Cows emit a massive amount of methane through belching, with a lesser amount through flatulence. Statistics vary regarding how much methane the average dairy cow expels. Some experts say 100 liters to 200 liters a day (or about 26 gallons to about 53 gallons), while others say it's up to 500 liters (about 132 gallons) a day.
1 According to author Stu Silverman the average cost of adding a garage begins at roughly $7,500, and for a two-car garage the average costs will go much higher.2  This sort of structure will average at $27,040. 3  The resale value of this update would hold at $21,635, or a nearly 81% return on investment.or the garage addition, the typical costs include: 1  According to author Stu Silverman the average cost of adding a garage begins at roughly $7,500, and for a two-car garage the average costs will go much higher. 2  The above figures place the garage addition at $40 per square foo t.
1 Building a garage typically costs about $35-$45 a square foot, or $8,400-$10,800 for a standard single-car garage and $13,300-$17,100 for a two-car garage.2  A custom outdoor greenhouse with a solid foundation, heating and electricity starts at $10,000-$20,000 for a small structure, but can cost $25,000-$50,000 or more. A bedroom addition consisting of 500 square feet of new floor space with two bedrooms and a bathroom can cost $50-$250 or more a square foot, or $25,000-$125,000.