Colin Pritchard

Solar cooling technologies in Greece. An economic viability analysis

In Greece, during the summer, the demand for electricity greatly increases because of the extensive use of air-conditioning systems. This is a source of major problems in the country’s electricity supply and contributes to an increase of the CO2 emissions. The use of solar energy (SE) to drive cooling cycles is attractive since the cooling load is roughly in phase with SE availability. An economic evaluation of two types of solar cooling systems is made (an absorption and an adsorption system). The analyses indicated that, because of their high investment cost, these systems would be marginally competitive with standard cooling systems at present energy prices.

Industrial Ecology as a learning process in business strategy

For Industrial Ecology to be successful, it will need to be adopted by many practitioners in industrial society, at different system levels (e.g. company, region, national). This paper adapts the technology transfer model developed by Seaton and Cordey-Hayes by combining it with the idea of industrial ecology as a learning process. The resulting model is applied at the company, network and government level. Its use is illustrated with case studies from research on regional industrial symbiosis in Scotland, the recently formed National Industrial Symbiosis Programme (UK) and the Scottish Industrial Symbiosis Programme. The model helps to understand how differing practitioners, at different levels, can be influenced by a range of factors and how IE can become part of their strategy. Industrial Symbiosis is seen as a way to induce a cultural shift by fostering inter-company co-operation within a region, building on previous partnerships, and involving a range of actors.

Energy recovery and plume reduction from an industrial spray drying unit using an absorption heat transformer

Abstract Spray drying is a widely used unit operation in the chemical industry. It is highly energy intensive, requiring hot, dry airstreams, at temperatures up to 550°C, to dry a wide range of products. Exhaust air from a dryer is usually vented to the atmosphere with little or no heat recovery. At best only the sensible heat associated with the air stream is recovered, although the majority of the streams energy is in the form of latent heat associated with the evaporated water. Exhaust airstreams usually contain moisture to cause visible plumes upon leaving the dryer stack. A two-stage absorption heat transformer (A.H.T.) has been designed and contructed to investigate the potential for dehumidifying and reheating a simulated dryer exhaust stream to make it suitable for recycling to the dryer inlet. The amount of air vented to atmosphere and also the amount of wasted heat would be reduced by incorporating an A.H.T. into the drying operation. Performance data for the A.H.T. indicates that an airstream can be reheated to a temperature of 160°C, using a lithium bromide solution of 68% w/w, with a circulation ratio (LiBr: steam flow) of 14.8. Temperature lifts between 50 and 70°C are possible in the reheat column when using a low circulation ratio and a high LiBr concentration. Experiments show that a humid air stream can be dehumidified to a level suitable for recycling by direct contact with a concentrated lithium bromide stream.

Wave powered desalination

Abstract This paper presents a novel form of vapour compression desalination unit driven directly by ocean waves. The process is described in two sections; that pertaining to distillation and that to feed preheating. Ideas for utilising wave energy in a secondary heat pump cycle for feed preheating are presented. Design methodology is discussed and the programme of research is described. Some early indications of the economics of the proposed system are given.

Absorption-dehumidification: a unit operation for heat recovery from dryers

Drying operations account for 10% of primary energy consumption of the main industrial sectors in Europe. Energy recovery is uncommon, and most drying processes discharge hot, humid air to atmosphere. The purpose of this work was to develop an absorption heat transformer (A.H.T.) to simultaneously dehumidify and reheat dryer exhaust streams for recycle to the drying process.

Wavepowered desalination: Experimental and mathematical modelling

Abstract This paper describes the development of, and results obtained from, experimental and mathematical models of a novel vapour compression desalination system which utilises the power of ocean waves directly. The results demonstrate the feasibility of this concept and provide preliminary data on which to base a full-scale design. Indications at this stage are that fresh water produced at the 1000 tonne/day scale in favourable wave climates would be substantially cheaper than that obtained from conventional fossil-fuelled plant.

