EXHIBIT 11 ENVIRONMENTAL POWER CORPORATION COMPUTATION OF EARNINGS PER SHARE SEPTEMBER 30, 1998 INCOME SHARES PER SHARE (NUMERATOR) (DENOMINATOR) AMOUNTS ------------------ -------------------- --------------- THREE MONTHS ENDED SEPTEMBER 30, 1998: - -------------------------------------- Income available to shareholders $ 437,182 11,406,783 $.04 Effect of dividends to preferred stockholders (1,250) ------------------ -------------------- --------------- Basic EPS - income available to common shareholders 435,932 11,406,783 .04 Effect of dilutive securities: Assumed exercise of dilutive stock options 22,597 ------------------ -------------------- --------------- Diluted EPS - income available to common shareholders $ 435,932 11,429,380 $.04 ================== ==================== =============== THREE MONTHS ENDED SEPTEMBER 30, 1997: - -------------------------------------- Income available to shareholders $1,102,918 11,097,870 $.10 Effect of dividends to preferred stockholders (1,250) ------------------ -------------------- --------------- Basic EPS - income available to common shareholders 1,101,668 11,097,870 .10 Effect of dilutive securities: Assumed exercise of dilutive stock options 147,365 ------------------ -------------------- --------------- Diluted EPS - income available to common shareholders $1,101,668 11,245,235 $.10 ================== ==================== =============== INCOME (LOSS) SHARES PER SHARE (NUMERATOR) (DENOMINATOR) AMOUNTS ------------------- -------------------- --------------- NINE MONTHS ENDED SEPTEMBER 30, 1998: - ------------------------------------- Income available to shareholders $ 54,054 11,406,783 $ --- Effect of dividends to preferred stockholders (3,750) ------------------- -------------------- --------------- Basic EPS - income available to common shareholders 50,304 11,406,783 --- Effect of dilutive securities: Assumed exercise of dilutive stock options 22,595 ------------------- -------------------- --------------- Diluted EPS - income available to common shareholders $ 50,304 11,429,378 $ --- =================== ==================== =============== NINE MONTHS ENDED SEPTEMBER 30, 1997: - ------------------------------------- Loss available to shareholders $(286,888) 11,083,889 $(.03) Effect of dividends to preferred stockholders (28,928) ------------------- -------------------- --------------- Basic EPS - loss available to common shareholders (315,816) 11,083,889 (.03) Effect of dilutive securities: Assumed exercise of dilutive stock options 134,137 ------------------- -------------------- --------------- Diluted EPS - loss available to common shareholders $(315,816) 11,218,026 $(.03) =================== ==================== ===============