università di Roma – 2017.
From: https://www.nextbigfuture.co m/2017/09/china-high- temperature-nuclear-reactor- could-replace-coal-plants-and- provide-industrial-heat.html
UTAH ASSOCIATED MUNICIPAL POWER SYSTEMS (UAMPS) CARBON FREE POWER PROJECT (CFPP) UAMPS formally launched the CFPP in 2015. In August 2015, DOE awarded a second, $33.2 million cost share award to NuScale for site selection, characterization and the preparation of a combined construction and operating license application (COLA) for the UAMPS CFPP. Initial licensing and investigative activities are underway with the expectation that the COLA preparation will be completed in 2020. From: https://www.nuscalepower.com/projects/carbon-free-power-project
Nuclear Can Be Friends With Renewables—If It’s Modular Nuclear startup NuScale crunches data on how its nuclear reactors can follow a wind farm. KATIE FEHRENBACHER JUNE 23, 2017 If all goes well, NuScale’s first commercial plant could be operating in Idaho by 2026 for Utah Associated Municipal Power Systems and operated by Energy Northwest. From: https://www.greentechmedia.com/articles/read/nuclear-can-be-friends-with-renewables#gs.R4YACvo
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Gli SMR nella strategia del Regno Unito (1/4) From: http://euanmearns.com/uk-electricity-2050-part-2-a-high-nuclear-model/#more-15604
Gli SMR nella strategia del Regno Unito (2/4) From: http://euanmearns.com/uk-electricity-2050-part-2-a-high-nuclear-model/#more-15604
Gli SMR nella strategia del Regno Unito (3/4) From: http://euanmearns.com/uk-electricity-2050-part-2-a-high-nuclear-model/#more-15604
Gli SMR nella strategia del Regno Unito (4/4) From: http://euanmearns.com/uk-electricity-2050-part-2-a-high-nuclear-model/#more-15604
Generazione distribuita:
• Teleriscaldamento (district heating): NHR200-II
della CGN e DHR-400 Yanlong della CNNC (Cina)
• Completa decarbonizzazione: elettricità, calore per
processi industriali e riscaldamento, acqua calda, ed
anche carburanti liquidi, per l’area metropolitana di
Helsinki (Finlandia), di 1,5 milioni di abitantiDistrict Heating of Northern Chinese Cities
China’s government agencies, the National Development and
Reform Commission (NDRC) and the National Energy
Administration have announced a five-year plan to convert
70% of northern cities to mostly natural gas heating
instead of coal.
(omissis)
Half of northern China should be converted to clean
heating by 2019. China General Nuclear (CGN) and China
National Nuclear Corporation (CNNC) are both looking to
develop small nuclear reactors for district heating.
From: https://www.nextbigfuture.com/2018/02/nuclear-reactors-for-heating-can-be-mass-
produced-and-each-would-take-two-years-to-build.htmlFrom: https://www.nextbigfuture.com/2018/02/nuclear-reactors-for-heating-can-be-mass- produced-and-each-would-take-two-years-to-build.html
The NHR200-II CGN and Tsinghua University are undertaking a feasibility study using the NHR200-II low-temperature heating reactor, a vessel type reactor of 200 MWt. This reactor already years ago passed a safety review by the National Nuclear Safety Administration, and came first in NEA’s review of small-scale nuclear reactor technology in 2016. CGN said the NHR200-II can be used to provide heat, water and steam for residential heating and industrial processes, and energy for remote areas. It is also flexible to location and can be built near to the end-users. Construction would take only two to three years if done on a mass scale. From: https://www.nextbigfuture.com/2018/02/nuclear-reactors-for-heating-can-be-mass- produced-and-each-would-take-two-years-to-build.html
The DHR-400 Yanlong
China National Nuclear Corp (CNNC) has already conducted
a successful 168-hour trial run in Beijing of the DHR-400, a
small district heating reactor know as the Yanlong.
This reactor is an alternative heat supplier, providing 400 MWt,
able to heat 200,000 urban households.