Squaring the circle: Sequestration of CO2 as liquid fuel

Publisher Summary This chapter presents the case for using CO2 as a feedstock to fix electrolytic hydrogen. Advantages include the avoidance of small scale reforming and associated un-recovered CO2 emissions for the production of hydrogen; the possibility for a large penetration of renewable generators of variable output into the electricity grid; and the production of clean fuel utilizing CO2 emissions. A preliminary analysis based on integrated heat balances indicates that the methanol-to-gasoline process uses less energy than the production of methanol or ethanol fuel. The Methanol to gasoline (MTG) process seemed to need no net heat input, due to its integration with the methanol process, and reduced distillation loads. In all cases, the extraction of CO2 using amine technology was not considered and would require 10.95 kWh/kmol (CO2+ H2) feed. Future work will look at the integration of this scheme with a fossil-fuel power technology requiring the less energy for CO2 extraction, in particular the chemical looping process.

The performance of novel compact heat exchangers with highly extended surfaces

Abstract The performance of highly extended surface heat exchangers has been evaluated in two heat pump applications: as the evaporator in a compression heat pump and as the absorber in an absorption heat transformer. Film heat transfer coefficients based on the equivalent plain tube area (p.t.a.), ranged from 200 W m−2 K−1, for gas-liquid contact, to 3800 Wm−2 K−1, in the evaporation of a liquid stream. Another measure of the heat transfer characteristics of the exchangers were the ‘UAo’ values, which were significantly better than the theoretical values calculated for each operation. The experimental results ranged from 12 W K−1 (gas) to 214 W K−1 (evaporation), while the theoretical values were 1 W K−1 (gas) and 43 K−1 (evaporation).

A Self-Regulating Heat Pump to Utilize Wind and Wave Energy Sources

Abstract Wind and wave energy devices produce their output in the form of shaft work, with a power output which varies over a wide range as the input energy intensity changes. For many processes (desalination, thermochemical processes, steam raising, space heating) energy is required in the form of heat. The conversion of shaft work directly to heat is thermodynamically very inefficient. This efficiency may be greatly improved by using the shaft work to drive a heat pump which abstracts thermal energy from the environment (the sea or airstream) and upgrades it to the requisite temperature level. In this regard, wind and wave energy are ideal sources, since the thermal energy contained in the airstream or sea exceeds by several orders of magnitude the mechanical energy that can be abstracted. Heat pumps have hitherto been designed to utilize a constant work input and a source of heat at variable temperature. But in order to harness renewable energy effectively, a heat pump is required that will utilize var...

Chasing the dragon's tail; Life cycle carbon analysis applied to CO2 sequestration

Publisher Summary This chapter investigates the use of various tools for comparing the effectiveness of different methods for reducing emissions of greenhouse gases. Of these, the technique of Life Cycle Carbon Analysis (LCCA) is developed as an effective tool for the comparison of options for the reduction of greenhouse gas emissions, for the introduction of energy-efficient processes, and for the utilization of renewables in power generation or liquid fuel production. Comparisons may be made in terms of carbon payback time per ton of carbon invested, or in terms of the lifetime cost per ton of CO2 foregone or sequestered. Examples are given of coal-fired power generation with CO2 removal and sequestration, domestic energy-saving equipment and small-scale renewable energy installations. These enable some generic conclusions to be drawn about the current state of technologies for greenhouse gas reduction/sequestration, and also lead to target costings per ton of CO2 equivalent avoided. These costings indicate that, with current technology, investments in the containment of HFCs, in CH4 leakage reduction, and in straightforward measures for energy efficiency and energy conservation, are all far more cost-effective than CO2 capture technologies. In particular, cost-effective and carbon-effective reductions in emissions of non-C02 green house gases are far more readily achievable than CO2 reduction measures, both economically and in engineering terms. LCCA demonstrates that policies that address the impact of these releases show the most immediate and tangible benefits.