[cmutel]

In our research, we see that the easy alternatives are being used almost to capacity already, making future improvement difficult. For example, there is basically no unused fly ash in Europe, and it is sometimes imported from as far away as India. Similarly, burning wastes for "free" heat is also limited by the availability of waste (residues from chemicals industry, tires, etc). This is particularly true in areas where waste incineration is the norm - plants built to service a certain volume of waste are struggling as wastes volumes decline due to diversion to recycling. Consumer waste has a rather high water content, so wastes with high energetic content help the incineration run better. This is why e.g. paper or plastic is sometimes burned instead of being recycled.

[the8472]

What about silicate based cements that are supposed to be carbon-negative (they were in the news a few years ago)? Those come from mined minerals and thus not limited by available waste products.

Would carbon taxes help evening cost differences?