20. COMMITMENTS AND CONTINGENCIES Commitments   We lease buildings and equipment under operating lease agreements that provide for the payment of both minimum and contingent rentals. We also have a noncancelable lease with SGP (Note 19) and a noncancelable lease for equipment under a capital lease obligation. Future minimum lease payments are as follows (in thousands): Other Operating Leases Year Ending December 31, Capital Lease Affiliate Others Total 2011 $ 346 $ 456 $ 1,445 $ 1,901 2012 141   763 763 2013 84   367 367 2014 13   367 367 2015     367 367 Thereafter     1,010 1,010 Total future minimum lease payments $ 584 $ 456 $ 4,319 $ 4,775 Less: amount representing interest (124 ) Present value of future minimum lease payments 460 Less: current portion (295 ) Long-term capital lease obligation $ 165 Rental expense (including rental expense incurred under operating lease agreements) was $7.2 million, $6.0 million and $5.6 million for the years ended December 31, 2010, 2009 and 2008, respectively. Our subsidiary, Mettiki (WV), entered into a capital lease agreement with Joy Technologies Inc., d/b/a Joy Mining Machinery, a Delaware corporation, on May 22, 2006, with an in-service date of November 20, 2006. The lease is a 5-year noncancelable lease with monthly rental payments of $42,930 and has one renewal period for 2 years with monthly rental payments of $24,680. The effective interest rate on the capital lease is 6.195%. Contractual Commitments   In connection with planned capital projects, we have contractual commitments of approximately $86.8 million at December 31, 2010. As of December 31, 2010, we had commitments to purchase, from external production sources, coal at an estimated cost up to $14.1 million in 2011. General Litigation   Various lawsuits, claims and regulatory proceedings incidental to our business are pending against the ARLP Partnership. We record an accrual for a potential loss related to these matters when, in management's opinion, such loss is probable and reasonably estimable. Based on