Fjo De Ridder

Four potential business cases for demand side integration

In this study, we explore briefly four different business cases for smart power by means of simulations. For that reason three types of intelligent systems for household applications are modeled: electric devices with a storage capacity like boilers, shiftable loads like washing machines and batteries. A district of 300 houses is simulated. Agents, representing devices can trade power on virtual markets, like the PowerMatcher. First, the relation between load flows and smart power is examined. We found, as a rule of thumb, that the variations in load flow decreases proportionally to the fraction smart controlled power. This might have important consequences for investment policies in power networks. Next, the stability of a cluster is examined. Here it is estimated how long a cluster can remain stable if a constant power flux is imposed. This flexibility can be traded, directly on an imbalance market or through a balance responsible party (BRP). In the next two business cases, the implications for retailers and end-users are examined for three billing types: a fixed tariff, a two tariff structure and an hourly “real-time” tariff structure. Compared to the fixed tariff structure, the incentive to use smart devices is small in the double tariff structure. In a real-time tariff structure the income increases and the risk decreases for the retailer, while end-users have the potential to decrease costs.

Isotopic model of oceanic silicon cycling: The Kerguelen Plateau case study

A box model is presented describing the time evolution for the three stable Si isotopes (or total concentration and natural isotopic compositions), both in the dissolved and biogenic pools. Temporal variations are controlled by uptake, dissolution (both with isotopic fractionation), settling/export and mixing/advection (without isotopic fractionation). The basic building blocks of the model are combined to form a setup for the Kerguelen Plateau where distinct ‘‘plateau’’ and ‘‘out-plateau’’ areas exist and where measurements were made at the end of the growth season (early 2005, KEOPS cruise: Kerguelen Ocean and Plateau compared Study). In addition, we distinguished between surface (0–100 m) and subsurface (100–400 m) water. This resulted in a model composed of eight compartments, each containing three variables (the three Si isotopes) whose time evolution can be modelled. The model does not assume steady state, and can therefore be used to simulate transient events like blooms. We applied the model to simulate the 2004–2005 growth season. The model parameterisations were kept as simple as possible. Still, the KEOPS measurements were satisfactorily reproduced and estimates of instantaneous and seasonally integrated fluxes compared well with previous literature. & 2012 Elsevier Ltd. All rights reserved.