Robert S. Cherry

Large hybrid energy systems for making low CO2 load-following power and synthetic fuel

Hybrid energy systems using nuclear heat sources can economically produce load-following electrical power by exploiting their surplus generation capacity, available at night or seasonally, to make synthetic fuel. Vehicle fuel is the only current energy use large enough to absorb all the energy capacity that might be diverted from the power industry, and its ease of storage obviates problems with discontinuous synfuel production. The potential benefits and challenges of synfuels integration are illustrated by the production of methanol from natural gas (as a source of carbon) using steam from a light water nuclear power reactor which is assumed to be available in accord with a years worth of power demand data. The synthesis of methanol is easily adapted to using 300 °C heat from a light water reactor and this simple compound can be further processed into gasoline, biodiesel (to esterify vegetable oils), or dimethyl ether, fuels which can be used with the current vehicle fleet. A supplemental feed to the methanol process of natural gas (for energy) allows operation at constant full rate when the nuclear heat is being used to produce electrical power. The higher capital costs of such a system are offset by a lower cost of heat and power production from a large base load type of plant and by reduced costs associated with much lower CO2 emissions. Other less tangible economic benefits of this and similar hybrid systems include better use of natural resources for fuels and greater energy supply reliability from the domestic production of vehicle fuel.

Framework for the Economic Analysis of Hybrid Systems Based on Exergy Consumption

Starting from an overview of the dynamic behavior of the electricity market the need of the introduction of energy users that will provide a damping capability to the system is derived as also a qualitative analysis of the impact of uncertainty, both in the demand and supply side, is performed. Then it follows an introduction to the investment analysis methodologies based on the discounting of the cash flow, and then work concludes with the illustration and application of the exergonomic principles to provide a sound methodology for the cost accounting of the plant components to be used in the cash flow analysis.

Analysis of the Production Cost for Various Grades of Biomass Thermal Treatment

Process flow sheets were developed for the thermal treatment of southern pine wood chips at four temperatures (150, 180, 230, and 270 degrees C) and two different scales (20 and 100 ton/hour). The larger capacity processes had as their primary heat source hot gas assumed to be available in quantity from an adjacent biorefinery. Mass and energy balances for these flow sheets were developed using Aspen Plus process simulation software. The hot gas demands in the larger processes, up to 1.9 million lb/hour, were of questionable feasibility because of the volume to be moved. This heat was of low utility because the torrefaction process, especially at higher temperatures, is a net heat producer if the organic byproduct gases are burned. A thermal treatment flow sheet using wood chips dried in the biorefinery to 10% moisture content (rather than 30% for green chips) with transfer of high temperature steam from the thermal treatment depot to the biorefinery was also examined. The equipment size information from all of these cases was used in several different equipment cost estimating methods to estimate the major equipment costs for each process. From these, factored estimates of other plant costs were determined, leading to estimates (+ / - 30% accuracy) of total plant capital cost. The 20 ton/hour processes were close to 25 million dollars except for the 230 degrees C case using dried wood chips which was only 15 million dollars because of its small furnace. The larger processes ranged from 64-120 million dollars. From these capital costs and projections of several categories of operating costs, the processing cost of thermally treated pine chips was found to be

Dynamic analysis of hybrid energy systems under flexible operation and variable renewable generation – Part II: Dynamic cost analysis

28-33 per ton depending on the degree of treatment and without any credits for steam generation. If the excess energy output of the two 20 ton/hr depot cases at 270 degrees C can be sold for

Nuclear-renewable hybrid energy systems: Opportunities, interconnections, and needs

10 per million BTU, the net processing cost dropped to

Dynamic Analysis of Hybrid Energy Systems under Flexible Operation and Variable Renewable Generation -- Part I: Dynamic Performance Analysis and Part II: Dynamic Cost

13/ton product starting with green wood chips or only

Low energy packed tower and caustic recovery for direct capture of CO2 from air

3 per ton if using dried chips from the biorefinery. Including a 12% return on invested capital raised all of the operating cost results by about

Removal of introduced inorganic content from chipped forest residues via air classification

20/ton.