Even with conventional generating plants, there has been some experience in the United Kingdom with schemes to use reject heat for greenhouse production of vegetables or for fish farming. The size of the reject heat stream, given the low conversion factors of the stations involved, is such that the entire national demand for greenhouse heating would be met by the output of just one of the United Kingdom's 2,000 megawatt power stations (Coleman, 1993). If the overall amount of reject heat from electricity generation declines as a result of applying industrial ecology, a better match between availability and demand may result.
There will probably continue to be local opportunities for such conversion of reject heat into consumables, but it is likely to remain a minor feature of industrial ecological integration.
A major barrier to the more widespread application of the proven technologies of small-scale, gas-fired CHP is the capital cost. Overcoming this barrier has led to the development of new relationships between equipment suppliers and energy uses. There are many variants, but often the supplier of the hardware also provides the financing, whereas the user pays over a period of time from the energy cost savings achieved. Such new energy-service companies are engineering organizations rather than finance houses. They may design, supply, erect, and operate the plant. They may purchase the fuel or the user may do so. Either may sell any surplus electricity. The contractual arrangements between the energy service company and the energy user can be as sophisticated as the parties choose. To encourage energy savings, there can be provisions to share future gains.
At several points in this paper, barriers have been identified—some of them formidable—that prevent better performance. Innovation is rarely easy, and the widespread introduction of industrial-ecology-based innovations into industrial and commercial life is, by any standards, a major innovative process. It is useful to review the key constraints affecting energy use and production and to explore how these barriers can be overcome.
Low energy prices do not encourage productive energy use; subsidies need to be removed. In manufacturing, energy is usually a small proportion of total costs. Energy costs, therefore, receive relatively little attention from the financial managers of companies. A perception that energy prices will rise would be a valuable nudge to businesses to give energy productivity more attention.