The pool-type design comprises a reactor core immersed in
a water-filled tank. It will require CNY1.5bn ($226.7m) in
investment, take three years to build and could be plugged
directly into existing heating network.
…continua…
From: https://www.nextbigfuture.com/2018/02/nuclear-reactors-for-heating-can-be-mass-
produced-and-each-would-take-two-years-to-build.htmlA 400-megawatt nuclear heating reactor, as the Yanlong, can generate as much heat per year as the burning of 320,000 tons of coal or 160 million cubic meters of natural gas, and Yanlong releases no carbon dioxide or dust into the air. Yanlong, if used as an alternative to coal-fired or gas-fired boilers of the same capacity, will reduce emissions of carbon dioxide by 640,000 tons or 204,600 tons per year. To produce a gigajoule of heat with a DHR-400 costs just 30-40 yuan ($4.58-6.1), on par with traditional coal-fired boilers, and around 40 percent of the cost to produce the same amount using a gas-fired boiler. From: https://www.nextbigfuture.com/2018/02/nuclear-reactors-for-heating-can-be-mass- produced-and-each-would-take-two-years-to-build.html
SMR per la generazione distribuita: una
proposta di completa decarbonizzazione
…continua…Electricity only accounts for roughly a third of our energy related
emissions. Industrial processes, space heating and hot water
use, along with liquid fuels for transportation make up most of the
rest of our energy demand. This energy use needs also to be
decarbonized by mid-century, either by electrifying it (and
producing that electricity cleanly) or by replacing burning of fuels
with other means.
This study presents a scenario in which small, advanced nuclear
reactors are used to achieve a relatively cost-effective deep
decarbonization of district heating, electricity, and
transportation fuels in a city of roughly 1.5 million
inhabitants. The used energy is divided as follows: 8 TWh for heat,
12 TWh for electricity, and 4 TWh for hydrogen production
every year.
…continua…KEY POINTS:
# Upcoming small, advanced nuclear reactors can offer a cost-effective and
reliable source of low-carbon heat and electricity for various uses, such as
cities with district heating networks.
# Combined heat and power (CHP) improves the economics of nuclear
reactors immensely. Instead of producing power at 35% efficiency, they
can produce heat and power at over 80% efficiency.
# Small, high-temperature reactors can be used to produce affordable
hydrogen with High Temperature Steam Electrolysis (HTSE). This can be
done as part of seasonal load following of energy demand.
# Affordable hydrogen can be used to decarbonize transportation fuels
by making synfuels from it, and other chemicals that use hydrogen (such as
ammonia for nitrogen fertilizer).
# The annual energy use of 8 TWh of heat, 12 TWh of electricity and 4
TWh of hydrogen can be produced with roughly 4 GWth of high-temperature
thermal nuclear capacity, or roughly ten small, advanced nuclear reactors
with a thermal capacity of 400 MW each.
…continua…This study explores how a city of approximately 1.5 million
people can be totally decarbonized by 2050, using mainly
advanced nuclear reactors. District heating, electricity, and
transportation fuels all need to be decarbonized by 2050, and
large-scale use of bioenergy is not a sustainable option. The
Helsinki metropolitan area is used as the background case for most
of the modelling, although there is little to stop anyone from
scaling and modifying the energy demand profile for other locations
as needed. With the large seasonal variations in heat and
electricity demand, Helsinki area presents a challenging
environment for any decarbonization effort. The advantage of using
dispatchable nuclear energy is that it works reliably in any
location and throughout the year. With a more stable seasonal
demand profile, the situation becomes easier.
…continua…The scenario presented in this paper has enough
baseload nuclear capacity to supply most of the heat
and power needs even during the high-demand
winter. During low demand in the summer, this extra
capacity is used to make hydrogen with High
Temperature Steam Electrolysis (HTSE). This allows a
relatively efficient system, where there is little need to
throttle back nuclear capacity, and one that also
decarbonizes not just electricity and heat, but also
transportation fuels and parts of chemical industry
feedstocks. Today, chemical industry is the third largest
greenhouse gas industrial emitter in Europe.
