制造化工产品十分耗费能源。因此，陶氏化学公司（Dow Chemical）能通过提高能效节约很多钱，这件事本身并不让人意外。真正让人吃惊的是他们所节约的能源和现金之巨。

    陶氏化学表示，绿色投资1994年以来已为其节约能源达1.8 千万亿英热单位——足以为美国加州所有家庭供电20个月。是的，公司为此付出成本近20亿美元。但由此节省的能源成本超过了90亿美元，创造净利润逾70亿美元。

    虽然没有一份美国企业界的最赚钱绿色投资名单，但显然陶氏化学凭借其巨额现金节约和投资回报应位列第一或非常接近第一。

    陶氏化学的可持续发展副总裁尼尔•霍金斯表示，关键是要首先清晰地认识到如何衡量环境的改善，然后“从经济角度认识到”这些对公司财务业绩的影响。陶氏化学每个季度都会公布 一系列广泛的环境措施。[在 一项相关的努力 中，陶氏化学耗资1,000万美元同大自然保护协会（The Nature Conservancy）合作，计算每项业务决策的生态系统成本和效益。]

    陶氏化学最初于上世纪90年代中期推出了一项提高能效的十年计划，目前正在推动第二个十年计划。“这些目标的设立以及我们基于此取得的成就，确实改变了陶氏化学的文化，”霍金斯本周在《财富》杂志（Fortune）举办的头脑风暴绿色会议（Brainstorm Green）上表示。

    不少能效改善是源于新的生产工艺，比如很多塑料的主要成分——环氧丙烷的新生产工艺。由于找到将过氧化氢转化为环氧丙烷的新方法，陶氏化学将耗能量减少了35%。[这种方法还减少废水排放量达70%以上，荣获了美国环境保护局（Environmental Protection Agency）颁发的绿化工挑战奖（Green Chemistry Challenge）。]

    霍金斯表示，还将有更多的此类节省效应。陶氏化学计划再投资1亿美元用于节能，并预计会获得类似的投资回报。

    Making chemicals takes energy -- a lot of it -- so the mere fact that Dow Chemical (DOW) can save a lot of money by improving their energy efficiency is not what's surprising. It's just how much energy and cash they've saved that's jaw-dropping.

    Dow Chemical says its green investments have saved 1.8 quadrillion British Thermal Units of energy since 1994 -- enough to power every home in California for 20 months. Yes, those savings cost money to achieve, nearly $2 billion. But they have so far generated over $9 billion in reduced energy costs, for a net profit topping $7 billion.

    While there's no definitive list of the most profitable green investments in corporate America, its clear that Dow's huge cash savings and return on investment place it at or near the very top.

    The key, says Neil Hawkins, Dow's vice president of sustainability, was first having a clear understanding of how to measure environmental improvements and then "building an economic understanding" of their effect on the company's financial results. Dow reports a wide array of environmental measures every quarter. (In a related effort, Dow is spending $10 million in collaboration with The Nature Conservancy to tally up the ecosystem costs and benefits of every business decision.)

    Dow first launched a 10 year plan to improve energy efficiency in the mid 1990s, and is now mid-way through a second decade-long effort. "Those sets of goals and the progress we made against them really changed the culture of Dow," says Hawkins, who discussed Dow's effort at Fortune's Brainstorm Green conference this week.

    Much of the efficiency gains have come from new ways of making chemicals such as propylene oxide, a key ingredient in many plastics. By finding a way to turn hydrogen peroxide into propylene oxide, the company cut the energy use by 35%. (It also cut waste water by over 70% and won the Environmental Protection Agency's, Green Chemistry Challenge.)

    There's more such savings to come, Hawkins says. Dow plans to put another $100 million in cutting energy use even further, and expects similar returns.