1,411 research outputs found
The role of demand response in mitigating market power - A quantitative analysis using a stochastic market equilibrium model. ESRI WP635, August 2019
Market power is a dominant feature of many modern electricity markets with an oligopolistic structure, resulting in
increased consumer cost. This work investigates how consumers, through demand response (DR), can mitigate against market
power. Within DR, our analysis particularly focusses on the impacts of load shifting and self-generation. A stochastic mixed
complementarity problem is presented to model an electricity market characterised by oligopoly with a competitive fringe. It
incorporates both energy and capacity markets, multiple generating firms and different consumer types. The model is applied to
a case study based on data for the Irish power system in 2025. The results demonstrate how DR can help consumers mitigate
against the negative effects of market power and that load shifting and self-generation are competing technologies, whose
effectivity against market power is similar for most consumers. We also find that DR does not necessarily reduce emissions in
the presence of market power
Time-dependent density functional theory for strong electromagnetic fields in crystalline solids
We apply the coupled dynamics of time-dependent density functional theory and
Maxwell equations to the interaction of intense laser pulses with crystalline
silicon. As a function of electromagnetic field intensity, we see several
regions in the response. At the lowest intensities, the pulse is reflected and
transmitted in accord with the dielectric response, and the characteristics of
the energy deposition is consistent with two-photon absorption. The absorption
process begins to deviate from that at laser intensities ~ 10^13 W/cm^2, where
the energy deposited is of the order of 1 eV per atom. Changes in the
reflectivity are seen as a function of intensity. When it passes a threshold of
about 3 \times 1012 W/cm2, there is a small decrease. At higher intensities,
above 2 \times 10^13 W/cm^2, the reflectivity increases strongly. This behavior
can be understood qualitatively in a model treating the excited electron-hole
pairs as a plasma.Comment: 27 pages; 11 figure
Analysing long-term interactions between demand response and different electricity markets using a stochastic market equilibrium model. ESRI WP585, February 2018
Power systems based on renewable energy sources (RES) are characterised by
increasingly distributed, volatile and uncertain supply leading to growing requirements for
flexibility. In this paper, we explore the role of demand response (DR) as a source of flexibility
that is considered to become increasingly important in future. The majority of research in this
context has focussed on the operation of power systems in energy only markets, mostly using
deterministic optimisation models. In contrast, we explore the impact of DR on generator
investments and profits from different markets, on costs for different consumers from
different markets, and on CO2 emissions under consideration of the uncertainties associated
with the RES generation. We also analyse the effect of the presence of a feed-in premium
(FIP) for RES generation on these impacts. We therefore develop a novel stochastic mixed
complementarity model in this paper that considers both operational and investment
decisions, that considers interactions between an energy market, a capacity market and a
feed-in premium and that takes into account the stochasticity of electricity generation by RES.
We use a Benders decomposition algorithm to reduce the computational expenses of the
model and apply the model to a case study based on the future Irish power system. We find
that DR particularly increases renewable generator profits. While DR may reduce consumer
costs from the energy market, these savings may be (over)compensated by increasing costs
from the capacity market and the feed-in premium. This result highlights the importance of
considering such interactions between different markets
How harmonic is dipole resonance of metal clusters?
We discuss the degree of anharmonicity of dipole plasmon resonances in metal
clusters. We employ the time-dependent variational principle and show that the
relative shift of the second phonon scales as in energy, being
the number of particles. This scaling property coincides with that for nuclear
giant resonances. Contrary to the previous study based on the boson-expansion
method, the deviation from the harmonic limit is found to be almost negligible
for Na clusters, the result being consistent with the recent experimental
observation.Comment: RevTex, 8 page
Coulomb Breakup Mechanism of Neutron-Halo Nuclei in a Time-Dependent Method
The mechanism of the Coulomb breakup reactions of the nuclei with
neutron-halo structure is investigated in detail. A time-dependent
Schr\"odinger equation for the halo neutron is numerically solved by treating
the Coulomb field of a target as an external field. The momentum distribution
and the post-acceleration effect of the final fragments are discussed in a
fully quantum mechanical way to clarify the limitation of the intuitive picture
based on the classical mechanics. The theory is applied to the Coulomb breakup
reaction of Be + Pb. The breakup mechanism is found to be
different between the channels of and
, reflecting the underlying structure of Be. The
calculated result reproduces the energy spectrum of the breakup fragments
reasonably well, but explains only about a half of the observed longitudinal
momentum difference.Comment: 15 pages,revtex, 9 figures (available upon request
Examining the benefits of demand reduction policies for electricity. ESRI Research Bulletin, 2018/03
Many governments have adopted policies that provide incentives to increase the
amount of electricity generated from clean and renewable sources. However, the
availability of such sources, e.g., solar or wind energy, is unpredictable and varies
throughout the day and seasons. To account for this variability electricity systems
need to become more flexible, i.e., there must be measures in place to ensure that
demand and supply are balanced when renewable sources are not available
Universal four-component Fermi gas in one dimension
A four-component Fermi gas in one dimension with a short-range four-body
interaction is shown to exhibit a one-dimensional analog of the BCS-BEC
crossover. Its low-energy physics is governed by a Tomonaga-Luttinger liquid
with three spin gaps. The spin gaps are exponentially small in the weak
coupling (BCS) limit where they arise from the charge-density-wave instability,
and become large in the strong coupling (BEC) limit because of the formation of
tightly-bound tetramers. We investigate the ground-state energy, the sound
velocity, and the gap spectrum in the BCS-BEC crossover and discuss exact
relationships valid in our system. We also show that a one-dimensional analog
of the Efimov effect occurs for five bosons while it is absent for fermions.
Our work opens up a very rich new field of universal few-body and many-body
physics in one dimension.Comment: 9 pages, 3 figures; (v2) Efimov effect for 5 bosons in 1D is
discussed; (v3) expanded versio
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