…continua…What if there is no district heating network? This is the situation in
most places, although according to Europe Heat Roadmap this
should change drastically in the coming decades – the aim is to
increase share of district heat from 10 percent to 50 percent of
households. Often these locations use natural gas, electricity, oil, and
solid fuels for heating needs. In Europe (EU-28), the annual demand
for space heating is over 3,000 TWh, industrial process heating
over 2,000 TWh and hot water use and other heating make up
almost 1,000 TWh. Well over two thirds of this energy is produced
with fossil fuels. Further, 42 percent of industrial heat uses
temperatures of over 500 degrees C, supplied almost exclusively
by burning fossil fuels. The total annual “heat market” of EU-28
countries is around 6,000 TWh, representing almost half of final
energy demand.
…continua…The hard, climate truth is that most burning should stop by mid-
century, and this will be extremely difficult. In Germany, if natural
gas was replaced with electricity, the gap between highest and
lowest electricity demand between summer and winter would
grow by 87 gigawatts from the current 11 gigawatts. Such a
shift in demand is a tall order, made only taller with the German
decisions to close nuclear power plants that currently provide
both baseload and load-following services in Germany.
Ways to make affordable synthetic methane or other fuels that
can be utilized with current infrastructure (gas heating and gas
stoves) would be of great help, while simultaneously the Germans
should clean their electricity production. The more we can use
existing infrastructure, the easier, cheaper and faster the
transition will be.
…continua…WHAT REACTORS WERE CHOSEN FOR THE STUDY AND WHY?
Some key-criteria in selecting the prospective reactors were:
• Likely commercial availability in the 2020s or early 2030s.
• Availability of key-specifications and other information.
• High enough operating temperature to make high temperature
steam electrolysis feasible (around 600 °C or higher).
• Nimble operation with the possibility to offer load-following
services in stabilizing the grid.
Based on these, two reactor types are looked in more detail.
HTR-PM pebble-bed reactor that China is currently building, and
Terrestrial Energy’s IMSR (Integral Molten-Salt Reactor) that is
currently being designed in North America.
…continua…ENERGY TRANSFER CONCEPTS
With molten salt reactor such as the IMSR, the actual reactor can
be several kilometers from the turbine-hall and district
heating network connection, and have the energy transferred as
molten salt. Of course, the longer the distance, the greater the costs
of building it and the more losses there will be along the way. But this
sort of flexibility of the reactor can be invaluable when siting the
reactor near populated areas.
Greater temperatures also enable other interesting options for
transferring the energy for even longer distances. One option is to
move the energy in a closed loop chemically. This is achieved by
having a steam reforming facility near the nuclear plant, which
utilizes nuclear heat in the process. The resulting mixture of carbon
monoxide and hydrogen is then transported via pipeline to a
methanation facility at the other end, where the exothermic
methanation process can supply relatively high temperature steam
(over 500 °C), either for industrial use or for electricity or CHP
production. After this has happened, the resulting methane is piped
back to the nuclear plant for steam reforming. Other chemical
reactions can also be used.
…continua……continua…
This is only one example, which has a timeline of 24 years
to reach full capacity. The capacities pictured above are
average operational capacities, but given the CHP
capabilities of most of the plants, the maximum capacity
is over 2,500 MW for heat and 1,800 MW for
electricity. HTSE capacity needs to be at around 650 MW
(see next chapter). The total thermal capacity of the
system above is 4 GW (10 x 400 MWth).
…continua…FLEXIBLE LOAD FOLLOWING
While smaller amounts of heat and electricity can be stored to
account for changes in daily or weekly demand, the northern
climate of Helsinki region offers a tremendous challenge for
meeting seasonal variability in heat and electricity demand.
Ramping production up and down with capital intensive energy
sources (nuclear, wind, solar) makes little sense from the owner’s
perspective, unless they are paid to do so (capacity payment,
n.d.r.).
One option is to make hydrogen/synfuels with the spare
capacity when demand is low (May-September) and store them
for periods when heat and power demand is high (November-
March).
