Venture capitalists increased investments in alternative energy by 73 percent over the past three months, according to a report issued Wednesday, an indication that the horrible market conditions from earlier this year may have abated. Investors are also be growing more confident because the government is making good on promises to try to shift the national energy policy more toward wind, solar and other renewable technologies. Venture capital investment totaled $572 million in the second quarter, according to Ernst & Young LLP.