def generate_alchemy_graph(alchemy_uri, prefixes=None, identifier="NautilusSparql"):
    """ Generate a graph and change the global graph to this one

    :param alchemy_uri: A Uri for the graph
    :param prefixes: A dictionary of prefixes and namespaces to bind to the graph
    :param identifier: An identifier that will identify the Graph root
    """
    registerplugins()
    ident = URIRef(identifier)
    uri = Literal(alchemy_uri)
    store = plugin.get("SQLAlchemy", Store)(identifier=ident)
    graph = Graph(store, identifier=ident)
    graph.open(uri, create=True)

    for prefix, ns in (prefixes or GRAPH_BINDINGS).items():
        if prefix == "":
            prefix = "cts"  # Fix until ALchemy Store accepts empty prefixes
        graph.bind(prefix, ns)

    return graph, identifier, uri