Declan Allison, from Friends of the Earth (FOE), warned there could be health implications for Tyrone people and the local farming industry.
Rose Energy is currently holding preliminary planning meetings for a chicken litter incinerator at Glenavy, County Antrim.
Residents are opposing the plans on the grounds that the company has not provided reassurances to protect the local landscape and communities from harm.
Mr Allison, a FOE campaigner, said: "Contrary to popular belief, incineration does not destroy waste. It merely converts it to ash which still needs to be landfilled. The ash from this proposed chicken litter incinerator will contain hazardous waste which will need to be disposed of in a fully licensed hazardous waste landfill site.
"No such site exists in Northern Ireland so the ash will have to be exported – probably to Scotland or England.
"Rose Energy should come clean and say where they intend to dispose of this ash."
On Tuesday representatives from Communities Against Lough Neagh Incinerator met with Rose Energy bosses.
Chair of the group, Ray Clarke said: "This proposal is being heralded as the solution to the poultry industry's problems, but we know too well in Northern Ireland that quick fixes never last. The Assembly should be working to find a solution that makes the most of modern, 'green' technologies."
Mr Clarke said the lack of assurances given to them during the meeting fuelled their concerns.
"We are extremely disappointed that this industrial size incinerator could go ahead with the support of our local Assembly without widespread consultation.
"Surely alternatives need to be considered before taxpayers' money is handed over to build it."
Following the meeting a spokesperson for Rose Energy said: "Since we announced our intentions in early January, we have met with various groups and individuals – including local residents on a number of occasions.
"We were pleased to meet with a representative group of residents from the Glenavy area and introduced them to three of our key consultants who are compiling an Environmental Impact Assessment which will form a crucial element of our planning application.
"These experts provided the group with our most recent project information and research findings on anticipated emission levels, local infrastructure assessment and health impact."