(MONEY Magazine) – Buy a TV, save a tree. That might well be the new motto of the Sierra Club, which is hoping its 370,000 environmentally minded members will sign up for its new Visa card, introduced in July in collaboration with Chase Lincoln First Bank of Rochester, N.Y. Sierra Club members (dues: $29 a year) pay no annual fee for the card, though they will face the usual 18% annual interest rate on unpaid balances. Every time the card is used, the San Francisco-based organization rings up a donation of one-half of 1% of the amount purchased -- or $1.50 on a $300 color TV. Club officials, who saw the plan as a way to raise funds, figure that perhaps 5% of the membership will eventually sign up for the card. ''If each one spends $2,000 a year,'' says the club's Leonard Levitt, ''we would get $10 per subscriber.'' Chase Lincoln Bank had similar money-raising motivations for going along with the venture. Says bank senior vice president Gary Radford: ''We saw it as a way to acquire more cardholders who may respond to the affinity with the Sierra Club.'' Or who want to cleanse their consciences the next time they maul the mall. For more information, call the Sierra Club (415-776-2211).