…continua…Seasonal load-following is done not with the energy
source itself, but with a storage medium that can also be
used for decarbonizing transportation fuels and other
chemical industry feedstocks.
…continua…Of course, the investor is then faced with investing in
electrolysers which will not be used at their full
capacity, or storage facilities that match this variability
in production and demand, not to mention the space
needed for such storage capabilities.
A more detailed cost-analysis is needed to calculate the
optimum mix of storage costs and number of full-load
hours that the electrolyser can operate. Below is a
chart with one option presented, along with a chart
mapping the storage capacity needed and its use
throughout the year.
…continua…In the above graphs, the average hydrogen production capacity
is around 450 MW, while the maximum capacity (used for 5
months) is around 650 MW. For the three coldest winter months
(December to February), the electrolysers are run at minimal
capacities, between 50 and 200 MW.
In this case, the electrolyser would be used at load factor of
around 70%. While it is not optimal, it is much higher than can be
achieved with solar and/or wind power surplus energy. A better
load factor reduces the share of capital costs on the hydrogen
produced and the need for massive storage.
…continua…Producing more hydrogen instead of heat and electricity in the
summer months would even out the maximum capacity
needed and increase the load factor for the nuclear reactors.
Below is chart showing the monthly demand for each of these in
such a scenario. The graph uses the following assumptions: 87 %
average thermal efficiency for CHP production, and 41 %
thermal efficiency for hydrogen production.
The energy system would have a maximum demand of around
4,000 MWth and an average demand of roughly 3750 MWth,
translating to a load factor of over 93 %. By timing maintenance
and other work smartly, the reactors could run at full steam all
the time.
…continua…COST ESTIMATES Estimating future costs of something often comes down to making various assumptions, and justifying those assumptions somehow. The reactors presented in this study have not yet been built and operated for sufficient periods to have hard data. The cost estimates presented here are either industry estimates or found from the genre literature. Terrestrial Energy, the developer/vendor of IMSR, has estimated the costs of producing energy with their reactor. The rough ballpark is: •
The cost of a single 400 MWth IMSR reactor is estimated at roughly around 800 million euros. This would imply that the total investment cost with ten 400 MWth reactors, with CHP and HTSE-capacity, would be roughly in the ballpark of 10 billion euros, invested over two decades. In comparison to traditional nuclear reactors – which cost roughly the same per MWth – these reactors offer higher temperatures and are therefore more versatile. They can be sited more flexibly in regard to size and possibility for CHP and district heating. Finally, they are built in series with the first ones bringing revenue long before the total 10 billion is reached (less money is spent on total cost of financing and interest rates). …continua…
An interesting quote from Terrestrial Energy is that they
estimate hydrogen production with their reactor and
High Temperature Steam Electrolysis to be
commercially competitive with current methods
(methane steam reform) by the time the reactor is ready to
enter the market – that is, in the 2020s.
Given that the price of natural gas in North America is
currently quite low compared to Europe, and given that
these methods of hydrogen production have externalized
their costs (emissions) quite efficiently, this is very
promising news.
…continua…The capital cost of the HTR-PM is estimated to be slightly
larger (5-20%) than a conventional light water reactor of
the same size. The price difference in produced electricity is small
due to higher efficiencies and also other opportunities
available with higher temperatures.
The construction times are shorter, so the capital cost should
be easier to bear. Perhaps the most promising feature of HTR-PM
reactor is that the first commercial scale prototype is
practically finished.
There are plans for serial production for these reactors in
China to replace supercritical coal plants, so that the old
infrastructure and turbines can be reused.
…continua…Conclusions – What makes sense? (1/3)
The most sensible solution for most decarbonization
schemes is likely to be a mix of various clean energy
sources, each according to their strengths and weaknesses.
Solar in northern latitudes is unlikely to be able to play a
large role in the mix due to seasonal variations that run
contrary to seasonal demand variations.
Wind is also intermittent, but more balanced throughout
the year, with more production in the winter. Therefore, it
would need less seasonal storage, but a significant amount
of intermediate storage (days, perhaps weeks).
