The Benefits of Sharing—Nice Guys and Girls do Finish First - Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs - page 27

FIGURE 2.7 Details of industrial symbiosis between glass manufacturing and a greenhouse
complex showing system structure and energy flows.
If properly treated, the carbon dioxide (CO 2 ) can be useful to the greenhouse complex.
Modern greenhouse operations utilize CO 2 enrichment in order to increase crop yields. Par-
ticularly in a tightly sealed greenhouse being heated in the winter time, CO 2 enrichment is
required at the minimum to maintain the atmospheric concentration of CO 2 at ambient levels
(around 380 ppm) to account for plant photosynthesis [ 35 ] . Utilizing extremely conservative
estimates, it has been found that a flat glass plant could support about a 4 acre greenhouse
complex in Canada, where 700 ton of tomatoes can be grown each year and offset from 1000 to
2000 ton of CO 2 annually. Additionally it has been shown that over a 20 year campaign with
a 10% MARR, the waste heat system is significantly less expensive to operate than a purely
natural gas system. Finally, the addition of a waste heat greenhouse can reduce the costs of
emissions compliance for a company, as the deferred costs of liquid CO 2 can fund millions of
dollars of emissions reductions retrofits [ 32 ] . The botom line of this analysis is that the waste
heat system is significantly more economical to operate than a purely natural gas system from
the greenhouse perspective. These economic gains can be transferred to the glass factory as
these by-products (heat and CO 2 ) can be sold for a profit, which thus can enable further re-
duction in glass costs, which in turn provide the potential to reduce the costs of PV modules.
These savings can provide a significant competitive advantage over PV manufacturers, which
do not look beyond their own gates for synergies.