06-04-2012 05:42 PM
I have read a few of the case studies for the use of CAT natgas engines in CHP applications for greenhouses, where the engine provides both power and heat, and that the plants can be fertilized with the CO2 in the exhaust.
In these applications I understand the emissions from the engine must be very low, often requiring oxidation catalysts and/or some SCR for significant NOx and HC reduction. Yet I have not found any reference to what the emissions must be (evidently ethylene levels that are too high can harm the plants).
Does anyone have any experience with this and can provide some insight to the required emissions for greenhouse applications?
06-07-2012 01:45 PM
You are correct. Most of the greenhouses use CO2 fertilizing from the gas gensets exhausts gases and a full CHP system to cool them down and recover the heat in the process.
Typically an SCR with urea injection is required. This does not necessarily means that the engine emissions have to be low, since the SCR will do most of the job to efficiently remove the emission. This allows setting the engine at optimal efficiency.
Ethylene is lethal to plants even in very small quantities.
Output levels will depend on crop type and local regulations.
Typical maximum outlet concentrations behind CO2 Catalyst systems are
NOx (average) 10-15 ppm
Nox maximum 30 ppm
Ethylene C2H4 < 450ppb
Ammonia, NH3 < 5mg/Nm3
Carbon monoxide, CO < 10ppm
In addition we are experiencing insurance company requirements on the top of the above Sine Jan-2007 inHollandfor instance, the max NO value required by the insurance companies decreased from 30- to 20 ppm.
Since the last 3-4 years, especially the most sensitive crops like, peppers, we initiate alarm at max. <300ppb ethylene.
In that case we increase the amount of Oxi materials inside the reactor.
More information on genset in greenhouse application on http://www.catelectricpowerinfo.com/gas/greenhouse
08-12-2012 06:00 AM
We bypass the obvious problem of using fossil fuels in a greenhouse by using ultra-clean, biomass-derived syngas.
The greenhouse waste (plant matter, organic waste, chemicals) are gasified on-site to produce the power, heat and the CO2 for the next crops.
Syngas generators have hardly any adverse emissions, certainly at least 500% below the CO OSHA workplace standard of 50 ppm.
Our patented PARS scrubber ensures that the syngas fuel is pure CO/H2/N2 mixture, with no hydrocarbons present.
We hope that this will become a model solution for greenhouses wordwide.