…continua…Conclusions – What makes sense? (2/3)
Small and/or High temperature advanced reactors offer
exciting possibilities for a system-wide decarbonization.
For example, the possibility to run High Temperature Steam
Electrolysis means that we can simultaneously run a much
larger fleet of reactors at full power year around, and
provide clean hydrogen for decarbonizing other sectors in the
society, such as transportation fuels and fertilizer industry.
This can also be done with traditional electrolysers and
intermittent production such as wind and solar, but it would
likely mean much lower average capacity factors for the
electrolysers.
…continua…Conclusions – What makes sense? (3/3) Heat in various forms represents around half of all our final energy use in the EU. Small nuclear reactors are one of the few options we have in supplying reliable low-carbon heat for industrial processes, district heating networks and other uses in a practical manner. Another key finding is that if nuclear reactors are used for combined heat and power, their overall efficiency and economics can improve enormously compared with producing just electricity (depending of course on the relative market prices for heat and electricity). This would lower the relative costs of our decarbonization efforts.
Una strategia a bassa emissione di carbonio Lo scenario e le opzioni progettuali L’energia elettrica rappresenta non più di un quarto o un quinto del consumo di energia primaria. Occorre allora mirare al soddisfacimento delle esigenze anche di combustibili e carburanti, da produrre ed utilizzare con ridotte o nulle emissioni di carbonio. Le opzioni energetiche da considerare sono: le rinnovabili elettriche, senz’altro la idroelettrica, ma anche quelle non- programmabili, come sole e vento; le biomasse e la nucleare, le quali sono programmabili e possono fornire sia elettricità che calore.
Lo studio del MIT sull’integrazione nucleare-rinnovabili Presso il Massachusets Institute of Technology, un gruppo di ricercatori, guidato da Charles W. Forsberg, ha iniziato una serie di studi per definire uno scenario a lungo termine in cui le energie rinnovabili, anche non-programmabili, siano integrate con l’energia nucleare, per soddisfare tutte le esigenze energetiche dell’Umanità con il minimo impatto sull’ambiente.
Sintesi del Rapporto MIT-NES-TR015 (1/5) Obiettivo: verso un mondo a basso tenore di carbonio. Opzioni energetiche che assicurino: • energia elettrica, ma anche • combustibili e carburanti; • ridotte o nulle emissioni di carbonio, ma anche • sicurezza ed autonomia energetica. Si considerano: • la nucleare, come fonte sia di elettricità che di calore; • le rinnovabili elettriche, anche quelle non-programmabili; • le biomasse.
Sintesi del Rapporto MIT-NES-TR015 (2/5) Vincoli operativi: sia la fonte nucleare, sia le rinnovabili elettriche, richiedono elevati investimenti nell’impianto, mentre i costi di gestione sono molto ridotti; allora: • gli impianti nucleari dovranno lavorare “a tavoletta”; • gli impianti per le rinnovabili elettriche non- programmabili (eolici, solari) dovranno poter immettere in rete tutta l’energia offerta momento per momento dagli eventi naturali.
This diagram shows that much of the electricity demand is in fact for continuous 24/7 supply (base-load), while some is for a lesser amount of predictable supply for about three quarters of the day, and less still for variable peak demand up to half of the time. (V. traduzione alla tavola seguente). Da: WNA “World Energy Needs and Nuclear Power (September 2009).
Carico di base e carichi variabili Nei Paesi industrializzati almeno due terzi della domanda elettrica è “carico di base”, costante nelle 24 ore e poco variabile durante la settimana e le stagioni: escluse le fonti fossili, la soluzione più conveniente per questo tipo di domanda, sarebbe senz’altro il nucleare. L’uso esclusivo delle rinnovabili intermittenti e non- programmabili come vento e sole, infatti, richiederebbe potenze installate molto superiori al picco della domanda, e la disponibilità di enormi e costosissimi sistemi di accumulo, che potrebbero anche più che raddoppiare il costo del kWh da rinnovabili.
Sintesi del Rapporto MIT-NES-TR015 (3/5) Per far fronte ai precedenti diagrammi di carico elettrico, occorrerebbe una fonte programmabile in grado di arrivare a coprire anche i picchi massimi (in caso di assenza completa di sole e vento!): questa non può che essere la nucleare (avendo escluso le fonti fossili). Ma quando il carico richiesto non è al massimo, e/o vi è produzione eolica o solare, la sovraproduzione degli impianti nucleari (che conviene operino sempre “a tavoletta”) deve essere utilizzata in altro modo, sia in forma elettrica che termica.
Sintesi del Rapporto MIT-NES-TR015 (4/5) La sovraproduzione degli impianti nucleari può allora essere utilmente utilizzata in forma elettrica (oggi, circa 1/3 della potenza primaria): • per ricaricare impianti idroelettrici ad accumulo; • per produrre idrogeno per via elettrolitica (anche elettrolisi ad alta temperatura). L’idrogeno può poi essere utilizzato come tale, o nella sintesi di carburanti da biomasse, o aggiunto nei gasdotti del gas naturale.
Da: Charles W. Forsberg - MIT-NES-TR-015 - September 2011.
Sintesi del Rapporto MIT-NES-TR015 (5/5) La sovraproduzione degli impianti nucleari può anche essere utilmente utilizzata in forma termica (oggi, da circa 2/3 fino all’intera potenza primaria): • per sfruttare i grandi giacimenti di idrocarburi non convenzionali (in sabbie, scisti) evitando emissioni di carbonio; • per produrre combustibili e carburanti da biomasse, evitando la loro combustione per il calore di processo; • per riscaldare grandi volumi di sottosuolo, da utilizzare come fonte di energia geotermica in tempi successivi.
SMES: Superconducting Magnetic Energy Storage. Da: Charles W. Forsberg - MIT-NES-TR-015 - September 2011.
Da: Charles W. Forsberg - MIT-NES-TR-015 - September 2011.
From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
LWR: Light Water Reactor. From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
From: C. Forsberg “Alternative Nuclear Energy Futures” Ohio State University - Columbus, August 13, 2012.
Bio- ed eco-carburanti Per la produzione di biocarburanti, l’energia nucleare può fornire calore di processo e idrogeno alla bioraffineria, evitando la combustione di biomasse a tale scopo, e triplicando quindi la quantità di carburanti liquidi prodotta per una data quantità di biomassa. Eco-carburanti liquidi possono essere anche prodotti partendo dall’anidride carbonica dell’aria e dall’idrogeno dell’acqua, col calore e l’elettricità forniti da un impianto nucleare. Secondo il citato gruppo del MIT, questa opzione potrebbe fornire quantità illimitate di carburante liquido ad un costo non superiore a 10-12 US$ al gallone.
Da: Charles W. Forsberg - MIT-NES-TR-015 - September 2011.
Da: Charles W. Forsberg - MIT-NES-TR-015 - September 2011.
Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.
Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.
Electricity storage (Battery and functionally equivalent) CAES: Compressed Air Energy Storage; SMES: Superconducting Magnetic Energy Storage; T&D: Transmission and Distribution; UPS: Uninterrupted Power Supply. Salvo in parte il Pumped Hydro, mancano adeguati accumuli stagionali! Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.
FIRES: Firebrick Resistance-Heated Energy Storage Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.
RATHS: Reactor Associated Thermal Heat Storage Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.
NUTOC: Nuclear Topping Cycle (1/4)
FHR: Fluoride salt-cooled High-temperature Reactor.
Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.NUTOC: Nuclear Topping Cycle (2/4)
FIRES: Firebrick Resistance-Heated Energy Storage.
Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.NUTOC: Nuclear Topping Cycle (3/4) FIRES: Firebrick Resistance-Heated Energy Storage. Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.
NUTOC: Nuclear Topping Cycle (4/4) Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.
Hybrid: Co-Produce Electricity and Second Product Da: Charles Forsberg - MIT-ANP-TR-162 – August 2015.
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